How to cut internal Acme threads in a finished piece?

Halligan142 said:
Stupid question, but couldn't you just use a belt sander or a file and make the end of the broom into a 5/8 peg? Or would that defeat the purpose? Figure a $9 file or $ 5 sanding belt and some time is a lot better than $60-$90 for a tap that won't get used often. That is if you don't have access to a lathe.
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Not stupid at all. Yes, you could certainly do that. The inner core of the painter's pole thread is almost exactly 5/8" so removing the Acme threads would indeed make the remaining stalk compatible with photo gear. But this isn't intended to be a one-off for my use exclusively. Most (nearly all, I would imagine) photographers are neither equipped nor inclined to perform the required surgery on a painter's pole. Also, there's the situation in which the photographer is shooting in a remote location. It would then make more sense to just buy another painter's pole at the destination rather than trying to travel with a 5-foot long
(or more) fiberglass pole. It would also be nice to be able to use the painter's pole as a painter's pole :)

Here's a very nicely machined commercial Acme-to-baby adapter:

http://www.kaceyenterprises.com/?page_id=447

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OldMachinist said:
1 foot of 3/4-5 acme from Mcmaster carr $10 plus shipping.

http://www.mcmaster.com/#general-purpose-acme-rods/=m8ignm

Grind some flutes in, sharpen it like a tap and case harden it should cut aluminum.
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Thank you for that but the 12"/$10 item on the McMaster site is made of plain steel which, I thought, would be too soft to serve as a tap. The Grade B7 Alloy Steel 12" rod is $23. Would case hardening (not that I know how to do that) make the plain steel suitable for use as a tap?
 
Case hardened mild steel will cut aluminum easily. How many parts do you need to tap?
 
There are a couple products on the market that will harden mild steel. Check out "Cherry Red". I can't recall the name of the other one, but I'm sure someone else will chime in. Basically you heat the steel part up with a torch till it is red and then dip it in the powder. Voila, instant hardened surface. The hardened layer isn't that thick, so would have to do it after initial shaping, but before final sharpening.

http://usaknifemaker.com/cherry-red-case-hardening-power-1lb.html
 
DMS said:
There are a couple products on the market that will harden mild steel. Check out "Cherry Red". I can't recall the name of the other one, but I'm sure someone else will chime in. Basically you heat the steel part up with a torch till it is red and then dip it in the powder. Voila, instant hardened surface. The hardened layer isn't that thick, so would have to do it after initial shaping, but before final sharpening.

http://usaknifemaker.com/cherry-red-case-hardening-power-1lb.html
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I just watched a short Cherry Red video on youtube. Sure, the process looks easy enough but, YOWSER, a 5 pound pail of the magic power costs $80!! Between the cost of the rod and the cost of the Cherry Red powder, it would make more sense to try to find a reasonably priced 3/4-5 tap.
 
The other product is Kasenite. Available at Brownells and others. It is available in #1 and #2 grinds. I use #2. You will need a torch that can get the metal to red and a bucket of water to quench after applying the compound.
Pierre
 
pdentrem said:
The other product is Kasenite. Available at Brownells and others. It is available in #1 and #2 grinds. I use #2. You will need a torch that can get the metal to red and a bucket of water to quench after applying the compound.
Pierre
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Kasenit is, apparently, no longer available.
 
I would make a threaded insert, aluminum or brass, or whatever, that would have the 3/4-5 Acme on the ID and say 7/8-14 thread on the OD and the length needed. Next bore and tap for 7/8-14 thread in the aluminum housing. Loctite the piece in the housing, and if you are worried about it coming loose later. Drill a hole tangent with the OD of the insert, just a little into the insert and install a small roll pin. It'll be there forever.
Ken

Oops, 7/8-14 might be a little small. Go with 1"-14!
 
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Did you ever consider epoxy or other plastic. I once wanted to adapt the male acme thread on the end of my aluminum boathook to allow a landing net to screw on. I cut the handle off the net leaving about a 2" stub of aluminum tubing. I plugged the bottom end of it, and filled it mostly full of epoxy resin and inserted the well waxed end of the booathook thread into it and set it up in a vertical position to cure. It screwed off fine and served me well for many years until I tried to land a good sized barracude when the boat was travelling too fast.
Michael
 
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