Wednesday, January 6, 2010

making screws

I could have had my ebony and aluminum brooch done a long time ago, but I didn't work at much of anything between Xmas and New Years. I worked on it a little last night, I'll probably finish it tonight.

I made the silver screws for it a few days ago. As far as I know there aren't any suppliers that sell sterling screws. Reactive Metals sells silver plated screws, but I want solid sterling screws. Anyway, I think it's better to make all the components of a piece myself.

I made up this process a few years ago. I don't know if there are better ways to do it, but this works for me.

Most of the screws I make or buy are 0-80. For 0-80 screws I make the head of the screw out of straight rod, I think I used something like 2.5mm diameter. I drill a 1.2mm hole in the center of the rod on my lathe.

I then tap the rod. A pin vise makes it easier to hold the rod. I use taps from McMaster-Carr. I have some from Reactive Metals Studio, but I don't like them as much as the ones from McMaster.

I tap the hole as deep as I can, about 1/2" I think.

After I am done tapping, I set my tube cutting jig to about 1.5mm and cut the rod into little 1.5mm pieces. After each piece I cut off I file the end of the rod flat and put a tiny chamfer on the corner so it looks nice before cutting off the next slice.

Next I make the threaded shank of the screw out of 1.6mm wire using a die.

It's good to straighten the wire before starting. I am kind of lazy and the wire was mostly straight. Straight enough that it would be ok once its cut in to 5 or 6mm pieces. If I was making a longer screw then I would take the time to properly straighten the wire by putting one end in a vise and pulling the other end before cutting the threads.

I hold the wire with a pin vise and thread an inch or inch and a half, then cut the threaded wire into pieces. Add about 1.5mm to what ever length you want the screws to be. After every time I cut a section of wire off I file the edge of the wire before cutting the next piece off. You will never get the screw to go in if there's a rough bur on the end from sawing it, and its easier to file the end when it's still attached to a longer piece of wire. After cutting off several pieces I thread the wire some more and cut off more sections.

Next the heads and shanks need to be screwed together.

Since I filed the end of the rod and threaded wire after each time I cut it, every piece has a nice end. If the screw is held vertical, with the head at the top, I put the screws together so the nice end of the head is the underside, and the nice end of the threaded rod is at the bottom, with the rougher ends of both pieces at the top so it will be easy to file them both flat.

Next I solder the pieces together. I embed the shank of the screw in a magnesia block so I don't have to worry about solder flowing down the shank, and put a piece of solder on the head of each screw.

I use my flexshaft like a lathe to clean up the screws. I have a little piece of threaded rod I put in my flex shaft to hold the screws while I work on them.

I file the top flat then sand the top and sides of the screw head. I then cut the slot in the screw with a jewelers saw and polish the head.

Finished screws:

1 comment:

Mauzy said...

Wow, you have more patience than I do! Thanks for sharing your process.