Drill chucks

[Rik ShawParticipant @rikshaw]

I have a good quantity of large diameter HSS drills laying idle because they are to big to fit in my 13mm capacity drill chuck. Before I spend my cash on a new larger capacity chuck may I ask for some advice please.>>

I have only ever used "keyed" chucks and have no experience in using a keyless chuck but am curious about this sort of thing:>>

http://www.ebay.co.uk/itm/290713508117?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649>>

Is a large drill – lets say 3/4" diameter – more likely to turn under load in this keyless type than it would in the keyed chuck?>>

Rik>>

[Rik ShawParticipant @rikshaw]

[Peter G. ShawParticipant @peterg-shaw75338]

Hi Rik,

Can't answer your question, but here's a suggestion instead.

As far as I know, drill shanks are relatively soft. Therefore why not turn them down to 13mm?

Regards,

Peter G. Shaw

[John McNamaraParticipant @johnmcnamara74883]

Agree with Peter G

A carbide tip will turn the shank of a HSS drill like butter. You get a nice finish too.

RE keyless chucks:
I have one on my drill press and with a MT3 shank for the lathe tailstock. On the lathe it makes it so easy to pop a centre in to spot a hole then change to a drill in seconds!.

Mine are branded Rohm from Germany and are really well made and very strong. Make sure you give the chuck a good twist to tighten it on the drill. After that It will self tighten if the drill starts to slip. They are no good for tapping because they release when turned the opposite way,

I keep a Keyed chuck for that. or use a tapping head.

Regards
John

Edited By John McNamara on 19/02/2014 10:37:39

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Problem with big keyless chucks is that if you do them up tight enough to be sure of holding they are pigs to undo again .

Keyless chucks work very well in small sizes but personally I wouldn’t use them for large drills for many reasons.

Turn shanks down as advised but ideally to a morse taper of largest possible size .

Reduced parallel shank drills are sold and used but I regard them as a bit agricultural .

You really need a gripping diameter at least approaching that of the cutting diameter for effective drive .

If you have a collet system see if you can adapt that rather than use a normal drill chuck – much better grip and alignment .

MikeW

[Gordon WParticipant @gordonw]

I tend to agree with Mike. The shank dia. should be in the same order as the drill dia. Blacksmith drills are very useful, I use them a lot, but for light machinery must go up in small steps. If the drill dia. allows ,better than turning down the shank is to put 3 flats on the shank. Small keyless chucks are a Godsend on portable drills, biggest problem is their physical size. I don't like them for drill machines or lathe use. This advice from someone who has just drilled 4 20mm. holes in his new van with a masonery drill.

[Ian S CParticipant @iansc]

Blacksmith drills are ideal for a lot of work in a Mill Drill/ vertical milling machine, specially if you have limited hight. as these drills tend to be shorter than jobbers drills.

The shank of a standard drill can be turned using HSS tools, some of my drills have been bought second hand, the mangled shank trued up, and the tip reground, I'v got a source of old tools at a very good price. Ian S C

[colin hawesParticipant @colinhawes85982]

An old lathe chuck can be used to hold large drills at the tailstock if you make a suitable arbour. Such an arbour should be restrained from slipping by a projecting bar that can be resting on the topslide. Colin

[John McNamaraParticipant @johnmcnamara74883]

Mike is right if you are going to push a drill hard into nasty fibrous steel…. Gee I have quite a bit of that…. you need a good grip, turned down shanks are weaker..

However these days after spot drilling with a spot or centre drill I tend to use a small drill just a bit over the width of the chisel point of a larger drill first then gently ease the bigger drill into the smaller hole. I find I get better cantering and a lot less stress on me pushing the drill. It also protects the 3 Morse taper in the tailstock on my lathe. When I got the lathe the previous owner had let a tool spin in the socket leaving a nasty ring that I had to carefully scrape down. it still annoys me. At low speed the torque on a toolroom lathe is enormous. something has got to give. The taper socket is a weak link. My tailstock quill does not grip the tang as a drilling machine will do.

For machinery used in manufacturing the extra step would not be acceptable for private use there is time.

Regards
John

 

Edited By John McNamara on 19/02/2014 12:36:50

Edited By John McNamara on 19/02/2014 12:41:00

[IanTParticipant @iant]

"Let me guess, a member of the double sided flat earth society who believes only in old iron, and who has many hours to waste."

Don't be too unkind to us John – some of us have more time than money (even though both are finite) and anyway have grown very fond of all the old iron we've accumulated over the years. I am always interested to hear of new things and I've learned a lot from yourself (and others) on the various forums. But I also find that many 'obsolete' practices suit my tools and specific modelling needs very well. Fortunately (for me at least) this is just a hobby and I don't have to make a living at it. "Pottering" is part of that enjoyment and it doesn't cost too much either!

By the way, I have a keyless chuck on my larger Bosch drill and it's very nice (as I don't have to search for the chuck key). All my other (taper) chucks are keyed and I'm not going to change them now. If I was buying over again of course, I think that the simple advantage of not trying to find where "the little man in my Shed" has hidden it would probably swing it for me.

Regards, IanT

[John McNamaraParticipant @johnmcnamara74883]

Hi Collin

I have never liked the tommy bar approach. Particularly with a bigger lathe. If the drill jams on an unseen obstacle or simply seizes up yes It can happen… Then I don't want the torque of the lathe twisting the work piece out of the chuck flaying about and breaking something. Maybe me.

Regards
John

[colin hawesParticipant @colinhawes85982]

John, it depends on how tightly the drill is gripped! Colin

[John McNamaraParticipant @johnmcnamara74883]

Hi Collin

This is why I don't like tommy bars.

Say drilling a hole at 200rpm look at the torque OK this is for a larger lathe; many members have one.

At 100rpm it is double.

**LINK**

Regards
John

 

Edited By John McNamara on 19/02/2014 13:37:54

[Tony Pratt 1Participant @tonypratt1]

You guys that don't like reduced shank drills are missing the point, if you want to drill an 1" hole say in steel you would centre / spot drill, then drill a series of ever larger holes to eventually use the 1" diameter drill. The power required to go straight in at 1" diameter is beyond most machines both hobby and industrial.

Tony

[jason udallParticipant @jasonudall57142]

Sorry tony but not true..we used what was known as D drills. .and if needed twist drills.. upto 40 mm and thats on a 42 mm cnc..one hit ..after 5 mm center…..
The d drill is in effect a arrow shaped insert in the end of boring holder. .main problem was chip clearance..mind you that was on a 20kW spindle…

[jason udallParticipant @jasonudall57142]

But it is true that reduced shanks are less stiff ( torsional sense)..so are not going to sustain the cut that a full shank will..
But..just what is your spindle hp anyway?…..
And good keyless chucks are a boon..prefer collets myself but there you go.

[Tony Pratt 1Participant @tonypratt1]

Ok Jason no problem, but that is some serious power!

Tony

[David ColwillParticipant @davidcolwill19261]

I use keyless chucks all the time and find them a great time saver. I have 3 that came from J&L and 2 from arc eurotrade. They do sometimes lock up on a drill and need " the key " to undo them. The key being a Britool filter wrench ( the type with the fabric strap) which works effortlessly every time.

David.

[michael mParticipant @michaelm]

Having used keyless chucks for a long time now I wouldn't want to go back to keyed. I bought my first many years ago (and it's still giving good service) at an ME exhibition. Rotagrip were giving a demonstration drilling 1/2" dia holes in steel with a drill press and after some discussion I bought one. It did come with a C-spanner which I was told was not necessary for tightening but as the chucks were self tightening in use it may be needed to release the drill after sustained heavy use. I have never needed to use it. I subsequently bought a couple of smaller ones, again with every satisfaction. I have never had a drill spin in a keyless engineering chuck but those fitted on cordless and corded pistol drills I've found somewhat indifferent, certainly in the case of my Bosch drill I find the drill slip very frustrating. Probably not by chance the screwdriver bits have a hex shank. I believe people's experience with DIY tools may have predjudiced them against keyless chucks. They're widely used in industry and looking at the various manufacturers' sites they would seem to be available with a smaller degree of run-out than the keyed version.

This forum seems at times to be very reactionary, but as engineers shouldn't we be be embracing, where possible, the best that modern technology has to offer? I appreciate and understand the views about "old iron" but who would want to go back to treadle lathes, carbon steel drills , no index dials on machines and gas lights? A look at some of the other forums will show an eager take-up of keyless drill chucks and some posters live in hope of keyless lathe chucks.

So I suggest Rik goes down the keyless route with every confidence. If he prefers reduced shank drills then fine, but don't worry too much about the reduced shank as the torsional shear becomes an issue with longer lengths and the reduced section of your drill is going to be little more than the length of the chuck jaws.

As an aside to all this, I once had a lathe with a D.C motor and power supply. (the old-fashioned transformer type.) It had a built-in ammeter and I was suprised at the amount of current taken by drilling, far in excess of that taken by turning or milling. With multistart thread tailstocks and rack and pinion drill presses it's easy to lose sight of the forces involved when drilling.

Michael

[Anonymous]

Ah well, I must have missed the point, and be stupid. My small industrial lathe (3hp) is more than capable of putting a 1" drill through cast iron with no pilot drill; at the time I didn't have a smaller drill that was long enough to drill a pilot hole all the way through.

Andrew

[jason udallParticipant @jasonudall57142]

Ahh Andrew..what feed rate. ....
But yes it is surprising just how well industrial kit does the job..but then hp is not the all..if machine flexes then you need to back off…….but then again these babies are drilling 24hrs a day and a tool set might need to last 8 hrs… (before check/replace)..

Edited By jason udall on 19/02/2014 21:03:13

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

(1) The discussion is about drill chucks for holding large drills not drills of 1/2 in or below .

(2) The holding shank part of a reduced section drill is very unlikely to break certainly but that is not the point at issue .

Its about gripping the thing well enough to carry what can be an enormous torque .

If shank and cutting diameter are something like the same there is not usually much problem but if shank gets to be less than about 0.6 times cutting diameter it will begin to slip under higher loading unless chuck is done up abnormally tightly .

(3)Purely out of interest the torque in a normal twist drill is carried by the whole cross section not just the core .

A few additional thoughts :

(1) There is a reasonable limit to the size of drill that any particular machine can handle . In the case of drilling machines the socket size is usually a good indication . For instance 2MT has a limit of about 5/8 in properly maybe stretched to about 3/4 in for lighter use .

(2) When drilling specifically in a lathe there is sometimes merit in mounting drills on the carriage rather than on tailstock .

They used to do this years ago , then the practice was forgotten , but now it has come back again with some CNC machines .

A lathe I had years ago had no tailstock . I made a simple drill chuck mount to go on the cross slide and used it very successfully .

(3) There are better ways of drilling big holes than using big twist drills – have a look at some modern drilling technolgy with inserted tip tooling .

Michael Williams .

[WALLACEParticipant @wallace]

For a lathe tailstock, I wouldn’t be without a keyless chuck.
But for the pillar drill without a spindle lock and guards which stop you (rightly !) grabbing hold of the pulley, I find a key chuck easier as it’s a bit tight to get two hands in to hold the locking collar while tightening it up

W.

[jason udallParticipant @jasonudall57142]

Just has a thought..on the subject of shank vs drill size…
How do boring heads get on?..
Or fly cutters..
Hole saws
..
..
.

I guess its a matter of depth of cut and feed rate

[jason udallParticipant @jasonudall57142]

Just has a thought..on the subject of shank vs drill size…
How do boring heads get on?..
Or fly cutters..
Hole saws
..
..
.

I guess its a matter of depth of cut and feed rate

[Author]

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