little 4" rotary table won't stay put!

[JFettig]

I've used my little 4" rotary table for indexing and it has been great for that, but as soon as it comes to any milling, even light milling it will not stay put! I stuck a 3/8" piece of drill rod in the chuck and went to take less than .01 off the end to square it up and it imidiately poped out of place. I did this using the standard toe clamps and grade 5 bolts(what I had on hand) and I'm cranking them down so hard that if I cranked any harder they'd probably break(specifically the one I had to turn down to fit under the bed of the table)

Is anyone else having similar troubles? I made a small 3/8" dia aluminum part that I had milled a flat on taking .02" passes and it ended up being .03 off after I milled that. The same has happened to me on other parts that I totally screwed up(using cnc and hogging some serious material) because of this.

Is there a solution to this? I was thinking about taking the 4x1" aluminum plate I have and drilling and tapping the rotary table to bolt it down to it and secure the whole thing to the table with 4 bolts.

Let me know.

Thanks,
Jon

[HuFlungDung]

Key the rotary table to the table. You can accomplish this with dowels or actual keys. This provides the most positive resistance to bumping the rotary table out of position with a milling cutter taking greedy bites out of your part as it enters the cut.

Strap clamps clamping two smooth surfaces together do not gain much increase in friction from the point of being "tight" to "bust-a-nut tight" You would be better to add more clamps or, add a friction increasing substance between the two surfaces. You can thoroughly degrease the surfaces to begin with, but a sheet of wet-or-dry sandpaper might also do the task without too much damage to the surfaces.

[JFettig]

Thanks, I might try that, I'll probably tear it down into components and see if its feasible to bolt it down to a larger piece.


Jon

[BrendaEM]

I wonder if the bottom of the rotary table is flat enough.

It would be interesting to dye or marker the bottom of the rotary table clamp it down, and give it a little tap to rub the dye, and remove the rotary table to see how much contact area there is.

I also wonder if the bolts are close enough to the vice.