I’m hoping against hope to get this type of ballscrew set up to work, but I’m kinda skeptical because I’ve never used a pulley system before…other than my Ox or 3d printers.
Everything works to a greater, or lesser extent. The question that remains is will it work well enough? Finish it and find out.
Nothing wrong with using pulleys as long as they are sized appropriate for the load and zero backlash such as GT2/3 series.
I have them on my large bench cnc with servo motors 4:1 reduction ratio, GT2 series.
My Z axis on the gantry is 4:1 reduction servo driving a NSK ballscrew.
In some ways using pulleys is better than direct drive. Very good zero backlash couplers can be expensive.
Lots of commercials machines use pulley reduction that handle far greater loads than what your machine will ever see.
Is that a gear reduction on the stepper already? Have you looked at the torque curve for the motors and thought about the speeds you want to run at?
@Paul_Shaw Maybe they have a really lazy twist on their lead screws? I know I typically run at 900 RPM. Though I’ve had my leads up to 2,000 RPM. It gets real over a grand, let me tell you.
Yeah the torque dies on my motors up in the RPM. I have better ones but haven’t got around to fitting. I’m guessing George is going to learn that lesson soon. Could gear back up with the timing belts that’s the main thing I’m getting at. Torque is nothing without speed.
Yes, that’s all new to me. I thought that using a gear reduction would cause less of a chance that the motor would stall on hard materials. I guess not.
@Paul_Shaw For torque at speed you need voltage to sustain current due to the inherent inductive reluctance of stepper motors themselves. I am running at 35 Volts now. Which is a fairly low value. Though as you say some motors maintain torque better than others do. That is because they are low inductance and high current draw to start out with. I run 2 Amp 200 oz/in motors on my X and Y axis. I have a stronger motor on my Z axis. I think it may be 300 oz/in? I forget now. I just know it is different, and a little better than the other motors that I have. It might even be 326 oz/in. That sounds familiar to me. They were cleaning out a stock room where a buddy of mine worked and he gave me some of the junk they were throwing away. That motor was some nice junk to me. It is an Astrosyn. I’m running the Chinese V1.2 TB6600 motor drives. I used to have 6560s. The 6600s are a nice performance bump.
You do have to set the current right on them to get maximum performance though. Too much current is not a good thing either. Stepper motors are so ass backwards. A Pollak must have invented them. To set the current I put an ammeter on one of the phases and I carefully step up to the highest reading I can get on my meter at rest while jogging in tiny steps and then I set it there. It is tricky to hit just the right step. But after a few go arounds I can spot the high point.
This is the good drive https://www.aliexpress.com/item/1pcs-TB6600-4-5A-Stepper-motor-drive-stepper-motor-driver-board-single-axis-controller-TB6600-New/32756389130.html
https://www.aliexpress.com/item/1pcs-TB6600-4-5A-Stepper-motor-drive-stepper-motor-driver-board-single-axis-controller-TB6600-New/32756389130.html?spm=2114.search0104.3.65.4fe7704b9XFgcg&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10065_10709_10151_10344_10068_10130_5722815_10324_10342_10547_10325_10343_10546_10340_10341_10548_5722915_10545_10697_5722615_10696_10084_10083_10618_10307_10710_5722715_5711215_10059_308_100031_10103_441_10624_10623_10622_5711315_5722515_10621_10620,searchweb201603_31,ppcSwitch_4&algo_expid=e9b757dd-5dc4-4bd3-bbcc-adda0c30abaf-9&algo_pvid=e9b757dd-5dc4-4bd3-bbcc-adda0c30abaf&priceBeautifyAB=0
These will be critical questions for my machine and I’ll really need your input. Currently, I have the set up like this: 2 425 Oz-in nema 23 motors for the long axis (I call it my y). A lesser powerful (not sure exactly) nema 23 with a planetary gear reduction, and a NEMA 34 on the Z-axis.
@Paul_Frederick what meter do you use? I have several and my best Fluke 5 1/2digit true rms doesn’t read the current good enough due to the high frequency PWM signal.
I happen to have a Digital scope with current probe. That’s the only way I can get a pretty accurate stepper motor peak current reading.
@Paul_Frederick I have 2 of the TB6600 drivers for the NEMA 23s and a DMT542T for the NEMA 34. The DMT542 was designed by Stepper online, but manufactured by leadshine.
@Jim_Fong I use an analog meter. I have the same problem with my air cooled spindle run off a SMPS. Analog meters deal with PWM. They average it right out.
@George_Allen you have the v1.2 TB6600 drives? There’s a few different drives that use TB6600 drive ICs, or say they do. I bought one drive that has some kind of a surface mount IC on it, but it says it is a TB6600. I don’t know what it really is. That drive still worked OK I guess. But I did not like it as much as v1.2 drives. What’s funny is that one bogus drive cost more than v1.2s do.
It is a different type of the one you have. I bought it off amazon from “my sweety”
@Paul_Frederick can’t recall the last time I pulled out the old radio shack analog. It’s somewhere in my closet full of old junk equipment. Yes they are good for that type of readings.
@Jim_Fong I kind of collect analog meters. So I have lots of them.
Yeah the 425oz 23 motors are very high inductance and you loose torque bad with RPM. What drives are you using what’s the pitch of your screws? I found some nema 24(odd size 1mm bigger than the 23 main thing was the reduced inductance and they have a higher current rating so less windings basically, Lower back emf gives much flatter torque curve.
@Paul_Shaw some people do get hung up with holding torque when running torque is what is needed.
@Paul_Frederick exactly it’s going to stay still well 
@Paul_Shaw yeah but they don’t call them motion controllers for nothing.