Taps and dies drill sizes

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Jarod888

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Mar 11, 2012
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Brighton, Colorado
Im assuming you mean for the special taps and dies we use for kitless pens.

For a metric die turn your tennon down to the size of the m#. So for an m13, the tennon needs to be 13mm. For the corresponding drill size, subtract the pitch from the m#. So in an m13x.8 the drill size for the tap would be 12.2 mm.

I highly sugest getting a set of the cobalt drill bits from harbor freight, the 115 bit set. It's like 69 $ with the coupon.

That will give you all the # drill bits, all the letters and the fractional from 1/16 to 1/2 by 64ths.

I've had really good luck with a 15/32 for the drill size for the m13x.8 triple start tap.

A good set of digital calipers will also do you wonders.

I have the following one saved as a shortcut on my phone.

 

monophoto

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Mar 13, 2010
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Saratoga Springs, NY
Several years ago, someone recommeded the iEngineer app. I find that it tells me just about everything I need to know about drills, holes, taps and dies.

in general, when creating a male thread, the tenon OD should be equal to the major diameter of the desired thread. When tapping a female thread, the starting ID of the hole must be slightly less than the thread diameter, and that’s where you will need either a table or an app to find the ideal starting diameter.
 

Darrin

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If you go to the Starrett web site, they will send you a real nice wall chart and some small cards with everything on it conversion wise.......and its all free.
 

Jans husband

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May 4, 2020
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Location
Doncaster England
As a relative newcomer to kitless pens, I asked this question about how to calculate the size of the tenon for using a die in a recent forum, and I had an excellent response from Monophoto. My die for the internal cap thread and the corresponding male thread is 12mm- .75. The 12mm tenon worked well on acrylic blanks, although being a novice at kitless pens, I am still waiting for a finished pen I can be proud of!!
However, after recently seeing an article on the Web about making an aluminium pen with a slimline kit on a woodturner's lathe, written by Walter Hall in Woodturners magazine a few years ago, I decided to attempt a kitless pen in aluminium after making a decent attempt using a kit.
However, I turned the tenon down to 12mm, but the die would not even attempt to make a thread, and in the end, I had to gradually turn the tenon down significantly to enable the thread to start. The pen was not successful but I am still trying. I bought a 1 metre length of 15mm rod for £10 (English) so I still have a lot to play with without it costing a lot, and I am learning a lot in the process.

However, the question is, what was wrong with the 12mm tenon size in aluminium for the die I was using?.

I have also now ordered a brass rod-so I can give that a try!

Keep safe and Cheers

Mike
 

magpens

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???????
@Jans husband

In this thread, above, monophoto says:

"when creating a male thread, the tenon OD should be equal to the major diameter of the desired thread "

This has worked very well for me ... always ... and very recently ... with aluminum (ie. aluminium).

So, I do not know what to make of your statement, immediately above, with regard to making a male 12mm thread ...

"I turned the tenon down to 12mm, but the die would not even attempt to make a thread, and in the end, I had to gradually turn the tenon down significantly to enable the thread to start. "
 

Ironwood

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May 31, 2010
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Mackay. Australia
As a relative newcomer to kitless pens, I asked this question about how to calculate the size of the tenon for using a die in a recent forum, and I had an excellent response from Monophoto. My die for the internal cap thread and the corresponding male thread is 12mm- .75. The 12mm tenon worked well on acrylic blanks, although being a novice at kitless pens, I am still waiting for a finished pen I can be proud of!!
However, after recently seeing an article on the Web about making an aluminium pen with a slimline kit on a woodturner's lathe, written by Walter Hall in Woodturners magazine a few years ago, I decided to attempt a kitless pen in aluminium after making a decent attempt using a kit.
However, I turned the tenon down to 12mm, but the die would not even attempt to make a thread, and in the end, I had to gradually turn the tenon down significantly to enable the thread to start. The pen was not successful but I am still trying. I bought a 1 metre length of 15mm rod for £10 (English) so I still have a lot to play with without it costing a lot, and I am learning a lot in the process.

However, the question is, what was wrong with the 12mm tenon size in aluminium for the die I was using?.

I have also now ordered a brass rod-so I can give that a try!

Keep safe and Cheers

Mike
Hi Mike, 12 mm tenon should work, I wouldn’t go to much less than that or you will end up with flat tops on your threads.
I find with all materials, but especially metals, it’s much easier to start the thread if you cut a chamfer on the end of the tenon, 45 degrees and to about the depth of your thread works well for me.
I am assuming you’re using a lubricant, WD40 or similar works well for aluminium.
 

More4dan

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Mar 17, 2016
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Katy, TX
Make sure your die is facing the right direction too. It should start with a taper toward the work. Then reverse after threading to cut full depth threads the full length. I turn to the stated diameter of the thread even in metals. The link to the site above also has a thread calculator that will give you max and min OD for an external thread. This will be your tendon size.

Danny


Sent from my iPhone using Penturners.org mobile app
 
Last edited:

Jans husband

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May 4, 2020
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Doncaster England
Sorry to upset you Magpens-I was just relating my experience as a novice, and looking for guidance!
I will carry on until I get it right.

Possibly I am not using enough initial pressure on the tailstock to get the thread started. I also need to experiment more with the chamfer

I have been using WD40 as a lubricant

Thanks for the help and comments

Mike
 

duncsuss

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Jun 29, 2012
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Wilmington, MA
... I also need to experiment more with the chamfer ... I have been using WD40 as a lubricant ...
Mike, I believe not having a chamfer at the end of the tenon is the main factor causing trouble. Some materials that are soft (acrylic acetate,, ebonite, celluloid) don't put up as much of a fight, but for the most part it's necessary to have some kind of ramp that the leading teeth of the die can slip over before they start to bite into the material.

I typically make the tenon a smidge smaller than the nominal size of the threads I'm using: for 12mm x 0.75, I'd aim for a tenon diameter between 11.9mm and 11.95mm. There's nothing wrong with having "flat topped threads" (so long as the part which is mating with them is fully-formed), and I actually like to have the tops flat because it is far more comfortable to hold a pen. (Plus it is a lot easier to get a high polish on the flat top that down in the valley of the thread, so they look better.)

For the chamfer, I aim for 1mm cut about 45 degrees - it doesn't have to be exact, and I don't worry if it's a bit longer. The partial-height threads at the beginning will make screwing the cap onto the pen easier than if the end of the barrel is dead square, as well as making it transition smoothly into the nib section instead of having a sharp step.

WD40 is probably good for metals, but I wouldn't use it for plastics - some of them have a nasty response to petroleum derivatives, forming "micro cracks" and end up looking like crazy paving. I've used spray-can cooking oil and even just soapy water as lubrication when drilling and threading plastics. Both work fine in my experience.
 
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