I got a request from a friend to see if I could make some Smith and Wesson revolver grips for him. I told him “sure, send me a set and I’ll see what I can do.”
It was a long and interesting process. The grips are an interesting shape and I decided I wanted to 3D model and machine them.
So step one was modeling them.
I have an Autodesk Inventor license through the high school robotics team, so I decided I might as well use the tool that I had. Inventor is pretty damned expensive, and I’m not sure what I’d use if I didn’t have it. I’ll have to play with some of the open source 3D modeling packages one of these days.
I took me five attempts to come up with a model that I liked. On the fourth attempt I decided to place one of the grips on my scanner, import the image into Inventor and trace the profile with lines and curves. That actually worked out quite well.
But it still took me another restart to figure out how to model all the curved surfaces. Fun times.
Then I had to decide how I was going to machine them. The grips have a profile cut in the back near the top, so I had to machine that first. Then I made a jig to hold them while I profiled and surfaced them.
I did all the CAM work except the surfacing by exporting the 2D curves from Inventor and pulling them into LibreCad. There I modeled up the jig, the stock and the back side recesses. It’s my opinion that simple is best and if you don’t need 3D, then you should do it in 2D.
I pulled the 2D model into CamBam and generated several CNC programs. One for the jig, one for the back side of each grip (mirror images) and one to mill the profile so the 3D surface program wouldn’t need to cut so much stock.
I made the jig by gluing and screwing some 3/4″ MDF together. Like the 1911 jig I made before, I put two locating dowels into the jig and table so that it mounts up square every time. If I were to ever get the limit switches installed I wouldn’t have to indicate the Zero location either. I’ve got to get on that.
I machined the profile into the back with an 1/8″ endmill. The corners where the curve meets the angled line need to be sharp, so I cleaned them up with a chisel.
After milling the backs I used my band saw to rough cut the profile so the blanks would fit on the jig and so there wouldn’t be as much material to machine away.
Next I chucked up a 1/4″ router bit and ran the profile program.
The pencil lines were just for the roughing out on the band saw, so no worries there.
The next step was to run the surfacing pass. To generate the 3D surfacing pass I mirrored the part in Inventor and then exported an STL file. I pulled that file into MeshCAM and generated the tool path. I have to say that MeshCAM is a very simple program to use and it works very well. It’s not super cheap like CamBam, but at $250 it’s not outrageous.
I was using the dust collection shoe that I made, but it’s not pulling all the swarf. Ah well, more to work on. Also the MDF dust clogs the filter in my shop vac something terrible.
There we go. I hit it with the shop vac and they look great. They are a little jaggy – I used a .020″ step over setting. I might regenerate the G Code with a .015″ or smaller step over for the next run. Or maybe try cutting them in both X and Y directions.
I had to do some sanding to smooth them out, but it wasn’t too bad.
If these grips fit properly then I have a new product line! These should fit any square butt K and L frame S&W revolvers.
Here is the jig after all the machining is done. Looks a little different now.