shroud repair bushing question
shroud repair bushing question
I decided to machine my own shroud repair bushing. Thanks for the print on this site. I machined it from mild steel. Then I decided to test the old bushing for hardness. It comes out to 62 rockwell c. Now I wonder if I should make a harder bushing. I can case harden this one but the inside will be softer than original. I tested the piece I cut off in the center where I cut it and it's 62c also. Reading Mr Baums manuals it looks like most of the pressure is in the camming section then the recoil pushes the bolt back and the recuperator pushes the barrel forward again. I'm wondering how much pounding is in the front section even with around .060" space from barrel to barrel bearing bottom. Question is what do you guys think? I haven't welded it in yet.
Re: shroud repair bushing question
Sorry I failed to mention that I am a new member here. I used steel I had on hand to make the repair bushing. Maybe I should get better steel like 4140 or similar and make a new one. I do have a pid controlled kiln to heat treat. My thinking was that I can case harden the mild steel bushing and not have to temper it like I would have to do with 4140. Case hardened mild steel would be soft on the inside. But with the gas pressure at the muzzle end would that deform the repair bushing and cause the barrel and bearing to stick in the bushing? What do you guys use? Thinking out loud here. Feel free to set me straight. Thanks.
Re: shroud repair bushing question
Hi Pk. The repair bushing is a somewhat complex part somewhat inexpensive to purchase new from RobertRTG.
The easiest way to install it in your shroud is to open a "window" half in the front, remove the old destroyed bushing, then re-install the window by clamping it good over the new bushing and welding it shut. Be sure to "time" it correctly...it only goes in one way.
The barrel should hit the "barrel stop" before it could ever bottom out the barrel bushing in the shroud bushing. Some people have used a dime or some washers between the barrel and the bushing to guarantee this free-play....
If I got any of this backwards, please let me know!....Phil
The easiest way to install it in your shroud is to open a "window" half in the front, remove the old destroyed bushing, then re-install the window by clamping it good over the new bushing and welding it shut. Be sure to "time" it correctly...it only goes in one way.
The barrel should hit the "barrel stop" before it could ever bottom out the barrel bushing in the shroud bushing. Some people have used a dime or some washers between the barrel and the bushing to guarantee this free-play....
If I got any of this backwards, please let me know!....Phil
Re: shroud repair bushing question
Thanks for the reply.
Yeah, I didn't think of that. The barrel would hit the barrel stop befrore bottoming out in the bearing and bushing, thanks. Since I don't have any 4140 and must buy some, plus my time to machine another bushing and run the kiln up to heat treating temps, I might as well bite the bullet and buy one. Plus I already cut the end of the shroud and punched the old bushing out. I'll have to tig weld the repair bushing in. I do this kinda stuff at work because that's where all my equipment is.
Yeah, I didn't think of that. The barrel would hit the barrel stop befrore bottoming out in the bearing and bushing, thanks. Since I don't have any 4140 and must buy some, plus my time to machine another bushing and run the kiln up to heat treating temps, I might as well bite the bullet and buy one. Plus I already cut the end of the shroud and punched the old bushing out. I'll have to tig weld the repair bushing in. I do this kinda stuff at work because that's where all my equipment is.