Favorite thread locker?

[Crimson Tim]

I drilled out the broken bolt. It did not go well. I could not get the drill bit to catch, and the largest left-handed bit that I had was 1/4” which still left too much meat on the 3/8” bolt. Couldn’t get it to collapse or rotate or anything else, so I had to drill it a couple places and at a couple angles before it would let go. This of course did not leave the shaft threads unscathed.
Surprisingly, I was easily able to screw the bolt into the threads that were remaining. Seems secure but only got about 5/8” engagement before it bottomed out. The hole itself is about an inch deep. I would have preferred more engagement than that, especially since the threads are damaged now.
The working plan at this point is to epoxy a longer bolt into the hole, install a castle nut, drill the bolt for the cotter pin, and then cut off the excess bolt. I really shouldn’t have to torque this down much. Just make it good and snug and let the cotter pin keep it from loosening. Therefore, the thread engagement is probably sufficient. The fact that the threads are damaged now actually means the epoxy will get a better grip on them.
I was thinking I should tap the threads deeper, which would require a run into town to purchase said taps, though it’s not like I won’t need them for 100 other things anyway. Maybe I should save myself the trip and just grind some threads off the end of the bolt so that it will extend further into the hole, and just let the additional epoxy contact area hold it. That should be quick and easy.
Hope to get that done tomorrow.

 

[Don McCombs]

Good luck with it.

 

[Crimson Tim]

Too many things to do. Opted not to bother with making any changes to any threads. Just thoroughly slathered the bolt with JB Weld, inserted as far as it would go and let it cure several days.
Seems like it’s good and strong, though. I could not tighten the nut all the way easily due to a little epoxy that seeped up the threads. After cleaning that off, I snugged it down and drilled my cotter pin hole. My regular set of bits is probably 10 years old and all the small ones have broken during some past project or other after serving me well, so I figured why not just use the left-handed set to drill the through hole, too? Well, it worked, but I have to admit, these Harbor Freight bits are very flexible and weak. I broke one drilling out the old bolt, and a second one drilling the through hole. Not impressed.

In any case, got it done. Got it snug. Got it wired. Seems secure. Will let it run for a bit as it is, and if there are no issues, I will cut off the extra length of bolt. It’s kind of a hazard right now, except that it’s up against the wall.