Plastic thread repair

[bigcountry78]

I have an old folding shovel, it may be army issued or it may be a cheap imitation, I’m not sure. I’ve had it forever. Anyway, the handle comes apart and has a saw blade that is supposed to screw into the handle to cut roots. But the threads are boogered and, while it screws in, they don’t catch and it will slip into the handle. Any ideas on how to get the threads to tighten up? Are there replacements saw blades available? I tried to wrap electrical tape around the threads but it was too thick and just peels off when it’s threaded in. Maybe Teflon tape would work better?

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[Doppleganger]

Is that smaller end part of the larger part and just worn down? Or does that smaller end thread into the larger part? Trying to visualize which threads ID/OD are boogered.

Do you know the size of the affected threads?

 

[Camar068]

Is it a thread size you can match? My thought would be fill in the threads with JB weld, good superglue, etc and then re-thread it.

If it's something of value to you, try on something else that's plastic until you get the process down pat.

 

[bigcountry78]

Is that smaller end part of the larger part and just worn down? Or does that smaller end thread into the larger part? Trying to visualize which threads ID/OD are boogered.

Do you know the size of the affected threads?

The smaller end threads into the larger piece, and the smaller threads are worn. ID of the outer piece is 7/8’s of an inch as best I can tell, I only have a tape measure. No caliper on hand.

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Edit: now that I look at it, it resembles a plastic pipe plug. Now I’m wondering if there’s a way to replace it with a steel pipe plug, and how I could attach the blade.

 

[bigcountry78]

Is it a thread size you can match? My thought would be fill in the threads with JB weld, good superglue, etc and then re-thread it.

If it's something of value to you, try on something else that's plastic until you get the process down pat.

I like those suggestions. I could probably match it with a trip to the hardware store. It’s not of any real value, just something I’d like to correct so that it’s useful. I keep it under the back seat of my truck, cause you never know.

 

[bucket]

The smaller end threads into the larger piece, and the smaller threads are worn. ID of the outer piece is 7/8’s of an inch as best I can tell, I only have a tape measure. No caliper on hand.

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Edit: now that I look at it, it resembles a plastic pipe plug. Now I’m wondering if there’s a way to replace it with a steel pipe plug, and how I could attach the blade.

Pipe plugs are tapered thread though. I guess you could run a pipe thread die over the bigger end so it could thread into the handle in either direction.

 

[Doppleganger]

Do you have any taps or thread dies?

I would use something like JB Weld or even POR-Patch (from the dreaded Por15 people but it makes JB look like play dough).

I bought a car once that the PO had broken a bolt off for an accessory bracket. He drilled it out crooked and it went into a water jacket. I drained and dried everything out - packed it full of por patch (can use JB too) then dipped the correct bolt into some grease and 'threaded' it in. The grease kept the bolt from welding itself in. Waited 24 hrs then gently unscrewed the bolt. Wallah - plugged the hole and made new threads that took the 20 ft lbs of torque.

 

[Ricko1966]

Run it in as secure as you can,drill a hole through the whole mess,put a cannon pin in it. Use it,screw it back on the other direction,put the Canon pin back so it doesn't get lost. Drill the hole tight to the pin size.

 

[Grit dog]

Do you have any taps or thread dies?

I would use something like JB Weld or even POR-Patch (from the dreaded Por15 people but it makes JB look like play dough).

I bought a car once that the PO had broken a bolt off for an accessory bracket. He drilled it out crooked and it went into a water jacket. I drained and dried everything out - packed it full of por patch (can use JB too) then dipped the correct bolt into some grease and 'threaded' it in. The grease kept the bolt from welding itself in. Waited 24 hrs then gently unscrewed the bolt. Wallah - plugged the hole and made new threads that took the 20 ft lbs of torque.

That would be a huge tap or die to have. And buying one would cost 3x as much as a new survival shovel.
I was going to suggest pinning it. Thread it in, drill a hole thru the handle and the plug.

 

[squaredeal91]

Electrical pipe/ conduit is straight thread if that helps. Back a long time ago all pipe had straight threads and when they came out with tapered they gave it to the plumbing world

 

[bigcountry78]

I do have a tap and die set, but nothing big enough to fit this. I woke up a little early this morning, and had time to lay in bed and ponder. I came up with an idea, maybe see if I can find a piece of hollow thread. Maybe that’s called conduit, I’m not sure lol. But find a piece that threads into the handle correctly. Then, sand down the plastic threads until the metal threads will slide over it, then secure it with glue? Epoxy? So basically sleeve the plastic threads with a metal thread section. That seems like the easiest option, but I’ll have to find a sleeve that fits.

 

[legopnuematic]

Sounds like it is time to buy a lathe…