I need to make a jig to hold and machine a 1"x2"x0.25" aluminum part on 5
sides (contour the outsides, mill a slot and a hole).
I have to make a few hundred of these a month and I want to minimize the
amount of set-up.
I was originally thinking double sided tape but it would likely end up being
be a big PITA. I am considering a small vacuum jig.
Any good suggestions for me?
That's not an ideal part for vacuum holding. With a maximum of 2 sq" surface
area, the most down force will be about 30 lb. If the slot and hole go
through the part, those areas will have to be sealed off too, reducing the
surface area. Could several parts be machined out of a larger, thicker
blank? The individual parts would be bandsawed off and then second op'ed to
face off the back.
Back in the bomber factory we stacked thin sheets of aluminum, riveted them
in places where a cutout would take place, then routed the hell out of them.
That might work for you since it sounds like you will have slots. Second ops
took out the rivets if necessary.
I did a run of sheet parts that were round on the outer dimension. They
had a bunch of through holes in them, too. So, I made a fixture with
tapped holes where the part had the through holes, and the top of the
fixture was a smaller OD than the actual part. I put this on the
machine and indicated the center. The fixture had 4 tapped holes for
clamps around the edge.
I stacked six bandsawed blanks on the fixture and installed the clamps
around the edge. I then ran a program to drill or bore all the holes in
the parts. I blew out the holes and inserted bolts that clamped the
parts. I could now remove the OD clamps and machine the exterior
dimension. This worked great.
If you need to machine the top, you could do that while the clamps
are placed outside the final OD, then clamp from the inside to machine
the 4 sides. This would require the blank to be made large enough
to clamp outside the final dimensions.
You may want to create some small tabs (places that don't get machined
away) to hold the parts in place, just machine something like 95% of the
od away and place 2 or 3 small tabs strategically so the parts won't get
snatched loose. The tabs can be also machined down to a much thinner
dimension for easy removal from the stock sheet after the machine cycle
is done. A few hold down allen bolts can be strategically placed to
reduce any vibration that may begin while the parts are milled.
Now that I'm thinking more clearly the price of a die to punch out these
parts is sounding like a reasonable option. That way I only need to drill 1
hole and mill 1 slot. Now if I can get the customer to eliminate the