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Thread chasing

paulm

paulm

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OK, some new toys arrived today, my Ashley Iles uni chaser, arm rest and other bit to dig a bit out at the back of the thread. Before I dive into the shed, one thing I can't find is how much bigger the male part of whatever I'm going to thread should be before putting a thread on it (if that make sense)? So say for instance I've drilled a hole 1" diameter and then put a thread on it, what diameter should the male end be? or is this a stupid question and both should just be 1"? maybe I should disappear into the shed and find out.

:thinks:
 
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Wyoming wood turner did a vid on thread chasing a few weeks ago.

If you cut both side to an inch then the threads won't work. I think you probably only need to make the male part marginally bigger (assuming an internal box female) so that the uncut male fits just on to the top of the threads of the female.

Does that make any sense? Never tried it myself.
 
bellringer

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well if it anything like metal turning the what we do is if the pitch of the thread is 2.5 mm we the make the male part to 2.5 mm smaller then the female part which would be the size of the thread

for Example for a 40 mm thread the male part would be 37.5 mm and the female would be 40.0 mm

but that for metal so it might be different
 
paulm

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Mr Finch said:
Wyoming wood turner did a vid on thread chasing a few weeks ago.

If you cut both side to an inch then the threads won't work. I think you probably only need to make the male part marginally bigger (assuming an internal box female) so that the uncut male fits just on to the top of the threads of the female.

Does that make any sense? Never tried it myself.
Click to expand...

Thanks Mr Finch, I was wondering if there was a science to this rather than trial and error.
 
paulm

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bellringer said:
well if it anything like metal turning the what we do is if the pitch of the thread is 2.5 mm we the make the male part to 2.5 mm smaller then the female part which would be the size of the thread

for Example for a 40 mm thread the male part would be 37.5 mm and the female would be 40.0 mm

but that for metal so it might be different
Click to expand...


That makes sense Alex, thanks.
 
Shaver

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I find the easiest way, (for me) is to do the female thread first, then when preparing the male end make it tapered so as the end just fits into the female round.

Press the female onto the male taper so as to leave a slight ring mark on the male end. This is your aiming mark, so cut down leaving the mark proud of the surface. Proceed to chase your thread.

This may sound a bit hap hazard, but timber doesn't need the accuracy that is normally used on metal. I just guess the thread depth needed, but always slightly more. As said, you can always take a bit off - etc!

One of the best chasers to start with is a 20tpi, and with the thread on that I usually give it approx. 1.5mm. If your using a 16tpi try 2mm, this is the allowance for cutting the threads. ALWAYS leave some to take off until you get some practice in.

Also I wouldn't bother with and arm rest to start with, just move your tool rest around. Most folks are hesitant when first beginning chasing, don't be just go for it. If too hesitant/slow you'll just strip the threads.
 
Jimjam66

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bellringer said:
for Example for a 40 mm thread the male part would be 37.5 mm and the female would be 40.0 mm
Click to expand...

Other way around, Alex. The Female part is drilled to a smaller diameter because the threads will cut 'outward' to the full diameter, while the male is is turned to the full diameter (or fractionally less) because the threads will cut 'inward' to match the peaks of the female thread.
 
bellringer

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Jimjam66 said:
Other way around, Alex. The Female part is drilled to a smaller diameter because the threads will cut 'outward' to the full diameter, while the male is is turned to the full diameter (or fractionally less) because the threads will cut 'inward' to match the peaks of the female thread.
Click to expand...

Ye it was a late night last night
 
paulm

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Thank everyone, I think I'm armed enough to do some damage (hope I don't offend anyone saying armed :thinks:) so I'll be off to the shed soon.
 
Jim

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Shaver said:
Tried to post a couple of pics of some thread chasing I did a while ago. Ended up throwing a tantrum. :sob: Will have a look at the way to post pics and see if I can get them up later.
Click to expand...

Shaver, this may help you adding a picture ... Click Me!! :thumbs:
 
Shaver

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As I said before I would post a couple of pics, (once I found out how to).

This was a commission from my brother in law as a annual prize in the gun club where he was a member. The idea being the cased 'priest' would be presented each year, and another priest would be given to the winner to keep. Anyway my BiL has now passed on but the club continues the presentation each year, where I still send on the extra priest.

I digress, the intention was to show some chasing I did when making the case. prize1.jpg.

The case was made of Walnut with Purpleheart ends, one fixed, one screw to close. I found the Walnut too soft to hold a thread, and the Purpleheart was just to brittle where the threads kept breaking. My answer was to make two inserts, one with a female thread in the lid, and a male threaded piece grafted to the top of the Walnut cylinder. The both threaded pieces where made from Box wood.

This was the finished piece, prize4.jpg

and this the thread inserts. prize3.jpg
 
paulm

paulm

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Thank you shaver that is very informative and what a lovely thing you've made there and so generous.
 
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