Question on Rotary Table

[zwdeal]

I have just converted a 4" rotary table, purchased at Harbor Freight for $99. But it has a huge backlash, as much as 1/5 of a turn on the "handle", this translates into 2 degrees on the table itself.

Is this useable? What is a better rotary table? Is Phase II 4" one good?

Thanks.

[Al_The_Man]

Try and pick up a Yuasa, one of the best in R.T's
Al.

[Geof]

On some low cost rotary tables the screw is mounted in an eccentric bearing housing which can be rotated to move the screw closer to the gear and reduce backlash. Does yours have this feature, you may be able to adjust it.

[zwdeal]

Yes, it has a set screw on the side, but I have tightened it to the point that it could not be done any more. It helped a little, now backlash is down to about 1.5 degrees for the table itself.

I am supperized that this R/T is made in India and has such poor quality. I openned it up, the inside tube is rusty, the T-slot finish looks like some kid carved it with a knife. The bottom bearing housing (not bearing itself however) was rusty, too. This is supposed to be BRAND NEW from HF.

I will disassemble it and try to put it back together. I think I am going to use it for my object movie photography, not for machining.

But thanks for your info.

[Al_The_Man]

This is an example of one I picked up on ebay for $120.00, silky smooth and no detectable backlash.
Probabally cost $600+ new.
Al.

[zwdeal]

I probably should have bought an used one. I read at "mini-lathe.com" that these are very bad R/T's. I bought that one on HF web, for some reason the mark -- "india" was erased on HF web's photo.

Thanks for the info. I will keep an eye on eBay to get a Yuasa.

[HuFlungDung]

Many of those cheap rotaries have very little in the way of thrust compensation on the worm screw, as in a shoulder bears against the main casting body. You might be able to figure out a way to make a precision shim washer or something to fill any gap present and it may make the thing more tolerable to use.

[dfurlano]

I retrofitted a Phase II 4" table and it has no backlash. But I also added thrust washers behind the handle nut.

Dan

[impact]

Is something like this any good?

[zwdeal]

OK, I will get Phase II 4" R/T then.

On my conversion, I actually added a thrust bearing bought from McMaster. It is hidden inside that front mounting plate which is 1/4 inch thick. I have no complains at "handle" part, no backlash as I was really carefull. It is the gears engagement section that has all the backlashes.

[zwdeal]

Originally Posted by HuFlungDung Many of those cheap rotaries have very little in the way of thrust compensation on the worm screw, as in a shoulder bears against the main casting body. You might be able to figure out a way to make a precision shim washer or something to fill any gap present and it may make the thing more tolerable to use.

I think the one I got does have thrust bearing instead of bearing against the main casting body. I believe it is the worm and worm gear (if I used the terminoloy right) that generates all backlash -- I can feel it, when I turn the coupler by hand, there is always this "free" zone, then I can feel that the gears are engaged.

Anyways, I just tested it out, it seems to be pretty good at handling vertical loads, I think I put about 50 lbs on it, with my 50 oz-in unipolar stepper, it runs smoothly. So I will use it for my photography hobby :-)

[zwdeal]

Originally Posted by dfurlano I retrofitted a Phase II 4" table and it has no backlash. But I also added thrust washers behind the handle nut. Dan

I will get that one as soon as I save enough money for it :-) I added a thrust bearing on my conversion, it is inside the first mounting plate.