Taps & Dies & Drill Bits

[Russ Hewitt]

I have been looking for an inclusive chart that would show what size drillbit to use with a given tap and die. There are quite a few available that show the drill bit size for a tap, but I can't find anything that lists the tenon size that is needed for a given die size. The other thing that seems to be missing is 13 mm sizes on all of the charts. Is 13 mm not a common size? I see quite a few people using 13 mm triple start. I have literally thousands of standard size drillbits but no letter size or metric, so I am trying to do some simple conversions. Thanks all

 

[Drewby108]

Tenon size would just be your major diameter give or take a thousandth. If you want sharp threads, having it at size or a tiny bit bigger will mean the die is cutting all the material to shape. If you want flats, then making it smaller will leave gaps between the die and the material uncut.

That's what I did for machining metal, at least. I can't imagine it is different for pens.

 

[Paul in OKC]

Yep, generally the tenon is a like .002-3 under nominal size.

 

[rherrell]

I use 10% of the thread pitch when using a die . An M10x 1.0 has a thread pitch of 1mm (.040") so 10% of that is .01mm or about .004". This formula is for steel so plastic will be a little less.

When I make my pen mandrels using a triple start die I increase the deduction by 50%, that would be .006" in the above example.

Anchor Lube is a great threading lubricant, it's water soluble and cleans up easily.

 

[monophoto]

Russ

There is an app for iPhones called iEngineer that prescribes pilot hole sizes for female threads. The app is free for the imperial thread version, but there is a small charge to add metric thread information. I don't know if its available for Android devices, but I think there are some other apps that do the same thing that work on Androids.

As Andrew and Paul have said, if you are turning a male thread,, the tenon diameter should be about the major diameter of the intended final threading - a little larger and you will have sharp threads, and a little smaller will result in flat tops.

 

[randyrls]

Hmmmmm I'll upload my tap and die list. This is only for single start threads, I'd have to think hard about how multi start impacts the drill size (and I'm only half awake yet!)

 

[Wayne]

Give this a try.

Multi-Start Thread Reference Guide - In The Loupe - Machinist Blog

A multi-start thread consists of two or more intertwined threads running parallel to one another. Intertwining threads allow the lead distance of a threa...

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