oxy-acetylene welding

[jimdvan]

I've been doing my build with tig and its very apparent that I am not a welder. At least not yet. I'll finish just in time for my wleds to get good. But, its coming along.

I do better work with an oxy-acetylene torch. My question is, is it acceptible to use an oxy-acetylene torch to flow the weld I put down with the tig to enhance the bond of the filler material to the receiver in iffy places? Also would it be OK to use it to fill in pin holes and cleaning things up here and there?

[DARIVS ARCHITECTVS]

I'm an experienced gas welder, and a beginner at TIG. The problem with gas welding is you have to heat up the surrounding metal so much to get one small molten spot. This causes warping. I do not advise using oxy-acetylene gas welding on sheet metal receivers. Imagine how pissed off you'd be if you heat-warped the receiver! That goof you can do without, and there's no fixing it. Learn to use TIG, and THEN proceed with your gun project. Never settle for less than quality skills and tools when you shell out HUNDREDS of dollars just for the parts alone. If you can't do it, hire an experienced TIG welder. You can do the setup with the jigs if you want to make sure it gets done right, but have an experienced TIG welder strike the arc. My friend Bernie White is one of the co-inventors of the Desert Eagle .44 pistol, and he's a world class machinist and has done a few MG-42 rewelds, and HE WILL NOT do any more because of what a pain in the A$$ they are to prevent warping and get perfectly straight so they work well. He has the jigs and all, but he'd rather do Bren guns, which he specializes in. If a world class gunsmith won't do a MG-42, then you can understand how tricky doing one of these reweld jobs is on a MG-42 receiver.

At my nuclear plant we have lots of Code qualified expert welders. If I needed a touchy weld job, I'd try to hire one of them on the side. Try calling boiler repair companies in your area, or call the pipefitters union hall. Ask around. You SHOULD be able to find a skilled welder. If you like rolling the dice on a project this expensive, you take your chances...

[www.Prussia.us]

Lots of good info there DA and ideas of where to find someone local.

[drooling idiot]

Try calling ..... the pipefitters union hall. Ask around. You SHOULD be able to find a skilled welder.

look for the sheetmetal workers union hall, their used to working with thin gauge metal.

[Bil]

Try-hot rod shop,auto customizer,body shop,motorcycle shop.All of these have guys that are used to doing painstaking work involving the exact skills needed for this build.They also have the equipment,and most have at least one guy that would be into something like this,maybe on a weekend or evening.Ask around,you may luck out. ---bil

[jimdvan]

Thanks, all. I got the three rear sections welded on my own and my gunsmith buddy welded the nose piece on. Not pretty but it works and looks solid. A friend turned me onto a welder near his shop and the guy told me he'd join the front and rear halves for me. Right under the cam piece. I think I'll have him do my 34 as well as soon as I get the jig.

I figured I needed precise work for the 42 front and rear sections to be joined since there is very little access to clean up on the inside.

[Michael J]

I figured I needed precise work for the 42 front and rear sections to be joined since there is very little access to clean up on the inside.

This never occurred to me, just how am i supposed to clean up welds on the inside ? You guys think a dremel will fit, or possibly a custom made "extended" dremel sanding bit?

[jimdvan]

My guess would be to use copper backing in the tight areas where the barrel extension reciprocates. That would minimize the build-up.

[Bil]

I used copper backing on all the welds,still some cleanup,but not as bad.The dremel will do all but the worst stuff. ---bil

[oakrodent]

Try the argon purge. It works great. Very little clean up. I have done a few re welds and have had to do very little clean up on the inside. Also remove as much stuff as possible. Don't try to re weld a trigger bracket/ recoup stop

[jimdvan]

Well, my tig wleding skills leave a lot to be desired. I decided to have a welder join the front and rear sections for me. In jigging it up for him I found I had warped the rear section in two different axis. Its not so bad that the welder said he couldn't fix it so it is salvagable. It should be done by Tuesday.

[DARIVS ARCHITECTVS]

Good Luck!

[88comm]

I have used MIG on my reweld and it worked well. I made a point of NOT doing long beads (all were less than an inch). No concentrated heat and no warping as a result. The other thought is the idea of cleaning up the inside of the welds. I backed my welds with copper so I did not have a lot of messy crap inside when I was done. But I also DID NOT spend extra effort making the inside perfect either. Two reasons - First, a little more metal in a weld is preferrable to a little less and second - I wanted evidence of construction to be obvious. If the piece is ever looked over by some authority that knows what they are looking at - I want them to easily see that it was constructed from scrapped (per AFT regulations) parts. If it looks perfect inside and outside, what is to keep the law from saying it is a unregistered, class 3 weapon? Perhaps you were/are just trying to conceal the fact by making it semi? Finishing touches will include engraving its date of construction, "semi-auto only", and a lengthened serial number (to include the original).

Think ahead about a future with a very anal AFT that wants to find any reason to snare those that play near the edge. Those on this board are, in the minds of the anti-gun types, already over the edge. Cross yout "t"s and dot your "i"s in this game or you leave yourself open. The other side would be thrilled to see some dramatic arrests with what they would certainly call "machine guns". They already believe all AR-15's (and all black guns) are fully automatic.

[gdmoore28]

Think ahead about a future with a very anal AFT that wants to find any reason to snare those that play near the edge. Those on this board are, in the minds of the anti-gun types, already over the edge. Cross yout "t"s and dot your "i"s in this game or you leave yourself open. The other side would be thrilled to see some dramatic arrests with what they would certainly call "machine guns". They already believe all AR-15's (and all black guns) are fully automatic.

Well said, my friend. I think you are right on target.

GeeDeeEmm

[DARIVS ARCHITECTVS]

But I also DID NOT spend extra effort making the inside perfect either. Two reasons - First, a little more metal in a weld is preferrable to a little less and second - I wanted evidence of construction to be obvious. If the piece is ever looked over by some authority that knows what they are looking at - I want them to easily see that it was constructed from scrapped (per AFT regulations) parts. If it looks perfect inside and outside, what is to keep the law from saying it is a unregistered, class 3 weapon? Perhaps you were/are just trying to conceal the fact by making it semi? Finishing touches will include engraving its date of construction, "semi-auto only", and a lengthened serial number (to include the original).

I don't think you need to worry about making it look TOO GOOD. One can see even the BEST welds by looking at the finish in good sunlight. The altered microstructure of weld and the heat affected zone near welds causes a change in the way the sufrace appears, even after bluing. You simply CANNOT remove all traces of rewelding. A microscope set at 50x can also find welds and the heat affected zone easily. So, I would not bother trying to convince an ATF agent by leaving the surfaces in crappy condition. If the agent is an (Try a different word.), he's going to abuse his power and screw with your life anyway.

[Bil]

As a precaution,you may want to carry a 50X microscope with the gun,just in case you meet the agent DA refers to! ---bil

[jimdvan]

GOOD NEWS! I got my receiver back from the welder today and he was able to straighten it! It looks good so far. I inserted the rails to check the hole spacing and while the front 3 holes on both sides match up, (no cuts in between them), I found that the rear holes were only about .015" too far forward. I'm guessing there is enough wiggle room in the receiver to accomodate that.

[42rocker]

Way to go jimdvan

I'm guessing that everyone thinks that TIG is the way to go and LOTS of practice before you even think about touching the receiver parts.

What thickness of copper backer is normally used?? Where can one normally find copper backer also??

Thanks

Later 42rocker

[Bil]

Some use flattened copper pipe,I got some scrap flashing from a roofing/sheet metal shop.Don't need much.You may be able to find it in a hobby shop also. ---bil

[Michael J]

I'm thinking something like 1/8" thick copper sheet, or is that too thick? I'll look around the metalshop for this piping, i get scrap metal for free, but will have to pay for some new stuff.