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SugarKaneBlanks

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I am having the hardest time getting good male threads on my pens. Female threads are working well, but everytime I try to put a male thread on with a die I shear the threads off.

I am using a cheap harbor freight wood lathe. I do have a sliding tailstock die holder, but am also using cheap dies. I am specifically struggling with 10mm x 0.75.

My process Trim tenon down to 10mm or 9.8. I have tried 9.8-10.5 with similar results. I then apply WD-40 and using the tailstock align it to the tenon. I use hand pressure to advance the die while slowly turning the tenon. I back turn every quarter turn. At the end the threads are complete stripped off and unusable.

I appreciate any tips. I am sure using a cheap wood lathe and cheap dies are not helping but surely there has to be a way to get this to work.

Thanks!
 
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A tenon of 10mm is too large. 9.8 should work fine. Even 9.9mm should work.

Check the die and make sure that you are starting it with the markings toward the tenon. This is the side with the gradual start. Once you have that worked out and the tenon threaded, you can flip it to get the threads cut better all the way to the shoulder.

Also, cut a small chamfer (45 degree cut) on the end of the tenon, to help the die get started.

Good Luck!
 
Try this, look closely at the die to see if one side has more chamfer (count how many threads are ground with flat tops) if there is a difference between the two sides start with the side that has more. Only tighten the set screw enough to keep the die from spinning. Slightly chamfer the tenon. Slide the die and holder close to the tenon. Bring it into contact and rotate the tenon counter clockwise slowly while jiggling the holder. This should center the die on the tenon. Without moving the die turn the tenon clock wise, putting light pressure on the die. Continue until your die is solidly on the tenon. Do not bottom the die hard on the tenon. This works for me. I don't think backing up the die is nearly as important with resin as it is with metal. Keep it well lubed, I think WD40 is too thin and use mineral oil.
Good luck.
 
@its_virgil beat me to that question - what are you threading? Some blanks are really not made to be threaded, like a lot of acrylic or acrylester blanks sold frequently to kit pen makers. The results you speak of are common with materials that will not easily accept threads. Practice on some different materials - you will get a sense of their acceptance of threading or not.

Any lathe - cheap or otherwise, needs to be carefully aligned to insure some of your issues aren't being introduced by an alignment problem between the headstock and the tailstock. If you haven't checked alignment, start there.

Kevin
 
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As others have mentioned, the material being threaded can be an issue, but also the cutting fluid you use as well.
I work mostly with Alumilite.
So far, I have found, any fluids with cleaning additives seem to cause problems (Option1 cutting fluid, WD40, etc). 3in1 oil has been pretty good, but my wife really complains about the smell, which gets on my hands and clothes.
I have heard mineral oil is good, but have not tried it yet.
 
When attempting to thread harder acrylic and polyester resin, a quarter turn is too much. I only thread 1/32 of a turn-ish, backoff, repeat. Takes a while but works for me. I also make my tenon 1/8" (ish) long and part off the beginning few threads. Just 'cuz it's what I have, I used Cobra Venom metal cutting fluid.
 
d_bondi said:
A tenon of 10mm is too large. 9.8 should work fine. Even 9.9mm should work.

Check the die and make sure that you are starting it with the markings toward the tenon. This is the side with the gradual start. Once you have that worked out and the tenon threaded, you can flip it to get the threads cut better all the way to the shoulder.

Also, cut a small chamfer (45 degree cut) on the end of the tenon, to help the die get started.

Good Luck!
Click to expand...
Thank you I will make sure and try this!
 
PatrickR said:
Try this, look closely at the die to see if one side has more chamfer (count how many threads are ground with flat tops) if there is a difference between the two sides start with the side that has more. Only tighten the set screw enough to keep the die from spinning. Slightly chamfer the tenon. Slide the die and holder close to the tenon. Bring it into contact and rotate the tenon counter clockwise slowly while jiggling the holder. This should center the die on the tenon. Without moving the die turn the tenon clock wise, putting light pressure on the die. Continue until your die is solidly on the tenon. Do not bottom the die hard on the tenon. This works for me. I don't think backing up the die is nearly as important with resin as it is with metal. Keep it well lubed, I think WD40 is too thin and use mineral oil.
Good luck.
Click to expand...
Thank you, I suspect maybe it wasn't completely centered. I will try the jiggling trick. Also good to know about the mineral oil.
 
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