Bone revisited

[gerryr]

Well, I'm trying to make a Jr. Statesman from bone. Following Frank's suggestion, I first tried to buy some turkey legs - sorry not until Thanksgiving around here. So I ordered some deer leg bones from Moscow Hide and Fur. I was surprised at how wide the marrow cavity is inside these things. The cap barrel was not a problem, but out of 10 bones, I was only able to get two that were definitely OK for the smaller barrel, managed to crack one almost full length while drilling and the remaning one has a crack in it about 1/2" long. The marrow cavity is oval shaped and therein lies the problem, even on bones that appear more or less round on the outside, the marrow cavity is still oval. There is also a problem in that the bones have a concave groove nearly full length and often on both sides of the bone, so while the marrow cavity might be OK, the grooves make it unuseable - had two of those. I'm thinking I need to increase the speed of the DP to drill this stuff, after I get some more. I usually run it at about 800 rpm, but I wonder if that's what caused the cracking. Any ideas?

I will say this stuff is beautiful. The cap barrel is turned and polished and looks just like ivory. MM to 12000 and buffed with white diamond. I painted the inside of holes with flat white Testor's enamel because I could see the tube even before I started to turn it.

 

[Rifleman1776]

First thought is to SLOW down the drill press. Might consider a different style bit or reaming. Your observations are interesting.

 

[gerryr]

Frank, any recommendations on a different type of bit to try? A carbide masonry bit? Or ? I've even thought about trying to ream it out with a 3/8" rattail file. I know it would take a while, but the bone shouldn't crack.

 

[Rifleman1776]

Originally posted by gerryr
<br />Frank, any recommendations on a different type of bit to try? A carbide masonry bit? Or ? I've even thought about trying to ream it out with a 3/8" rattail file. I know it would take a while, but the bone shouldn't crack.

Those were two of my thoughts. But you are in an area I haven't ventured before. Worth experimenting.

 

[DCBluesman]

Bone should drill like elephant ivory. I drill in steps, starting with a 1/4" bit and work my way up. Do not let the bone or the bit get very warm. With ivory I often drill the blanks in two day operations to be sure nothing gets too hot.

 

[gerryr]

Lou,
I think you're right that the bone itself should drill like ivory. The problem, I think, arises from trying to drill where there's already a hole, but the hole is oval shaped. I don't think heat was the problem because I was only removing a small amount of material, but now that I have an air compressor, I might try to rig something up to blow air into the hole while I drill it. I plan to do some experimenting tonight and I'll try your method as well. I almost feel like Captain Kirk. LOL

 

[redfishsc]

Originally posted by DCBluesman
<br />Bone should drill like elephant ivory. I drill in steps, starting with a 1/4" bit and work my way up. Do not let the bone or the bit get very warm. With ivory I often drill the blanks in two day operations to be sure nothing gets too hot.

I still think Lou has a point in just removing a tiny amount with each drill bit. If you start with a bit that cleans out the marrow and only a small amount of bone, then work up the next 1/16th or millimeter size.

Can you drill this stuff on the lathe? Meaning, is it straight enough?

 

[ctEaglesc]

Try wrapping the bone with cotton string and stabilizing it with CA.
let it cure before drilling.
If you do this you can establish centers& turn round and drill on the lathe.
The string will reinforce the material so it won't blow out.
Your compressor with<b>out</b> the moisture drained out may help(DAMHIKT)

 

[gerryr]

The bone is quite straight, straighter than a lot of blanks I've drilled on the lathe so there isn't any need to turn it between centers first. The string may help and I'll give it a try. This is not solid material, the interior of the bone is hollow. I don't know how they got the marrow out, but there isn't any there. The stuff I bought was "professionally cleaned" so maybe it's part of the cleaning process.