I guess I neglected to post about putting the top profile on the 1911 grips. I came up with a good tool chain – I drew the part as a solid model in Autodesk Inventor, exported an STL file and machined it with FreeMill (can’t beat the price.) It was pretty easy and turned out quite well.
I used a 1/4″ ball end mill with a .030″ step over and they came out pretty smooth. Just hit them with a little sandpaper and they will be ready for finish. Sweet. The program took about 15 minutes to run – much less time than doing it by hand and much more accurate.
I also played around with engraving, but I still need to figure out how to map the image onto the surface to generate the tool path.
I also needed to run off a couple of inserts to hold .50 BMG rounds in an ammo can. These are made up of 1-1/2″ glued up MDF stock. They have a relief cut into the back and a bunch of 1-1/16″ deep, 13/16″ diameter holes in them.
In the past I used the router table and the drill press to make these, but I thought the ShapeOko would possibly be better.
Well, the jury is out on this one still. Milling the relief in the back worked fine, but was a little slower than using the router table. I could probably get more aggressive with the depth per pass and make it a wash.
Boring the holes was slow and a little frustrating. I started with a 1/4″ two flute down-spiral carbide router bit and got about 30 holes done before I decided that was not going to do it. It was at least twice as slow as using the drill press.
Then I realized that I had a 1/2″ diameter two flute straight carbide bit with a 1/4″ shank. That made the holes take half as long since they could be done in one pass.
But… MDF is hard on bits. The bits are pretty dull now and you could tell the difference from the first hole to the last with the 1/2″ bit. I have ordered some higher quality bits to try and will see if I can sharpen the straight bit again.
But the MDF also caused sharpness issues with the Forstner bits I was using in the drill press, so this is not really a mill related issue.
The other annoying thing was having to pause to move the clamps out of the way. I had to re-position them due to the fact that the dust shield ran into them because the bits are not long enough.
But I have a plan in the back of my head on how to deal with that issue…
