Carbide Compact Router max power, max torque and torque curve

I’m trying to figure out the Carbide Compact Router’s max HP/torque and torque curve for HSMAdvisor – hopefully this data is useful to GWizard people as well – and want some feedback or another set of eyes. Here’s what I have:


  • Specs are identical to Makita RT0701c
  • Constant torque router
  • Max power per Makita specs: 1.25 HP (932.12W)
  • Max amps per Makita specs: 6.5A
  • Efficiency (assumed): 90%
  • Power factor (assumed): 90%
  • Real-world max power: 0.847 HP (631.8W): 120 * 6.5 * 0.9 * 0.9 = 631.8W

Therefore, we have:

  • Max power: 0.847 HP (631.8W)
  • Max torque: 0.1392 ft-lb (0.1887N-M): 0.847HP / 32,000RPM = 0.1392 ft-lb

And since the router is constant torque, we have enough information to derive our torque curve (with only full stops on the RPM dial):

RPM Power (HP) Torque (ft-lb)
10000 0.27 0.14
14000 0.37 0.14
18000 0.48 0.14
23000 0.61 0.14
27000 0.72 0.14
32000 0.85 0.14

*Ignore the rounded-up, barely over-spec power/torque values in the table. That’s HSMAdvisor rounding things off.

Any thoughts or corrections to help nail this down would be a huge help. Thanks in advance.


I will be very surprised if @gmack does not reply with a great answer to this.
(no pressure, Gerald :slight_smile: )


That would be really cool and useful. But all of those AC routers likely have series wound universal motors, so it won’t be that easy. The only info that I was able to find for them when I looked into it years ago is in this folder Suhner (568.9 KB). It’s higher power and likely more efficient, but maybe it’s performance could be scaled with reasonable accuracy. Please go for it (submariner?)!


Hey @gmack, just a quick follow-up. I’m over my head wading through the AC motor stuff so I might still have some things wrong, but the Wikipedia article on Universal motors says this on series wound:

The speed-torque characteristic is an almost perfectly straight line between the stall torque and the no-load speed.

I built my table using a straight line. It sounds like you think it’s not in fact straight or there’s a mystery factor unaccounted for?

Also, from the same Wikipedia article:

[T]he torque rises in proportion to the square of the current since the same current flows in both the armature and the field windings.

The Suhner chart shows a linear increase in torque with respect to current, though. It turns out motors are complicated beasts. Can you provide a bit more color on these two points on what I’m missing? Sounds like you’re the resident expert on this 'round these parts. Thanks for weighing in.

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I’m no expert - so I don’t really know, but maybe the efficiency, power factor, shaft mounted fan, and/or other losses flatten the torque/ router input current curve? I don’t know the origins of the curves, but they look like measured data to me.


Turns out that’s a pretty good question and it seems that the Wikipedia article is a little short on punctuation, or a separate paragraph to indicate what that sentence refers to.


“However, universal motors are usually relatively inefficient: around 30% for smaller motors and up to 70–75% for larger ones”

Yuck, the more I see the better the battery powered BLDC alternatives look

But back to the current / torque characteristics, there are several consistent torque speed curves I’ve seen, here are a few;

All of those seem to be consistent with the torque being proportional to the square of current and reducing non-linearly with motor running speed, for any given speed setting in your speed controller

There are various methods of speed control, from series resistances through noisy triac choppers to microprocessor controlled PWM and fiddling with field windings, I think the linear torque reference in Wikipedia refers to the linear reduction in torque with linear reduction in speed as the effective voltage is changed by a speed control mechanism, see this on Quora

As gmack says, it’s a lot more complex than just the underlying motor characteristic, apparently universal motors need friction to avoid self-destruction through speed overrun if run completely unloaded, they’re horribly inefficient and they have large cooling fans which will absorb power approximately proportional to the cube of the rotational speed.

So, if what you’re looking at is “available torque at a given speed controlled speed” then it’s quite likely there’s some underlying linear relationship.

If what you’re looking at is “how does the motor torque change as I slow down the motor with applied load at one set speed control point?” that’s not likely to be linear.

It would seem that the table you have is referring to a variable voltage (effectively) speed control.

Does that make any sense?


Eldar Gerfanov says: “There probably should be a “Max cutting force” value in the machine profile. I will add in the future updates [to HSMAdvisor].” (see the pinned comments). Most/all CNC gantry routers are limited by rigidity (hence cutting force) rather than spindle power. If he follows through with that, HSMAdvisor would be much more useful. Maybe some added encouragement would help?

But, it would be really good to be able to estimate cutting forces from measurements of spindle power and/or current. :slightly_smiling_face:


Appreciate the links, @LiamN. It’s a lot to chew through and will take a while to sort out, but enough to get me on my feet. The possible 30% efficiency made me cringe as well. When I searched high and low for router torque curves and didn’t find much info, I should have known I was in for treat.

@gmack I certainly plan on bugging him. I think there’s an added problem for aluminum machines of not only rigidity, but also vibration. And having taken a class on vibrations in my school days, I wouldn’t wish those calculations on anyone. For our rinky-dink desktop machines, it’s a testament to their design that they’re as versatile and performant as they are.

I guess that’s Router Bob’s argument for steel, but the aluminum machine’s performance shown in that YouTube link was pretty impressive, as is a lot of the stuff that @Vince.Fab has done on Shapeokos and Nomads.

And there’s lots of things that can be done to make Aluminium damp vibration, like filling it with epoxy granite etc. This is done to cast steel machines as well. A combination of materials is commonly used where you want to get a mix of properties, check out the excellent loss-coefficient by youngs modulus chart on this page.


I think the TLDR is that the router, at 100% speed has a ‘normal’ torque curve where the torque is zero at max speed (so, 32,000 RPM) and the torque is max at stalled zero speed (0.14 ft-lb) with that characteristic curve inbetween those points.

Then, as you turn the speed down in a simple voltage controller you would lose stall torque by dropping the voltage, however, this assumes no feedback and simple voltage control.

Did you have a source for the torque being constant at different speed settings on the router?

Also, discussing with @gmack has led me a lot of reading about the various types of motors and their power input vs. output. It seems that the common power tools may be rated for power input (if the spec says things like “input wattage” whilst things like the VFD spindles are rated for shaft power output and take quite a bit more input power.

The upside of the horrid efficiency numbers is that apparently they get better as the motor goes faster.


That seems to be the case on your side of the “pond” too. The AMB Kress 1050 claims
“* MAXX-Power 1050 Watt motor * Effective power 560W”. Unlike horsepower, Watts are appropriate for use for output power. For whatever reason, universal motors in things like routers, shop vacuums, etc. here claim “Peak Horsepowers” and make no claims of real “Effective Power”.

Those trim routers have hall sensors that they use for speed regulation when the load changes.

Sounds like a diy rc motor dyno project.

One of my machines has sand filled extrusions, +20 pounds on an S3. Imo knocks the edge off that high level vibin.

That could be a real money maker. Nothing is available commercially that’s even close to being affordable. You and @LiamN/others should get together and do it!

That’s probably one of those awful EU regulations that Britain voted to take back control to get away from…

That then would be quite the opposite, if there’s active speed control then the ‘natural’ speed / torque curve of the motor sets the upper bound and the controls will operate within that curve, what does your rpm / torque power calculation fu say about the 32kRPM and 14 lbs ft of torque as a power? Is it feasible within the Wattage of the motor?

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I’m not sure what you’re asking, but 1.25 peak HP (932 peak Watts) at the router’s maximum 30000 RPM would be 2.63 in-lbf. The rated 120V @ 6.5 A input would be 780 Watts and I guess you could say 1560 Watts peak? This downloadable calculator makes power and unit conversions easy for those of us still stuck with “British” units.


Ah great, link followed,

I can’t remember how to do the power calcs in my head for SI units so…

And I should have re-read seawolf’s original post properly too, now I see that the calculation was back from the motor rated performance and not taken from a manufacturer motor spec, sorry.

There will be, somewhere, a vendor torque curve for the motor used in the Carbide router, but we don’t have access to that.

I think the calculation is a reasonable assumption, although I’d probably pull the assumed efficiency down to something more like 70%, I have no idea what the PF would be for this type of motor so I’m not going to argue with the assumed value.

Looking at the EU equivalent product Makita states 710W power input (rather than amps).

It would appear that the no load speed of the motor is sufficiently higher than the stated 30,000RPM to allow it to have a substantial torque even at that ‘max’ speed, this is similar to what the folks on the Brushless Makita thread have found with the DC version, it is apparently common with Universal motors to have to regulate the top speed so that’s consistent.

As you say, it’s being managed by an electronic speed control using a hall sensor then it’s reasonable to expect the motor to be able to deliver at least the same max torque at a lower speed.

Did you look at the info that I posted for the 1050W? Suhner router?

Yes, thanks,

That looks a lot like the Kress spec wise, the input and output power suggests around 70% efficient which is consistent with our expectations for high speed universal motor.

Was there data on the torque curve in there that I managed to miss?

Did you see the jpg?