Kit less blunder

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lorbay

lorbay

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Jul 2, 2009
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BC. Canada
Well I have started on my kitless journey and was doing some practice pieces to day and I am having terrible trouble doing an inside thread. I was trying to make the cap thread with a M12 x 1.0. Made the tenon and did the thread fine, so then I drilled out the cap blanks for the same above thread. So I drilled the hole to 27/64 ( M12 - 1 = 27/64), tried all kinds of lubricant and cannot get a thread to save my life. Did it the same way as this tutorial with no success today.
http://content.penturners.org/library/pens/kitless_pen.pdf
Need your help please.

Lin.
 
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11mm is .4331 inches. 27/64 is .4219 inches. That is .0112 smaller. That is why you can't cut a clean thread. The tap is also trying to open the hole at the same time it is cutting the thread. Something it isn't made to do. Best is to get an 11mm or 11.1mm drill bit or try the 7/16 already mentioned.
 
Lin, I agree that you are using too small of a bit and should try a 7/16" (.437") or a 11.2mm (.440") bit.

When I tap the female threads in a cap, I use a collet chuck to hold the blank and put the blank all the way inside the collet leaving the edge flush with the collet. I have found that when tapping soft material like ebonite and alumilite that the blank will swell slightly and sometimes will crack. Having the collet clamping all the way around the blank does not allow any swelling and forces the tap to take cleaner cuts.
 
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Curly said:
11mm is .4331 inches. 27/64 is .4219 inches. That is .0112 smaller. That is why you can't cut a clean thread. The tap is also trying to open the hole at the same time it is cutting the thread. Something it isn't made to do. Best is to get an 11mm or 11.1mm drill bit or try the 7/16 already mentioned.
Click to expand...

OK new test went with the 7/16 still no threads, I am going very slow backing up every 1/4 turn and it seems to be threading but when I back it out the is no threads there.:confused:

Lin.
 
Texatdurango said:
Lin, I agree that you are using too small of a bit and should try a 7/16" (.437") or a 11.2mm (.440") bit.

When I tap the female threads in a cap, I use a collet chuck to hold the blank and put the blank all the way inside the collet leaving the edge flush with the collet. I have found that when tapping soft material like ebonite and alumilite that the blank will swell slightly and sometimes will crack. Having the collet clamping all the way around the blank does not allow any swelling and forces the tap to take cleaner cuts.
Click to expand...

George I went and tried this as I was using a collet chuck but not that far in, I have now tried it all the way in and still no success. I have tried it in PR, Alumilite and also acrylic. I have also tried different size taps and none will cut the thread.

Lin.
 
lorbay said:
Curly said:
11mm is .4331 inches. 27/64 is .4219 inches. That is .0112 smaller. That is why you can't cut a clean thread. The tap is also trying to open the hole at the same time it is cutting the thread. Something it isn't made to do. Best is to get an 11mm or 11.1mm drill bit or try the 7/16 already mentioned.
Click to expand...

OK new test went with the 7/16 still no threads, I am going very slow backing up every 1/4 turn and it seems to be threading but when I back it out the is no threads there.:confused:

Lin.
Click to expand...

Lin, just for grins, drill the hole and tap the threads all at once without backing up every 1/4 turn then withdraw the tap all at once and see what happens.

I don't thread "by the book" in that I just run the tap into the blank then remove it. I don't stop and go backwards every 1/4, 1/2 or 1 turn. If I were tapping metals where the hard chips would interfere I would but with the soft materials we're using, I don't see the need.

I can only imagine that you are not applying enough forward pressure when tapping and the tap is just grinding away the threads you just cut. Let me know how the "all in at once" works if you decide to try it.
 
Last edited:
Don't back out until you are in several threads if not all all the way done Hand tapping in steel you go in 3/4 and back out 1/4 to break the chip. With plastic you can pretty much cut all the way non-stop.

There are some plastics and castings that are brittle making them hard to thread. What are you playing with?

Sent from my iPhone using Forum Runner because I can't reach my desktop!
 
Curly said:
Don't back out until you are in several threads if not all all the way done Hand tapping in steel you go in 3/4 and back out 1/4 to break the chip. With plastic you can pretty much cut all the way non-stop.

There are some plastics and castings that are brittle making them hard to thread. What are you playing with?

Sent from my iPhone using Forum Runner because I can't reach my desktop!
Click to expand...

Tried every thing, PR, Alumilite and acrylic.

Lin
 
lorbay said:
Curly said:
11mm is .4331 inches. 27/64 is .4219 inches. That is .0112 smaller. That is why you can't cut a clean thread. The tap is also trying to open the hole at the same time it is cutting the thread. Something it isn't made to do. Best is to get an 11mm or 11.1mm drill bit or try the 7/16 already mentioned.
Click to expand...

OK new test went with the 7/16 still no threads, I am going very slow backing up every 1/4 turn and it seems to be threading but when I back it out the is no threads there.:confused:

Lin.
Click to expand...
Lin, I want to let George help you out with this issue, but I can't figure this. Are you using a die holder? Any kind of lubrication? This has me puzzled as well as you now.
 
Texatdurango said:
lorbay said:
Curly said:
11mm is .4331 inches. 27/64 is .4219 inches. That is .0112 smaller. That is why you can't cut a clean thread. The tap is also trying to open the hole at the same time it is cutting the thread. Something it isn't made to do. Best is to get an 11mm or 11.1mm drill bit or try the 7/16 already mentioned.
Click to expand...

OK new test went with the 7/16 still no threads, I am going very slow backing up every 1/4 turn and it seems to be threading but when I back it out the is no threads there.:confused:

Lin.
Click to expand...

Lin, just for grins, drill the hole and tap the threads all at once without backing up every 1/4 turn then withdraw the tap all at once and see what happens.

I don't thread "by the book" in that I just run the tap into the blank then remove it. I don't stop and go backwards every 1/4, 1/2 or 1 turn. If I were tapping metals where the hard chips would interfere I would but with the soft materials we're using, I don't see the need.

I can only imagine that you are not applying enough forward pressure when tapping and the tap is just grinding away the threads you just cut. Let me know how the "all in at once" works if you decide to try it.
Click to expand...
Yep I think that was the problem being to careful with it. Once I put the pressure to it and didn't stop till I got to where I wanted to be it was fine.

Thanks for all the responses.

Lin.
 
Glad it sounds like you got it figured out. I was doing some threading just yesterday and thinking why the heck did I ever have trouble doing this. My first few attempts went the same way as yours and now I seem to be able to do it 10 different ways and it never goes wrong.
 
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