Removing Chucks

[Colin LLoydParticipant @colinlloyd53450]

As the proud owner of a new 4 jaw chuck and 160mm faceplate for my Amadeal CJ18A mini-lathe – it looks like I might be changing chucks quite often. The 100mm chucks locate on a precise shoulder on the mandrel (very precise) so that it has been quite difficult to take the original supplied 3-jaw chuck off. I have used a thin flat-headed screwdriver and mallet to get between the chuck and mandrel shoulder surfaces – but that is hardly elegant and will, with time, begin to exhibit damage to the chuck and mandrel.

I was planning to mill 3 and 4 small flat-headed screwdriver-sized slots on the periphery of the 3-jaw and 4-jaw chucks so that I could use these to lever off the chucks.

Before I do that – is there some other way to easily remove the chucks. I thought about pairs of expanding triangle blocks that could be screwed together behind the chuck securing bolts and thus pushing the chuck bolts and attached chuck out in a controlled manner – but that seemed an over-engineered solution.

[Colin LLoydParticipant @colinlloyd53450]

[John RuddParticipant @johnrudd16576]

You would be better inserting some round bar into the chuck and securing it, this then gives you something to,'waggle' when removing the chuck rather than bruteforceing it with a screwdriver……

Dont forget the obligatory piece of ply/soft wood on top of the bed where the is likely to fall as it comes away…..!

[SillyOldDufferModerator @sillyoldduffer]

The chucks on a new lathe are likely to be very tight until they've been on and off a few times. You should find they soon settle into a much more reasonable fit. No need for wedges or peripheral slots.

John's Rod in the chuck to waggle it is a good idea but be careful to waggle evenly so you don't wedge the chuck sideways on the register. (This makes the fit even tighter, and you may have done just that with your screwdriver.)

Also, with a suitable bit of wood between the chuck studding and the headstock, you can use the chuck's securing nuts to push the chuck off for 4 or 5mm. Once the chuck's moved a little John's rod should do the rest.

Dave

[Colin LLoydParticipant @colinlloyd53450]

To John and Dave – thanks for that info. I will go with your suggestions – just needed to check what the experts did.

[not done it yetParticipant @notdoneityet]

I would suggest that threaded holes in the mandrel would be the ideal means of jacking the chuck off. It should be a tight fit to maintain concentricity. The faceplate should be machined as a tight fit as well.

A better alternative is the bar in the chuck jaws and use it as a slide hammer, to pull the chuck off square (think here a suitable bolt, with nut, and a lump of suitable metal bored to slide on the bolt).

Also, best to refit your chuck(s) in the same position every time they are replaced, particularly for a self centering chuck, or a different concentrity error may be apparent on replacement.

[norman valentineParticipant @normanvalentine78682]

I am happy that my lathe is "well bedded in", I change chucks 3 or 4 or 5 times a day. I find it quicker to change chucks than to change from inside to outside jaws and consequently I have two 3 jaw (actually three) and two 4 jaw chucks. (and two faceplates)

[not done it yetParticipant @notdoneityet]

I find it quicker to change chucks than to change from inside to outside jaws

Norman,

Are you still using the Loughborough? I little different than a chuck bolted on the spindle. So much quicker to change chucks with a theaded spindle, but the bolted on type can be used, under power, in both directions, unlike the threaded spindle lathes.

[JasonBModerator @jasonb]

Long bar that passes through the spindle and out the back, tighten chuck onto bar, tap other end of bar with copper/lead hammer. Added bonus is the chuck won't drop onto the bed if you forget to put a board on it for protection.

[SillyOldDufferModerator @sillyoldduffer]

Posted by JasonB on 26/10/2017 20:33:14:

Long bar that passes through the spindle and out the back, tighten chuck onto bar, tap other end of bar with copper/lead hammer. Added bonus is the chuck won't drop onto the bed if you forget to put a board on it for protection.

Brilliant!

[MalcBParticipant @malcb52554]

Posted by JasonB on 26/10/2017 20:33:14:

Long bar that passes through the spindle and out the back, tighten chuck onto bar, tap other end of bar with copper/lead hammer. Added bonus is the chuck won't drop onto the bed if you forget to put a board on it for protection.

And should also keep the chuck square the spindle as it comes off. A good fit in the spindle would help.

[not done it yetParticipant @notdoneityet]

Yep, brill idea, as long as everyone can accomodate their machine with sufficient space behind the spindle. I'm currently repositioning my lathe to leave space for longer bars of stock to protrude rearwards. There is always the exception that defeats the rule!

Edited to add that I like Joe Pie's wooden chuck support blocks (u-toob) where he just slides the chuck along on the appropriate block and it mates/aligns almost perfectly with the spindle.

Edited By not done it yet on 26/10/2017 21:33:20

[norman valentineParticipant @normanvalentine78682]

Yes. I am still using my Loughborough lathe, I used to have access to a Myford 254. Changing chucks on that was a pain in the arse. I have never needed to run a lathe backwards so threaded chucks are fine as far as I am concerned..

[OldironParticipant @oldiron]

Posted by norman valentine on 26/10/2017 21:33:32:

Yes. I am still using my Loughborough lathe, I used to have access to a Myford 254. Changing chucks on that was a pain in the arse. I have never needed to run a lathe backwards so threaded chucks are fine as far as I am concerned..

I did my machine shop training in the Royal Navy in the 60's and the instructor told us " why the heck would a manufacturer put a reversing switch on a lathe with a threaded spindle if they thought it was going to fly off."

I have never seen or had one come off but I suppose some idiots can make it happen.

[norman valentineParticipant @normanvalentine78682]

NDIY. If you have a problem with not enough room for material sticking out of the back of your lathe just drill a hole in the wall. you can always put a plug in it when it is not needed.

[not done it yetParticipant @notdoneityet]

just drill a hole in the wall. you can always put a plug in it when it is not needed.

Again the exception? My lathe is not positioned against a wall. The item immediately behind the lathe it is not a suitable candidate for having holes drilled through it (nor easily moved).

[jimmy bParticipant @jimmyb]

I’ll be using that tip jason. I’ve been using a bar on my Crusader, I’d never thought about pushing it into the spindle. Simple and brilliant, just goes to show, been doing this a long time and still learning.

Jim

[HopperParticipant @hopper]

If all else fails you can always ease the mating surfaces with a bit of emery paper to make them a neat sliding fit rather than an interference fit.

Or if you havent got room to use the mentioned long bar and big 'ammer through the chuck, you could grip a large nut in the chuck and tighten a large bolt down against the end of the spindle, protected by suitable plug of brass etc, and ease the chuck off that way. Half inch diameter UNF or similar nut and bolt would do the job.

Edited By Hopper on 27/10/2017 08:26:18

[MuzzerParticipant @muzzer]

Posted by not done it yet on 26/10/2017 23:03:19:

just drill a hole in the wall. you can always put a plug in it when it is not needed.

Again the exception? My lathe is not positioned against a wall. The item immediately behind the lathe it is not a suitable candidate for having holes drilled through it (nor easily moved).

Use a slide hammer version of Jason's tip. The sliding part would be above the bed, so surely no lack of room no matter what your workshop looks like. And you can insert additional length into the spindle if you want to stop the chuck plummeting.

Murray

[not done it yetParticipant @notdoneityet]

Use a slide hammer version of Jason's tip

Clearly not read my post before Jason's, where I suggested the slide hammer? (@16:36:35).

[Bob StevensonParticipant @bobstevenson13909]

The best way to remove Chinese chucks from their seating is to use the securing nuts as 'jacks'……place a piece of brass or similar behind the chuck and a spanner to loosen the nut until it is pushing against it's thread……jack out all three (or four) nuts in turn and the chuck will start to leave the spindle under the force of it's own securing nuts.

[BazyleParticipant @bazyle]

All this hammering doesn't sound like the best treatment of the bearings. Until it eases off do make sure you aren't trying to take it off after a bit of running has warmed up the bearings and hence the mandrel but the chuck is still cold. Also don't put a hot chuck on a cold nose.

It looks like the chuck bolts are actually studs that go through to the back of the mandrel nose plate with nuts at the back. Same as my Hobbymat.
Make a spacer that fits between the back of a stud and the front of the headstock with 1/2mm clearance then as you undo the nut it will hit this spacer. Half a turn with the spanner will jack the chuck forward. Then move round to the next stud etc and you have effectively built in jacking points. No impact stress on the bearings.

You can also make a card washer (postcard or birthday card) to fit between the chuck and nose plate. Actually 3 slips of card is all that is needed. This will form a gap that may help avoid the very tightest part and forms a slot if you still resort to the screwdriver.

[Brian GParticipant @briang]

One advantage of using the nuts to jack the chuck off of the flange is that it will release before the nuts are fully undone, so there is no risk of it landing on the ways, the sort of "sods law" event that is almost guaranteed should you forget the wooden block. To make it easier I have fitted longer studs to the chucks – the nuts can (and must) now be fitted before it engages with the register, which avoids a lot of the faffing around due to lack of access behind an 80mm chuck.

Brian

[BazyleParticipant @bazyle]

After thinking about it the best thing would be to make some special long nuts or get some coupling nuts and cut to length.

[Neil WyattModerator @neilwyatt]

Colin won't have enough space behind the studs to fit long nuts.

Get a bar of aluminium or brass that fits between end of stud and headstock.

Lever each stud gently forwards a touch, in turn while supporting the chuck with your other hand. It only has to move about 1mm to come free.

Don't be tempted to ease anything, the chuck may be what's tight rather than the register. A tight fit is good for accuracy, but it will ease slightly in time so a gentle tap with the base of your hand will probably be enough.

Neil

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