Casting Screws Into A Blank

Signed-In Members Don't See This Ad
C

crokett

Member
Joined
Dec 4, 2012
Messages
610
Location
Mebane, North Carolina
A machinist friend sent me some aluminum and brass screws he wants me to cast into a clear polyresin blank. I think the only way to do this is going to be to cast in layers. He wants the cast in clear layers, will I be able to see the layers? My other thought was to cast a thin tube of resin, then glue the screws around that, then cast it. That thin tube will most likely get drilled out, so even if there is a visible boundary between the castings it won't matter.
 
Signed-In Members Don't See This Ad
Interesting little job. Personally, I'd just use a belt sander to make them at least half as thick, then glue them to a painted tube. Kind of like a watch part pen.
Turning could be fun. A breeze with a metal lathe, but tricky with a wood lathe and hand chisels. Just remember to clean the parts of all oil and dirt so the resin can stick.
I'm looking forward to seeing your results. Good luck!! :)
 
Layer casting is done quite often with both PR and Epoxy resin. Not sure about Alumilite.

Best bet though it to do a tube in cast. Glue the screws to the tube and cast it that way. This way the screws would be exactly where you want them. less change of a screw up. (sorry, had to).
 
crokett said:
A machinist friend sent me some aluminum and brass screws he wants me to cast into a clear polyresin blank. I think the only way to do this is going to be to cast in layers. He wants the cast in clear layers, will I be able to see the layers? My other thought was to cast a thin tube of resin, then glue the screws around that, then cast it. That thin tube will most likely get drilled out, so even if there is a visible boundary between the castings it won't matter.
Click to expand...

I did cast come brass screws once (actually gave it 2 tries). Make sure you clean the screws with some kind of solvent bec a "friend of mine" didn't take that step and although the drilling went uneventful the turning part turned into a BB avoidance course. On the second try HE washed the screws and they stuck much better. Also, be aware that when drilling it will generate more heat than when drilling wood or plastic so use a lubricant (WD40 works), drill slowly and in a couple of tries. The second one I did I screwed the tips into a 3/32" dowel and cast them and after turning it looked like brass dots. The second one I just cast the screws with nothing in the center and it cast fine but that is the one that became the shooting gallery when turning it bec I did not use the solvent.

Eugene.
 
The simpliest way I've found to cast a screw is as follows.

Step 1: Clean the screw with a wire brush or a wire wheel on a grinder.

Step 2: Soak the screw overnight in acetone to remove any remaining coating that you missed with the wire brush or wire wheel.

Step 3: Pour a layer of PR (I like silmar 41) about 1/2 inch deep into something like a pill bottle, clear tube, etc and let the resin hardened overnight.

Step 4: If the screw is a flat head screw, very neatly coat the head of the screw with thick CA and put the screw into the pill bottle HEAD first. Allow the CA Glue to dry and offgas over night.

NOTE: if the head of the screw is "rounded", take a correctly sized countersink bit and make a dimple hole in the hardened PR. Then, with a long Qtip, add enough thick CA to fill in the dimple. Then place the screw head down into the glue and let it sit overnight to cure and offgas.

Step 5: depending on the thread pitch, size, etc, it is sometimes difficult to make a cast that is bubblefree around the threads. FOR THIS REASON, I would thin the PR to a waterlike consistency. Then cast to a level above the tip of the screw.

I have cast this way, WITH and WITHOUT pressure and both seemed to work equally well.

Good Luck!
 
Last edited:
skiprat said:
Interesting little job. Personally, I'd just use a belt sander to make them at least half as thick, then glue them to a painted tube. Kind of like a watch part pen.
Turning could be fun. A breeze with a metal lathe, but tricky with a wood lathe and hand chisels. Just remember to clean the parts of all oil and dirt so the resin can stick.
I'm looking forward to seeing your results. Good luck!! :)
Click to expand...

Dont forget heat build up on the metal parts causing the resin to burn.
 
You must log in or register to reply here.
Back
Top Bottom