C&P 8x12 Sidearm Pin
Hello everybody,
I recently acquired a C&P 8x12 OS that I am busy cleaning at the moment and noticed that there is something missing/wrong with the left sidearm (flywheel side).
The pin that is connecting the arm to the small cam together was not fully inserted and there is a spacer/bushing missing.
The pin itself fits very snugly once in place (which should be a good sign that it is not worn out?), I cannot move it manually, only a wrench would do. However, each time the sidearm does a full rotation, the pin slowly works its way out.
It looks like the end of the pin was hammered down at some point. Was this to create a “cap” of some sort that would keep it in place? Does anyone know if that’s how it was originally secured? What would be the correct way to fix this?
Any help/info you may have regarding this would be greatly appreciated.
Also thank you to Briar Press and all the contributors for all the precious information you are putting out there!!
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For whatever reason, the threaded portion has been cut off from that bolt. Take a look inside the hole to determine if there is a piece remaining inside, or if the internal threads have been stripped. Either case, you’ve a challenge ahead.
Without familiarity with that C&P mechanism, IF there is clearance between the back side of the “disc” in which that pin inserts, all the way around its 360 degrees of rotation, and IF there is at least one portion of that circuit where the back side of that hole for the bearing pin is exposed, one possible solution could be to have the back, rough, end of the pin machined flat such that when the pin is fully inserted in the hole the back, machined, side is a few thousandths of an inch short, have a hole bored in the center and threaded for the largest flathead machine screw available, and a flat “bolster” washer slightly larger in diameter than the hole for the pin and about 1/8” thick (assuming there is that much clearance in one full rotation) and countersunk so the flat-head screw is flush with the washer when tightened, then after making certain that the pin can freely rotate 360 degrees in the arm bearing, install the pin, washer, and screw, preferably with LocTite and tightened as much as possible. If good lubrication is maintained on the arm bearing the repair should make the press operate correctly again, but it would be best to ensure that the direction of rotation of the connection is such that any friction between the pin and the arm tends to tighten the threads of the screw on the back end, meaning tends to rotate the pin clockwise as seen from the arm end.
Long explanations are my specialty :-)
The mangled end of that pin was probably “peened” over to lock it into place. It looks like a lot of that material is gone. The pin itself, could be “knurled” to again prvide a tight fit. To fix this properly however, I would remove the head cam,(big round metal thingy), counter-sink the back side of the hole a bit. Then have shop that does the work, bore,drill, into the stud 1/8”-3/16”. Upon driving the stud back into the head, you could then peen it out for a reman stock fit. Where are you?
Thank you all.
The pin was indeed “peened”. I think the previous owner ran the press like this. There is no weird movements or noise going on. Everything seems to run smoothly, sidearm and cam are doing their job. It’s just that the pin isn’t fixed to the cam and walks out a bit (about 1/8”).
Could some loctite 620 fix the pin back to the cam? I am not sure how easy it would be to peen it back. There is not much clearance and would the pin need to be hot in order to be malleable? I feel all this may be causing more damage than good.
If the pin is moving in the head cam at all, then indeed it is wearing/worn out. All movement needs to be stopped. A new pin could be made. I would be wary of a used one. This, in a best case scenario, should be fixed as a package.( new pin, a bit oversized, clean up hole to straighten and square). A little expensive, but not impossible. Like I said tho, you could drill out a pocket in the mangled end. This would allow easier peeling. The peeling alone might be enough to stabilize the pin. The head cam would have to come off, pin work done, then installed. Quite a project, but definitely doable.