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Posted: 12/23/2006 1:38:46 PM EDT
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I have a registered receiver that I am looking for someone to remove the SAFE and FIRE markings by welding over and then engraving SAFE, SEMI and Auto on it. Then having it finished. Does anyone have anyone in mind besides Tom Sawyer or Orion. Thanks Mike |
I must STRONGLY agree. Who pays if it get's ruined?? It CANNOT be replaced. Although, you would be a favorite of the BATF for getting rid of another RR. Good luck with that. PS: I would insure it heavily before letting ANYONE take a torch to it. 
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I'm not trying to argue that the aluminum won't crack, because it could. I'm just here to note that you will not cause stress CORROSION cracking by welding. It can occur in a weld, specifically in the heat affected zone surrounding it, but this is after the part has been welded, stress relieved & put into service. Stress corrosion cracking is a condition in which a portion of the part has either become embrittled by corrosion/oxidation or the subsequent loss in thickness has weakened the part. Cyclical stresses such as vibration can also play a part & usually do. The problem he was talking about is rapid expansion in a localized area, followed by rapid contraction. All this puts undue stress on the surrounding material during the welding process & subsequently leaves a great deal of stress in the actual welded area. Now that I'm done, I'll repeat that the part may very well crack if welded, just not from stress corrosion cracking. Even if it doesn't you'd have a problem controlling warpage, especially in something as geometrically complex as a lower receiver. |
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In 7075 the stress from solidification creates intergranular boundary cracks which becomes the site for contamination and thus begins the incubation period for SCC. Your right SCC doesn't happen overnight and add the other factors you mentioned and SCC will propagate. Stress relieving can result in post-weld heat treatment cracking further propagating the boundary cracks. If you don't stress relieve the tensile stress in the weld further exacerbates the problem. |
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John Norrell used to weld M16 demilled lowers back together on a regular basis. The only issue he had was the jig used to hold the two halves needed to be .040 longer as the aluminum shrank that much after welding. He never reported any issues after welding and grinding the weld down. Are talking possible or probable results from welding 7075? |
Someone posted information showing older lowers were 6061 not 7075. |
Never could figure why you would remove the safe marking and then put it back on again. |
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The reason behind it all was that the marking were installed very lightly and you can barely see it. In fact all of the markings on it is like that. Tom Sawyer Engraving Company when that company was in business was originally going to do the job. They were going to apply an aluminum type of paste then engrave and finish it off. The new company Orion will now only engrave it an finish the markings. Better to just add the auto and copy it all on the right side. Mike |
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