Thread: Tapping 2M

Are you using standard hand taps either Carbon or HSS.

How deep is the hole you are tapping.

Are you using the taper to start with then progressing through the range.

Hi Brian ,I do a lot of tapping below 2 mm, on models and for 2 mm I use a 1.6 mm drill as it is slightly larger than 1/16 and is the correct size drill to use for general work, and if using in mild steel, you should not have any trouble, and using as PIpeclay suggests.

Eddie.

Don't know if this helps but I'm going to make insert holders 'soon', can't remember at the moment if I need to tap M2.0 or M2.5.

I have in mind to counterbore the hole from the underside of the holder so that I'm only tapping a 4 or 5mm thickness of steel, ie screw diameter x 2.

The proper hole diameter for tapping M2 (M2x0.4) should be between 1.567 to 1.679mm. Depending on required tolerance and workpiece material. In Steel I would probably rather aim at the larger hole, choosing a 1.7mm drill, and in Aluminium I would aim at the lower end choosing a 1.6mm drill. Of course, I would recommend to use a new or near new drill. If possible in a small high speed drill press.

You are using 1/16" which is 1.587mm and really close to the smaller limit. Try a 1.7mm drill. For your application, you want some slight slop in the thread anyway, because it is impossible to keep a toolholder dust free, and fine machining dust may cause the high tensile M2 torx screw to bind and rip out your female thread.

Use a lubricant when threading. And use either a very small tap wrench suitable for such a small tap, along with a guide to keep the tap orthogonal. Or else use a very small chuck in a small drill press - I mean a chuck for 6mm (1/4") or smaller with little inertia that you can turn by hand and still "feel" how the tap cuts. A Unimat type milling attachment is an ideal drill press for such small jobs. And I recommend you use a good quality tap, one that is precision ground all over. I know, the brain finds it difficult to understand why a tiny M2 tap should cost as much as an M12 tap, but that that is how it is. Taps smaller than M2.5 are very easy to break, you need a good "feeling", you need to feel the tiny difference just before the tap is going to bind, you need to feel the tiny torsion in the tap before it breaks. You actually need need to expect the tap to bind at anytime and handle it like an egg - a small caviar egg I mean. Turn it backwards often, flush away the small chips or dust with lubricant. And as the previous poster recommends, do you really need the thread all the way through your 10mm toolholder? Or can you drill out the hole with a 2mm drill halfway (5mm) up from the rear before tapping?

Thanks for all the useful responses.
I am using HSS taps and I bought 5 in anticipation of breaking a few. (Ive broken 2 already!)
The idea of counterboring the hole is an awesome idea thanks--Ohh how simple things can be with some wisdom.
I will search around for a 1.7mm drill and see if that helps.
I had been taking things very easy, and I found that watching the tap gave me some idea of it twisting and of course I have done my best to not twist it that much.
I have been using cutting fluid mixed with a drop of reel grease.
I am determined not to let this beat me, so thanks everyone for your help and guidance
regards Brian

How deep is the hole your trying to tap?

What are the taps that you have bought?(what are they made from)

Are the taps as a set or just individual types,taper/intermediate/plug.(seeing that you have bought 5,they usually come in sets of 3 ).

Have you considered using a Spiral point tap?

I've never tried it but I'm told that coconut oil is very good as a lubricant for hard to tap materials

Michael

Originally Posted by Michael G

I've never tried it but I'm told that coconut oil is very good as a lubricant for hard to tao materials

Michael

Is tao similar to tabioca or something? Careful with the coconut oil. Read a while ago about a wife managed to kill her rather new husband (both middle aged) with a curry. Turned out he was allergic to the coconut oil she put in it. Never trust a curry, or a wife.

Dean

What has that got to do with the question asked apart from being idiotic.

Brian,
I used a spring loaded 'pump centre' to align the tap when I was tapping the M2 holes in a couple of engine blocks. The blocks were aluminium, so obviously a lot easier on the tap than steel, but you get the idea.
Chris

Originally Posted by Briangoldcoast

..........I will search around for a 1.7mm drill and see if that helps.............I have been using cutting fluid mixed with a drop of reel grease......... \

Brian, a bigger drill will certainly help a lot. Longish threaded holes (longer than 2x diameter) often call for a larger drill diameter too. As do certain materials that have a tendency to "flow" during the cut into the thread valleys and cause seizing-up of the tap. You may find that you can perfectly well use a 1.75 or 1.8mm drill for your 10mm deep hole. Or something in between like an imperial #50 or 51 drill: Drill Size Chart - Machining.

As for cutting fluid, try just plain old lard

Sorry I didnt answer your question pipeclay. The toolholder is 10mm square MS, but I only need to tap enough thread to hold a tiny insert in place and that's why counterboring from below would help to solve the problem, I think.
jack620--Thanks that's exactly what I think I need to keep the tap vertical and to maintain just the right amount of pressure while I tap. Another little project!
Thanks to everyone for your help.
I'm setting aside an afternoon to attack the problem again
regards Brian

pipeclay--The taps are HSS and all taper taps which I thought would be ok since the hole goes right through

You may find with the use of the taper in such a short depth of thread, and at the tapping drill size you have used, that the cutting edge of the tap is not able to bite into the material you are tapping (as described by your reaming comment).

If you drill your tapping hole larger as said previously and you still have the reaming type problem, try and grind some of the taper off the tap to achieve an intermediate type.