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Posted: 3/28/2009 7:34:57 PM EDT
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How do most flat builders attach their internal rails? The Russian way is to spot weld the rails inside the receiver.
I took my receiver to a local body shop and asked them to spot weld the rails not knowing they don't use spot welders much anymore. The result was shocking to see MIG weld beads where the bolt carrier is supposed to go. I had to Dremel the weld beads away and clean up with a file. I asked the body shop owner why he didn't use a spot welder and he told me that they don't use them much because they either MIG weld or use structural adhesive. Some automakers do use structural adhesives where they can't spot weld and the joint is strong enough to hold up in a crash. I worked in body engineering and the adhesives used cure in the bake cycle after the body is dipped in E coat. Has anyone used structural adhesives to attach the rails? The surfaces would have to be extremely clean before the adhesive would be applied to the receiver and rails for a good bond. I would like to hear from other builders what they think about this. |
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since i had to borrow a spot welder and go through the trouble of buying 2 feet of copper rod and bench grind modify it to go inside the rec. i was kinda curious of an alternatve method besides screws. most welding would be too much for little stuff like this and would burn right through the 1mm rec. and its way too inconvienent and costly to buy a tig even though ill need one for my HK mp5/g3 projects but not now.
the wood glue method is holding up good, i only got blown up twice.   
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Quoted:
i use wood glue Wood glue will work for your wood stocks.! This was not intended as a joke but to see whether other builders used adhesives to bond the rails to the receiver after the MIG weld disaster I had where I had to Dremel the weld beads to make the receiver usable. Structural adhesives are extremely strong and are used on card and aircraft. How do you think they bond composites to titanium with wood glue? No they use structural adhesives. I worked at Douglas Aircraft where some applications call for structural adhesives and some control surfaces are made of a honeycomb core bonded to the aluminum outer skins. They had an air force program called PABST; Primary Adhesive Bonded Structure where they built a fuselage section where the structure was bonded not fastened to save weight. The bonded structure tested to have a longer life cycle than the fastened structure. Aircraft undergo higher stresses and endure greater temperature extremes than cars or AKs do. Furthermore these adhesives are a lot stronger than epoxy or cyanoacrylates (Super Glues) . |
| i know you were not joking but im unfamiliar with the bonding adhesive. i was kinda curious how it works. if it actually welds the metal or is a solid adhesive that seeps into the pores of the metal and is strong enough to withstand the force of ejection. for the guide rail i wouldnt see problem if its used in aircraft structural bonding. where do you buy this and how much?? |
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i know you were not joking but im unfamiliar with the bonding adhesive. i was kinda curious how it works. if it actually welds the metal or is a solid adhesive that seeps into the pores of the metal and is strong enough to withstand the force of ejection. for the guide rail i wouldn't see problem if its used in aircraft structural bonding. where do you buy this and how much?? This is what I am trying to find out. This does not weld but is an adhesive. I had someone on another forum tell me that in his body shop the adhesive sales rep bonded two pieces of sheet metal and then they pulled them off on an frame machine and the sheet metal tore off. The rails are also being held in place by the center support which would strengthen the bond. The rails have a lot of surface. I got some Loctite 430 adhesive for bonding steel from Grainger and used it on my receiver. I first cleaned the steel with a degreaser then after drying, I applied an adhesion promoter for cyanoacrylates then after positioning the rails I applied the adhesive. I removed the center support which was temporarily placed and tried to see how strong the bond was and it's strong and I doubt it would break while shooting. I then hammered the center support to rivet it in place. |
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Quoted:
I got some Loctite 430 adhesive for bonding steel from Grainger and used it on my receiver. I first cleaned the steel with a degreaser then after drying, I applied an adhesion promoter for cyanoacrylates then after positioning the rails I applied the adhesive. I removed the center support which was temporarily placed and tried to see how strong the bond was and it's strong and I doubt it would break while shooting. I then hammered the center support to rivet it in place. Let us know how it works. ETA: If it failed (let's say due to improper prep) can you remove the adhesive by sanding? |
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I've been using a mig welder on all my falt builds so far.
I thought about using JB weld for the lower rails. What's the worst that could happen? Jam? Failure to eject the spent round? I mean, there's already a big rivet going across the receiver. That's not going anywhere.
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Quoted:
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I got some Loctite 430 adhesive for bonding steel from Grainger and used it on my receiver. I first cleaned the steel with a degreaser then after drying, I applied an adhesion promoter for cyanoacrylates then after positioning the rails I applied the adhesive. I removed the center support which was temporarily placed and tried to see how strong the bond was and it's strong and I doubt it would break while shooting. I then hammered the center support to rivet it in place. Let us know how it works. ETA: If it failed (let's say due to improper prep) can you remove the adhesive by sanding? You can sand off the adhesive and properly prep the surfaced and either try again or weld them. Turbosc20 is correct the cross member is also riveted and it holds the rails in place. |
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[You can sand off the adhesive and properly prep the surfaced and either try again or weld them. I think I'll try this when I rebuild the first rifle I built. I looked up the specs for Loctite 430 and the strength is 3600 lbs/sq. in. The cartridge moves off the bolt face with about 2 lbs pressure, so this might work. |
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