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drill size for m6 tap
Paul (Notts) - 10/2/08 at 07:05 AM

Quick question...

What size drill bit should I use so that
i can cut a M6 thread?

Cheers

Paul

last job before SVA

rayward - 10/2/08 at 07:28 AM

5MM

hth

Ray

madteg - 10/2/08 at 08:26 AM

Easy way to work out size
6x1.25mm =-1.25 =4.75 tap
8x1.25mm=-1.25 =6.75 tap
10x1.5mm=-1.5=-1.5=8.5 tap
and so on.

triumphdave - 10/2/08 at 08:38 AM

quote:
Originally posted by madteg
Easy way to work out size
6x1.25mm =-1.25 =4.75 tap
8x1.25mm=-1.25 =6.75 tap
10x1.5mm=-1.5=-1.5=8.5 tap
and so on.


6mm tap is 1mm pitch so a 5mm drill

zilspeed - 10/2/08 at 08:51 AM

Or, use of these here puppies.
Makes the job a real piece of cake.

Your local grumpy engineering supplies shop buried on an industrial estate soemwhere will have them.


rusty nuts - 10/2/08 at 09:21 AM

Little tip for drilling for ANY thread size is to take a nut and for the thread you want to tap and find the largest drill bit that goes through it.
Works with all thread types

carpmart - 10/2/08 at 09:30 AM

quote:
Originally posted by rusty nuts
Little tip for drilling for ANY thread size is to take a nut and for the thread you want to tap and find the largest drill bit that goes through it.
Works with all thread types


Great tip that!

Hellfire - 10/2/08 at 10:14 AM

quote:
Originally posted by rusty nuts
Little tip for drilling for ANY thread size is to take a nut and for the thread you want to tap and find the largest drill bit that goes through it.
Works with all thread types


This only applies of you want weak threads. Mass produced nuts are produced with oversize bores. They are then thread rolled, this deforms the thread (not cut) making the thread slightly stronger. IMO - this is not the way to produce a proper tapped hole, though it does work for a while.

It also depends very much on the pitch of the thread. A 6mm Tap is available in 3 (yes 3) common Pitch's. 1mm, 0.75mm and 0.5mm therefore the drill size varies from size to size.

The prferred way of finding out the drill size is to use a Zeus Book - (Engineers Bible) but if this is not available to you then use a Drill & Tap Chart like this one

DRILL & TAP CHART

Steve

bob - 10/2/08 at 10:46 AM

Plenty of charts on the net, got a few for various jobs i use.

This one is pretty easy to read

linky

and another

[Edited on 10/2/08 by bob]

carpmart - 10/2/08 at 11:28 AM

quote:
Originally posted by carpmart
quote:
Originally posted by rusty nuts
Little tip for drilling for ANY thread size is to take a nut and for the thread you want to tap and find the largest drill bit that goes through it.
Works with all thread types


Great tip that!


It appears it wasn't such a great tip after all!