Rotary table use

[Mr Ron]

I'm trying to clamp a piece, 4-1/2" wide to a 6" diameter RT. There is no room for the usual nut/stud/clamp/step block setup. I know toe clamps would work, but aside from they being expensive, I don't possess any. Any ideas?

[BadDog]

Make some long cantilever t-nuts to extend the table? Just be careful of forces that may break a chunk out of the table due to the localized load (fulcrum) and extended leverage.

I've also seen tooling plate used to quickly make a larger work surface on smaller tables. But that could get a bit expensive, particularly for pieces over 1/2" thick, but I've seen it up to 2" thick ($$$). If you have a surface grinder you could make it from steel, or if minor imperfections are acceptable, with a fly cutter.

If possible you might add holding features to the part itself. Counter bored holes in non-critical areas allow bolting on with t-nuts. If pockets and shelves are acceptable along the perimeter, that could allow for custom strap clamps, or maybe even bolts to t-nuts.

Maybe glue or double-sided tape if pressures are not high, and/or not oriented to apply too much shear load against the table with low/no force lifting the part from the table?

[Russ Hanscom]

Make your own clamps. I have made several styles of short clamps for the exact purpose you describe. Remember that we have the tools to make the tools to make....

[RSG]

Make some long cantilever t-nuts to extend the table?

Good idea BadDog

extended t nut by Ron gradner, on Flickr

[Mr Ron]

After giving this some more thought, I finally came up with a solution. I did it and it works just fine. I used a T-nut, stud and nut and a short clamp with a custom made spacer. By angling the clamp, I was able to securely clamp the piece to the RT. In such a situation, I was not able to use the step blocks as they would have no place on the RT to sit. Using a 1/4" end mill, I was able to make a 3.500" diameter cut in 1/2" thick aluminum plate, but before I could complete the cut, the belt on my mill broke, but I am well on my way of making this clamp. I set the X-axis stops so I can limit travel from zero to the 3-1/2" perimeter. I will try to take a picture of the setup and post it. Thanks for your help. As the old saying goes; "there are many ways to skin a cat".

[Mr Ron]

In lieu of a picture, I made a quick sketch of the setup.

[warmstrong1955]

Not sure what you are doing, nor the precision you require, but I have machined 14" and larger parts on an 8" rotary table.
Some, I just drilled a hole in the center, and others 2, and even 4 holes to bolt them down. Depends on how aggressively I needed, or wanted to mill, and how flat the plate was.

When the milling was done, I just welded up the holes. In some cases, I needed one or two anyway, for sight gages. Most were hydraulic & fuel tank clean out covers, and some filter covers, so not a great degree of accuracy required for an o-ring groove, or grooves, or mounting for a bypass valve.

Just a thought.


Bill

[Mr Ron]

Put a new belt on the mill and continued milling. I now have two clamps made that both read the same bore diameter. I'm learning as I go, but I'm running out of time.