First threads!

DavidR8 said:
Thanks @higgite, I like the idea of picking a set number of turns to back out the cross slide. Seems it would lead to less confusion.

It was 23 degrees from perpendicular to the centre line of the spindle.

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You want it 29.5 degrees from perpendicular to the spindle axis. That's why your threads look like they do. A common mistake for newcomers to threading. They hear 29.5 degrees and set the compound by the protractor on their machine which usually indicates degrees from parallel with the spindle axis. Don't ask me how I know that. ;)

Tom
 
Thanks Tom, I’m going to retry tomorrow with the compound at the correct angle.
Really appreciate everyone’s advice.


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Looks like you're getting going. :)

Don't tell anyone, but I'm one of those crazy people who don't thread with the compound... Lol.. In part due to having it removed most of the time and not wanting to bother reinstalling it.
 
ttabbal said:
Looks like you're getting going. :)

Don't tell anyone, but I'm one of those crazy people who don't thread with the compound... Lol.. In part due to having it removed most of the time and not wanting to bother reinstalling it.
Click to expand...

Hah, I was going to say you took it off and lost it!
 
When I was an apprentice we were not allowed to set the compound slide to any angle but square to the lathe except when we were turning a feature that had an angle, but absolutely not for threading

Oh, we knew the procedure existed, and once we had perfected screwcutting, we were then allowed to use it.

The training was hard, but in the end we were pretty good at what we did, because we not only knew how to do it, but why.
 
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Good for you David,
You’re getting to know your lathe.
 
DavidR8 said:
Oh jeepers! I forgot to set the compound to 29.5 degrees!!!
It was set to 23 degrees.
What impact would that have had on the operation?
Click to expand...

Your threads may not be 60 degrees, but no matter, you were practicing the operation.
Besides it sounds like you cut it at a random diameter, so you were never going to check it with a nut anyway!
It is still a win!

One thing that might make the next one easier.....
Cut a groove near the end where you finish the threads. It's a place to temporarily park the cutter at the end of cut when you disengage the half-nuts.
Make it about ~2 threads wide, and it takes away some of the panic at the end.

-brino
 
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The angle of the compound will not effect the threads if you are feeding with the cross slide only. It will when using the compound. Yep, I know that from experience.
Looking good Dave.
Another tip is to cut a finer pitch thread. The carriage is moving a lot slower. Try cutting a 20 tpi and see the difference.
I use a dial indicator on the carriage to measure when you are nearing the end of the thread.
Joe Hynes
 
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