dialing in a 4th axis?

[RP Designs]

I finally got around to finishing wiring up my rotary table and rough set-up of the parameters but I will need to dial in the table for accuracy and It occurred to me, that I don't have a good procedure for this. So how do you guys check angular accuracy of your rotary axis?

[HuFlungDung]

I have never checked, I only assumed it was accurate enough for my purposes: if there is very low or zero backlash in all positions of a worm drive table, and no tight spots/loose spots, then its good. Anything less than an almost perfect gear will not operate with low backlash as you will have to give the worm and gear enough clearance to get past the tight spots.

Now if this is not good enough, then you probably should not have built a rotary table with gears of unknown quality. To do better, you need accurately hobbed gears and ground thread worms that have verified runout that is less than your specification.

[jess fuqua]

Tram it in, up and down left and right.
After That Put somting in it thats flat.
Indecate it in at 0 then rotate you 4th 90 degrees and see if its still 0 on the indacator.

[RP Designs]

I have never checked, I only assumed it was accurate enough for my purposes: if there is very low or zero backlash in all positions of a worm drive table, and no tight spots/loose spots, then its good. Anything less than an almost perfect gear will not operate with low backlash as you will have to give the worm and gear enough clearance to get past the tight spots.

Now if this is not good enough, then you probably should not have built a rotary table with gears of unknown quality. To do better, you need accurately hobbed gears and ground thread worms that have verified runout that is less than your specification.

It is an old Haas 4th axis that looks like a converted Rotary table, bought off ebay. Everything feels pretty solid, just want to get the control dialed in

[JBON440]

Sweep in your radial axis of table with coaxis indicator using spindle then rotate table. Should be zero-ish. If you have 5th axis: align the lateral "Z" to tilt and repeat "XY"/radial.