Thread chaser

JHZR2

JHZR2

Staff member
Joined
Dec 14, 2002
Messages
52,832
Location
New Jersey
I tried cutting one. I’m not sure if I did that great. How important are straight, perpendicular cuts to the threads?

72B057D9-F945-452E-AC70-2B17DA5D2672.jpeg
A58C4929-63E3-43BF-8DBA-AF656E9CDCEE.jpeg


I also knocked down the first thread a bit so that it’s easier to thread into any hole.

A tap would have very sharp straight deliberate edges… but I’m not trying to cut threads either, just clean and shape the material into place.

Does it much matter?
 
I don't think it matters. You can get spiral flute taps like a drill bit, so......
 
Astro14 said:
I try to have a sharp leading edge - so that as it screws in, debris is picked up by the sharp edge, instead of being trapped and compressed by a beveled edge. A dremel gives a finer cut than a die grinder. Better results with a Dremel.

I would re-cut a new bolt.
Click to expand...
I thought since you wanted to clean and shape threads and not really cut, you wanted a sharp trailing edge and then a deep area to hold junk. Wouldn’t an overly sharp leading edge potentially bite in and damage or gall weakened threads?
 
JHZR2 said:
No I don’t. And I was cutting a big piece of steel already, so…
Click to expand...
I don't know what the difference is between a bolt with slots cut in it from a dedicated thread chaser, but there's gotta be something if they're in the business of selling them.
 
JHZR2 said:
I thought since you wanted to clean and shape threads and not really cut, you wanted a sharp trailing edge and then a deep area to hold junk. Wouldn’t an overly sharp leading edge potentially bite in and damage or gall weakened threads?
Click to expand...
Exactly.

So, to clean the threads, a sharp leading edge to pick up gunk - the slot gives it a place to go.

A gradual leading edge forces the gunk deeper into the threads being cleaned.

Commercial thread chasers have sharp leading edges. A finely cut slot with sharp edges on both sides.

Whether I use a commercial thread chaser, or a home-made one, I haven’t seen any evidence that they are damaging the threads with that sharp edge. Even in an aluminum casting. There aren’t any metal shavings from cleaned threads present on removal, but there is corrosion, dirt, grease, etc.
 
I have a couple lisle thread chasers around and I can't tell a difference on the leading and trailing edge, visually or feel. However I am not a machinist so its entirely possible that level of detail is beyond my skill set.
 
bullwinkle said:
Thread chaser is tool steel, can be used over & over. A bolt with slits cut in it might work once...
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Depends on the bolt. I’ve got several that work well. They all have a sharp edged slot cut in them. I‘ve used them many times. I even made one from a sparkplug because the commercial sparkplug chaser would not fit on the plug well.

And if one wears out, it’s pretty easy to make another.
 
JHZR2 said:
I tried cutting one. I’m not sure if I did that great. How important are straight, perpendicular cuts to the threads?

View attachment 154985View attachment 154986

I also knocked down the first thread a bit so that it’s easier to thread into any hole.

A tap would have very sharp straight deliberate edges… but I’m not trying to cut threads either, just clean and shape the material into place.

Does it much matter?
Click to expand...

Try it, I find making one out of a 12.9 bolt help keep them alive longer.
 
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