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View Full Version : anyone make precision keyed chucks?



dan s
01-01-2009, 11:14 PM
I'm in the market for some drill chucks (lathe & mill), and I can't get over the cost of keyless chucks. Does anyone make precision keyed chucks?

The best I've seen are Jacobs super chucks $$$ at .004" T.I.R. which pales in comparison to keyless chucks at .002" T.I.R.

MickeyD
01-02-2009, 01:05 AM
I went through the same thing last year for my cnc mill and ended up just adding some more ER collets to my collection. I don't run keyless chucks in the cnc because I have had them open up on deceleration and toss the bit out - rather annoying, and the handful of Jacobs keyed super chucks that I have have more runout than was acceptable. I guess it is just the nature of the beast - collet systems are simple with just 3 moving parts (the holder, the collet, and the nut) while drill chucks are more complicated and things move in a dirty environment. The ER collets are not that expensive compared to buying a couple of good chucks, and you really get a better grip on the drill bit and runout under .0005".

oldtiffie
01-02-2009, 06:10 AM
Question.

Why do you need a chuck to be so precise?

If I was drilling without centre-punching and/or the positional accuracy had to be very high, there would be a boring-head operation.

I have always found that, with rare exception, if I mark the job out with a scribing block or surface guage or height guage and perhaps a square and a rule and scriber, that if I centre-punch the hole position, I can get a 1/8" drill to bend/flex and still "follow" the centre-punch. I drill it for about 1/8" to "spot" it, and then drill right through with a 1/8" or 1/4" drill and then just increase the size/s of the "follow-up" drill/s until I am "right/there".

I frequently find that I don't need a mill set-up or DRO's or edge-finders etc., in fact I can and do do it on the pedestal drill.

Any drill with a centre "chisel edge" (ie most drills) - including "centre" and "spotting" drills - will "wander off" unless following a centre-punch or an accurately-sized and positioned hole in a jig/fixture.

If I had enough to do to warrant the effort, I'd make a jig or fixture and not only not have to mark it out but would not need the mill either as it would all be done on a pedestal drill.

My "Jacobs" (Chinese) chuck supplied with my mills (2) are very accurate (within about 0.002/0.003"), but my pedestal drill chuck (Chinese but older - had a hard life!!) is not quite so accurate but works fine with centre-punched holes and jigs/fixtures.

When I am drilling, in the mill or anywhre else, I make sure that I have allowed plenty of "clearance" and positional allownace for "ordinary" drilling.

For real "fussy" "drilling-only" work in the mill, I use (ER) collets and a "fine-nosed" "starting" ("stubby") drill followed by a centre-drill and then the rest of the drills in order.

Some may find this "long-winded", "tedious", "too slow" etc. but it has always worked for me.

The short answer is that I never seem to need a drill chuck that is approaching collet tolerances.

I don't seem to have any trouble with either "Jacobs" or "key-less" chucks.

John Stevenson
01-02-2009, 06:54 AM
Question.

Why do you need a chuck to be so precise?

If I was drilling without centre-punching and/or the positional accuracy had to be very high, there would be a boring-head operation.

doing 11,208 holes a day at 2.5mm diameter but using a boring head is a tad unreasonable :D




Any drill with a centre "chisel edge" (ie most drills) - including "centre" and "spotting" drills - will "wander off" unless following a centre-punch or an accurately-sized and positioned hole in a jig/fixture.

Rubbish.




My "Jacobs" (Chinese) chuck supplied with my mills (2) are very accurate (within about 0.002/0.003"), .

Which isn't accurate unless you have missed a nought off.





For real "fussy" "drilling-only" work in the mill, I use (ER) collets and a "fine-nosed" "starting" ("stubby") drill followed by a centre-drill and then the rest of the drills in order.

Which won't work if you read your second quote above.

.

oldtiffie
01-02-2009, 08:11 AM
Thanks John for another aspect and your point of view.

But.

Once again we seem to agree to differ.

Might be different hemispheres or seasons and solstices 180 degree out of phase.

Or something.

Circlip
01-02-2009, 09:24 AM
In a previous life, some of the circlips we used to make were about 3ft dia. rolled from rectangular section "Wire" (3/4" x 3/8") and the holes in the ends were drilled on a pillar drill. Saw the guy that drilled them one day marking the hole centres with a piece of chalk, when I asked him about the accuracy he was drilling to, the dry reply came back, "When I want to get them spot on, I sharpen the Chalk"

Regards Ian.

Ian B
01-02-2009, 10:11 AM
"Does anyone make precision keyed chucks?"

Well, yes:

http://cgi.ebay.de/1-Stueck-Bohrfutter-SK40-DIN-2080-1-16-Rechnung_W0QQitemZ260339956324QQcmdZViewItemQQptZG artenbauwerkzeuge?hash=item260339956324&_trksid=p3286.c0.m14&_trkparms=72%3A1230%7C66%3A2%7C65%3A12%7C39%3A1%7C 240%3A1318

In German I'm afraid, it's keyed with an Allen key. Probably the same runout as a keyless chuck, and a similar price too. I guess you're paying for the quality of the chuck rather than the method of tightening.

Ian

MickeyD
01-02-2009, 10:15 AM
The reason that I want such precision is that I don't want to center drill (eats up a place in the tool changer), and even when I am doing manual work I don't center punch, I do everything from a coordinate system if at all possible. Personally, I can work a lot faster off of a sheet of paper with coordinates and notes (sort of looks like bastardized G-Code) and a lot more accurately. So if I use stub length sharp drill bits in collets working from a coordinate system, I can quickly put a bunch of holes where they need to be without an extra tool change and getting layout dye on my clothes.

Paul Alciatore
01-02-2009, 10:42 AM
If you are doing 11K+ same sized holes a day, just break down and get the collet in that size. I still wonder if you will get any better tolerance due to the nature of drills. If the hole is shallow, a jobber length drill will flex enough to follow it's own course and chip accumulation will cause more size problems than the chuck would. Location could still be a problem.

Rustybolt
01-02-2009, 11:26 AM
For truly accurate hole positioning you really should center drill first. You can get around this somewhat by first using a collet and then having the drill length reduced to that which is needed to get the job done. Something a tool grinder can do for you. If it were me with those constraints I'd look into having a cutter made.

BobWarfield
01-02-2009, 11:38 AM
I'll have to go measure the TIR on my keyless chucks. I haven't noticed anything amiss. Usually the small bits make it really obvious if the chuck is out much (sometimes painfully obvious).

If it's going to be a job done over and over again, I too would lean towards ER collets.

The only other thing I'll mention is I sure do love my screw machine length bits.

Cheers,

BW

John Stevenson
01-02-2009, 12:21 PM
If you are doing 11K+ same sized holes a day, just break down and get the collet in that size. I still wonder if you will get any better tolerance due to the nature of drills. If the hole is shallow, a jobber length drill will flex enough to follow it's own course and chip accumulation will cause more size problems than the chuck would. Location could still be a problem.

Paul, the drill is held in a dedicated ER11 collet chuck mounted to a 4:1 speed increaser.

Drills are 4 facet ground stub drills, originally new from WNT then reground on a 12K German drill grinder. New drill every day, then regrind the old one.

.

dan s
01-02-2009, 02:34 PM
OK let's move past the why.

Any difference in accuracy between ball bearing and non ball bearing?

John Stevenson
01-02-2009, 04:02 PM
Any difference in accuracy between ball bearing and non ball bearing?

dunno but my grandfather had one of the first ball bearing push bikes around here and there are more bastard Stevensons than anywhere else in the country ......:rolleyes:

.

J.Ramsey
01-02-2009, 04:55 PM
I'm in the market for some drill chucks (lathe & mill), and I can't get over the cost of keyless chucks. Does anyone make precision keyed chucks?

The best I've seen are Jacobs super chucks $$$ at .004" T.I.R. which pales in comparison to keyless chucks at .002" T.I.R.

Since most Jacobs chucks have been made in China the last 4 years I then switched to ROHM chucks which are still made in Germany.

ROHM ball bearing keyed and keyless chucks are 1/2 to 2/3rds the price of the Jacobs with ALBRECHT accuracy.

oldtiffie
01-02-2009, 06:12 PM
I've never noticed whether my chucks have ball bearings or not. They work well. I just presumed they had ball bearings.

One thing I've noticed is that even though they are pretty good, the drill etc. held in the chuck spins true enough, but the body of the chuck is or seems to be "out" quite a bit.

For me, its not so much whether the chuck had ball bearings or is or is not keyed or key-less or not, but rather how well it works on the job.

Perhaps I am a little "old-fashioned" but I can work from a sketch on a scrap of paper or from my head etc. and I can mark out and see if its right before I centre-punch it. I can quite often "try" the mark-out to see if it fits the job. Its surprising how many errors are "caught" that way.

If I am marking-out and using the pedestal or a portable drill, I have no machine set-up to do and will be on the drill before I have calculated off-sets and co-ordinates as well as set up the mill.

If I have to set it up on the mill, I will do it without hesitation.

Its just that I like to keep it as simple as possible and I rather prefer "hand" work to "machine" work.

So, to re-address the OP: I have no particular preference as regards keyed or key-less chucks and I find that I have all the accuracy I need.

If the "start-off" of the hole has to be "accurate" I will use collets (ER-32) - but only if a chuck won't do the job.

If drilling (with "centre-punched" holes), I "spot" with either a 1/8" drill from the set/stand or one of a set of about 12 or so HSS drill-bits that are "double-ended", very effective and quite cheap. They are used by Plumbers and Electricians etc. for 1/8" rivets etc. and as "starter-drills" for larger/"follow-up" holes.

Many will have noticed how difficult it can be to "start" a drill in sheet-metal but how easy it is with a "centre-punched" spot.

Now back to the chucks and the "accuracy" of them and whether they should/must be "Jacobs" ("keyed"), "key-less", ball-bearing-ed, and accurate - or not.

I find that drills are pretty flexible, but once "started" they stay where they start. Further, any inaccuracies in the chuck or "play" or "slop" in a quill is largely negated if the drill cutting end is as far out from the chuck as possible as the drill bit has most use of its flexibility.

Most of the above is very applicable to portable drills ("mains", battery or air powered) too.

When starting from/at a centre-punched hole whether on the mill or drill, I put some saliva ("spit") on my finger and transfer it to the drill just before it starts to cut. Its an old practice but very effective. If I have to use another fluid, I will opt for cutting oil.

(Urine - aka "piss" works well as a cutting fluid too - but be careful how you get it onto the cutter/drill!!).