What To Put On Bolt Threads Before Applying Jb Weld

Try the red LocTite (#271). If you ever need to take it apart, you'll have to apply heat (like from a torch). But at least you can take it apart if you have to. I'm guessing that epoxy would be permanent and may make a mess putting it together. The LocTite product is very thin and should get into the grooves better than thicker epoxy.

http://www.loctiteproducts.com/p/t_lkr_red/overview/Loctite-Threadlocker-Red-271.htm

Last edited: May 18, 2016

If all else fails, use JB Weld. Had a friend that used to use it to fill in the water jackets on his Pro Street cars. But in this situation, as long as all threads are clean, JB Weld is more permanent and resilient than Locktite or epoxy.
But either is easy to clean up with acetone later to try JB

I've used JB weld both successfully and unsuccessfully. It is a wonderful product to fill holes. If you buy the High heat version you can repair most things on engines. Some things like plastics it doesn't bond well too. I have peeled it off with a pocket knife. I would second the loctite to bond threads. I think part of the problem with some epoxies is the joint gets starved if the threads fit too close. When I've had sloppy fits on some jigs I simply fill the nut with epoxy, put a bolt in and let it dry, then just force the bolt out. It usually come free fairly easily. Loctite will hold a bolt very solidly but does come apart if you use heat.

Bill Boehme

I use a lot of JB weld around the farm. I read that JB weld is an epoxy with a filler, is that correct? If so, I wonder if the filler would interfere with a good bond in tight threads.

One perhaps interesting thing I discovered about JB weld - the filler is ferromagnetic, perhaps iron or steel powder. I once used JB to glue a small supermagnet into a fence staple holder to better hold the staple while hammering. I drilled and filled a hole, coated the magnet, then built a smooth fillet of JB weld on the outside. As I watched, the JB weld began to mound up over the magnet! I completed the tool by continuously smoothing the JB weld to where I wanted it until it started to set up.

JKJ

Yes, it is powdered iron in epoxy. The particle size is microscopic ... small enough that it could be somewhat of a thread lubricant. But, the thing that gives JB Weld it's great metal bonding properties is that the high percentage of iron filler mean that rhe coefficient of thermal expansion is very close to that of iron and steel. So for iron and steel parts that are subjected to operation over a wide temperature range there is less mechanical stress across the bond due to thermal expansion and contraction. Since epoxy cures to a very hard resin, the bond will eventually fail from fatigue unless the coefficients of both materials are closely matched.

BTW, the main difference between what we typically call iron or steel is the percentage of carbon.