AccuTORQ 600SG vs ProModeler DS630BLHV

A servo matchUP (comparison article) comes about from time to time and nearly always in response to a question regarding a specific servo like; 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?, or words to that effect.

The answer to the above is a ProModeler DS180DLHV and because we don’t hide from these questions, we buy a competing servo, take it apart and show what’s what using side-by-side photos. This, so you can suss out which side of the bread is buttered for yourself because nobody likes being told what to do.

Note this example photo . . .

Anyway, this AccuTORQ 600SG vs ProModeler DS630BLHV article runs a bit longer than usual because an investment in such expensive servos deserves our best effort at guiding you. So there are lots of photos plus lots of yap-yap explaining what to look for, and why.

• Note: if you’re short of time, the Page Down key is your friend because you may skip from picture-to-picture reading captions and also learn the story . . . without so many words!

So once we had the AccuTORQ 600SG in hand, we took a slew of photos, which I’ll share as I explain what the important details are. By the time we’re done you’ll be up to speed not just about these servos and ours but for any servos you’ll see in future because you’ll learn what’s important, and which shortcuts some try slipping by their customers.

To begin, and quite honestly, this is a very nice servo. It’s nicely made, handsome, and performance-wise, it’s both smooth and powerful. In further honesty? We can readily see why it’s popular. Priced at $110, it represents fair value to many modelers, else AccuTORQ don’t succeed to the extent they have in the market.

Against it we offer the ProModeler DS630BLHV, which at $130 costs more money. Question is, why? And is it worth it? Since that’s the point of a these matchUP articles, let’s find out . . . together!

Of course, it stands to reason we feel we’re offering you a better servo, else what are we doing in this business in the first place? But while we believe the DS630BLHV is easily worth the extra $20, it’s not really on us to decide. That’s your call and since neither is exactly cheap, thanks for even giving us a shot at earning your business!

Appearance

To begin, this is a very handsome servo. Someone has gone to a lot of trouble in designing the presentation. Unquestionable a pro at marketing has had a hand in this. It presents a classy look, a very, very rich appearance. It’s downright pretty and has a silky smooth feel due to the bead blasted finish.

This combines to give it a very sophisticated appearance, which is partly due to using three complementary case colors. I’ve never seen anything like this surface treatment, but overall I must admit to being impressed. This is a seriously nice looking servo.

Added to which, the laser etching (for the branding on top) is first class. If we’re being brutally honest? This distinguished looking servo will appeal to folks for whom the industrial look our CNC-machined servos will appear rather drab (some refer to our servos as having a steampunk look). Some consider our servos plain looking.

Can’t be helped because we’re engineers so our focus isn’t on appearance. We’re all about form follows function. Doesn’t stop us recognizing when something looks better, so let’s score this a clean win for AccuTORQ. Right from the get go, this makes the score 0-1.

• Note; both the AccuTORQ 600SG and the ProModeler DS630BLHV are considered standard-class servos, which means a basic 40x20mm footprint. The ProModeler is a skosh wider due to the space required for case o-rings – but this is no big deal when fitting to your model.

Next, let’s touch on performance.

Performance

The respective torque and speed ratings for these two servos are;

• AccuTORQU 600SG – 600oz-in @ 0.13sec/60°
• ProModeler DS630BLHV – 630oz-in @ 0.10sec/60°

Torque

ProModeler edges the AccuTORQ narrowly torque-wise. For some a win is a win, but let’s be honest. A mere 30oz-in in a 600-class servo works out to 5%, so this isn’t enough to move the needle for anybody other than an idiot.

We’ll find other reasons to crow because this modest difference is within the noise. So it’s our opinion, when it comes to torque, these two servos score – in the real world – a draw.

Speed

In terms of quickness, it’s a another story for the simple reason that 0.10sec/60° vs 0.13sec/60° is a significant performance difference.

• We’re talking about the AccuTORQ being 30% slower.

Without question, 30% is a big deal with high performance aircraft. Thus, in terms of the overall performance, taking into account a tie in terms of torque but a huge win speed-wise, we take the overall win.

If you’re keeping score, it’s now tied 1-1.

Next, let’s remove the upper transmission case section. Both use Allen head fasteners so let’s expose the gear train to view so we may cast the old set of Eyeball Mark II for a close look to see for what we can learn.

What’s interesting is there are 6-Allen head fasteners securing the transmission section to our center case. The AccuTORQ 600SG relies on just four long screws to secure the entire assembly. And these are accessed from the bottom. Whatever.

• Note; the SG in 600SG means steel gears.

Transmission section

The AccuTORQ 600SG does indeed have steel gears. The blue-ish cast of some is a wear coating, which is good stuff. We use it also although we are transitioning toward more expensive stainless steel gear trains.

And while both are steel, different grades are more rugged and stainless is a lot better. We use stainless for several important gears, the output gear (the one with 25T splines), also the 6/7 combo gear, and the motor pinion, too (again, because stainless steel is tougher and more durable).

We do note about the 600SG, there are only four bolts securing the upper transmission case. Also, there’s no o-ring sealing the two case sections (between the upper case and the center section). Point being, this servo won’t keep water or smoke oil out. Maybe it matters, maybe it doesn’t. Depends.

Similarly, there’s no o-ring at the splined output shaft while the ProModeler DS630BLHV has o-ring case seals plus we use a bright green Viton seal at the exit of the output shaft juncture.

Seals are very important for longevity. Note the green seal below.

So with regard to o-rings and seals, maybe it’s no big deal if you only fly jets or electric models – but – because servos don’t know in what they’re installed, then maybe it does matter. Like maybe one day you want to use these servos for a giant scale gasser. So what?

Well, reason you should care is because it’s very common to mount flight control servos in giant scale models such that the upper case is exposed to exhaust oil. And in particular, especially if the allure of smoke systems appeals, exposure to smoke oil, too. The latter, especially, will ruin a set of servos in no time, so heads up!

So I mentioned the ProModeler DS630BLHV uses six bolts to secure the transmission case vs four. And that theirs enter from the bottom, thus doing double-duty because they secure three sections together instead of one (four surfaces instead of two). Maybe smart, maybe not, let’s see.

If you look at a force diagram, 4-bolts securing 4-faces (bottom-to-center ‘and’ center-to-top) deliver less clamping force (assuming the same size bolts) than 4-bolts for just two faces (bottom-to-center) and another 6-bolts for (center to top) for the two upper faces.

So 10 bolts threaded to the center case means ProModeler has more than 2X clamping force when assembled. This means it’s stiffer just because it can’t move.

Moreover, what else matters is in having 6-bolts at the top case, there are two added bolts boxing near the bearing (at the output shaft). Why this matters is the case assembly becomes considerably stiffer around the output shaft. It’s a big deal, else we don’t bother. And if you look at other high quality competitive servos, like Futaba A703, they do it also.

• Futaba A703 versus ProModeler DS930BLHV

So all ProModeler servos are secured together to the center case in a similar manner. We even use 10-bolts for our micro servos, and entry level servos costing a mere $30.

And each has an o-ring hidden beneath the socket cap head.

So staying on the theme, stiffer matters in terms of gear wear.

Like we go to a lot of trouble to make the servo stiff because high performance models – ones flown by pilots utilizing the full measure of the servo’s output – can torque the servo cases severely. Literally twisting the gears such that the mesh goes out of spec!

So look back at the photo of the porcupine, note how we’re using 6-bolts instead of four for the upper case, or transmission section. Note how the 4 near the output shaft are close to the bearing.

This keeps the assembly from flexing. Like maybe you don’t fly that hard, maybe you do, dunno. But maybe some day in future, you will want to put the pedal to the metal.

Since it’s impossible to predict the predict the future, then all things being equal, wouldn’t you rather your servo be torsionally stiffer because it’s using 10-bolts instead of just four?

Also, with regard to their being o-rings beneath the bolt heads, and the seal at the output shaft, plus more o-rings at the case sections, this is part of what you’re getting with the ProModeler servo which meet a total of eight MIL-STDS. The two, which matter right now, are;

MIL-STD-810H

• Sand and Dust – Test Method 510.7
• Water Intrusion – Test Method 514.5

So if you’re scoring, ProModeler takes a win for 6-bolts vs 4-bolts and for the o-rings and seals buttoning it up against environmental intrusion.

So for this section, it’s an uncontested win, and the score now is 2-1.

Gears train, part 1

Both servos have steel gears but ours are better because some of the gears are made of stainless, which is more rugged. These being the output gear (nomenclature is gear 8), the 6/7 gear, and as we’ll see in a bit, also the motor drive pinion gear. The other two combo gears are performance coated similar to how the AccuTORQ 600SG uses coatings.

Our output gear, especially, is more rugged for being made of stainless. Important because it takes the brunt of the abuse. And it’s made of especially durable 303 stainless, as is the bull gear of the 6/7 combo.

Combo means two gears in one. So a big one and a small one are pressed together, hence combo-gear. The big one is called a bull, and it’s also hobbed of 303 stainless. The smaller gear (the one pressed into the bull) is called a pinion.

And importantly, the pinion is hobbed of 412 stainless, which is a stronger material than 303. What’s more, it’s subsequently sent out for hardening. As for the motor drive pinion gear, which we’ll show you in a bit, this too is hardened 412.

• Bottom line? In terms of materials, our stainless is mo’ betta!

However, if you look closely, you’ll also see the 6/7 and the 4/5 gear are also thicker than theirs. Thicker presents more surface area, so it means a lower pressure loading.

And because – in general – when it comes to wear and durability more surface area is better, then because ProModeler brings more metal to bear along with better materials, you get a better gear train just because of physics.

Gear train, part 2

So the next move is to field strip the servos. This means removing the gears. So in this next photo the gears have been slid off the gear shafts.

We used a gear puller to remove gear 8 (for both) leaving the bearing on the case. This, because removing the delicate bearing is completely pointless as it exposes it to being damaged for no reason.

So what is there to see in this photo?

There are two HUGE differences here. First, the ProModeler gear shafts, the ones supporting the gear train, are much larger diameter. We used a mic to measure – there’s a difference of 2mm vs 1.5mm.

Our shafts are made of 304 stainless steel. And while we have no clue regarding the composition of the AccuTORQ 600SG gear shafts, assuming they’re also using 304, theirs are significantly weaker for being 30% smaller in diameter! This is a big deal during a crash.

But it gets worse because pound of force for pound of force, a small shaft transfers more force to the case where the shafts fit the bores. Why does this matter?

Let me me show you the bores in the case, next.

So I said it gets worse for the AccuTORQ servo because their gear shafts are smaller in diameter. Eyeball where the 2nd shaft is seated directly in a raw aluminum bore.

With the ProModeler, the shaft is fitted to a bushing, which is pressed into the aluminum case. This is a big deal because the bushing serves as a hard point in the soft alloy.

So this is a foundational element of the servo. Like we go to a lot of trouble – and not just in pressing it into place – but with another operation. And the 2nd op after pressing in the bushings sees us using the jig boring machine. This, because it ensures this bore is both exactly the right size and placed where we want it. Why does this matter? Simple, it’s because ‘this’ is what determines gear mesh.

Point being, any slop that develops at this bore puts paid to the utility of the servo because a new set of gears won’t fix it, it requires a new case, also. So visualize a crash. The output gear has an arm fixed to it and gets thumped. As it twists, it forces the 6/7 gear to absorb the force. The 6/7 along with the 2/3 combo live on the 2nd shaft. This shaft is support in a raw aluminum bore in theirs and in a bushing in ours. Worse, being 1.5mm in diameter instead of 2mm like ours, it cuts almost like a knife into the soft aluminum. Result? Round bore becomes egg shaped. Gear mesh? Gone to Hell. Done.

So at this point, our engineering opinion is the game’s over. Score a point for ProModeler DS630BLHV vs AccuTORQ 600SG making it 3-1 but this is the exact place where there’s no recovery in our estimation.

Saying the AccuTORQ 600SG, no matter what, can never defeat the ProModeler DS630BLHV. One crash which breaks the gears likely damages the case, also. Means this servo is one-and-done.

The ProModeler? It – almost to a certainty – lives to be rebuilt. To learn more about this, review this article:

• On rebuilding damaged DS505s

Moving on, next let’s review the gear that’s pressed onto the servo motor itself, the motor drive pinion gear.

Gear train, part 3

Since fair’s fair, even though we think you may as well put on Willie Nelson to sing, ‘Turn off the lights, the party’s over’, let’s keep looking.

So in this next photo we’ve now removed both gear shafts. We’ve also rotated the servo 180° for the express purpose of letting us examine the motor drive pinion gear. This little bugger is what makes everything happen in a servo.

This teeny-tiny gear is pressed onto the motor shaft. While they’re using a brass gear, we’re once again using 412 stainless, which is hardened, also. Honestly? This is a much longer lasting solution. Costs more to do, also, as do the stainless gears in the set. So we charge more – but – we also give you more!

• Note; the AccuTORQ 600SG uses a brass motor pinion gear.

Honestly? While brass is a wonderful gear material (we know because we use it ourselves in lower torque applications), the facts are the stainless is stronger and more durable. So because of the motor drive pinion, and the bushing, we’re now really running up the score – call it 4-1.

So next, let’s turn our attention more closely to the gear train, again.

Gear train, part 4

This next image showcases the gear train for both servos laid out side-by-side in closer detail. The AccuTORQ 600SG is on the left and the ProModeler DS630BLHV gear train is on the right.

Note the soft sheen of the stainless gears. Also take note how the 6/7 combo gears (between both output gears) are ordinary steel for the AccuTORQ 600SG vs stainless, and ours is thicker. Finally, again note the thicker gear shafts.

So there are no further points to score as we tallied a point for better gears and stronger shafts, already. Before wrapping up the gear section, let’s eyeball the upper case sections, what secures the gears to the center, the transmission case.

Upper transmission case

This is an important place to look at any servo because it shows the care with which it’s been designed. We have already examined the outside of the upper case section. Now let’s flip them over and see how they’re made because as the old saying goes, beauty is only skin deep, but ugly goes through and through.

We think what we’re going to show you qualifies as ugly. But you be the judge. And we’re going to sing that same old song, the lack of bushings in the case.

This time note the AccuTORQ 600SG upper lacks bushings – zero.

If it seems like we’re beating a dead horse it’s because we are. These bushings are really, really important when you’re trying to harness 600oz-in and have the servo live.

Put another way, for your investment in pricey servos lasting. Like unless your money grows on trees, durability matters, right? So we beat the dead horse!

Like it’s your money and we want to earn it fair and square. Saying not pressing bushings into the case is the difference between maybe not lasting out a season! So we’ll proudly take another point – now almost like taking candy from a baby – and call it 5-1.

And allow me to add, these are details that accrue to your benefit when your servos are created by someone whose focus is entirely on servos. This, versus servos principally offered by someone buying servos to private label (perhaps in hopes of creating value amongst folks who don’t know better when padding the margin for a model).

Anyway, let’s move on. If you were to flip a servo over it exposes the bottom cover. Theirs came off with the four bolts securing the upper case. For ours, it’s time to remove four more bolts. These are what secure the cover to the porcupine center to protect the electronics.

Electronics cover

So the bottom of the servo typically doesn’t get much love and attention. If you reviewed the Futaba A703 matchUP to the ProModeler DS930BLHV theirs got silkscreening and laser treatment. Some do, some don’t, ours generally don’t get much attention since who sees it after it’s installed. The AccuTORQ 600SG doesn’t either. Kudos to them. Especially as all it does is hide the electronics from view.

But before we skip past them, let’s eyeball the covers themselves to see what we can learn. This allows us to circle back to o-rings used for sealing the case, once again. Another dead horse!

And no, there are no more points to be scored because we already took the points for o-rings, earlier. Nevertheless, a quick look.

So what this part of the servo, the electronics cover, protects are the electronics (duh). So ours is better at shielding your investment against environmental intrusion like water and smoke oil because we use an o-rings. And as we mentioned earlier, theirs doesn’t.

But beyond liquids, the o-rings also serves to shield against sand and dust. And importantly, we also earn a MIL-STD for protecting your servos against humidity.

Like you want anything getting into your servo? We didn’t think so.

MIL-STD-810H

• Humidity -Test Method 507.5
• Sand and Dust – Test Method 510.7

Let’s begin to wrap this up. Before we do, let’s eyeball the PCB (printed circuit board). This, because it’s where the servo is controlled leading a motor to end up moving a servo horn.

Printed Circuit Board (PCB)

Both servos use a microprocessor. Both use FETs to drive the motor. Theirs uses two and ours uses three.

What else is important to realize? Well, for starters, you can see the components of their board. Ours? It’s covered in white stuff called potting compound.

Why does this matter? Like icing on a cupcake, this makes it better.

The white stuff is what’s protecting the guts from shock, vibration, and acceleration. It’s why we earn three more MIL-STDS.

MIL-STD-810H

• Shock – Test Method 516.6
• Vibration – Test Method 514.6
• Acceleration – Test Method 513.6

What’s important to see in the above image? It’s not just the way the pig tail flops open exposing the lead entrance to contaminants. Instead, look closer at the cooling fins. Like it’s the ones on the AccuTORQ 600SG center case section are so shallow as to just be more about decoration versus function. Who’s to say?

But also note how even the small details like the mounting beams are thicker and more rugged on the ProModeler servo. So here’s the thing, all this little stuff begins to add up.

Means we’ll take another point for potting compound, better cooling, and stronger mounting beams – and although the latter don’t much matter to folks who fly models – if the servo is mounted within an industrial robot, or an RC truck, then this matters really, really bigly.

So now the score is 6-1. What’s left? Fasteners and we’re about done in part because this is getting embarrassing but also in part because the servos still have to go back together.

Fasteners

They used good fasteners – just not enough of them in our opinion. We say ten bolts beats four. Period.

Added to which, ours have o-rings for sealing, also!

It’s said God is in the details, and it’s in the smallest of places, hidden beneath the bolt heads that you find the ten o-rings we get from a Rolex supplier of winding stem seals.

These are the final touch when it comes to buttoning up your ProModeler servos. And if you never open the servo, you don’t even know they’re there because they’re hidden from view.

Anyway, if you’re still keeping score (we are), we’ll take our point here making it 7-1 and something of a rout. So let’s try and wrap this up.

Recapping

When it comes to the specs, ProModeler offers 630oz-in vs 600oz-in, which is a wash in the real world. However, speed-wise, ours at 0.10sec/60° is considerably faster than theirs at 0.13sec/60°, we’re talking about 30% faster, which is a really big deal.

• Many modelers buy based on just two things, torque and price.

They’re both 600oz-in class servos, and theirs is cheaper. So in theory theirs is the better deal. In practice, not so much.

This is because for similar money, ours is made better. Not saying the AccuTORQ 600SG is cheaply made. Instead saying we give you more.

Like bushings reinforcing the case, larger diameter gear shafts, better gear materials and larger to boot, more bolts securing the assembly together, with two boxing in the bearing at the output shaft, plus 13 seals and o-rings . . . and a partridge in a pear tree.

Just kidding, but you’re getting a servo meeting these MIL-STDs;

MIL-STD-810H

• Shock – Test Method 516.6
• Humidity -Test Method 507.5
• Vibration – Test Method 514.6
• Acceleration – Test Method 513.6
• Sand and Dust – Test Method 510.7
• Water Intrusion – Test Method 514.5
• Altitude <70,000’ – Test Method 500.6
• High Temperature – Test Method 501.5

And now for what drives a stake through it’s heart . . . with the DS630BLHV you get the highest quality brushless motor, with theirs you get an inexpensive coreless motor. What!?!?!?

Specifications – in detail

Yes, all this to reach the heart of the matter and learn their servo uses a coreless motor. So here’s the deal. What often happens is guys get wrapped about the axle with the performance-specs and fail to notice-component specs.

So someone whose focus is on 600oz-in and $100 misses the crucial detail the AccuTORQ 600SG comes with a coreless motor. Us? Once we get to a certain stage, we go for the good stuff, brushless motors!

It’s similar to how inexpensively made private label servos give you a few lines of specs, and call it done. They share price, torque, and speed, usually at two levels of voltage, 6V and 8.4V. That’s pretty much it. Is this enough? For some? Yes . . . but not for the savvy.

Why not? Simple, because the highly experienced modeler studies specs just like professional engineers speccing a servo for a $100k UAS do. They delve in and absorb the specs through their skin!

Let’s eyeball, of what the five columns in the first section inform us.

5V

To begin, believe it or not, there are projects which continue to rely on 4-cell NiCd packs. Legacy applications that have been flying missions for a decade! Don’t laugh, they’re a very mature technology, and reliable, so they keep being produced. We proudly supply the servos.

6V

Similarly there are applications using 5-cell NiCds (or NiMH, which are virtually the same voltage level packs). So these two voltage levels correspond to the 1st and 2nd columns, 5V and 6V.

6.6V

The middle column, 6.6V? That correlates to a 2S LFP battery pack. Bit more expensive than LiPo but really easy to live with.

7.4V

4th column? That’s the real world for a 2S LiPo and LiIon.

8.4V

And the 5th column? Fully charged LiPo – but this absolutely doesn’t reflect reality – at least not for long. However, it is where synthetic current often operates, generated using BEC-circuits, so we tell you want to expect performance-wise, from this, also.

With a ProModeler servo you get in-depth details. Exhaustive details. Honestly? Maybe more than you want – but – our military and civilian contractors want them, so we make them available to modelers, also.

So if you notice ProModeler specs seem over the top, there’s a reason. That, and we can never predict what a customer wants to know.

For this reason you get the specs not for just two voltages but for a wide range encompassing five levels. And you get loads of other details too.

These include control frequency, range of travel, even details regarding the gear ratio. The other guys? Hah!

Next, let’s touch on the motor which drives the servo.

Servo Motor – brushless

So now let’s get down to business and discuss the servo’s motor. This is the heart of any servo and if you look in the 2nd group of the specs, third line down, the motor description is brushless.

As I mentioned, our competitor, the AccuTORQ 600SG uses a much less expensive coreless motor. Honestly? Compared to a brushless, it’s no contest because the brushless motors lasts 5X longer.

Moreover, brushless motors (by definition) don’t generate dust from the brush particles as they decompose (due to use, se.g. parking on the commutator ring). Means brushless motors operate cooler, too because there’s no brush build up or heat generated by sparking.

Cost more money? Oh yes, that they do. Worth it? Oh Hell yes!

Don’t know squat about the subject of the motors within servos? You’re not alone and we have this white paper to help guide you!

Read all of this and you’ll become the expert in your club, I promise. Here’s a link to the article. Maybe read it when you’re on the throne!

• About RC servo motors

So the kicker in all this is their servo is priced right in there with ours, like really close, which on inspection is ludicrous. Like even if you ignore the better construction and quality of the ProModeler servos, just in light of being supplied with a coreless versus brushless motor!

Bottom line? It’s our opinion this is an inexpensively made, private label import. And while it’s dressed to kill in an all-alloy case, complete with sophisticated multi-finish surfaces, which admittedly look fabulous, when you look under the hood it’s rather less than impressive.

However, you know what they say about opinions, they’re like belly buttons in that we all have one. This is ours. Real question is, however . . . what’s your opinion?

Intangibles

It’s hard to know what matters to someone. All ProModeler servos give you soft start. Soft star means when avionics power is applied to the system, if a servo isn’t centered, then it slowly moves into position instead of doing it with a bang.

It’s far more gentle on surfaces and looks neat, also. Does this matter? If so, then give us another point (we’ve run it up so high I don’t even know the score).

Closing

So all that’s left is to say is this; we’ve tried to be fair in this presentation. Don’t think we have been? Call us out.

This matchUP has pitted the AccuTORQ 600SG, which is a perfectly decent import priced at $100 against a ProModeler DS630BLHV, which goes for an extra $20. Which is the better of the two? That’s your call but unless your money grows on trees, we believe this decision is something of a no brainer.

Bottom line? Our focus has been on helping you compare and contrast the two servos. The point being, since you decides which servo offers you the most bang for the buck, it means you need enough information. Like not just how it specs and costs, but for how long can a reasonable man expect them to deliver said performance?

We’ve principally brought up issues, which color our perception of the build quality, and those which affect durability. Your take may be different, and we accept your verdict. What’s more, if you think the AccuTORQ 600SG servo is a better deal, please clue us in regarding why because we’re open to learning different viewpoints.

Finally, if you have further questions, reach out, we’re here for you via email: info@promodeler.com or by phone: 407-302-3361