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Author Topic: Machining internal threads on lathe.... Seeking advice...  (Read 1332 times))

Offline Duane38

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Re: Machining internal threads on lathe.... Seeking advice...
« Reply #20 on: February 23, 2021, 10:12:08 PM »
Hi Phil,

You're using insert tooling...assume the geometry on the insert to be correct. The "flat" on your cutter shank should be horizontal, insert will be tipped downward.

A shot in the dark here, but some lathes (like the Smithy I learned on) are not at the "30degrees" you NEED when set AT 30degrees. With some lathes, you need to set @ 60 degrees. Having this wrong, produces a mess similar to what you describe, and THIS was the "hump" that I struggled with learning to single point.

If you look at it from the top, does the compound actually appear to be on the correct angle to follow the desired thread profile?


Aside...good to see you still kicking around. :)

Regards,
Al

Hey, buddy.  Yeah, I'm still around!  Been super busy over the past few years...  I'm more settled in and in the Northern Virginia/D.C. region.  Heck, been here almost 9 years now.  Sure doesn't feel like it with how fast paced life is out here.  Hope you've been well.

Sure enough, the tool does tilt toward by design.  Also did check the compound angle in relation the the cross slide with a degrees too once squaring up the tool post with the chuck.  Everything is up to snuff.

The carbide insert which came with bar/holder does seem to have no relief.  The threads are pretty and crisp, but the bore just grows and the threads seem to meet a certain point in depth until it grows again.  In fact, the threads get to a little more than 50 percent of what the thread gauge is before growing bore larger.  Also, have a threaded tester that felt real tight upon threading in, then suddenly super loose.

I'm canning that tool for this project.  Ordered a properly ground HSS solid inside thread tool from LMS. 

This weekend the valve will be completed. 

  • Stafford, Va

Offline WhatUPSbox?

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Re: Machining internal threads on lathe.... Seeking advice...
« Reply #21 on: February 25, 2021, 01:25:52 AM »
I have not tried this, but it looks interesting.
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Offline rsterne

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Re: Machining internal threads on lathe.... Seeking advice...
« Reply #22 on: February 25, 2021, 01:53:10 PM »
Really clever, and something I have never thought or heard of....  8)

Bob
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Offline Duane38

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Re: Machining internal threads on lathe.... Seeking advice...
« Reply #23 on: February 25, 2021, 07:10:10 PM »
Saw that the other day when it came across my tube notification.  I like Tony.  Amusing and educational!

I'm gonna try this out several times as a test....
« Last Edit: February 25, 2021, 07:14:11 PM by Duane38 »
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Offline Duane38

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Re: Machining internal threads on lathe.... Seeking advice...
« Reply #24 on: February 28, 2021, 07:13:52 PM »
Yay!  I did it.  Finally! 
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Offline Rob M

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Re: Machining internal threads on lathe.... Seeking advice...
« Reply #25 on: February 28, 2021, 09:08:12 PM »
Yay!  I did it.  Finally! 

nice , looking forward to the tube and lever assembly.
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