Adhesives for aluminum to carbon fiber attachment?
I am revisiting a problem I encountered a few months ago: I have only a tiny amount of clearance between a rail section (for a BUIS front sight) Mlok nut and a gas block. The handguard is carbon fiber, and I have only one spot for the BUIS to go. After basic assembly, there was contact between the Mlok screw and the block. Even after shortening the screw, there is less than the thickness of a 3x5 card between the gas block and the nut, and barrel whip/flux/flex/vibration/whatever continues to cause contact. Go ahead and laugh at me, but it's a situation I would rather not have.
Currently, I am using only the front Mlok screw and nut. I can solve the problem by leaving off the rear screw and nut, but I would rather have another point of attachment. Swapping out gas blocks would probably not solve the problem. (The difference between a relatively tall block, like the Geissele, and a short one, like the BCM, is only about 0.012".) I could grind off a chunk of the gas block, buy a different barrel (with a shorter gas system), or buy a longer handguard.
Or, because I am strange and stubborn, I could try an adhesive to make the front sight base a "bomb proof" installation. I consider a front sight base to be a fairly permanent addition, so that doesn't bother me. After scouring the web for ideas, at websites used by bicyclists, hobbyists, archers, etc., I have collected (and offer for your amusement) only a few suggestions. Evidently, aluminum and carbon fiber to not work well together with most glues. In this case, the front sight base is a specialty low profile item, so a Magpul plastic base will not work. They are:
Specialty adhesives: used by the aerospace industry; obscure, expensive, and difficult to find.
Fiberglass strips as a bridge: both aluminum and carbon fiber would rather attach to fiberglass via epoxies than to each other.
High temp epoxies: even if you get a good bond with a fiberglass strip or a specialty epoxy, most glues start to fail at about 350 degrees F; assembly would be sitting right over the gas block, so maybe a crappy hold for a high temp epoxy is better than a good hold that will fail at high heat.
Chewing gum: No kidding; it came from a Brit archery guy who had to attach aluminum points to carbon fiber shafts; easy to apply and replace as necessary.
Any other more specific suggestions?
'That whole effort was held together by sweat, shame, and a tiny bit of pride.' -- Son of Commander Paisley
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