well I posted all these pics with the thought
that I would be able to go back and edit/add text to each of these pictures at will so they would make more sense. Had I known the edit feature no longer existed i would have been a little more careful in giving descriptions of exactly what was going on in each picture. I guess I will just lump all the text in a couple of paragraphs below and hopefully it will make sense.Anyway if you have any questions or need a better shot of whats going on in any of these feel free to ask.
Hopefully these will help give everybody an understanding of what makes the semi 34 work. Not a tutorial but other than what filler rod was used or the mechanics of reassembling the other parts there isnt much else to the 34 semi build.
On the rewelding of the rec scrap, I used an aluminum bar to fill the bolt channel and a brass rod to fill the recoup hole. I had to pull one of the cams out to get the rod in the reoup hole, not a big deal to rivet back in place. In addition to the aluminum bar in the center of the rec scrap I used a 2" sq steel bar as the main component of my jig . The bar in the bolt channel doesnt have a large enough cross secton to even begin to keep the rec from distorting during welding so i relyed on it soley to keep the weld material from flowing into the bolt channel. The two inch sq steel bar was cut to fit on the flat top side of the rec where the topcover would normaly lay and a series of large welding clamps were used to pull the rec down tight against the bar. I also used a piece of 1"x2" steel bar clamped to the side of the rec opposite from where I was welding.
I did not get in any rush to weld , used a miller 250 amp mig with mild steel wire (70.000psi tensile) and welded a number of passes to fill the gaps. One of the gaps was aprox 3/4" wide. I just welded on each side of the gap until it was small enough to fuse both sides together. Most of the small gaps required 3-4 passes each to weld the large one took at least a dozen. When welding a project like this its best to weld a small pass on one side, wait for it to cool, flip it over and weld a small pass on the other side and repeat as neccesary. Since I used the 2" sq bar on top and a smaller one on the side opposite welding I must have clamped and reclamped 50+ times during the process. One of the big advantages of welding small passes and allowing complete cooling then reclamping between passes is you can tell exactly which weld/area creates any distortion as you go and can correct it at that point.
Patience is the other big key, I did the rewweld in the top pic over the course of an 8 hour day while I did other stuff, allowing plenty of time for it to cool between every pass. In reality the actual weld time was probably about 20 minutes , probably 2 hours spent on all the various clampig and reclamping procedures and 5+ hours allowing it to cool between passes.
My method isnt as easy breezy as some of the other welding jigs pictured and the constant reclamping was a pain but the upsides are that I was able to use stuff I had laying around the shop and my rec came out almost perfectly straight. No grinding broaching or other fixes needed to get the bolt to drop in, just cleaned up the insides of each weld with the die grinder and dropped the bolt with sear nothc removed straight thru.