My Vise Problem

My Vise Problem

Yes, that's "vise" with an "s" not a "c".

I mentioned a while back that the mill vise that comes with the Sherline vertical mill just doesn't hold objects tightly enough (especially if they are made of Delrin, or are very tall relative to their width) to machine well. There are a number of other mill vises out there, but you pay quite a bit to get just bit more capacity.

I found a solution, lying around the shop. I have a 4" drill press vise--one of these cast iron things that Harbor Freight sells. Okay, they aren't going to spectacularly accurate, but for the bigger items that I need to mill, I can settle for coarse machining, then use the mill vise to remove the last ten or twenty thousandths of an inch more accurately.

And was I mistaken. I discovered that the flanges of the drill press vise, where you bolt them to a drill press table, were exactly the right height for the Sherline mill vise hold down clamps to grab. And then I took six 1/4" thick pieces of Delrin that I use for the ScopeRoller 11 units, and decided to get them all the same width. I had cut these on a chop saw, and they were pretty close to the same width and length--but I could immediately feel that they were at least .010" difference in dimensions, sometimes considerably more than that. I figured that using the drill press vise wouldn't be thousandths of an inch accurate, but at least better.

So I put them in with a spacer to take care of a dip at the edge of the vise's bed, and ran a flycutter across all four edges at once. And wow. When I was done, all six pieces were square within .002". And five of them were within .002" of the others on dimensions. (The sixth one, closest to the dip at the edge of the vise's bed, was about .007" different dimension from the other five.) This cheap Chinese stuff is made more parallel and square than I would have guessed.

So the next step is to square the drill press vise. I put the flycutter in the mill, and ran it across the bottom of the vise bed--so it is as parallel to its base as the mill is capable of cutting. The next step will be to use an end mill to make the opposing jaws as parallel as I can. Then I will square the outer dimensions of the drill press vise to make it a bit smaller on the outside, and easier to square against the vertical mill table.