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1/25/2018 7:38:29 AM
Posted: 12/16/2005 6:56:27 AM EST
I proceeded to tear down my romy kit for building (first build). Everything was pretty easy EXCEPT the rear trunnion. I couldn't get the rivet shanks out !
I couldn't hand punch them. I put them on a hand press, couldn't move them. Tried to drill them, but the pilot hole was crooked, so that stopped that idea. Then I milled a 3/16 hole partway through, then used a 3/16 hardened dowel to push the shanks out. That worked....problem is that the dowels are jammed tight in there. I think they are broken in there too!
hindsight says grease or anti-sieze should have been put in first.

I think I'm gonna have to look for a new rear trunnion unless someone here has some ideas.

Link Posted: 12/16/2005 7:28:54 AM EST
Rear trunnions are available at a pretty cheap price, you just have to look, i think centerfire has them. To get them out can be a pain, I mount them in a drill press vice, center punch them and drill slowly to get them out, I've taken several out without a hitch doing that way. McM
Link Posted: 12/16/2005 7:35:44 AM EST
[Last Edit: 12/16/2005 7:36:09 AM EST by NeedMoreAmmo]
Copes has rear trunions for 20 bucks.

Link Posted: 12/16/2005 1:10:28 PM EST
I initially tried using the 3/16", but went down to the 5/32" after the 3/16" felt tight. The smaller bit worked great, so that's the one I use now. The extra material follows the bit out every time.

Link Posted: 12/16/2005 1:48:28 PM EST
When drilling rear trunions or Yugo front trunions for that matter; use a smaller bit than the rivet by half or more to start with. The rivets are metric and equal a 5/32" size ARO. Using a small bit allows you some fudge room when you change to drilling with a larger bit. Use plenty of lube (I use Tapmagic as it is great) while drillling and go slow.....removing the drillings frequently. I have never broken a bit doing it this way with quite a few finished correctly....
Link Posted: 12/23/2005 5:28:16 AM EST
I did my 2nd rear trunnion. It was a LOT easier.

First, I drilled through 3/32. Then I drilled about 1/2" deep with a 9/64.
Then I put a 3/8" long 1/8" diameter hardened dowel pin in the hole, and another on top of that, and pressed it as far as I could. Then I tipped the 3/8" long out (the first one gets a bit stuck, thats why 2), and replaced it with a 1/2" long pin, pressed as far as I could. I changed/added different length pins as I went along. This way, I didn't have to worry much about things getting crooked under pressure. I also used a needle nose pliers to hold the pins in place. Note that this was with only 3/8" and 1/2" long pins.

After the rivets came out, I was able to poke the first dowel out with a piece of wire through the 3/32 hole.

Piece of cake!

Link Posted: 12/23/2005 5:31:08 AM EST
Oh, and incidently, after measuring the rivets after removal, a #15 drill bit (.180) would be good for drilling out, as would a #14 (.182). the rivets I measured were .183-.185 in diameter. I haven't measured the diameter of my replacement rivets, so I don't know how much they may have expand after squeezing.

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