Option for Higher Torque Stepper Motors Options for Elite Series Machines

There are numerous accounts on the internet of noisy / rough running motors when running both X and Y axis at the same time. Numerous accounts also reference a degradation in quality of cut. Some of the discussions on solutions to this is to increase the resolution from 400 to 800 on the motors but this apparently had a great impact on torque of the motors. Just as there is an option for a stiffy rail and a different mount for the router, have an option of a higher torque motor.

I have not seen any reports of reduction of torque when adjusting from 400 to 800, I am looking at doing this and asked the forum in another thread if there have been issues and have not gotten one negative response, Curious where you see this, on this forum or FB?
Pat

I think the discussion is based on the idea that when increasing the number of micro-steps per full step, the incremental torque per step drops off dramatically.

Whether this results in a noticeable change in performance with an Elite CNC - between a Masso motors 400 vs 800 setting - would depend on many factors.

I do not know of anyone who has done any quantitative testing of this.

I was reading this on the FB user group (the unofficial Onefinity user group). I was ready to order an elite machine until I saw some of these posts. Mind you there seem to be many happy customers so can’t be all bad but quite a number of negative responses on motor noise when both x & y run simultaneously and would hate to spend over $6k (cdn) to have a machine that appears to have quite a bit of noise and some accounts say chatter.

I have not changed my settings but probably will but I do not experience any noise that you mention here, might have to do with certain Gcode with way too many nodes in the vectors, this can cause what you describe.
Thanks, Pat

Very good to hear that you are not experiencing the same thing, to me that means there must be some differences between machines. I do not have one, would love to buy one if I can be assured I won’t end up with one that has the same “problem”. Based on the videos I have seen/heard, the noise is evident when following a circular path when doing an air cut. The people seem to be quite CNC knowledgeable so I do not think it is a path with excessive nodes.

The likely source of the “problem” is not the machine but the way the program is being generated - if curve is made of thousands of individual points in CAD when exported to a g-code program it will have thousands of moves that could be only a few thousandths of an inch at a time causing the noise that is reported. Reducing the number of points (nodes) in the curve can alleviate the noise issue without sacrificing precision.

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The only documented way people were able to improve the situation was to increase the resolution to the motors from 400 to 800. I can’t tell you for sure that your theory is correct or not, but from the many postings listed, I believe people would have tried this first. Many people have been able to re-create the problem by air cutting a circle. I would think a circle would not by default have thousands of nodes vs more complex shapes.

Whether you are cutting air or wood makes no difference, I have seen the node count on circles very high, made up of hundreds of very short lines. I made a model in F 360 of a rolling pin revolved around the centerline, when I machined it it was cylindrical but with dozens of facets, flat spots, no where near cylindrical.
Just my 2 cents worth.
Pat

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I’m confident I recall people duplicating this on FB just by jogging the machine, so while the theory of excessive nodes is sound, that’s not likely to be the cause of what these people observed.

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After making that change have they then reported the torque of the stepper motors is insufficient?

That is an interesting question.

What would that look like/how would they determine this?
How would it be quantified?

I ask these as serious questions that add on to what you are asking.

I would expect not, so long as the speed is set to match the original RPM. Which is what the results of the testing TMT linked to in another thread demonstrates (here: Elite Machines low motor resolution - #12 by TMToronto)

IMO, I’ll summarize that testing like this: The torque curve is the torque curve. That means you’re not going to change that curve, which show the characteristics of the motor, by changing its pulse frequency. The torque curve is the torque curve.

That is what I would suspect as well, there’s a few parallel threads here theorizing that there’s a problem where one hasn’t been reported. 0.5Nm of torque in a 50% efficient conversion (which is low for a ball screw) with a 16mm pitch is going to deliver around 140Nm or 30 lbs of force at the tool which is sufficient for the typical chip loads. In the event it is not sufficient, the closed loop feedback will attempt to correct the deviation.

In those torque charts we’re going to be running in the sub 250RPM range (250 RPM = 4000mm/min) so the exponential loss in torque above that really doesn’t apply.

I’ve asked a number of people who made the change that same question. No one has answered that it has, most people who made the change have commented that they do not notice any difference but numerous people (with experience configuring stepper motors) have stated that by making the change from 400 to 800 has the effect of decreasing the torque substantially. One of the people making that statement that this impacts torque substantially was the tech support from Onefinity. I’d like to pose the question to Masso tech support.

I believe what those with experience are saying, but unless there is any data provided to support their claim, it remains merely an qualitative observation and for me personally carries less value. I would like to see experiments done, but as I asked earlier, how would this increase or decrease in torque be measured.

At the same time you reach out to Masso support in their forum, I would also ask Onefinity for the data they collected that supports the statement that “making the change from 400 to 800 has the effect of decreasing the torque substantially” (and by data I mean from testing done with their actual machines).

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I agree with your statement of data is really the only true answer.

I did get a response from Masso (they were extremely quick to respond). They said the change in resolution from 400 to 800 should have no impact on torque at all and their recommendation was to set to 800…so based on that, my original request for higher torque stepper motors really isn’t that important (to me anyway). Wish I would have reached out to Masso first.

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I know you already got your answer from MASSO, but I just came across this thread today, and a few hours later, this popped up in my YouTube feed. It shows the difference on finish between 400 and 4000 resolution. It’s interesting to see. The 4000 looks a lot nicer.

400 vs 4000 stepper resolution

No doubt the 4000 is better but neither is very good in my opinion.
Pat

Thanks for sharing!

I recently set mine to 2000 pulses per revolution and had no noticeable lack of performance or speed.

Instead at a speed 8m/min and 50000m/s2 of acceleration the axis were still moving so violently that my QCW folding table was shaking and skating back and forth on the floor.

This had never happened before with the buildbotics controller.

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