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View Full Version : Choosing a collet for slot-drill.



Peter.
01-21-2009, 02:02 PM
I have mostly metric slot-drills but imperial sized collets. Some slot-drills will fit in either a slightly-under or much-more-over sized collet. I've found that either will clamp the drill but I'm worried that I'm risking damage to something. In this case which would be the correct collet to use and why?

SDL
01-21-2009, 02:08 PM
I have mostly metric slot-drills but imperial sized collets. Some slot-drills will fit in either a slightly-under or much-more-over sized collet. I've found that either will clamp the drill but I'm worried that I'm risking damage to something. In this case which would be the correct collet to use and why?
What sort of collets have you got?

What type of slot drill? plain shank, threaded, sidelock?

Steve Larner

Peter.
01-21-2009, 02:22 PM
Hi Steve - the collets are Alfred Herbert type, I can post a pic if you like but they have a steep taper, narrow stem about finger thickness and 3 slots. Slot drills I have are all smooth round stem with a thread on the end - no flats or keys.

Circlip
01-21-2009, 02:48 PM
Aww Peter, Have a look on here http://homeworkshop.org.uk/ Autolock chucks are reasonably cheap, and safe.

Regards Ian.

Other way is to make some correct fitting adaptors with a stem to fit the largest collet and the bore to fit the slot drills and grind a notch in the cutter shank and retain with a grubscrew

Fasttrack
01-21-2009, 06:40 PM
Erm... what exactly is a slot drill, anyway? I assume it's a two-flute center cutting endmill... ?

SDL
01-21-2009, 06:55 PM
Hi Steve - the collets are Alfred Herbert type, I can post a pic if you like but they have a steep taper, narrow stem about finger thickness and 3 slots. Slot drills I have are all smooth round stem with a thread on the end - no flats or keys.

My guess from the age would be that they only fit nominal size correctly \change to clarkson or ER, what's the machine taper?

I would go Er and get the collets from WNT who always have them on offer.

Steve Larner

SDL
01-21-2009, 06:57 PM
Erm... what exactly is a slot drill, anyway? I assume it's a two-flute center cutting endmill... ?

Correct in the English speaking world slot drill but in the Americas two-flute centre cutting endmill.;)

Steve Larner

Fasttrack
01-21-2009, 06:59 PM
Ahh! Slot drill is much easier. :)

Teenage_Machinist
01-21-2009, 07:50 PM
Frankly I would call a 2-flute center cutting EM a slot mill, and the drill point end mill a slot drill. They are more drilly.