[TTalma]

I use a timing belt on my 4th axis. Last night I noticed it moving a tiny bit while making a cut. I messed around with it a looked at a bunch of things before I found the problem. The belt "teeth" (Not sure of correct names) are slightly smaller than the "teeth" on the pulley, This allows it to move back and forth.

Is there a belt/pulley combination that I can buy that will eliminate the backlash or reduce it?

I am using a 270oz stepper motor and am using a 16 tooth pulley on the motor and a 48 tooth on the 4th axis shaft. I am using the pulleys to gain a little accuracy. Is there a better way to make the 4th axis?

[machinedude]

there are a few different series of timing belts and pulley's the GT series seem to do the best with backlash from what i have seen in the documentation. the HTD series are good too just not as good.

this PDF has a lot of good information about timing pulley's

[peteeng]

Hi Talma - What belt series is it? The best belt section for location purposes is the ATL series. This is a zero gap version of the AT series. The AT series is the "advanced" T series that is mentioned in prior pdf doc. Even though one tooth may have a small clearance if the belt has enough wrap on the pulley it should have no play in total if tensioned correctly. So perhaps a bit more tension will solve your problem. cheers Peter

[ger21]

Is there a better way to make the 4th axis?

Harmonic drive or zero backlash planetary gear box.

[TTalma]

I did some quick reading, and it looks like a Harmonic drive is the way to go.

Does anyone make a 4th axis that can hold a 100mm (4") chuck that is $500 or less?