tootall said:
I hope it wasn't some sub-standard welding that is the problem
This is a bit of a joke between G37 and mysefl. He knew I am a metal fabricator, so he PMed me a few days ago. His mount plate fell off his brand new rifle, and he wondered if I could put it back on.
It seems that the mounting plate is held on by two very small welds, and one of them broke away (or never was properly fused together) almost as soon as he attempted to mount a rail to it. Then the other weld broke soon after.
I thought it was a "spot" or resistance weld, in which the two pieces (mount plate and reciever) are held together and current is passed through them via contacts that press onto the two pieces.
But it looks more like a plug weld, in which a hole is drilled in one plate, and an arc is struck to fill in the hole, locking both pices together.
Anyway, we decided to try and do another pair of plug welds, so I drilled out the original welds, and opened the holes up a bit to allow the arc to reach to the lower plate.
We the clamped the parts together, hoping that we were lined up properly!
A pair of welds later, it was joined.
Then we gring down the welds flush to the plate.
Unfortunately...................................
it didn't work.
The welds did not properly fuse to the reciever again. This is the problem with trying to weld into a blind hole of such small diameter. Also, I was very concerned about cooking the reciever, so i had the machine set low.
So..., instead, I put two fillet welds along the narrow portion of the plate. I didn't think to photo this version, maybe G37 has pics. Anyway, you can see the narrow part in the first pic. I welded along the edges, then he ground down the excess to allow the rail to mount on. It worked fine, plenty strong, except that there is a minute amount of play in the plate/rail connection.
So, while the quick detach idea is convenient, it really doesn't work for long range accuracy.
