pulley help!

[DrStein99]

I'm developing a machine that uses pulleys. Using "XL" series belting, 3/8" thick, i have stepper motors with 1/4" shafts; and 30-tooth pulleys.

I made my own linear bearings, and they ride in aluminum-etrdude. (this design is actually a work in progress).

So, as the "kart" slides along the rail back and fourth, an idle pulley on one-side and the motor-drive pulley on the other. The rails are 36" long.

Sounds easy? yes?

Anyway. I'm finding that the motor locks up when I high higher speeds, or if I tighten the belt too much. I never worked with belts/pulleys before, the machine I made in the past is a cnc-router, that uses leadscrews.

I was wondering if anyone had any links, or tutorial links on designing a machine to use pulleys driving with long belts, thanks.

[ViperTX]

Well generally steppers are directly coupled....in your case the stepper is much too small to overcome the torque reflected back to it.....checkout http://www.sdp-si.com and request their catalogs.

[DrStein99]

I just re/ordered pulleys from that site; mcMaster sent me ones that were off-balance and wobbling.

I had them send me catalogs; what I got was something the size of a large bible with equasions big enough to cause a headache. Far from a friendly tutorial.

[2muchstuff]

Yep, that's the one. Don't worry,there are more parts than formulas. They do a good job of explaining the formulas and breaking them down into little pieces.

[DrStein99]

I think viper is right; my motors might be underpowered. I think they are 38-oz holding. So I'm probably at my max speed now. Its kinda fast, like as if you were to gauge the pace on someone's arm when painting a house with a paint-brush.

I was looking for something like the speed of "OMG how in the world does that thing move back and fourth that fast?" style.

[unterhaus]

You might run into problems with the belts if you are at OMG speed. The problem with really high speeds is that you either are going to have to move to bigger step sizes or step multiplier, hardware step generator, or analog servo drive. There is a limit to how fast you can drive a parallel port which hasn't been increasing significantly with the clock speed of computers.

If you can handle Linux, there are many options with EMC. Under windows, you're pretty much stuck with Mach, although Mach in combination with the new GRex from Gecko should get you up in the omg step rates.

[DrStein99]

unterhaus; you are quite right. I am using mach-2, in windows - and tested 150 oz nema 34 steppers.

It definately moves at OMG speed now. I can even take the rail and run it vertical from ceiling to floor and have it climb and descend at high speed too.

Nice to be able to have the power and just work on balancing the distribution instead of struggling to get more power - this is good.