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Posted: 5/1/2008 9:01:35 PM EDT
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I started the demill on my Romy G kit. Everything was going fine untill i Started the rear trunnion. i have broken 2 bits, and cannot manage to get the revits out. I ever bought brand new bits of this project. Is there any where i can get another trunnion that has been demilled, or any other way to get the rivit out? thanks nick |
| How far in are you with the bits, and are you centered? I have only gotten those out by drilling +/- their full length. Bits could be breaking from hitting the hard trunnion or if things are not in a vise, maybe something is moving. I did break bits, so maybe my advice is bad. |
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Assuming that there is not 1/4 of a hardened drill bit in the bottom of the hole...Right? Anyway I start with as close to center center punch hole (on both ends of the old rivets head) and the with a lot of cutting oil I start drilling with a small (1/16" or slightly larger) drill bit and only drill half way through the trunnion. Then trun the receiver stub over and repeat. I then go up a size of two on the drill bit and repeat it all over again going up to nearly the size of the shaft of the rivet. One of thwo things usually happen by the time I am up to the size of the rivet's shaft: The rivet breaks free (either half of it or all of it) and comes out when I pull the drill dit out, or the rivet is weakened enough that it can be punched out with a punch and hammer. Have you tried punching them out yet? You may be able to press them out with a press. Do you have access to a press? |
| Also be sure to run your drill at the slowest speed possible. High speed heats up very fast and dulls/weakens the bit. Stop often to clear any metal bits, and use lots and lots of oil. Cutting oil is best, but regular 4in1 household oil will work too. Drill a little bit, stop, clear metal shaving, put another drop or so of oil on bit/hole, then repeat. |
I'd advise against trying pressing the rivet out. the trunnion holes are countersunk: and if the material over the countersunk is still attached to the rivet you won't be able to press it out... when I had this problem, it took a tungsten carbide cutter with a dremel, a long time, and patience to get the drill bits out both sides.  $15 for a de-milled trunnion is a good deal too... |
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