Holding milling cutters in a drill chuck

[nigel jones 5Participant @nigeljones5]

I can get away with up to 6mm cutter on my X2, my friend who has a Bridgeport uses nothing other than a drill chuck for milling with no noticeable adverse effect. Might it be a rigidity thing?

[JasonBModerator @jasonb]

And Ian has just come back and asked if I could post his reply:

"This is a method that has worked well for me over many years. It gives convenience, speed of use, sufficient accuracy for most work & better access in restricted areas. If I'm taking heavy cuts or need maximum tool accuracy ( normally only when using a slot drill of the size of the slot I'm cutting ), I use an ER collect."

And not only does the method of holding work well for Ian, so does the threshing drum, this is it in action recently.

[AjohnwParticipant @ajohnw51620]

The one I tried was Chinese. Maybe he uses an older Jacob's from when men were men and drilled holes in etc etc.

For ex rugby players. Might remind some of them of drunken evenings.

Thought I had better add some of

John

–

Edited By Ajohnw on 05/10/2016 13:28:20

[Gordon WParticipant @gordonw]

I've only ever used a drill chuck, I had nothing else, only once and a small cutter, about 1/8". I must have drilled hundreds of holes with a hand drill and wiggled about a bit to enlarge the hole. Never had a bit come loose when using a key. Is this not similar to milling? Now I will use a EN collett when I need to.

[Nigel BennettParticipant @nigelbennett69913]

I once tried using a 2" diameter slot drill in the Myford-Burnerd 4" Griptru chuck. I was only taking very light cuts, and it was the only way I had of holding it. Without putting a six foot length of gas pipe on the chuck key and making "Nninnnggg!" noises, there was no way I could stop the cutter "walking" out of the chuck. DO NOT TRY THIS AT HOME!

If you're using a 1/16" milling cutter with a 1/4" shank, it's unlikely that you'd have any problems at all holding it in a Jacobs chuck or similar for all milling purposes, if suitably tightened. The side loads would not be sufficient to cause problems other than the pinging noise you get occasionally when the cutter breaks…

Hence there is a limit somewhere between 1/16" and 2"…

Using cutters in Jacobs chucks (or even keyless) for plunge-cutting, as others have said, is not a problem and I do it all the time.

[MWParticipant @mw27036]

Interestingly. Does the same rule apply to a hex(or tri-flats) shank tool?

Don't see many of them though.

Michael W

[Tony Pratt 1Participant @tonypratt1]

Holding a milling cutter in a drill chuck is like lighting a barbeque with petrol, you may get away with it or you may not.

Tony

[Russell EberhardtParticipant @russelleberhardt48058]

I always thought that the main reason for not holding a milling cutter in a drill chuck was that the drill chuck is usually attached to the spindle by means of one or two tapers and they are liable to work loose if subjected to side forces. A milling chuck is secured to with a draw bar.

Russell.

[JonParticipant @jon]

Most decent drill/mill machines come with drawbar type drill chuck.

As said keyed drill chucks have around same holding power of ER nothing to get hyped up ill founded about.

[EmgeeParticipant @emgee]

Isn't it the case that a sideways force is applied to any centre cutting slot drill because of unequal length lips ? if so this would apply regardless of holding device.

No doubt like many others I have used some of the smaller size milling cutters and slot drills held in a drill chuck, I stopped the practise after finding the slot became deeper and wider as the tool moved along it's intended path.

Emgee

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Jon on 05/10/2016 16:51:40:

Most decent drill/mill machines come with drawbar type drill chuck.

They usually come on an arbour with a drawbar thread but that won't help much as the chuck is usually fitted to the arbour using a Jacobs taper fitting. A sideways force, particularly when combined with a vibration, can detach the chuck from the arbour. Don't ask how I know!

Russell.

[JonParticipant @jon]

Tried getting one apart with a wedge Russ. Takes a lot more effort than cutting force to part the JT6 been milling on current mill since 2004 where one day with me is around 6 months to mr average. Used to do on previous mill/drill 5 years without any clamping of the JT6 in the taper and know a fair few others that do likewise.

Don't get me wrong anything accurate will use collets but for general roughing and slightly oversize slots etc will retain and continue using the chuck.

Mine is clamped by three pull up screws any way and supplied cheap Chinese 5/8".

Milling on a drill with compound slide I always had cutters and drill drop out due to vibration of the machine, it had no drawbar.

[VicParticipant @vic]

Posted by Russell Eberhardt on 05/10/2016 20:34:52:

They usually come on an arbour with a drawbar thread but that won't help much as the chuck is usually fitted to the arbour using a Jacobs taper fitting. A sideways force, particularly when combined with a vibration, can detach the chuck from the arbour. Don't ask how I know!

Russell.

Yes agreed. I've had my Jacobs chuck drop off the taper before now as well. As for draw bars on drilling machines, I've never seen one. Certainly my progress number one doesn't have a draw bar.

I think that any publication that shows this practice isn't doing its readers any favours.

[JasonBModerator @jasonb]

The photos in question were on a small/medium round column mill not a drilling machine.

Its a pity some of those replying have not seen that article, some of the best work I have seen in ME for a while, pitty all the work is hidden insid ethe pink box.

If it was entered at MEX I would not hesitate to give it a gold medal, its got all the credentials from research, making own patterns, casting own parts many varied and intricate parts all manually machined and it's not just a glass case model it actually works. I think this is the type of work that should be featuredin the mag not just another loco or rear toolpost.

Also interesting that most of those who say they have used a drill chuck to hold milling cutters are those that seem to actually produce work and show it and those against we don't see much work from

Edited By JasonB on 05/10/2016 21:02:04

[Tony Pratt 1Participant @tonypratt1]

Also interesting that most of those who say they have used a drill chuck to hold milling cutters are those that seem to actually produce work and show it and those against we don't see much work from

Edited By JasonB on 05/10/2016 21:02:04

What is more relevant is that my comments come from half a life time working as a Toolroom shift leader who used every conceivable machine tool on a daily basis, I am not an 'arm chair engineer' but some one who has actually worked in engineering to earn a living.

Just trying to smooth the path for budding engineers

Tony

[julian atkinsParticipant @julianatkins58923]

For what it is worth, I regularly use end mills and slot drills in a jacobs chuck in the lathe tailstock. In pre Mill days, all milling was done with a vertical slide with endmils and slotdrills held in the lathe 3-jaw, and job in the vertical slide.

Never ever had a mill slip or problems. I am talking up to 3/8" dia mills in quite a small antiquated basic lathe.

Pin drills in the pillar drill. They can be quite effective.

Cheers,

Julian

[Phil H1Participant @philh196021]

I have used a 3/4" end mill in a 3 jaw chuck to clean up the sides and bottom of main horns held in a vertical slide. I did that because I have read it in one or two of the old construction manuals. I used the same procedure to clean up the slots of the steel frames before fitting the gunmetal horns.

I also use end mils and slot drills in the tailstock chuck to clean the sides and bottom of pre drilled holes.

I don't quite understand why this is such a problem.

Phil H

[HopperParticipant @hopper]

Posted by Ed Duffner on 05/10/2016 10:56:54:

I wonder how many articles in ME and MEW show endmills being used in a 3-jaw lathe chuck along with a verticle slide? or is that considered ok?

Ed.

It's OK by me. I do all my milling that way – up to a 7/8" diameter endmill used to clean up the edges of some 1" steel plate. You do have to nip up the chuck key good and tight but no pipes on chuck key involved.

[JasonBModerator @jasonb]

Posted by Phil Hale 1 on 05/10/2016 23:59:45:

I also use end mils and slot drills in the tailstock chuck to clean the sides and bottom of pre drilled holes.

I don't quite understand why this is such a problem.

Phil H

There is no real issue when using milling cutters like this as the loads are no different to when drilling. There is a possible risk of the cutter comming loose when it is used as a milling cutter and sideways forces applied which can also cause a vibration as each flute takes a cut.

I also expect the condition of the jaws in both the drill chuck and 3-jaw lathe chuck play a part, if you have got bell mouthed old jaws then the grip won't be as good.

J

[Neil WyattModerator @neilwyatt]

You have to look at this two ways – is it a safety issue or is it about getting the best results?

Chucks are not designed to take side loads and are less accurate.

The risks are two-fold:

1. The big one is the cutter walking out of the chuck or being pulled out by the work or even the chuck itself dropping off its taper. This is only likely with larger cutters and could pose a hazard if the cutter could be thrown out of the machine or snap.
2. The smaller risk is that the inaccuracies could lead to spoilt work or chipped cutters.

The danger of a flying or snapped cutter is always present in ordinary milling operations, if not as likely – has anyone here NOT snapped a cutter in a proper milling chuck? A chuck falling off its taper rarely causes anything to fly around. If you avoid using large cutters or heavy cuts you make these problems less likely. The ordinary safety gear you probably use already (guard, goggles) should protect you from serious injury from a smaller cutter if it came out. So we can manage that risk.

The risk of spoiled work/chipped cutters is much greater and is something that each person can only judge according to their equipment and the job in hand.

In summary, it's not best practice to use a drill chuck, but common sense can mitigate the safety risks and experience can tell us when other problems might occur.

Neil

P.S. holding cutters in three-jaw lathe chucks is a special issue – hardened cutters are not held as securely by hardened jaws.

[JasonBModerator @jasonb]

The not suitable for side loads is an interesting thing.

As some of you know woodwork is my thing and I have had a couple of what are known as Combi machines on which a slot morticer takes its drive from the end of the planer/thicknesser cutter block. The cutters which can be upto 1/2" dia and 4-5" long are held in a 3-jaw "drill" chuck that fits onto the cutter block (screw fitting) and then get spun up at several thousand reves. These are then plunged into the wood which is then moved sideways agaist the cutter.

Never had one of those come loose either

[Martin KyteParticipant @martinkyte99762]

I quite happily use a milling cutter in a drill chuck (in the drill press) to counter bore holes on occasion. Perhaps this might deemed to be a 'legitimate setup'.? There are not any side loads and the hole is sized with a standard twist drill first for location so the milling cutter is just cleaning up the bottom of the hole. (They are called slot 'drills' after all).

regards Martin

[MuzzerParticipant @muzzer]

Difference between a slot and a hole? Clue's in the name?

My point about runout was related to uneven loading of the cutter leading to breakage. This is particularly relevant to small diameter cutters. Bludgeoning a large slot with a 1/2" cutter in a Jacob's chuck isn't what I had in mind.

[JasonBModerator @jasonb]

Difference between a slot & a drill, clue is in the name

They can be plunge cut -No probls in a drill chuck

They can also be used to cut a slot – problems for some in a drill chuck not others

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 06/10/2016 07:53:26:

P.S. holding cutters in three-jaw lathe chucks is a special issue – hardened cutters are not held as securely by hardened jaws.

.

^^^

An obvious, and very appropriate, use for custom-machined Soft Jaws.

MichaelG.

[Author]

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