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holding JB weld in a horizontal hole until it dries

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Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
Long story I have to rethread a horizontal hole in a greasy lathe apron. It will be 6/32. A 6/32 tap broke off and I removed it with a small carbide endmill. the hole ended up too large so I plan to fill it with jb weld then drill and tap the patch.
This screw is not a oil seal and it is just to hold on a thin aluminum plate that has knob marking/directions. So no real load.
My question is I think the jb weld will flow out of the hole while it hardens? So can I use something like electrical tape to cover it while it dries? I will ahve to ry to get the casting clean enough for everything to stick in place.
BILL D
 
Bill D --

I think that tape would hold the JB Weld in place while it cures, and I think you can make the hole in the iron rough or big-at-bottom enough that its adhesive strength wouldn't be the "tall pole" in retention, but I think that fully-filling the hole with the JB Weld would be challenging unless you can inject it with something along the lines of a grease gun fitted with a lube needle.

My suggestion would be to drill and tap for a thread-repair insert. (My "go to" choice for most uses is an EZ-Lok insert, which comes factory-coated with an encapsulated Loc-Tite anaerobic, which would make it worthwhile to blast the tapped hole with spray-can brake cleaner.) You might also consider gluing the plate in place with contact cement or RTV.

John
 
Tape wax paper over the hole if you want to use the JB stuff. I wouldn't use JB and thread a hole into it. I like the insert idea. A custom insert would probably be the ticket. Enlarge the hole slightly and JB weld a bushing that already has your thread.
 
Tape will work fine to keep it in place while it cures. I've done stuff like that many times and it works great.

As for getting the hole completely full, it probably doesn't matter. If it's just to hold a nameplate in place, it should be fine.

Blast the hole clean with some spray solvent to get it relatively clean and then use a small putty knife or screwdriver and just keep jamming it in there until it won't take no more. If you start by loading the bottom of the hole and keep loading more and more forcing it in at the bottom, it should pretty much fill from the bottom up and get most of the air out the top before it closes completely. Stick the tape in place and wait for cure.

Injecting with a syringe would be the best way to do it, but depending on how how finicky you are about the repair, it probably isn't necessary. Also, you might need more working time than the quick curing stuff.

It's just a small hole (like what I would expect after removing a 6-32 tap) you should be able to mix, fill, and tape fast enough that the quick cure would be enough time.

Worst thing that happens is it doesn't work and you have to drill it out and start over? Easy-peasy. It's just epoxy.
 
I have done something similar but used body putty instead of JB Weld.
I figured this was the fastest and easiest way. It worked fine, if it failed I would have drilled and tapped for 8/32 screw.
mike
 
I filled a 2" rusted-out hole in a steel skin wood core exterior door by cleaning out the rust and some of the core and filling with epoxy. My trick was to cover the drippy epoxy with clear mylar packing tape. I could see through the tape to make sure there were no voids. Then I put a couple of welding magnet squares over the tape to eliminate most of the bulge under the tape. Finished with a flush router on an offset base to level the epoxy without needing to use a sander on the door skin. Worked fine and new paint made the door look like new.

Larry
 
mike 44 said:
I have done something similar but used body putty instead of JB Weld.
I figured this was the fastest and easiest way. It worked fine, if it failed I would have drilled and tapped for 8/32 screw.
mike
Click to expand...

Forget the JB Weld. Go for the 8-32 as Mike 44 sais.
 
I would go for 8/32 since I know the 6/32 is a difficult size to tap. But I only have 1/4"-3/8 of an inch and I do not want to accidentally drill clear through and make another leak point on a English machine.
I like the clear tape and magnet idea. If I have to I will enlarge to #8 screws. I do have an old amalgam packer used in dentistry which would be perfect but not sure how it would be cleaned? I tried it a few times with wood filler and it is a bear to load and clean.
Bill D
 
^^^ This. I'm with Mike and the gang. You might not even have to drill-- just run the tap thru.
Avoid breakage this time around, of course. ;)

To load in the hole, get a short length of drink straw, make a slit so it can become a little cone-shaped funnel, and push in epoxy with the end of that broken 6-32 tap that's still lying around. Throw it all away when you're finished.

Chip
 
Would have been dry by now, should have simply used a piece of tape to hold it in there.....:toetap:

Why not start a new thread, this time run it as a poll....:nutter:
 
Why even tap it..if it just to hold on a thin aluminum plate.. why not put in the good screw and shove in the other into a cleaned hole with some JB or other filler..hold it pressed in tight till hard and let it go at that
 
You'll never get all the air out to get the top 10% of the hole filled, especially in the threads. I agree with the numerous other responses to use a thread insert, tap the next size larger, or put epoxy in hole & insert the screw while still wet (holding it in-place until it's cured).
 
Bill D said:
Long story I have to rethread a horizontal hole in a greasy lathe apron. It will be 6/32. A 6/32 tap broke off and I removed it with a small carbide endmill. the hole ended up too large so I plan to fill it with jb weld then drill and tap the patch.
This screw is not a oil seal and it is just to hold on a thin aluminum plate that has knob marking/directions. So no real load.
My question is I think the jb weld will flow out of the hole while it hardens? So can I use something like electrical tape to cover it while it dries? I will ahve to ry to get the casting clean enough for everything to stick in place.
BILL D
Click to expand...

.
epoxy is a plastic which normally has a 5000 psi tensile strength where cast iron can be 20,000 to 60,000 psi tensile strength. epoxy will never be strong enough.
 
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