Holding milling cutters in a drill chuck

A little off topic but Jacobs used to supply a "headstock chuck". It was of the standard drill chuck pattern but designed to screw onto the headstock to hold small diameter (up to 3/4 inch) work accurately as a convenient alternative to collets.

Russell.

The 4thou tir applies to virtually all Jacobs list. Extracted from rotagrip's link.

Martin

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Thanks for that, Martin

I have no further comment

[simply because I have already said what I have to say]

MichaelG.

Hi there, all,

I'd like to put in a word for the 'holder for throw-away end mills' described by Tubal Cain on pages 106 & following of his book 'Simple Workshop Devices'.

I was recently given some small 'throw away' end-mills which have 6 mm shanks and a grub-screw flat. Tubal Cain's account is based on a Jacobs chuck arbor and describes a method for removing the tang and drilling & tapping for a draw-bar but I made mine from a 2 MT blank end arbor with a 1" diameter by 1" long blank end and its rear end tapped 3/8" BSW. I reduced the blank end to ¾" OD and still had plenty of wall thickness for the 2 BA by ¼" socket grub-screw. The 1" OD would have left plenty of meat for a bigger end-mill if that had been my requirement.  3/8" or maybe even ½". 

NB, we are talking about end-mills with a grub-screw flat here.

If I still had access to 'the Company skip' as I had before retirement, I might well have looked for a broken 2MT shank drill but the blank end arbor was quite affordable. I also had to buy a 6 mm reamer but making one end-mill holder in no way uses up all the life of the reamer!!

Once I had material and tooling to hand, it didn't take long, even for me, to make the holder. I am now able to use my 'throw away' end-mills safely and without any of the fear or uncertainty associated with holding them in a drill-chuck.

Try it - you'll like it!

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 06/10/2016 11:11:48

Edited By Swarf, Mostly! on 06/10/2016 11:12:08

Edited By Swarf, Mostly! on 06/10/2016 11:12:40

Alot of people might not know that jacobs make alot of small chucks as well, if you're intending to use small drills but can't grip them in a lathe sized chuck. I have 3 small ones, normally covering an imperial range, they weren't cheap but are very useful for the small drills department.(all have 1/4" threaded J0-J1 taper shanks)

So, for mill shanks that have ground flats on them,(my question kinda got lost in all the hubub!) surely the same rule no longer applies with regards to grip, as this is far superior to a round shanks grip with a jacobs?

As with regards to S.M's post, I have a cigarette tin full of the described HSS throw away cutters, mostly 1/4" shank with the said grub holder, very very useful! some 3/16" too.

The name is a bit of a misnomer,probably described original purpose,  because the edges are still quite sharp after along time in a dusty cavernous workshop. 

Sherline actually sell a grubscrew endmill holder but they are so simple to make, it would be no trouble with the usual workshop equipment. 

Michael W

Edited By Michael Walters on 06/10/2016 11:35:20

Thank you, Michael, for your post, especially for your endorsement that the holders are easy to make. I would have posted earlier in the thread but held off until I had the opportunity to take a photo of my holder - then I decided that a photo wouldn't really contribute to the subject.

I agree with what you say about 'throw away' being a misnomer.

You say that your end-mills have  ¼" shanks - so did Tubal Cain's.  I actually bought two blank end arbors, a 6 mm reamer and a ¼" reamer to play safe but, so far, my gift seems to include only 6 mm shanks.

And I make no apology for my plug for Tubal Cain's book.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 06/10/2016 11:48:26

Bingo! It's the tapers holding that is the issue. a threaded drill chuck (like Jason's EMCO work) would be fine in this regard.

John.

Made two "Adaptors" to allow use of "Weldon" throwaway cutters (plain shank grubscrew flatted notch) in a Modeloy Clarkson type cutter holder. One for 1/4" dia body and one for 6mm dia. Adaptors fitted 12mm bore threaded collet.

Using a drill chuck to hold cutters? Only needed one clip behind lughole from toolroom foreman.

Regards Ian.

No problem, you just reminded me of them really! i actually think it is a point worth bringing up here. I think the whole problem around using jacobs for mills is kind of a backlash if that makes sense? Like "no, i wont follow convention!". It's also very fiddly to change collets and arbors all the time and they are also expensive. So maybe this is where the idea comes from people who know better essentially.

This would be a great post, or "mini article" if you could do it because it would provide a neat solution to hold cutters in an affordable chuck, you would only need 1 collet with straight/plain shank or taper to hold the arbor and can hold a variety of end mills of the same shank size. I'd certainly read it and it would only encourage other people. This way is condoned by a whole host of writers and manufacturers as a safe way to hold them.

Kind regards,

Michael Walters

That's awful, I'd expect any decent milling chuck to be less than a thou TIR, and preferably only a few tenths.

Andrew

Exactly. Some otherwise inteligent folks on here though just don't seem to get it. A threaded drill chuck may still not be ideal but it would at least be safe.

Infact if you already have a finger or ER collet you can make very simple holders for teh FC-3 type cutters and other things as well. Handy when you need all your mills head room and don't have a suitable size finger collet. Run out is only as good as the fit of the cutter in the holder and the "nominal" 6mm or 1/4" shanks can vary slightly from one maker to another

For those that don't want to make a holder for the Wealden shank cutters Uncle Ketan has them in his ARC

JT tapers coming loose ? They are supposed to be very accurately made and joined with some force.

The more taper is far more likely to loosen hence draw bars.

The threaded chucks are generally aimed at hand drills.

It's possible to make a "disposable" cutter out of threaded end milling cutters and other type via an off hand grinder. Just add the flat. Reams could be written about doing that as there could be some obvious problems.

Sounds to me like Neil should recall all issues of this particular magazine issue on the grounds of health and safety and as people have paid for them, get the who lot reprinted and sent back to the people who bought them. Or maybe full kevlar body armour is in order not forgetting the head or a very impact resistant transparent face mask. People who are concerned about this area should clearly take out a class action against the publishers.

Maybe another thread should be started on people who dangle things that are way to big on the end of 2 and 3 morse tapers.

John

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Or a thread for people who again don't read the posts and refer to the wrong magazine

I don't buy the mags any more Jason so for all I know it could be in Women's Weekly. ??? Might that be a good place to put it ?

John

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The usual advice that comes with a new pillar drill is retract the chuck jaws fully, put a block of wood on the table and pull on the feed lever very hard...

"That's awful, I'd expect any decent milling chuck to be less than a thou TIR, and preferably only a few tenths.

Andrew"

Totally agree Andrew, I was a little surprised myself. I would have expected better from a Jacobs.

Martin

As I don't have a press I generally use a rather sharp whack with a heavy hammer on the tang. I can't recollect having to clean that up but generally my chucks have come with what ever lathe I have bought.

I did use a screw on drill chuck on a Hobbymat. I cut down a used reamer and screw cut it for an extremely sexy fit. I asked a local supplier for a good chuck. It was by Jacob's and suitable for hammer drills. 3/8" capacity I think,

When I fitted an arbour with a draw bar to the chuck for my DW there was wood in the way of the hammer and I can with a bit of care arrange to keep one of those square when it hits. Maybe I should have put a shortened bolt in it.

John

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Edited By Ajohnw on 06/10/2016 14:15:51

Weldon shank end mill holders.

Ok - not that it matters much to us, but for precision machining, OR for long production runs:

1) There is play in a Weldon-shank end mill holder. (there HAS to be, otherwise one can not put the end mill in!) This means that, by definition, the end mill is not centered, thus will wobble;

2) Long production runs, the end mill flexes around the juncture of the set screw, leading to wear on the collet. And, when they start to wear, the wear increases quickly, and the end mill is not held securely.

At least ER collets will hold end mills securely for the length of the collet-endmill interface, and the end mill is at least close to centered...

Food for thought;

John.