timing belt reduction

[drwc]

I have converted a prazi 400 mill to cnc with flashcut stepper drive,using 4:1 timing belt speed reduction on steppers.This gives a max feed rate of 8 in per minute. I have stock acme threaded screws. I went with the 4:1 ratio to give greater positioning accuracy and greater torque at low speeds but clearly rapids are limited by slippage to 8 in per minute.What do you all think ,should i have gone with a lesser ratio? What would be the best compromise between speed and torque?

[2muchstuff]

You should not be having any slippage if you are using timing belts and pulleys. Is the slippage due to the belt jumping on the sprocket. Do you have enough belt tension. What size/ pitch belt are you using.

[Splint]

Are the pulleys securely fixed to the shafts?

[Idle hands]

Assuming there is no slippage, what stepping do you have? "Drivers are available in full-half step or micro-stepping versions"? What is the lead on your screws VS the max RPM of your output shaft? Hope any of this helps, good luck with it.

[drwc]

sorry, slippage is the wrong term, the drives lose steps and accuracy ,i presume due to torque fall off at higher stepper motor speeds.

[ger21]

Try gearing 2:1 instead.

[JFettig]

You might even want to try 1:1 direct drive. The stepper motors highest torque comes from the lowest rpm and drops off quickly after that.

It also depends on stepper size and size of the machine.

Jon