Phil, input voltage affect torque at speed on steppers. Rotational torque decrease as RPM increase, this is why a stepper eventually stall when you go faster and faster. With higher voltage through the driver, you can give the stepper more power (V*A) hence the torque fall-off happen at higher RPM.
1 Like
https://www.geckodrive.com/support/step-motor-basics.html
https://www.geckodrive.com/media/wysiwyg/Support/Step_Motor_Basics/Index/SMBFig2.jpg
1 Like
That was some informative reading material. I felt like I was in school again but actually enjoyed the topic. I did skim the math cuz the teacher wasn’t watching too closely.
And that’s where the steppers torque curve comes into play. Your stepper doesn’t have a published one but this one can be used for reference:
Notice at 75 RPM and 24V, it’s only at 140 N-cm which is 198 oz-in. 75 rpm on standard belts is 118 ipm.
Your 9mm belts is probably even lower rpm so you maintain higher torque but it’s still not close to the holding torque.
The Z axis is even worse as 75 rpm on the microcarve would only roughly be 50 ipm.
So at the cutting levels and speeds etc that the Xcarve is capable of, the idea of high RPM may only come into play on non-fast Z axis motions. The X and Y should maintain a good amount of torque BUT if you were to double the drive voltage, you’d probably maintain close to full holding torque at the low RPM range of the Xcarve.
1 Like
So what determines the machines acceleration capability? Torque? Torque at speed level x? As that’s the one setting that in the end determines cut time.
Acceleration is primarily a power thing but the timing quality / drive algorithm of the step driver greatly affect performance 
Acceleration is ability of the stepper to overcome the back EMF. It’s a function of the driver and the drive voltage to overcome that effect.
The higher the drive voltage, the quicker to overcome the effect.
At least that’s my understanding.
1 Like
In an acceleration limited system, that’s correct.
However, you could probably increase acceleration with a better matched system but then you’d run into rigidity issues with the structure.
Your aluminum plate and Y supports would help.
1 Like
Yes, up to a certain RPM point you have full torque available. My understanding is - the threshold is where the intended speed * torque fall off total power capacity of the driver which is governed by voltage * amps. Say 25V and 2A current limit.
50W power is 50W power and if 50W is required to do 50IPM at 200oz then anything above that is where you trade torque for speed.
If you dont do any carving higher than 50IPM then you dont need more power, but if you are intent on doing 200IPM and need 200oz then change is required.
All numbers are arbitrary BTW
But all out speed isn’t the holy grail either, at one point is is better to improve system rigidity so one can go deeper with higher quality/precision. MRR is what counts when time is money 
But you got a DEMON that rock your boat! 
My own “Demon” isn’t my weak link
2 Likes
Did I order the right parts? And did I miss anything?
1 Like
Thanks. Appreciate it.
1 Like
Is this right? Looks different.
Aideepen Proto Screw Shield Assembled Terminal Point Prototype Expansion Board Opening Source Reset Button PCB Bareboard D13 Universal LED for Arduino https://www.amazon.com/dp/B01JFQQXRS/ref=cm_sw_r_cp_api_oj9YAb1B9ZZ06
I lose out on not needing to solder so less practice. Oh well.
I’m gonna reread your blog on the controller to familiarize myself with the wiring.
1 Like
Is my understanding correct, that if I provide the power that the stepper truly wants I can fully utilize its torque rating?
Yes, at speed.
A given amount of voltage multiplied with the current setting provide an overall power capacity. The power translate into torque and speed. At one point the torque and speed combined require more power than supplied, this is where torque start to taper off.
Increase in voltage raise the power capacity therefore push the torque taper point to higher rpm.
With increased voltage there will be a net torque increase from the taper point, throughout the rpm range.
As per the graph Justin posted 
The wiring is really simple, but start with a single driver and get that done first. The others are basically repeat. I didnt use a shield like Phil did and felt a bit intimidated before I sat down and got dirty with it.
Thanks for the advice. Wiring I’m familiar with as I work them professionally similar to @PhilJohnson but not even close. Lol.
Follow up question what’s the formula for figuring out rpm to $110 max value?
If I want to set my max rpm (4K) as my max speed what’s the formula to figure that out?
Based on the leadscrews I use.
Then multiply per stepping?
Oops I meant divide.