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Installing drill chuck arbor

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MikeK04/02/2022 20:26:17
226 forum posts
17 photos

So I rehabbed my lathe drill chuck (in another thread) - and then I found another identical chuck in a drawer and did that one too. I installed the arbor with a 1 lb deadblow hammer, just holding the chuck in my hand. But I was thinking...Is that the proper method? Will it have more runout than another method?

So I removed it and used my car/truck ball joint tool to press the arbor in place. And now I'm wondering...Did I go overboard? It might have been a ton of force I used. Literally, 2000 lbs. based on my calculation. Will the arbor be a pain to remove in a few years? Am I worrying for nothing? Do I need slapped across the face with a fish?

Bill Davies 204/02/2022 20:53:47
283 forum posts
11 photos

Well, Mike, these shallow tapers are effectively wedges, so rely on friction to hold them together and also transmit force. It doesn't take much, as you'll know if you have used morse tapers. So I think you may struggle in the future in getting them apart. Are you likely to want to do that?

Bill

old mart04/02/2022 21:36:17
3771 forum posts
233 photos

With most keyed chucks, you can open up the jaws and put a drill bit in the lathe chuck to drill through the body of the chuck. There is a short cavity between the chuck and the end of the arbor. Then you can remove the arbor with a parallel punch. Your method of fitting the chuck to the arbor should work, just withdraw the jaws first to avoid damaging them.

MikeK04/02/2022 23:15:08
226 forum posts
17 photos

In a recent thread someone from ARC Euro commented that "hitting (shocking) the arbor into the chuck with blow hammer... not ideal method, but just done for the purpose of these pictures".

Which is what prompts me to ask: "Okay, what is the ideal method?"

Mike Poole05/02/2022 09:03:16
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Moderator
3335 forum posts
73 photos

A morse taper only needs a light tap to grip enough to drive the drill so I don’t think the taper in the chuck needs too much of a hit to grip firmly, fitting a MT shank drill I would either press down on a piece of wood using the quill or give the drill a light tap with the Barson drift. I usually have a small copper mallet handy now to give the drill a light tap. Once you have run some drills near the capacity of the chuck the drilling pressure will secure the chuck but obviously you initially need the chuck to grip well enough to not slip. It does not need a severe beating to grip well.

Mike

HOWARDT05/02/2022 09:14:28
908 forum posts
39 photos

I have always. Clean both parts, place and wring the two pieces together, then holding the assembly chuck up strike the end of the arbor on a wooden bench top.

SillyOldDuffer05/02/2022 10:21:37
Moderator
8684 forum posts
1967 photos
Posted by MikeK on 04/02/2022 23:15:08:

In a recent thread someone from ARC Euro commented that "hitting (shocking) the arbor into the chuck with blow hammer... not ideal method, but just done for the purpose of these pictures".

Which is what prompts me to ask: "Okay, what is the ideal method?"

Look at it from the perspective of the designer. It's useful to make drill chucks that will fit any number of machines and useful for machines to take any tool. Ideally the answer should be simple, cheap, accurately resettable, and reliable. Tapers are a good solution because tapered plug-sockets provide a high-friction joint by wedging together, and it's easy to make adaptors that fit accurately along a radial axis.

Tapers are often used as a quick release mechanism. This variety needs to be tight enough to not slip, but loose enough to remove without drama. Over-tightening them is a serious sin, and being slapped in the face with a wet fish is inadequate punishment.

The other type, such as drill-chucks, are rarely removed from their arbours, perhaps never, so little harm done by fixing them firmly. An effective way to do this is to deep freeze the arbour whilst warming the chuck in an oven. Then quickly assemble the two and tap home once with a dead-blow hammer. The arbour expands on warming while the chuck contracts on cooling - the forces involved are enormous.

Firmly assembling a taper is declaring there's no intention to break the joint in future, which is usually fine. I suspect it's mostly amateurs who remove drill-chucks, either because they like repairing and re-using things, or are too careful with their money to buy two! Anyone making a living by cutting metal is less likely to waste time mending old tools or swapping arbours. Pairs of wedges are sold for removing drill-chucks, though I haven't seen any recently?

Drilling tends to tighten the taper, so no need for anything else unless a big drill does something unusual like widen an already big hole. (Lots of twist coupled with low down pressure.) Milling is different! It applies sideways forces and vibrations which tend to loosen the joint, so the taper has to be held firm with a drawbar.

My drill-chucks were all attached by plonking the chuck body head-down on a bench, pushing the cleaned arbour firmly into the cleaned chuck, and a single sharp tap on the arbour. None of them have ever come loose. I've only once needed to remove a drill chuck. It was after accidentally attaching a new one to the wrong arbour...

blush

Dave

Tim Stevens05/02/2022 11:11:19
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1598 forum posts

There is a tendency in many of us to seek out the 'Ideal Method', whatever we are doing. But the answer, in my experience, is always 'It all depends'. Not only that, what it depends on can only be decided in many cases, at a later date. In my current occupation*, rewiring old cars, how a job is done depends on whether the car is intended to be a reliable holiday transport for several years, or a twice-a-year concours entry (and if so, what the rules actually say, and how clued up is the judge), or perhaps for sale, and in that case, whether the price is going to depend on how completely original the car is (or looks, not the same thing at all) or what, exactly? As we are no good at seeing into the future, we cannot know what the test of 'ideal' is going to be.

In this case, for example - does concentricity matter more than repairability?

Philosophy is a wonderful tool, as long as you don't mind the delay in completing the job.

* did you see what I did, there?

Cheers, Tim

MikeK05/02/2022 11:52:48
226 forum posts
17 photos

Thanks, gents! Good advice.

Emgee05/02/2022 13:35:17
2426 forum posts
290 photos
Posted by HOWARDT on 05/02/2022 09:14:28:

I have always. Clean both parts, place and wring the two pieces together, then holding the assembly chuck up strike the end of the arbor on a wooden bench top.

I use this same method but strike the arbor/tang on a steel block.

Emgee

Howard Lewis05/02/2022 14:44:25
6104 forum posts
14 photos

An additional method of getting a tight (Possibly non removeable ) fit would be to put the arbor into the freezer over night, and fit into the chuck while it is still cold.

A variation on the "Heat and Freeze" technique, that should get you an extra few tenths of interference once everything soaks back to ambient temperature.

HTH

Howard

Roger Best06/02/2022 21:08:33
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369 forum posts
56 photos

There must be a maximum safe force, at some point the ring of steel will break, it might take a hell of a lot though.

Getting it off again is useful as I have found myself.

DMB06/02/2022 21:43:37
1312 forum posts
1 photos

Just the opposite! I acquired a second hand drill chuck which had an unwanted tang end of the MT2, as I really wanted to use in with the drawbar for drilling on the mill. It resisted my efforts to remove the taper. I settled for using it in the tailstock. Couldn't believe my luck one day, using it and chuck simply fell off it's taper! Immediately ordered a drawbar type from Arceuro, so it only now gets used on the mill. Maker; CVA, holds smaller drills than the Jacobs one now only used on the lathe. Mill is painted blue, so I painted a blue ring around the outer body of the CVA chuck and blue paint on the chuck key, so they don't get muddled up. Keys are not interchangeable.

Edited By DMB on 06/02/2022 21:48:54

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