Threading issues

[Leadfootsmurf92]

Good evening, I'm new to the forum, and new to machining. I have a HF 7x10 lathe and the small HF mill. I've been working on threading on the lathe, and have so far not been successful. I am currently using a sandvik tool holder with a 16er ag60 insert. Compound is set at 29.5 degrees, and I've given up using the threading dial, and resorted to just backing off and reversing the lathe to restart the thread. I'm still having issues with the insert not following the existing thread. Any help would be greatly appreciated!

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[mikey]

Welcome to HM, Smurf!

The first thing that came to my mind here is to wonder if your compound is set to 29.5 or is it 60.5 degrees. The degree markings vary with the lathe and on my Emco lathe, I have to set the compound to 60.5 to get the right angle. Otherwise, the thread form is distorted.

When the compound angle is set correctly, your thread dial indicator will work properly. Why not give it a try or maybe show us a pic of your set up and the problems you are having.

 

[Leadfootsmurf92]

I just tightened a screw that pulled some of the slop out of what i assume would be the x axis. I think that will help (i will try again tomorrow). Here are some pics of my setup.

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[mikey]

Yes, your cross slide movement is the X-axis.

Judging from the pics, you compound is set at the wrong angle. It should look like this:


Maybe this one will help:



See the difference in the angle? Try setting the index under the compound to 60.5 degrees and try again.

 

[higgite]

In before someone says "plunge cut and forget all these silly angles".

Mikey beat me to it with the angle analysis. I type too slow. If you don't already have one, you might want to pick up a protractor similar to this one. And don't fret, your mistake is a common one.

Tom

 

[Leadfootsmurf92]

Ok that makes sense. But my angle marks only go to 45, so I need to use a different method to calculate the angle?

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[middle.road]

Hit up YouTube, search on threading videos. this is one of my favourites:

I used it to get out of a bind threading some 7/8"-32 piece parts.
@mikey's recommendations are on the mark and valid. Follow them.
The whole 29.5° method is like discussing religion or politics. But it's been done that way for so long that it is
taken for granted as being the best and only method.

 

[Leadfootsmurf92]

Ha i just saw your response. Ok I will get one of those and give it a try!

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[Leadfootsmurf92]

7/8-32 was the thread I was just trying before I posted this! It started good, and then went down hill lol.

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[mikey]

Ok that makes sense. But my angle marks only go to 45, so I need to use a different method to calculate the angle?

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Use a protractor like Tom/@higgite said and set it once. Then make an angle gauge from plywood/plastic/aluminum/whatever and reference it off your chuck face and the side of your compound. Then its a snap to set the compound at the right angle whenever you thread something and away you go.