Thursday, April 7, 2022

Machining Clamps

I have a tilting table. This is used to put a workpiece at some angle other than flat, say you need to mill a surface that is a 33 degree angle to the other parallel sides. The Sherline tilting table comes with holes for attaching the Sherline milling vise, the rotating table and a variety of other Sherline accessories.

The Sherline milling vise is somewhat limited in the size of the workpiece it can hold.  Worse, it is rather weak in grip.  It is very easy to mill something with enough force to pull it right out of the vise.  The SHCS that locks down the vise also gets rounded out over time.

So I bought this stupendously wonderful and sensibly cheap mill vise from Little Machine Shop:

It is theoretically cosmetically challenged but I cannot find the finish defects.  Perhaps I am easily pleased. 

How to attach the mill vise to the tilting table? The clamping slots are a little higher than the Sherline mill vise.  For use directly on the mill table, I machined some steel clamps tall enough to hold it down in the T-slots.  But the tilting table holds stuff down with threaded holes, not clamps.  

So I made these clamps that go into the slots on the side of the bigger mill vise; they will be held in place to the tilting part of the tilting table with 10-32 SHCS that go into the holes that are not in the right places on the tilting table.
The large mill vise is about 1.8" narrower than the "ears" of the tilting table so the clamps have a limited width in which to fit.  I had to machine the 1"x1"x1/8" angle aluminum to .5"x.9" to fit in the available space.

The next step is to drill and tap four holes in the tilting plate of the tilting table.  It is too large to go into the vise obviously, so I am using the holddown parts that I have never previously used.
The problem is that the minimum height of the spindle is above where I need to drill pilot holes with the center drill. (This doubtless prevents a number of software/user stupidity errors that unintentionally machine the mill table.)

Solution: use a piece of acetal thick enough to raise the workpiece to a sufficient altitude to drill the tilting plate.  While it is probably overkill, I am going to mill the top and bottom to be as close to parallel as I can.  Because this may make the resulting combination too thick for the holddown screws, I may need to locate some longer 10-32 screws.

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