Milling Fixtures

This isn’t as much of a tutorial, but it does show some of the steps. This should be relatively simple, I think.

 
Everybody needs some setups every now and then. This started with making a box out of aluminum plate for the lathe tachometer. I noticed that I really didn’t have a good way of milling the ends square, and I didn’t have a good way of drilling the holes in the edge of the plate.

I decided that I needed some sturdy fixtures, and that 1/4 inch steel would be good enough. Not willing to leave well enough alone, I decided that the minimum of setups would be the best idea if I could manage.

The first thing I needed was a good base plate that came already aligned when I used it.

 
This is the base plate. It is 1/2 inch steel, and all the holes are spaced to go between the T posts in the mill table. There’s a 3/8 inch hole in each corner, and that is for the cap head screws that go into the T nuts for the table.

The holes were drilled and tapped, all 27 of them, with the plate aligned on the milling table.

 
The T nuts that hold the plate down are in the slots, of course. However, they can’t be seen, so I’ve poked one out a bit so it can be seen. The bar running along the front is attached to the base plate, not the table. It’s milled down to a little less than the table height for most of the length. Not only couldn’t I mill more in one pass, but there might be a really good reason for leaving the 1 inch stock high at the right side…. Perhaps...

 
The positioning bar holds the table absolutely parallel to the front of the table. While this may not be accurate, the holes drilled are. Only the x feed was used to position a row of holes at a time, so they’re all in a line, X wise. The positioning bar is cut so it does not rest on the scale.

 
The bottom of this angle was 2 inches wide. It was cut short on a radial arm saw with an abrasive blade. It was then turned over on the table, and the short bottom was edge milled flat. This should make it square. The other side of the mounting holes was also milled flat, but that was to accommodate the screw heads.

 
The vertical plate mounted, it’s about 3 inches high, and will be used for 3 to 4 1/2 inch high objects. There are two holes in the right side, drilled and tapped for 1/4-20, which are for the length stop. This is 1/4 inch angle, and should be fairly rigid. It is square, too, after the milling. It was cut a little short for convenience sake.

 
Here’s how the work will be held. There’s a clamp on the other side that you can’t see. What looks like two more holes in the angle are really the holes in the side of the aluminum plate. Now the plate should be positioned vertically, and fairly immovably, I hope. However, for production drilling, something is missing.

 
Here’s what those holes were for. The cutoff portion of the angle was drilled to be able to fit on the angle as a length stop. Now all the plates that are put on this fixture can be accurately drilled. The edge facing the plate was milled, and the edge is also perpendicular to the table. Hopefully, drilling edge holes should be easy.

 
This is an HF spin indexer for 5C collets. It has 36 holes spaced at 10 degree intervals and 10 vernier holes to add 0 through 9 degrees to the offset. The 5C collets I have go from 1/8 inch to 1 inch capacity. The handle tightens the collets and the knob on top locks the assembly in place.

 

 

 

The same base plate philosophy is used, which allows the entire assembly to be put on the milling table with two or four bolts as desired. It’s the equivalent of a quick change toolpost for the mill.

 
This can be used as an indexing head for small work, and is seen here holding the flashlight body so it can be milled into an octagonal shape.

 
Here is a vertical/horizontal collet fixture, also for 5C collets. It doesn’t fit too well horizontally, and I already have something that will work on a horizontal basis, the spin indexer. So I’ll mount this vertically with the same sort of system, and have a vertical collet vise. The collar on the top is turned with the handle to tighten the collet. The collet is pressed downwards into the fixture to tighten it.

 
Here’s how the work will be held. This is the end of the flashlight barrel ready to be trimmed. The collet doesn’t mar the aluminum at all.

 
With all those chips, it’s hard to see what’s going on. But the work is done.

 
I’ve mounted the tilting vise on the same kind of quick mount plate. It’s automatically aligned when I put it on. This saves a great deal of time.