Making an acrylic stem copy

I got in a Radice Rubino with a damaged oval stem. I wanted to try my hand at making a copy in acrylic rod stock using my newly acquired Jet lathe.

The original stem had 3 stress fractures that I repaired used Stewmac 10 superglue. It has a 5 second cure time but is thin enough to fill the thinnest cracks, if you work fast. After drying, I sanded and buffed. The cracks are slightly visible but stable.

I was told to repair that stem or make a new one. I did not have an oval stem blank that large but I did have a black acrylic rod! I chucked it in the 3 jaw chuck on the lathe. First I used a Forstner bit to face it up. Then I drilled a 5/16 mortise in the end about 1/2″ to accept the delrin tenon. Followed that with a 5/32″ long bit to drill the airway to about an inch from the end. Then a 1/16″ long bit to pierce the end. I inserted the delrin tenon, flipped it over to create a slot with my dremel wheel. Funneling it down to meet the 5/32 airway with the slot tool, files and sandpaper.

The fit was light tight against the shank.

I used the 1×30 belt sander to cut down a bit end chunk and shaped the bit and bite area. Also worked the rough oval shape.

While working the button, it fell about 8″ and chipped off a large portion!

After measuring, I ground down the old bit. Using files, I was barely able to cut a new button.

Using my belt sander i created the double saddle stem.

I used the dremel sanding drum to cut in the curves and smoothed with sandpaper. I sanded my stem and matched the shank with files to shave off the last excess acrylic. More sanding, a bend and it’s done.

I’m amazed at how its almost an exact copy of the original. Putting in the dots will have to wait for another project. Oh yeah, it took 12-16 hours!