Drill chuck for a mill

[trlvn]

Hi:

The mill/drill I recently purchased did not come with a drill chuck. I have a couple of chucks that I could use if I get a new arbor or arbors but i'd like some input first.

Searching here and elsewhere, there are a few things that I didn't consider at first. First off, I was thinking to get a big chuck since the mill/drill has more power than my lathe or drill press. But then I found that some people don't use a drill chuck--they'll use collets. That makes sense to me, especially for larger drill bits. I need to check, but my hodge-podge of larger drill bits are mostly of the Silver & Deming reduced shank type. So as long as they fit my R8 collets, that would seem to be a good way to drive them.

For smaller holes, I think a drill chuck makes sense. Typically one needs at least a centre drill, the drill itself and a countersink. Or maybe an undersize drill and a reamer. Switching collets for those steps would be a drag. A keyless chuck would shine here.

I have a couple of keyed chucks: an older Rohm 1/32-1/2 inch (JT33 mount) and a newish Chinese 3-16mm (JT3 mount). Both of these are on MT3 arbors that don't fit in anything I've got and therefore I can't check runout. I think I'll get an arbor for the Rohm and see if it works OK. I'm tempted to buy a 0-3/8" keyless but the cost of a new, decent quality chuck is likely to put me (back) in the doghouse!

So, am I missing anything obvious. I am a real greenhorn when it comes to milling machines so I may be completely out to lunch.

Craig

 

[Bofobo]

The answer is both a collet set and drill chuck, find an R8 -JT33 arbour (got mine at busy bee, also on eBay) and swap one of the chucks from your old mt3 arbour (and ship it my way lol jk) they have R8 collets for >$10 at our KMS (imperial) most common used size for me on my bench top mini mill is 1/2”, and my cheapo metric endmills have a hard time finding just the right imperial size collet. collets for quick changing, drill chuck for everything you don’t have a collet for. 1/2” collet works great on those large reduced shank drill bits

 

[ZeljkoV.]

Keyless Chucks are very handy when changing tools a lot.
From Drill , to Tap or Reamer.

For regular use you have Rohm ( made in Germany) Chuck that is very good

 

[Brent H]

Hey Craig,

So I am in your state of flux as well. I took my two chucks I have (0-3/8) and a 0-1/2” and made arbors on the lathe to fit both. The 0-3/8 has a 1/2” shank and the 0–1/2” has a 5/8” shank. Typical “drilling” is using either chuck and a centre drill and then the bit required.

Run out ....... well both chucks are older Jacobs chucks and its not precise but within a couple thou.

Busy Bee does sell a decent keyless chuck and it does goes on sale. I have a jacobs that came from my recent lathe purchase (another thread) and I was hoping to adapt it as it is an older Jacobs - however, like the original 3 jaw chuck, it will be heading for the scrap.

 

[trlvn]

Hi Brent:

So you cut the appropriate Jacobs taper(s) to fit the your chucks? Did you use the compound to produce the angled section? My impression is that the taper should be ground to get a truly good lock between the arbor and chuck.

Have you looked into a kit to repair your Jacobs? If it is a ball-bearing Super chuck, it might be worth it. Tom Lipton did a Youtube video recently on resurrecting a "Zombie" chuck. Initially seized and badly rusted. After a soak in a rust converter (Evaporust), it freed up. He then pressed it apart and lubricated. You may be able to get a kit from eBay with new jaws and whatnot if they're too far gone.

There is an auction lot coming up in the next few weeks with multiple rusty old chucks. If it doesn't go too high, I may grab it and see if I can salvage a few.

Craig

 

[trlvn]

BTW, I watched a couple of videos about removing Jacobs taper arbors from a chuck. It is astonishing just how tight the connection is! With that in mind, I think my first step is to see if I can get the arbor out of one of my existing chucks: going to try the Rohm 0-1/2" first.

I'm going to try making my own removal wedges. Tubalcain did a video on this (Tips $519) and making the wedges looks like a pretty good little project for my meager machining skills. Hopefully might get some time tomorrow...

Craig

 

[gsg9.ca]

I've been shopping the last couple of weeks myself. About the best deal I've found so far is an Accusize R8 arbour ( $ 18 ) and LFA keyless drill chuck on amazon canada. ** dooh, 1/2 chuck was $ 38 last week, jumped to $ 58 now that only one is left.

 

[Brent H]

Hi Craig,

Both my chucks were threaded so that was not difficult. I did cut the threads on the lathe so they were accurate for centre.

You can get an R8 to MT adaptor. They are about $32 on Amazon. Since you have an R8 machine it doesn't reduce your drill height much. Busy bee may have them as well

Brent

 

[Chipper5783]

As Bofobo says, you'll end up needing a chuck and collets (even just a select few collets). Of course a drill chuck is quick and handy, but sometimes it takes up too much room vertically. Depending on the job (and what type of mill drill you have), you may be forced to change the head elevation and goof up the positioning. I have a smaller mill and a bigger mill. For the work I do, the drill chuck hardly ever goes in the small mill - the Z-axis room is too small. For that machine I mostly use collets. The larger mill has plenty of room, so the drill chuck is fine and direct #40 collets are very uncommon with the 5/8-11 thread.

It depends on the machine and the task at hand. Start by sorting out a drill chuck, and get a few collets. Go with the chucks you have - drilling is not a real precision task anyway. If you have a little runout, so what.

David

 

[Brent H]

Hey Craig,

The bad chuck is a regular Jacobs - nothing extraordinary other than it is out

Makes for really shaky drilling. At first I thought it was the worn tailstock but it wobbles like crazy at the drill tip in my drill press and mill. I may pop out the taper and save it for something else. My “good” chuck is a Metabo keyless and it is great. As David said, drilling isn’t all that precise anyway.

I did make a NMTB 30 x 1” arbor for my mill to hold slit saws. As your skills get going Craig you can make lots of R8 adaptors for things like fly cutters, arbors for gear cutters etc

 

[PeterT]

Brent, forgive my dumb question. I don't quite understand your runout test mounted in the lathe tailstock picture. I could see if it was free turning in the mill/drill quill & indicator on the dowel pin, but how are you distinguishing chuck runout when its fixed in the tailstock & indicator base reference from the lathe itself?

 

[trlvn]

Brent, forgive my dumb question. I don't quite understand your runout test mounted in the lathe tailstock picture. I could see if it was free turning in the mill/drill quill & indicator on the dowel pin, but how are you distinguishing chuck runout when its fixed in the tailstock & indicator base reference from the lathe itself?

I may be wrong but I think the magnetic indicator base is mounted to the carriage and he is observing that the rod held in the chuck is not parallel to the lathe bed. Most likely, either the chuck jaws are worn or the chuck is not mounted concentric to the tailstock bore.

My impression is that the rebuild kits are worth the investment for the more-valuable Super chucks but less so for a basic Jacobs.

Craig

 

[PeterT]

If the tailstock is pointed inward/outward slightly and/or or pointing up or down slightly the DTI cannot distinguish what is cumulative runout. This just introduces one more level of ambiguity to the dowel, chuck jaws, chuck/arbor fit, arbor/quill fit. And its static, not rotating.

Alternatively, if you put the chuck+arbor in a quill & rotate it with fixed DTI resting on the dowel, at least you can narrow it down a bit. I've actually seen significant runout on just the (albeit cheapo) male end of the arbor held in the quill, no chuck attached. If the chuck socket is perfect 0.000" and axial to perfect jaws, but mated to an arbor end which is 0.005" runout, the combination of mated chuck + arbor gives you 0.005" runout.

 

[Chipper5783]

As Brent pointed out, making an arbor is not a big deal. In fact, you can somewhat remedy a drill chuck that is in poor condition by making an arbor to compensate for the chuck problems. I have not done this, but the process has been posted elsewhere on other machining sites. Of course no commercial operator would do this, as the machinist's time would not be worth the resulting chuck - however for a hobbyist and a learning exercise, go for it. The jist of the procedure is as follows. Start by cleaning up the chuck as best you can - even take it apart and get it as good as you can (don't rebuild it - afterall, the point here is doing this on the cheap). If the taper in the back of the chuck is damaged - recut it (the size does not really matter since you will be making the mating part). Select a nice piece of bar for your arbor to be (face both ends). Machine the chuck end of the arbor for a quality fit (threaded or taper - what ever is required. Sure, grind it if you can, but it isn't necessary). Mount the chuck seriously hard (even chill the arbor and warm the chuck - you want it on as if it will never come off). The next step is to chuck a decent size piece of scrap bar and machine to a nice size for the chuck (maybe 3/8", maybe 1/2" depending on where you think the wear is in the chuck). Do not remove the bar from the chuck until all done (it is running perfectly true to your machine). Grip the bar with the drill chuck - leaving the soon to be arbor hanging way out. Carefully, with a sharp, small center drill, drill a center in the end of the arbor to be. Then switch to a center and machine the new arbor. You can even remove the arbor to check for sizing/fit in the mill drill (make sure to mark the orientation of the drill chuck in the lathe so it goes back in the same position).

The result won't be perfect - but will be as good as that chuck will do.

 

[Brent H]

Sorry if my picture was a bit unclear - essentially I slid the chuck into the the tailstock taper and rotated it around to find the lowest reading on the dial indicator and then set the indicator to zero. further rotating the chuck carefully in the taper I got the 0.025" discrepancy. Doing the same test with my other keyless chuck I only got about 0.003"

Yes the "test" is not 100% but it seemed to show a vast difference in the two. I will chuck the jacobs in my mill and post a wee pic of that and see what I get. The Chuck will be fitted to an NMTB30 to MT2 adaptor and the chuck mounted in that.

The chuck is a Jacobs 34KD - there is a parts kit available ($50 on amazon but "temporarily out of stock" and there are 3 available on amazon.com and that will be $57 shipped to me (i went through the check out process. but them I have to press the chuck apart and could end up with nothing....

I could buy a new 34 type (0-1/2") for a few bucks more..

 

[Brent H]

Here are the results spinning in my mill with the same rod and the Jacobs chuck compared to my keyless metabo chuck.

So you can see the old Jacobs is out even worse at 0.035 and the keyless is only 0.003.

According to the Jacobs website the 34 series has a run out of 0.004” max at 1/2 capacity.

Running the jacobs in the mill or trying to drill a centre hole on the lathe is just not going to happen.

At about $60 to get repair parts and then hope I can press the case apart - I am thinking it will be heading for the bin. I’ll try to salvage the taper.

 

[Brent H]

Inserted a pin punch through the chuck, nice sharp hammer blow and viola!

If anyone wants to repair the old chuck i won’t bin it just yet.

 

[PeterT]

Perfect, we're on the same page. Tom Lipton did a chuck rebuild vid earlier THIS spring? There are others out there too but he kind of talks through the generic process, pressing etc. Apparently the common culprit of many 'bad' chucks is issues with worn or distorted jaws. So if you can land on a reasonable rebuild kit for what is an otherwise good chuck model, hopefully get another 30 years of reasonable TIR service.

Like I was saying earlier, when you get the arbor removed from chuck, repeat the test in your last pic but with dial only on the arbor end. If its out .001" that will only aggravate the combined runout unless you can somehow clock +.001 arbor to -.001 chuck socket to achieve 0.000 TIR if you get my drift.

I have a so-called precision mini chuck for teeny drills that has problematic runout. The arbor is actually pretty good & so is the repeat-ability of jaws, so I think the issue is chuck socket centering. I don't have much to lose because its not of much value to me now, 2-3 thou is too much for teeny drills. I'm trying to think of a way to jig the assembly with a small annular gap on the mating surface to basically 'glue' them into position with permanent retainer or epoxy to achieve zero runout. I haven't seen this done or even discussed so might be hair brained.

 

[Brent H]

Hey Peter,

The arbor dialled out to a couple tenths

 

[trlvn]

I'm a badass mill operator!

First time milling steel. First time using my 5" sine bar and Jo blocks. Despite that, went almost flawlessly. The only hiccup was that my milling cutter has been re-sharpened and cuts a 0.621 slot. I thought it was 0.625 and the 4 thou difference was go/no go for the large end of the JT33 taper. But I got it back in the vise and cut the extra few thous easily enough. No blood, no drama!

After cutting off each of the wedges, they worked quite well to pop the chuck off the arbor:

The arbor and the socket in the chuck seem to be in good condition. Next step is to get an R8 to JT33 arbor and I'm off to the drilling-on-the-mill races! Or at least I get to find out how much run out the chuck has.

Craig