Hitec D645MW vs DS180DLHV

A servo matchUP (comparison article) comes about from time to time in response to a question regarding a specific servo. This time after someone wrote asking . . .

I’ve been using Hitec D645MW servos for years but a buddy said I should look at ProModeler, so what have you got to compare, and what recommends them?

I responded with . . . The Hitec D645MW is a very fine HV servo (it upgrades the now discontinued HS-5685MH). I know it’s a fine product for the simple reason I’ve flown both of them, and the HS-5645MG (its 6V-predecessor), for a considerable number of years. And all three are built very similarly.

As an aside, my experience with Hitec servos goes all the way back to the days of analog servos, thus predating all of these. Talking about the popular HS-645MG, as well as less powerful models like HS-625MG and HS-422, which have been used in my models, also.

Point being, I totally understand why folks automatically turn to Hitec for quality products because I’ve used them myself in my own models over the course of many years. Also means I tend to hold Hitec servos in high regard due to my generally good experience, and this is just God’s honest truth.

So this leaves me conflicted because I know the D645MW is a pretty decent servo – but – at the same time, in knowing what I do about servos, it also means I can readily point out lots of places where a reasonable guy concludes ours have significantly more substance.

So I shared a few photos with the guy and moved on. Two days later, more questions, which led to more photos. Next thing you know, I had enough material for a full-blown matchUP article, so here we are.

Anyway, Hitec are king in the hobby market for good reason, not because they’re 10′ tall or jump in their pants with both legs at once. Saying if you give us a few minutes, I’m thinking I can also show you why considering our servos for your next model makes good sense.

So because we don’t hide from tough questions like his, if we don’t already have an example servo on hand, we buy one. Then we take it apart and with side-by-side photos, show you what’s what. This, so you can suss out which side of the bread is buttered for yourself.

Heads up; this matchUP runs long, like really long. Several dozen photos plus explanations of what to look for. After all, these are expensive servos and you deserve our best effort.

Major point being, if you don’t have time to dive deep, then dipping a toe by skipping through (maybe just reading photo-captions) could be a reasonable work/life balance. Depends.

Intro: the contenders

These are the two servos in question. They’re both what are called standard class servos (about a 40x20mm footprint). What’s more, they both output about the same torque, transit in about the exact same time, and are both more than a little pricey at $40 a pop.

But which is better for you? Let’s see if we can help you figure it out.

So the focus of this matchUP is on how our DS180DLHV servo compares to the Hitec D645MW. But not in terms of torque and speed because at – 180oz-in @ 0.17sec/60° – they basically offer the same performance.

Instead, we’ll focus on which delivers the most bang for the buck. Or put another way, what’s in it for you? We’ll use photos so you may compare and contrast using Eyeballs, Mark II to figure it out because unless you’re terminally stupid, an engineering degree isn’t needed to grok the actual real world benefits based on what you’ll see.

And photos are always good because you probably prefer deciding these things for yourself vs being told what to buy. Rookies ask on forums and Facebook instead of digging in and doing the research.

Note: the above links to servos, in common with links throughout the site, open within their own tab so you don't lose your place within an article.

To begin, these days, before a servo comes into existence, it’s only pixels in a computer. The DS180DLHV was no exception and to be honest, we expressly took aim at Hitec when designing it. This is why the specs are the same. Wondering why would we do this?

Simple, it’s because Hitec is the absolute king at virtually every flying field in the country. And because 180oz-in @ 0.17sec/60° is good enough for like 90% of the model airplanes made (with the other 10% being folks who buy our $100-300 servos), I’m saying the sweet spot is addressed perfectly by their servo . . . and now ours, also!

So to be clear, both are at the same level of performance because, first, it’s good business to address customers where they are. And second, because knocking off 2nd best isn’t how the game is played in America. This is why we’re going after the king with this servo.

So with Hitec established in the market as the king, this put me in mind of the famous Ralph Waldo Emerson quote (responding to future Supreme Court justice, Oliver Wendell Holmes) when he said;

'When you strike at a king, you must kill him.'

. . . so we drew a bead on the top ‘dawg and their finest servo! But remember, we have to deliver a kill shot, else what’s the point?

Question is, do we? Well, that’s on you to decide, isn’t it?

Background

In the old days, design happened with a pencil and calculator at a drafting table (we still have two because I’m loath to get rid of them).

These days? It’s a computer workstation with CAD software, instead.

What’s more, when designing servos, each and every component parts is drawn up, fitted into the whole, and it happens by hand. So whether done with a computer or pencil the creation process is pretty much unchanged!

Circling back, our remit was both simple and straightforward. Improve on Hitec’s servo, and bring it to market for the same price.

David vs Goliath

So the improved part isn’t hard at all because we’re full of ideas. But the at the same price part is where things get a bit tricky.

Making things harder on us in the role of David is because Goliath (literally, they’re huge) have a significant advantage. They get better prices because they buy more in a week than we do in a year. It’s why they’re the 800lb gorilla (if I may mix my metaphors). So earning your business means working not just harder, but smarter!

We began with a wish list.

The list

Due to experience, I felt Hitec had a few weaknesses we could take advantage of. A minor one being a long reliance on a low cost hybrid combo gear (hybrid in the sense it uses plastic and steel, both).

They name this plastic Karbonite, and it’s their part number 55016. And amazingly, they refer to the D645MW product within marketing materials as Metal Gear Servo. Confuses me, but not my lookout.

So I knew there was a plastic gear inside from when I still flew Hitec servos because occasionally, I’d break one. And that they offer these in 3-packs says something important if you’re paying attention.

Point being, all metal gears are an obvious area of improvement. And if you agree, we’re already getting your attention.

Note; servo transmissions use gears to multiply the torque of a weak motor to deliver strong output. The motor is equipped with one tiny gear called a pinion. And the output shaft spline gear is also solo, but it's a large bull gear. All the others are combo gears comprising both bull and pinion. They're numbered in the direction of torque multiplication, so the pinion gear on the motor is gear 1. This drives the bull of the #2/3 combo gear. It's pinion, the #3 drives the bull of the #4/5 combo gear. Which in turns drives the #6/7 combo gear, which drives the final output, the #8 gear (the one with splines). Learn more: On servo gear trains

Next, I love to fly warbirds equipped with large gassers (sometimes referred to as paint shakers). These are rough on airframes so I had considerable experience with another perceived shortcoming; unacceptable case wear.

Basically, engine vibration shakes the crap out of ailerons and elevators. This feeds back into the gear train through the linkages. The consequences first show up as case wear at the gear shaft pockets.

Then once gear shafts aren’t in their proper position, gear wear accelerates. This, because gear mesh goes to Hell with the loss of precision (because the shaft itself is shifting at its base a little bit).

It also shows up at the output shaft itself because the ball bearing (being metal) stretches the plastic opening. This manifests as slop also but now because the entire splined shaft is shifting.

The fix is easy.

First, reinforce the plastic case with bronze bushings where the gear shafts are fitted. So along with all-metal gears, bushings made the list. But another area of concern is case wear at the output shaft.

Being plastic, the bearing supporting the splined shaft elongates the opening. This is another easy fix because adding two more bolts at the bearing boxes it in neatly and stiffens the assembly considerably (and thus, it now uses 6-bolts vs 4-bolts). Reducing flex is better!

And in a similar vein, in an attempt to further reduce flex, because the steel bearing rides in plastic and beats the bearing opening to death, we reinforced here with more material (output shaft opening). Once this starts wearing the damage at the #2 gearshaft pocket is unavoidable.

This last led us to pony up for a new mold as part of updating the servo case a few years back. Basically, a few grams of plastic did a world of good in terms of reinforcing the opening. More later.

Next, I still remember selling a model whilst flying it (and for an astonishing sum). So I quickly landed to consummate the deal (before I crashed, or he came to his senses). And since servos weren’t part of the deal, immediately set about removing them.

Took all of 5-min, but I recall being astonished they were still warm. Turns out this is normal, but I figured if we substitute for the plastic case one made of aluminum and milled cooling fins in, then the case would now act as a heat sink.

After all, servos are expensive so shedding excess heat prolongs service life (because heat is bad for electronics). Aluminum vs plastic makes for a better servo. We do this for 100% of ProModeler servos!

Next, I still remember a pop up rain shower, which out of the blue caught me by surprise (seriously, scattered clouds, sun was shining). While I landed quickly, I was totally soaked. Model was also.

And servos mounted on the side of the fuselage (short linkages to the stabs) led me to open one as a precaution (you know, just to look). I was shocked at finding water, so o-rings made the list, also.

Add to it, my Uncle got involved and insisted on servos meeting certain MIL-STD if I wanted his business. While there was no horse head in the sheets, I definitely wanted to cooperate – catch my drift?

Recapping;

• All metal gears
• Bronze bushing
• Boxed bearings
• Beefy shaft opening
• Heat sink case
• Seals and o-rings
• MIL-STDS.

So let’s poke around these issues to see how we addressed them. And note; while making an immediate improvement through the use of all-metal gears is easy, this is not enough. Frankly, they would suffer accelerated wear and failure if not properly supported because the root problem is vibration.

And interestingly enough, while we first think of gassers, as it turns out turbines – thought by most as perfectly smooth – actually aren’t. So although the data proving it came with a NDA (meaning we can’t share), you can generate your own. Saying you can prove it for yourself with a free phone app and gaffer tape. Curious? We share details below on how.

So first up, how we dealt with vibration!

Vibration, part 1

What happens, and mostly because engines shake the crap out of the model’s structure (and everything attached, e.g. servos), the perfectly round bores within the plastic (where gear shafts fit), begins to wear into an oval shape. Vibration is destructive as Hell.

Shake things hard enough and long enough and things wear and/or break. End result? Gear mesh goes to Hell and there’s backlash.

Pocket wear – experiment

To demonstrate how it happens in the real world, we used my Top Flight F4U Corsair (powered by a DA85) as a test bed. Flown for a season with DS180DLHV on ailerons of one side and D645MW on the other, we recorded 80 flights before a bad landing put paid to further testing.

The basic idea was instead of simulating use, we wanted to see how pocket wear happens due to actual use . . . gathering real world data. So the only practical way to achieve this is through actual flying, and not by accelerated wear testing (which can also be performed in the test facility).

The obvious purpose being to see how plastic case servos, mounted within a model powered by a DA-85 (in it’s own class as paint shakers go), would fare throughout a season of flying.

It went about as expected.

Pocket wear – background

Both servos were disassembled following 10 flights, cleaned, inspected, relubed, and reinstalled. ProModeler recommended service intervals are clean-and-relube the gear train at 10 hours, and every 50 hours, subsequently.

So for this purpose, we cleaned and lubed the gear train a ‘lot’ more frequently – even someone who babies their servos likely wouldn’t do this so often. Interestingly, wear at the pockets was not really discernible in the D645MW until the 50 flight inspection.

Then after this, it got progressively a little bit worse each time. E.g. at 60 flights it was a bit worse than at 50, and after 70 flights, a little worse than at 60. After all, unlike our bodies, these things don’t heal themselves!

Unfortunately, the experiment ended on flight #80 as a botched landing resulted in my ripping out both Robart main gear units. Model suffered typical wing damage and has been repaired. Still chasing down parts to repair the gear (and considering a switch to Sierra).

Pocket wear – results

Disassembly at 80 flights showed what we expected, a little further deterioration. The wear in the #2 gearshaft pocket within the upper case is obvious.

This can be seen as a subtle lean of the #2 gear shaft in the photo below, and in person, as a pronounced wiggle if you touch the tip of the shaft and rock it slightly. The shaft fitted to the bushing supported ProModeler upper shows nil pocket wear, or movement.

And while gearshaft pocket #3 has a small amount of wear, also, it’s not very bad, as expected since these pockets don’t seem to suffer much wear to speak of.

Pocket wear – maintenance

So how do you stay ahead of this? Simple, preventive maintenance.

While NOT a recommendation because it’s not our product, we suspect replacing Hitec plastic case components (about $10) and metal gear set (about $28) at 100 flights would be a good maintenance schedule. As for the Karbonite gears ($28 for a 3-pack) do these as needed.

With regard to the ProModeler case and gears, both remain perfectly serviceable after 80 flights. Case life is indefinite (unless a crash breaks it, at which point all bets are off).

With regard to gear replacement, we offer both the previous generation brass/steel gears ($25), and current generation stainless steel gears ($30) for the set. There are no plastic gears.

On what schedule? As needed – but at 80 flights – wear was not an issue. I wish I could tell you exactly but this will be a judgement call on your part (not just for ours but the Hitec, also). That said, I wouldn’t be surprised for you to attain hundreds of flights before wear became an issue with the ProModeler servo. Depends.

Pocket wear – disclosure

So in all honestly, it’s possible the crash played a role in the case damage – but – we judged the crash (really more of a shitty landing) as relatively minor (as these things go). Thus, leading us to suspect the root cause was entirely due to the engine vibration because we’d already been seeing and could feel things getting a bit sloppy.

So what we saw at 80 flights was consistent with the magnitude of change from 50-60, and similarly 60-70. Thus, the 70-80 interval looked about right despite the hard arrival.

Granted, this isn’t the best data in the world, but data is data, so make of it what you will because these things happen to models.

Pocket wear – lessons

Note; the way gear loading works with regard to case deformation is the bearing supported output shaft (considered gearshaft #1) takes the brunt of the loads. That’s why it gets a bearing.

The next set of gears, #6/7 along with #2/3 mounted at the bottom of gearshaft #2), are next to suffer abuse. Which with a good whack, the teeth of #7 (of the #6/7 combo) usually break any time the teeth of the #8 break).

Pocket wear – birdwalk

You can see this within this article regarding repair of a set of DS505 servos, which admittedly costs considerably more, but is nevertheless, instructive.

• On rebuilding damaged DS505s

Pocket wear – continuing

So the #6 of the #6/7 combo gears suffer the brunt of the load. The plastic #2 gear of the Hitec #2/3 combo also breaks readily (explaining why they’re offered in 3-packs).

Both sets of combo gears on the #2 gearshaft take a real pounding, which can be seen in the vast majority of pocket wear occurring at the #2 gear shaft pockets.

And the most lightly loaded are the #4/5 combo gears (alone on the #3 gearshaft). These generally survive unscathed no matter what (hence the greatly reduced wear as shown in the photo above).

Major point being, the once perfectly round shaft bores in the #2 pockets in the photo above have been pounded silly by the steel gearshaft itself due to the DA-85 vibration. Deformation occurs as the steel shaft easily forces the plastic to take an oval shape.

Meanwhile, the servo reinforced with bronze bushings, the ProModeler DS180DLHV still looks good as brand new.

Bottom line? Engine vibrations are bad juju on plastic case servos so reinforcing with a bronze bushing makes good sense. We’re not alone in making this judgment because even Hitec do it.

Pocket wear – Hitec alternatives

For example eyeball the HSB-9370TH case below in the composite image showing close detail of the bronze case reinforcements which just like ours, are done in both upper and intermediate case sections.

So Hitec extends the benefit of bronze bushing within polymer case sections to pricier servos. This HSB-9370TH ($190) has them, so a business decisions leads to popularly priced servos like D645MW not having them (or at least not at the time of this writing, summer-2024 . . . we’ll see if market pressure changes this).

Pocket wear – ProModeler alternatives

And heads up, at a 7950TH price point (ish), we’re even reinforcing all-aluminum cases, not just polymer ones – witness this powerful and incredibly quick DS635BLHV ($140) – 635oz-in @ 0.04sec/60°.

Point being, since all ProModeler servos have bushing-reinforcement, we all – even the proletariat if I channel Marx – benefit from better durability! And it’s true beginning at $30 servos like our DS90DLHV (and FYI, the DS90DLHV is built identically to the DS180DLHV). The DS90DLHV viewed as the best servo deal in America since it’s perfect for 40-60 models, or about 3/4 of engine-powered models!

Pocket wear – recommendations

Anyway, wear makes it hard for models to stay in trim and generally reduces the pleasure of a trip to the flying field. Fact. What do you do about it?

The usual solution is to buy a new gear set every couple of years depending on how good a pilot you are (e.g. how sensitive you are). But gears only addresses half the problem because effecting a real fix involves replacing not just the gears, but the case set, also. Remember, the case wearing first is what lets the gears begin to experience excessive wear. Can’t put the cart ahead of the horse.

Pocket wear – idle thoughts

Thing is, adding up the price for both gears and case makes it something of an open question whether you’ll want to spend that much money on an old set of servo(s).

And note; not directly related but important, my experience with the D645MW predecessors (HS-5685MH and HS-5645MG, and analog models HS-645MG and 625MG, also) is they have 24T-splines.

With the D645MW, we see Hitec upgrading to a 25T spline shaft. Since 25T is also what we use (Futaba originated it), an argument for sticking with Hitec to reuse expensive alloy servo arms is moot.

Point being, you’re going to need new servo arms whether you get the D645MW, or embrace ProModeler servos. Speaking of which, a further brief birdwalk into a discussion about servo arms is in order.

Servo arms

Once you buy servos, opening the package reveals the included arms only rarely are suitable for your project. And like Hitec, we offer accessory aluminum arms because it’s impossibly to predict need.

However, what recommends our alloy arms over everybody else is instead of 6061-T6, we use 7075-T6, instead. This stuff has a yield strength rivaling some mild steels. It’s seriously good stuff.

We feel our design is better, too. This photo is an example of a 32mm long arm fitted to a DS180DLHV. Note the H-beam cross section and enough meat that adding a locking nut to the bottom is pointless.

What’s more, we have these available in lengths ranging from a 15mm long arm suitable for SPA competition models, to 60mm long for the XA guys flying 40% models (double-sided tiller arms, also).

Also note, because it’s important, there’s a backlash compensating clamp screw, also. Means an M3 axial screw fixes the arm to the shaft, and radial clamp-screw ensures it’s a perfect fit to the splines!

So when don’t we use a radial clamp screw? With special arms for RC trucks and for pulleys. Pulleys?

Servo Pulleys

Yes, when you’re dealing with pull-pull sets up, e.g for rudders, or many WWI models using cables for all the flight control surfaces involve pulleys. They’re the solution mariners discovered centuries, if not millennia ago. So when it comes to cables for model use, we’d guide you toward pulleys instead of tiller arms. Here, eyeball this.

Note, from the servo the cables usually cross on their way to the ass end of the model (but not necessarily so, the pulley doesn’t care).

So at the rudder end, this is a fairly typical set up.

So what’s the purpose of tiller arms? Honestly? They’re about ganging servos together, not pull-pull cables. Think 40% models needing more than 1000oz-in at the rudder. Giants like this.

So it’s in ginormous models when you see two servos tied together using tillers (dual-sided servo horns). Something like this.

Point of all this being, just because you see someone doing something doesn’t mean it’s the right way of doing it. Sometimes if’s just expediency.

When I see someone using a double horn tiller for cables, I groan.

As for why I groan, it’s because it’s the wrong tool for the job. Prove it to yourself and input some rudder, then pluck the non-pulling cable. Instead of being taunt, it’ll be loose. With a pulley the excess cable is wrapped on the circumference and thus, the control stays tighter.

A pulley is the right tool for the job. We offer them in 34mm, 50mm, 80mm, and 100mm diameter. Poke around on the site within servo arms and you’ll find some interesting things.

So because we’re already birdwalking, let’s touch on the subject of splines because for Hitec to change from 30 years of using the 24T splines to 25T is kind of an Earth shaking event. Let’s see what we can suss out from this move.

Output shaft spline

So before continuing with vibration, let’s discuss the splined output shaft. This, because out of the blue, the D645MW updates a long standing 24T design and shifts to the competing 25T design we use.

As background, Hitec has long used a 24T output spline. We used 25T from the get go. Not because we copied Futaba but because we did the math and for a ø6mm shaft, we feel 25T is better.

So with new releases, Hitec shifting to a 25T spline like ours, is a big deal. So let’s delve a bit deeper into this and posit why this may be.

From directly overhead – they don’t really look all that different.

So next, let’s rotate the view and look at them from the end, instead and in this next photo, the HS-5645MG is on the left, the D645MW on the right.

Despite the spline shafts being the same diameter, a different color anodizing (7075-T6 aircraft aluminum, I suspect), means the 25T seems to stand a bit more proud of the case surface. Longer in other words.

Question is, is this an optical illusion because the anodizing is lighter colored on the D645MW splined shaft?

If the 25T spline is actually longer, then this mean it’s presents more surface area for the servo arm to grip. Basically, means the 25T is stronger than the 24T.

This may explain the shift because more powerful servos are beginning to expose the weakness of this shaft size.

So now let’s look at this another way, by matching them up head-to-head because this should quickly put to rest any doubts about our eyes deceiving us (without breaking out tools with which measure).

So in this extreme close up image, it’s obvious the Hitec D645MW 25T spline shaft on the left is longer than the 24T spline shaft of the HS-5456MG on the right. Longer means more metal to grab hold of so this is a stronger design.

And in their defense, Hitec has been making servos for quite a long time, from when servos didn’t output such ferocious quantities of torque. Saying nothing wrong with changing with the times so don’t take my observations as throwing my competitor under the bus!

So in presenting them head-to-head, it’s quite obvious the 25T spline shaft is significantly longer, by maybe 20%. That’s a lot.

This begs the question, how does the Hitec 25T length compare to that of the ProModeler DS180DLHV? And in full disclosure, Hitec isn’t the only outfit to update the spline shaft of a standard size servo, we have also – more later.

So head-to-head quickly shows us how both 25T spline shafts compare. And obviously, both are basically the same. Note the ProModeler’s significantly larger material ring surrounding the shaft.

So with the update, it seems Hitec is admitting a need for a stronger splined shaft by adopting the 25T standard (as 1st used by Futaba).

Standards are good. They help folks like us because you can buy servo arms to fit many different brands with just one purchase.

So I mentioned we too have made an update to standard class servo spline shafts. But not for ordinary servos. We did it for a few very expensive and quite extraordinary examples. Why?

Simple, they’re so strong and fast, that because we use steel for our output shafts, they can rip the splines out of an aluminum servo arm. Like you may as well hit it with a 1/4″ drill bit as the splines totally disappear. So what did we do about it? We upped our game!

ø6mm vs ø8mm

Since we’re already birdwalking, the next three photos are easily worth a thousand words. And it’s nothing to do with D645 vs DS180

Round 1

First up, the before and after of damage done by an über fast ProModeler DS635BLHV servo ($140) to an alloy horn’s splines. At 0.04sec/60° it transits so fast (and at more than 600oz-in of torque, hits so hard), it can readily annihilate the broached splines of an alloy servo horn made of 6061-T6 aircraft aluminum.

Basically, with this servo we created something never before seen in the world, and at the same time, also crated a whole new problem!

Silly thing is so fast and strong, the stainless steel 25T splines act like a 1/4″ drill bit. Incredibly, they may wipe out the broached splines within an arm made of 6061-T6. No good for flight.

An easy fix was substitute 7075-T6 for 6061-T6 b because the tensile strength of 7075 is about double that of 6061, and shear strength is 1.5X higher. End of problem, right?

Nope!

Round 2

So 7075-T6 servo horns puts paid to the problem of the 25T spline acting like a drill bit and destroying the splines . . . yes, but no! Cue up the next photo in the sequence. Or when ø6mm spline shaft meets 7075-T6, aka . . .

The paradox of the Immovable Object meeting the Irresistible Force!

End result? Something’s got to give! Now it’s the shaft that can’t handle the forces. Hmmm.

So we sat back, had a cold beer, and slipped on our thinking cap.

If harder material fixes the issue of the splines in the arm getting wiped out, but the stronger material leads to the shaft failing, what next? Well, bigger is better became a saying for good reason, right?

Round 3

So instead of ø6mm 25T splines, what if we used the same spline as our quarter class servos? After all, these gnarly ø8mm 15T monsters harness north of 2500oz-in . . . this will definitely solve the problem!

End result? Standard class servos equipped with a gnarly 15T spline!

Moral of the story? ProModeler doesn’t pussyfoot around when it comes to solving problems!. So when the 25T splined shafts have been found wanting, we brought out a freakin’ bazooka!

And ‘this’ is how you make a product change to address a weakness.

This begs the questions, is this necessary for a 200oz-in servo? Nope, not in a million years! So we’re not criticizing Hitec’s approach, merely observing our approach.

So because vibration is an issue to do with physics, it’s to physics that we turned for a solution. And not surprising, the solution’s a little bit expensive. Maybe too expensive for hobby grade servos at the $40 price point, but you get it anyway with ours. And our view is some day all servos will do this because we’re forcing the issue.

Vibration, part 2 – foundation

Did we invent the bronze bushing? Nope! Instead, I did what every good engineer does. I looked to see how others have sorted this issue in hopes of finding something to copy. I sought inspiration!

I turned to another good quality servo. Another with which I’ve had loads of experience. And not even a current servo, but one from 20 years back!

I looked at how JR had solved the case wear issue for their 155oz-in 0.16sec/60° high torque servo, the DS8411 back in the day. After all, if it worked for theirs, with similar performance, it would work for ours, too!

The real trick was, could we afford to do it for a $40 servo, today?

It’s obvious in the above photo Japanese engineers felt brass inserts were a suitable solution to address the case wear issue. And more than 20 years ago! So I figured this would probably still work just fine, today.

Fortunately, I don’t suffer from ‘not invented here’ because at university, it was drilled into me something Sir Issac Newton had written to his competitor, Robert Hooke in 1675 . . .

If I have seen further it is by standing on the shoulders of Giants.

So I’m not too proud to steal better ideas, file off the serial numbers, and adopt them as they my own. So instead of a straight plastic case like our competitor, we stole an old idea and made it like brand new again. And honestly, I felt we had no choice.

Like is anyone surprised at failure if building on a weak foundation?

Hardpoints

So let’s look more closely at reinforcing the plastic bores where the gear shafts are fitted to the polymer. And note; all we’ve done is mill a window into the case – these still work perfectly!

So if you look at closely at the above photo, you’ll see what we call the money shot. While individually they’re not horribly expensive, an insert mold process for the bronze bushings adds significant costs because a man has to manually place them on pins before closing the mold. Each and every time! Explains why this technique is usually reserved for servos costing north of $100.

Once you can see inside the transmission section, then not only can you see the gears and the materials, and how tightly packed everything is, but how they’re supported.

Next, let’s eyeball more closely. First D645MW then the DS180DLHV.

The ProModeler advantage is obvious in terms of service life because now the steel shaft won’t wallow out the plastic. Remember, plastic comes from the Greek plastikos, which means flow or deformation. And believe me, plastic deforms readily when repeated loads are applied over time (or at one go due to a crash).

So does anchoring gear shafts in plastic strike you as a less than stellar idea? Does learning about hardpoints incline you to prefer ours for your next set of servos?

Good, that’s my intent in showing you!

Fasteners

Next up, the tools required. In the case of the Hitec you need a #1 Phillips screwdriver. For ours, a 1.5mm Allen-driver does the trick.

This immediately brings up a place we beat them. E.g. where we score a point – right out of the gate – simply for better fasteners.

In fact, let’s keep score as we go. I’m going to call it 1-0 due to using high quality Allen head machine bolts instead Phillips head screws.

Of course, if you prefer Phillips, then score it the other way around. But most folks will opine the grade 12.9 we use makes ProModeler about a million times better. What’s your opinion, Phillips or Allen?

Upper transmission case

Below is one last photo our our bronze bushings, which we insert mold into our plastic cases. The shiny gold-colored bits in the case top are the hard points.

Yes, we’re really so proud we can’t shut up about it! And yes, we also know by this point it’s akin to beating a dead horse. Moving on.

O-ring: transmission section

The next thing we see are the gears (makes sense since we’re in the great train section of this comparison).

But before we get there, take a quick note of what is being pinched between thumb and forefinger. It’s a very fine custom made o-ring.

At about 3/4 of a millimeter in diameter, its purpose is to protect the environmental integrity of the transmission section. It’s one of 8 seals buttoning up just the upper, or transmission case, section.

So far we’ve seen the transmission case hardpoints, the Allen head bolts, and the o-ring for the case seal.

Before we jump to the gear train itself, take a look at how the output shaft is sealed. This is another custom seal, but made of Viton™ a high performance fluoroelastomers (the green ring on forefinger).

The washer-like thingy is actually a packing shim to preload the seal (so it fits the shaft properly). It’s required for it to work as designed.

So the D645MW hasn’t got diddly in terms of case sealing components. No o-rings, no Viton™seals, no nothing, Paco!

If you engage in float flying, or have been caught by an unexpected summer pop up rain shower, or had servos exposed to exhaust oil (and especially smoke oil), then which design do you prefer, the one with o-rings or without? Especially for the exact same money!

Anyway, we’re going to score another point to our side of the ledger, thus, making it 2-0. That’s 1 point for better fasteners, and this 2nd for the seals and o-rings.

Now let’s move onto the gears themselves.

Gear Materials

So other than the Karbonite hybrid gear #2/3, a combo of plastic bull gear and steel pinion, the Hitec D645MW has a metal gear train. The ProModeler gives you an all metal gear train – 100%.

But are all metals equal? In point of fact, no! Let’s look at another picture and judge for ourselves.

Note in the above photo, the Hitec #6/7 combo gear consists of two different metals, brass and steel. Steel because pinion gears drive bull gears, have fewer teeth, hence a shorter lever (from center), and thus, are subjected to higher forces. FYI, the smaller of the two is the pinion, and it’s pressed into the larger gear called a bull. The pinion is made of steel.

Speaking of the bull gear (always the larger of the two), it’s made of brass. Brass is softer than steel. But the two materials together actually work very well. How do I know?

Simple, it’s because we once used brass/steel combo gears with the DS180DLHV. This, before we upgraded them to stainless steel.

Birdwalk:

Allow me a brief birdwalk. There’s a concept in business called evolve, or die. Point being, just as we buy Hitec servos to study, then you’d better believe Hitec buys servos made by other, too. Same reason Chevrolet buys an F-150 each year to see what Ford’s up to.

So we buy theirs because when you know your competition, you can try to clean their clock. Guess what? They’re buying servos also, all in an attempt to return the favor. After all, these things aren’t referred to as competing products for no darn reason!

So because we cleaned their clock with the DS180DLHV back when the matchUP was between it, and the HS-5685MH (the D645MW is the upgrade). We knew good and well what was coming (because what goes around comes around).

Point being, we knew a proud company like Hitec wouldn’t just sit on their duffs and take it, take my meaning? Anticipating their response, we – and in light of the evolve or die concept – have diligently further developed the DS180DLHV. Yes, time for another bit of birdwalking!

Evolution:

So while some companies change product number to distinguish an update, we don’t. Instead, we emulate Porsche and their 911, which after +50 years of refinement, is while visually still the same car, with the same model number.

So a 911 is still the famous 911, but new release models have parts, which no longer fit to older models. Same with us.

For example, from the outside, it’s easy to distinguish the present and previous iterations of the DS180DLHV. The present iteration uses stainless gears and this is easy for the trained eye to distinguish. Stainless has a soft sheen to it that once seen can never been unseen – make sense? Trust me, it’s true.

However, the larger ring of material surrounding the output shaft bearing to accommodate the Viton™ seal is the real visual tip off. This makes IDing the latest version dead nuts simple.

And yes, we updated the label color, also.

So the exterior of the transmission case is changed, and guess what? Besides being made of stainless now, some the gears are also updated, too. Thus, just like a fender from this year’s 911 won’t fit one from a few years ago, the stainless gears in the present DS180 won’t retrofit to an older iteration, either. Why not?

Well, it’s not that we’re dicks! It’s because we made subtle changes to them, also. Like the #6 gear. Not only did it go from brass to 303 stainless, it’s now thicker, also.

Why did we do this if Hitec is fine using brass for their D645MW? Well, reason is besides the DS180, within the same assembly, whilst the motors and gear ratios change, we offer a whole family of servos based on this one servo.

In fact, there are 5 servos in the DL-range!

So the five servos in the DL-series include a DS90, DS130, the DS180 we’re discussing, as well as DS270 (the quickest of the bunch), and topping out with the DS360DLHV. Yes, a stout 360oz-in!

Anyway, it’s for the express benefit of the DS360DLHV owners that we wanted to bring more gear material to bear. This, because it’s basically imparting 2X the amount of force as the DS180.

The corollary being, does this mean the other four servos in the series are overbuilt because they don’t need nearly this much steel? Well, yes it does, but I like overkill. What about you?

Meanwhile, have you broken the super secret servo code regarding what the model numbers mean with ProModeler servos, yet? Turns out it’s so easy you don’t need a secret decoder ring!

Refinement galore

But that’s not the end of it. Like you, and probably every modeler on the face of the planet, I’m a tinkerer. This means once I get started making improvements, I really have a hard time stopping.

For example, I mentioned the previous iteration of the gear train used brass/steel combo gears like the Hitec D645MW. This, versus 303/412 stainless steel combo gears.

And FYI, 412 is a type of stainless that can be hardened, making it perfect for driving 303 bull gears.

SS versus SUS

SUS? Isn’t the abbreviation of stainless steel actually SS? Well, yes, sort of. You see, SUS conforms to Japanese Industrial Standards (JIS), where the designation means ‘Steel Use Stainless’.

Hence, SUS is the term we use because our gears are hobbed in Japan. Or so we thought. One last brief detour in this birdwalk, and then we’ll get back on track with comparing the Hitec D645MW and ProModeler DS180DLHV servos, I promise!

You see, when COVID struck back in 2020, getting work done became more difficult. Lock downs, folks out sick, etc. meant someone charged with driving a fork lift may have been packing orders. And mistakes, naturally enough, happened.

And I doubt we were the only ones scrambling to get the job done whilst short handed. Thinking so was everybody else. So one day a pallet of gears arrive. A short while later I get a call saying, ‘Hey, John, have you switched gear suppliers because nobody told me?‘

So I hustled my fat ass over and sure enough, totally different packaging. Gears? They looked the same. Were the same.

But the packaging, the boxes were different. Then I noticed the printing on one of the individual boxes looked different. Not like I speak Japanese, or any other Asian language – but – we’ve been seeing their printing for years. Not only did the packaging look different, the printed characters looked totally unfamiliar.

So I whipped out the phone, took a photo, and turned to Dr. Google. Google even translated the address! And I learned the writing was Chinese, instead of Japanese. Hmmmm, what do you know?

Note: if you’re curious, the written characters amongst the major Asian languages look radically different!

So when I reached out, turns out the actual hobber was in Taiwan, instead of Japan. What happened? I imagine the folks in Japan had the same labor issues we did in America. Short version, someone screwed up.

For us, this meant eliminating a middleman (the Holy Grail).

Worked to your benefit, too. How? Simple, instead of being greedy (like, everybody’s been hiking prices), because we found the actual hobber and eliminated a middleman, we’re now buying SUS gears for about the same price were paying for brass/steel before.

So I made an executive decision to hold the line price-wise. Is it because I’m an altruist? Nope, expressly to put pressure on Hitec!

And for you – you do only you care about you, right? What’s in it for you is you’re paying the price as before but now you’re getting our servos with super durable stainless steel gears!

This is what we really mean about more bang for the bucks! Even better servos than before . . . for the same price!

And we’re not done, it gets better.

Tiny spot welding

Last thing before I get this matchUP back on track, one small detail the average guy might miss.

So the new combo gears are 303 and 412, but because some guys are using these with RC trucks (remember, servos don’t know in what they’re installed), then because unlike model airplanes, where the control surfaces are the last to arrive at the scene of the crash, trucks lead with their chin (steering wheels are on the front).

So I have the hobber reinforce them. How? Four teeny-tiny spot welds where the #6/7 combo gears mate together!

What advantage is this to you? Probably not much unless you crash. But it’s a big help to a guy who can’t afford $100 servos for his 8 y/o running an RC model truck.

That said, maybe you dumb thumb your SIG Four Star 60 into a corn field one day. Maybe spot welded gears works out to your advantage. Better than not spot welding them, agreed? Win-win!

So circling back around to the principal purpose of this white paper, let’s see what else we can learn by field stripping these servos down to their components parts.

Karbonite gear

So we left off with the gear train mostly in pieces.

We’re at this point in the process, the photo below of the D645MW gear train shows the Karbonite gear. It’s the 2/3 gear because the #1 gear, the motor pinion, drives it (and 2/3 pinion drives the 4/5 gear).

Now eyeball the output gear (it’s in the back of the photo, top right corner). I suspect it’s hobbed of 7075-T6 (a good grade of alloy). Probably with a wear coating, also.

Good stuff, but in no world is it the same league with 303 stainless!

Se next, let’s wrap up our look at the gear train with the gear sets themselves. In this next photo we have both of them laid out. These are the entire sets (both) arrayed for close inspection.

On the left are the individual gear components of the Hitec gearset. And the ones for ProModeler, are on the right. Easy to distinguish stainless steel from brass/steel, isn’t it? What about the aluminum gear #8, the splined output gear? Again, easy to distinguish stainless from wear coated aluminum, right? And the plastic gear is dead nuts simple to identify.

So the question for you is this; which set of gears would you rather have? After all, both servos will set you back the same forty bucks.

Recapping

So that pretty much covers the transmission section of these servos.

Since we’re keeping score, let’s tally up where we stand. It was 1 point for the Allen head vs Phillips fasteners. Plus another point for sealing the 8-openings in the upper case.

By the way, do you grok how gears work? They actually slide one face against another. To work, the faces have a special shape called an involute (fancy word for curve). Means grease isn’t optional.

Switching gears, let’s also reiterate regarding the seals and o-rings.

Just for the upper section (ignoring the lower for now) meant attending to 8 openings. A case o-ring (where transmission section meets the middle, what we call the intermediate). Then there are 6 teeny-tiny o-rings, one beneath each bolt head (we source these from a supplier of Rolex watch stem seals). Plus the pricey Viton™ seal at the splined output shaft.

Between fasteners and seals, the score 2-0 by our count.

So let’s add another point for the brass hard points. You’ll recall these reinforce the upper transmission case. And FYI, the end result of a hybrid case set up is an über lightweight assembly with the durability of an all-alloy case (except in a bad crash when the plastic will likely fracture, but the replacement parts are cheap enough).

Note; there’s another hard point within the intermediate case section (but it’s part of the same point as for the upper section). Anyway, this makes the score’s 3-0.

By the way, for this photo we dug this hard point out just for giggles and grins. Don’t go doing this to your servos. Reason is they’ll never again seat as nicely. And since they can’t fall out on their own, we’re not paying for your foolishness. Consider yourself warned. And this is the last mention of hardpoints.

OK, I lied. Just this . . . we don’t make these brass hard points. Guy I know has a shop equipped with Swiss lathes. Make them for us because it’s tough to beat a man at his own craft.

Also, did you spot how they’re knurled? This helps them grip really well in the plastic. Means removing one requires a bit of digging to lever it out in order to show it to you.

Anyway, before moving on, let’s eyeball both case assemblies.

Case assembly

So the Hitec D645 case assembly consists of three injection molded parts, none of which are reinforced. The ProModeler also has three injection molded parts, two of which are reinforced with brass hard points. Plus an alloy center.

So let’s touch on the center case, and what this brings to the game.

Center case

When a servo is working, especially when it’s working hard, the motor gets hot. How hot? Really warm to the touch. Operate it long enough and it can come close to burning.

Why? Simple, and for the answer, let’s turn to the formula for Watts.

Basically, Watts can be calculated as the product of Volts X Amps. So we know the servo operates on up to 8.4V and if we turn to the specs (every ProModeler servo gives you extensive specs like these) then we can work out the answer.

Hint, look in the fifth column.

5V and 6V

So the reason the chart is divided into 5 columns is 5V represents an old school 4-cell NiCd battery pack. Similarly, 6V is a 5-cell NiCd (or NiMh). Don’t laugh!

First, plenty of modelers still trust these more than lithium. This is reinforced every time there’s a news article about a battery fire.

And second, some UAS are certified with this battery technology and once adopted, the components basically never change. Like I get it, why screw with what works?

6.6V – A123 (LFP)

The middle column is my favorite battery technology, A123. While superficially similar to the el cheapo LiFe packs sold to hobbyists, these (A123, aka LFP for Lithium Iron Phosphate) are a much better chemistry to live with.

Especially due to a) being packaged within a durable metal shell instead of being vulnerable in an aluminized plastic bag, and b) not needing to be put in storage mode if plans change after charging.

7.4V and 8.4V

So the 4th and 5th columns are related. The 7.4V columns is a depleted 2S LiPo. Depleted meaning, as with all these, this is the nominal voltage.

Means when you measure 7.4V, the pack’s done. And for pretty much the same reason if you measure 12V on your car battery, there’s not a chance in Hell it’ll start the car even though we all ‘know’ they’re 12V batteries!

And 8.4V is about where a 2S LiPo packs ends up after a charge (not quite but close enough for government work). What 8.4V really represents in regulated voltage some guys like to use. E.g. the juice coming off a source using FETs to make whatever level the designer selected. Maybe a box system.

Me? I don’t care for the things but I’m not stupid and if you want to buy one, then we have them (two in fact). But wise up, take a pass on regulated power. Learn more, here;

• The case against synthetic voltage

So why have I gone around the world with this voltage business? Well, take note of the current spec in each column. Look at the worst case (engineers love the worst case because it sets the end points for the real world). So this is a measure of current when the servo is stalled, e.g. making rated torque.

Anyway, for the DS180DLHV at 8.4VDC, it’s 3.3A. So going back to our formula for Watts, plug in 8.4V and 3.3A and multiply and we get 27.72W, call it 25W.

So I have a question for you; ever touched a 25W light bulb you didn’t let cool long enough before trying to remove? Burned the crap out of you, right?

So with our servo you get an aircraft aluminum center instead of one molded of plastic. And it has cooling fins so it works like a heat sink. Do you have any doubts which one cools better?

Meanwhile, with regard to Watts for the competing product, I don’t feel I can speak for the Hitec (the specs state 2650mA but not at what level of voltage). That said, I suspect the consumption figures are similar to ours. Close enough to go with it.

And if you’re wondering where I’m going with this, it’s this; in my opinion they’ve basically made no serious provisions for cooling that servo’s motor. So because heat is the enemy of electronics, a case that’s basically a heat sink is ‘mo betta! Next let’s look more closely.

Enter the porcupine

The case for every ProModeler servo is CNC-machined from a solid billet of 6061-T6 aluminum. Even our least expensive servo, one going for $30 (DS90DLHV) gets our best alloy center case. Pretty much the same as for a $160 servo outputting 1155oz-in. No short cuts.

In fact, all ProModeler servos – 100% of them – get the good stuff. Why? Simple, because an alloy case sheds heat better than plastic, which is more akin to an insulator. In fact, it’s not even close!

This is the porcupine.

Anyway, next you must understand something important about us. Modelers fly for maybe 15 minutes and land. Means hobby-grade servos only have to cool long enough for modelers flying on an intermittent basis. Our primary customer need better.

You benefit from his needs even when yours aren’t as arduous. This, because we have customers flying missions lasting hours. So a plastic case that’s fine for a model won’t shed enough heat longer term. This is why we use an aluminum case as a heat sink.

Also note the porcupine’s cooling fins. They’re not decorative. Even with them, the servo gets pretty warm. Not just our servos, any servo on this planet will get warm shedding that many watts as heat.

Not a matter of my opinion, or yours . . . this is down to physics because no matter what, W=VxA and watts are a measure of heat!

Time for another birdwalk because I can see my EE readers about to blow a gasket. This is because watts in their world are a measure of electrical power. And for them, the formula is actually P=V*I, where

• Power = Watts
• V = voltage, and
• I = Amps

So to cover my ass with the ones who will nitpick me to death if I don’t clear this up, in the real world a watt is a unit of power. It’s defined as one joule per second, so 1W = 1 J/s in the SI system.

And this is a measure of the rate at which energy is converted. So electrical watts are covered by the P=V*I formula. Same result as using W=V*A . . . which in my book is a difference without a distinction, but whatever.

Thing is, watts also measure the rate of heat transfer. The technical term is thermal energy conversion. And while heat transfer is the same as the temperature difference or thermal resistance, it’s still measured in watts. So my EE’s need to chill because the term is being used loosely, but it’s also an accurate representation of the real world.

So back to what matters to you, with a DS180DLHV your servos shed heat better because of the finned alloy case vs the DS645MW with a plastic case. So riddle me this; would you rather your next set of $40 servos come with plastic center cases, or finned alloy?

Like it’s your money but I suspect most reasonable folks won’t quibble with our taking another point for superior cooling.

What’s the score now, 4-0? Starting to look like a runaway!

And we’re not done. Let’s flip these puppies over and see what else we can learn. Yup, time for the electronics.

So the next step in the process is to investigate these things from the bottom. We’re going to eyeball what we call the hot section. This is where the motor, potentiometer, and printed circuit board live.

Bottom cover

So popping off out bottom cover for standard class ProModeler servos requires the 1.5mm Allen driver, once again.

And if you didn’t notice them earlier (when we showed a photo of the transmission cover coming off), check out the teeny-tiny o-rings below the socket cap screw head.

Are those little buggers cute, or what?

And what we’re presented with is the PCB, or printed circuit board. This is the card to which surface mount components, like microprocessor, diodes, resistors, etc. are soldered.

Vibration, part 3

So here’s the thing. Vibration may break the fragile solder joints, also. Not kidding about vibration being the big bad wolf! And we know because have a lot of experience with this. Comes of work earning MIL-STDS – involved a distressingly long learning curve.

Saying there’s more to success than meets the eye. Nor are we embarrassed by failure. Badge of honor kind of thing if viewed in a certain light. Speaking of failure, this next photo is of a vibration induced failure. Yes, the microprocessor simply fell off the PCB as the individual legs failed due to vibration.

And this servo? Believe it or not, by simply soldering the microprocessor back in place, we brought it back to life!

All that’s required is a low power bench top microscope (we use a Leica 3X), plus a fine hand. Coffee is to be avoided!

So I’ve been inadvertently birdwalking again. I’m bad to do this.

Anyway, once the electronics cover is removed, what’s there to see? Largely the same with both because each servo presents a PCB plus the endbell of a DC-motor to the eye.

Big difference between ours and the Hitec D645MW is theirs is naked. By naked, I mean something like unprotected sex. But instead of a condom, naked means no potting compound. Say what?

Since a picture is worth a thousand words, here’s the pertinent photo. And there’s a huge difference between these, believe me!

So the white stuff is what’s called in the trade, potting compound. This is what keeps surface mount components from falling off due to shock and vibration.

The stuff stinks, is sticky as hell, and takes a while to setup. We refer to it as monkey snot. Sold in white, black, and translucent. Doesn’t matter which you use.

Setup time means it’s a multi-step operation. Hobby grade servos don’t do this because time is money, so the process eats up a fair bit of the budget.

Can’t be helped because our primary customer demands it.

So you may have heard our servos meet some MIL-STDS. This one now meets eight because of some recent applications. These added humidity for one customer, heat as well as sand and dust intrusion for another, plus low pressure (altitude) for yet another.

So what do these mean for you? Well, a lot in my opinion. And yet for some reason, it never fails that some bozo on a forum makes the claim (usually proffered with the mention of serving in the military) of how MIL-STDS don’t mean anything.

Well, no offense, but anyone saying that is an idiot. Full stop.

Vibration, part 4

For example, if your model has an internal combustion engine it vibrates. Want to know how much? Strap a cell phone to the exterior of the model (or wedge it inside), and go fly.

But leave off the protective case! After all, measuring vibration is the whole point. Before staring the engine, or throttling up the turbine, start the app. And heads up, these vibration apps are free!

So vibration apps are available on the Apple store and/or Google Play. You’re going to be astonished, believe me! Links to sources;

• iOS free vibration app
• Android free vibration app

By the way, if you’re game to try this, then buy a roll of gaffer’s tape to secure the phone to the model. I promise it will stay in place yet the tape peels up without damaging the model’s finish.

FYI, gaffer’s tape is amazing stuff. Developed for the film industry so they could place audio cables and such – on location – without worrying about damaging somebody’s walls or ceiling, it’s what’s used by the crews setting up within Buckingham palace!

So I like the stuff Filmtools sell, but you can find off-brand on Amazon too (for much less, and it’s probably plenty good enough for the job). Anyway, either believe me about vibration being a bigger deal than you image, or try learning more about it using a vibration app.

Point being, what you’ll discover in an afternoon is eye opening (and true even of electric models and turbines, which have surprising amounts of vibration). Add to it, beside propulsion source vibrations, there are also vibes off props, as well as the shocks and judders resulting from maneuvering the model.

I’m saying this will blow you away once you play with it for just an afternoon. Also means you’ll really begin to see the value of potting compound. But enough birdwalking or I’ll never finish the piece.

Next are close ups of the PCB. First, the Hitec board, which as I said, we refer to as naked due to the general lack of protective coating.

So here’s the thing; even if you build ARFs, they’re not cheap these days. So a servo going tits up due to vibration induced failure sucks.

As for us, our civilian user base include modelers who value their aircraft greatly because they took years to build!

So how the PCB is protected is a big deal. And instead of sending it naked out into the world, a ProModeler PCB gets a nice coating of potting compound.

Potentiometer – Noble 1mc

So take note how the potentiometer is held in with two screws in your ProModeler servo. This, as opposed to just one securing it in the Hitec D645MW.

Does this matter? Dunno, not my call, yours. If I didn’t think it mattered we’d only use one, also. Not just to save the price of the screw – but – for the added time during the build.

As the shop foreman has even got me saying . . . time is money!

Speaking of the potentiometer, with ours you get the famous Japanese Noble 1mc. Costly but reliable, so we use it for everything from micro servos through quarter class servos costing hundreds.

Same pot in every single one, even if the servo’s just $30. And if you want to learn more, click the image and review this article.

So where are we score-wise? While we can’t take a point for the pot because I don’t know what they’re using (they say it’s a million cycle, and I believe them), thing is, I don’t know which one. We’ve looked at several but never found one we trust – not like we do the Nobel 1mc.

Anyway, we will take another point for the potting compound. Plus an additional point for the MIL-STDS. Now running up the score, which stands at 6-0 by pretty much any reasonable measure of accounting.

This brings us to buttoning the servos back up.

Electronics cover

The bottom of the ProModeler requires four Allen head bolts, each equipped with an o-ring beneath the head. They screw into aluminum with machine thread bolts (M2x0.4 mm).

The Hitec D645MW also uses four screws, but instead of machine threads going into metal, theirs relies on four long-ish Phillips head screws. These are equipped with coarse threads tapping into plastic.

Again, a photo is worth a thousand words.

So the downside about steel screws in plastic is because coarse cheesecutter screws, which self-tap into plastic can damage the bore. Basically, after assembly, subsequent disassembly diminishes the integrity of the plastic thread.

Like how may times can it be screwed together and have it tighten securely? Once? Ten times? Dunno. But they’re not as good as machine threads going into metal. Not even close.

What’s left? A summary, I guess.

Summary

We started off with great respect for the Hitec D645MW product. Guess what? We still respect it. The D645MW may be the greatest hobby grade servo on the market. No, not kidding. And this isn’t a left handed compliment. Here’s why.

Their $40 against ours for the same $40 was never a fair contest.

You’re buying ours direct. Theirs sees many hands touching it without contributing to the production process. So it means many are being paid for their role in merely getting it into a store (and, of course, each one wets their beak along the way).

Think about it. I’ve been picking on this servo expressly because folks are so familiar with it. Everyone knows what they’re going to get for their $40. My job has been to show you why ours is a better deal for the same $40. But it hasn’t been a fair contest.

You’re probably familiar with the Hitec D645MW, or it’s predecessor, HS-5645MG or HS-5685MH. Means you know torque and speed are basically the same – 180 oz-in and 0.17sec/60° – so what’s the difference? Build quality.

We spend more money producing our servo. Don’t even have to be an engineer to appreciate the difference as long as you’re not blind (or stupid). Behind the scenes, our $40 DS180DLHV costs about $32, so we make $8, give or take.

Meanwhile, a Hitec D645MW – also selling for $40 – costs far less to actually make, perhaps just $7. The reason a $7 servo costs you $40 is due to a business model designed to put the product in a store’s display case.

With the D645MW it’s all about getting the product ‘to’ the customer.

So the Hitec business model makes it very convenient to drive over and buy the D645MW in a hobby shop. Thing is, we don’t sell to dealers. Or distributors.

So you’re buying direct. Means place an order and wait a few days for delivery. Is it worth it? To some no, to others, Hell yes!

Ultimately, this process of getting a D645MW into a hobby shop adds to the price you pay. The importer scores 15% for touching it. The distributor earns 25% as their cut, again for just touching it. And the hobby dealer? He operates off a 40% margin.

Are you getting screwed? No, you actually aren’t. Don’t believe me? Eyeball what a hobby shop owner’s wife drives. Bet you a good milkshake it’s not a new Cadillac. Keep this in the back of your mind when grousing about prices in a hobby shop; everybody has the eat.

Ultimately, the process by which Hitec produce and bring to market is different from ours because they have a different goal. Their reach is immense, ours is quite limited. It’s how they got to be the 800 pound gorilla, so I’m not saying they’re wrong.

So how does the DS645MW stack up against the ProModeler DS180DLHV in your eyes? I think ours is better but my opinion doesn’t matter. Especially because opinions are like belly buttons in that we all have one. So this is mine.

Saying the only opinion that matters is yours!

Recapping:

Let’s list what we’ve touched on.

• Allen head fasteners
• 13 seals and o-rings
• Bronze hard points
• Boxing the output shaft
• Stainless steel gear train
• Finned aluminum center case
• Potting compound
• Eight MIL-STD
• Same $40

Final thoughts

Allow me offer a few final thoughts. The right servo for you is a reflection of yourself, your goals, your dreams, and your budget. We put a better grade of servos in your hands. But nobody can make you buy them. This you decide for yourself.

Any questions? Feel free to reach out, we’re readily available;

• Telephone: 407-302-3361
• Email: info@promodeler.com

. . . and together we can suss out what’s best for you!

I’ll close with this, one thing’s certain, best is a race that’s never finished. Best right now? ProModeler, but far from David vs Goliath, we’re more akin to a flea on the elephant’s back in this battle.

Means we need your help. Presuming you like our servos, then do us the favor of taking one to a club meeting. Pass it around. Maybe even pull out a 1.5mm Allen driver and open it up – you’ve seen how they go together, there’s nothing to be afraid of. And please, show them to a pal.

But most of all, kindly grace us with a photo sharing your thoughts. What for? To put on the website, and within articles like this. Basically, for telling the next guy what you like about our servos.

We’re Jones-ing for photos like this one because your favor is priceless and can’t be bought. We know this. So do others.

Last thing

Have you enjoyed this? If you like reading and are interested in learning more, then maybe find time to review more articles like this;

• matchUP: Futaba HPS-A703 vs DS930BLHV
• matchUP: AccuTORQ 600SG vs DS630BLHV
• matchUP: ProModeler vs JR DS8711
• On the batteries John prefers using
• About pots vs Hall Effect sensors
• On selecting battery packs
• Pro tips for improving your ARF
• Amazon servo vs DS505s
• Why’s my pack got two JR-connectors?
• Rip Van Winkle, on returning to RC
• How to guide a rocket using servos
• Phoenix Models 70in Strega guide
• Advantages of pull-pull via pulley
• Bret Becker: Mr. Top Gun
• Will ProModeler servos work with NiCds?
• How to determine flight time for a 2S850 LiIon
• Hangar 9 60cc Pitts S-2B servos
• Fear of loss, or how to stack the odds in your favor!
• When LiFePO4 is mistakenly charged as LiIon
• Idle thoughts regarding chargers

. . . and hundreds more. Best part? They’re all free!