trunnion rivet

[wayne]

I am at the stage of securing the trunnion in place by riveting it. In the past, I had bad experience in riveting. What is the best way to rivet the trunnion rivet? I do not have a tig..The only tool I have is a C-clamp, ball peen hammer, and a propane torch. Do I need to cut the rivet so it will mushroom like the other side. Help Help..I don't want to mess this up....

[striker754]

im not even gonna rivet mine. just pop it in and shoot

[Mike]

Use a 6mm socket head cap screw

[wayne]

How did you guys smash the rivet for the trunnion? Did you heat up the rivet first then smashed it ? Do you have to heat it up or could you just smash it...What type of tools did you used. I have only hand tools..No tig..or rivet squezzer, just a large c clamp...

[041x]

I would be kind of scared of just putting a pin in it and not riveting it. The caming piece could spread apart and break. I just put a new brp (Mcmaster Carr) rivet layed the rounded head on an anvil and flatened rivet out on the bottom of the camming piece. It turned out really nice and the camming half is held very tight on the other camming piece so there is no need for a c-clamp.

[TOM R]

my pin just sits in there as I am still in need of tweeking incase it needs removing, my second gun will have the trunion bolt like mg3

[wayne]

Did you have to heat the rivet first before you smashed it with a hammer. Is the rivet soft material, where it is easy to smash.

[Bullwinkle]

It is actually better to rivet COLD instead of hot...(yea, I know, we've ALL seen the pictures of the riveters throwing red hot rivets across the room building ships and buildings...)

Riveting cold gives the best fit for firearms. Heating can (and will) change the temper of the rivet steel, the rivet will shrink slightly when it cools which is good along the long the long axis {end to end} because it pulls the rivets heads together/towards one another, on the otherhand, the short axis {the shaft of the rivet} shrinks as well. In high vibration applications like aircraft/guns this will lead to failures due to metal fatigue. The ever so small gaps create a small point of flexation. It also creates small pockets for corrsion/rust ..which again leads to failure....

Just SMASH the &*^$#@!! out of them cold and you will have attached the rails as per the factory/design specs....

[wayne]

This is what happened when I did not know how to rivet...I have two questions..The first one is how can I remove the bent rivet? The second How can I put in a second rivet without having the same result. The way I installed the rivet, I used a 12 ton press to smash the rivet. The rivet was cold...I really need some good advise...Thanks

[striker754]

Did you have the rivet backed up firmly? That rivet is going to be tough. It will probably buckle like that with 12 tons on it with no support on the shaft. Use a hammer or similar.

[Cruiser133]

I had better luck with an airhammer with a proper size rivet head fitting on it and backed up to a vise.

[propos]

That looks like it is going to be fun getting it out. Ouch. BTW, where can I buy a camming piece bolt instead of a rivet. I'm going to use either the original rivet or a metric bolt to initially test fire the "rifle". Once it is tweaked and operating properly then I intend to install the rivet or bolt. I'm leaning towards using the bolt rather than the rivet. That way if something goes wrong and I have to remove the camming piece I won't have to deal with screwing around with a rivet. A bolt would be easier to remove and replace.
BTW, it appears that the best way to remove that rivet might be a cut-off disc and cut the rivet shaft near the prongs of the camming piece. Kind of a tight place to work in though.

[TANKER]

You could try drilling into the side of the rivet in two places. One at the upper edge of the slide in cam piece and another at the lower end of the slide in cam. Use a drill bit about the same size as the rivet and it won't leave much metal to deal with to pop the bent section out.

[DARIVS ARCHITECTVS]

Being an experience medieval armourer, I was able to add weld metal onto the shank of the original rivet, grind to fit through the hole, heat the end of the shank with a oxy-acetylene torch WITHOUT HEATING THE CAMMMING PIECE, and use a ball peen hammer to form the head hot. Back up the opposite end of the pin with an inverted rivet set held in a vise. Hold the gun real steady. The trick is to use LOTS of light taps, orbiting the center of the rivet head at various radii to form the dome. You slam on it, and you'll get what that unfortunate sot above has.. a bent pin! Reheat the rivet head as needed. Hot riveting is fast an lessened the chance of splitting the head. Aim the torch from the side and do NOT apply heat to the other gun parts or you wil mess up their finish! Finish the head it with a rivet set, sand off the facets with a dremel, and polish it. It can look totally hemispherical and INDISTINGUISHABLE from the original! Cold blue to match the gun and apply oil to harden the bluing overnight. It CAN be done! I had to repair a C&R MG-42 with a new camming piece set, and it's fully restored such that you cannot tell the repair was ever made.

[propos]

Until I get this thing shooting, I'm using a 6mm bolt in the camming piece. That way if I have to remove the camming piece for any reason I can. Once I am satisfied that everything is functioning properly I am going to use an MG-42 camming piece bolt. I like the idea of being able to remove the camming piece with as little difficulty as possible. I know that is heresy to some people, but I've been a victim of Murphy's Law too many times. Until I'm sure I have this gun built correctly, I'm hedging my bets.

[DARIVS ARCHITECTVS]

The removable bolt sounds like a good plan, but unless the camming pieces are loose or somehow out of position, they will generally not be the problem with functionality, other items will be the problem, such as rail and receiver lineup with the foreend of the gun.

[propos]

I had the rails in and they lined up with the camming piece and the bolt locked up. There doesn't seem to be any misalignment with the front of the receiver. This is just my way of trying to hoodwink Murphy.