Avoiding stuck chuck – intermitterent cuts

[BWParticipant @bw]

Hello,

It seems to me that I get stuck chucks when I do interrupted cuts. Friends have also told me that slitting saws and even flycutters can also cause a stuck chuck due to the constant clunk clunk clunk.

However from what I read people have been doing interrupted cuts for over 100 years and in general I get the impression that stuck chucks arent considered to be a drawback.

Is there any preventative measures I can take before doing an interrupted cut that would help avoid a stuck chuck ?

What has been common practice in the past to avoid stuck chuck from interrupted cut ?

Am aware of using a collet chuck whenever possible.

Am aware that modern lathes don't have screw on chucks.

Regards

Bill

[BWParticipant @bw]

[Ady1Participant @ady1]

If you have backgear then a stuck-chuck is easy to release

Make a block of wood for fitting between a chuck jaw at 3 o'clock and the lathe bed, move the lathe backwards via the pulley with the backgear engaged and relatively little force will be required to free your chuck. Zero violence is required. Sometimes a rod in the pulley oil hole is needed for a bit of extra leverage

[Robin KingParticipant @robinking15611]

Many decades ago an old toolmaker friend told me to put a little oil on the mandrel nose thread before fitting the chuck. It works – I've never had a problem with a stuck chuck since then.

[Peter KroghParticipant @peterkrogh76576]

Posted by Robin King on 10/12/2015 09:59:18:

Many decades ago an old toolmaker friend told me to put a little oil on the mandrel nose thread before fitting the chuck. It works – I've never had a problem with a stuck chuck since then.

Same here. Just a lick of oil does the trick!

Pete

[egaParticipant @ega]

I have had my share of stuck chucks on my Super Seven, but much less so since adopting the practice of a quick squirt of oil on the register and thread when changing chucks. These items should, of course, be kept scrupulously clean.

I have also seen the suggestion that a chuck which has been used for heavy or intermittent cuts should not be left on the spindle overnight (the chuck should, perhaps, also be loosened at intervals during the job).

Prevention apart, there are two requirements for removal: immobilising the spindle and safely applying releasing torque to the chuck. Lawrence Sparey has very good advice on these points in his little book "A Man and his Lathe", in particular his design for a spanner to lock the mandrel without risk of damage to the backgear. I could post a photo of my version of this if anyone is interested. His suggested way of rotating the chuck is via a bar gripped in the jaws.

In my view there should be no objection to my posting a short extract from the book but I would like a nod from management before doing so.

[BazyleParticipant @bazyle]

Anyone really need to be told to put oil on a screw thread?

Also don't fit a warm chuck onto a cold spindle. (less of a problem with chucks but the inverse applies for fitting morse taper tools)

[egaParticipant @ega]

Bazyle:

I take it that you are advising against putting a cold male MT into a warm lathe spindle, a topical point in view of the recent thread about use of the headstock taper. I suppose the workers who stand a mug of hot tea on top of the tailstock might need to take care, too!

On the oil on threads point, I recall that an eminent woman cyclist was once asked what single piece of advice she would give to the world and replied "Grease all threads!". I believe she did her own maintenance.

[LambtonParticipant @lambton]

I use Rocol Anti-seize compound on the mandrel threads and never have a problem. Oiling is also good practice.

[JimmieSParticipant @jimmies]

I was advised years ago to put a thick card packer (a post card folded in two) on the spindle before screwing the chuck on. Seemed to work.

[BWParticipant @bw]

Posted by Bazyle on 10/12/2015 12:25:53:

Anyone really need to be told to put oil on a screw thread?

Weeeellll yes ……….

Some of us have little or no experience and we ask questions and learn from others.

Is there any possibility that oiling a chuck thread might have the reverse effect ie the oil somehow turns to glue and makes the problem worse ?

Bill

[BWParticipant @bw]

Posted by ega on 10/12/2015 12:09:54:

in particular his design for a spanner to lock the mandrel without risk of damage to the backgear. I could post a photo of my version of this if anyone is interested.

Yes please I'd be interested in seeing a photograph of your spanner.

Bill

[mechman48Participant @mechman48]

Might I suggest a touch of 'Copperslip anti-seize' compound on threads as an alternative to Rocol, I have used it for years during my working career & latterly in my 'man cave' on threaded bits ' n' pieces … e.g. on my chuck studs, tool post handle…

George.

[egaParticipant @ega]

Bill Wood 2:

Thank you for your interest. A couple of photos: the first shows the spanner installed on the S7 spindle, the second the device itself with the loose pin which engages in one of the holes in the bullwheel. When used in earnest, I interpose a bit of brass between the projection on the spanner and the lip of the headstock.

The spanner was just sawn and filed up from a scrap piece of 8 gauge MS, hence the redundant hole. The pin is a bit of HT material but MS would do.

I will send you a PM with more information.

[egaParticipant @ega]

What actually happens when a chuck "sticks"? And is a steel backplate more prone to do so than cast iron?

My understanding is that metal to metal contact allows some sort of welding or sticking to occur, hence an oil film prevents this. My guess is that the problem arises at the register/shoulder, which should be a close fit, rather than the thread. Other things being equal, anti-seize compound no doubt is more effective but the presence of thick grease (or cardboard) might affect the accuracy of the mounting.

Purely by the way, an eminent woodturner, the late Peter Child, recommended a thick leather washer to prevent screw-on chucks from unscrewing when run in reverse.

I realise that the modern tendency is to secure the chuck by bolts, etc but I do value the ability to change chucks rapidly (or, indeed, to use the headstock taper).

Edited By ega on 12/12/2015 11:42:16

[BazyleParticipant @bazyle]

On the Drummond yahoo group John Kiely showed a section of thick aluminium cut with teeth matching the bull wheel in curvature and spacing so on the inside of the curve. This distributes the stress over several teeth and the soft aluminium bends to help this spreading of the load. May be an idea for lathes without convenient holes.

Ega – nice idea perhaps for the 'small articles' issue. Off topic but I see a another thing on your picture just below the 'R'. ???

[egaParticipant @ega]

Bazyle:

It's certainly a useful "gadget" (when needed) but, as I said, not my own invention. If the editor thinks it suitable I could submit a dimensioned drawing of my version for the Myford Super Seven; the idea would also work on the ML7.

From what I have read there does seem to be a real danger of damaging the bullwheel if abused and I feel more comfortable with the Sparey method. I suppose that in extremis one could always machine the chuck off!

OT: the other "thing" is the fixing point for the latch on the GHT headstock dividing attachment which, for me at least, was a major project some years ago. GHT was standing on the shoulders of J A Radford, whom he considered a very quick worker, but I don't think even JAR would call his original device small.

[Robin KingParticipant @robinking15611]

Bill Wood 2

In answer to your query about oil thickening and turning to 'glue' – for what it's worth I've never had that happen even though my lathe has on occasions stood untouched for long periods, with chuck fitted, and it has then unscrewed without any difficulty. The oil I use is just a good quality machine oil, or occasionally a smear of SAE 90 which is around the shop – whichever is nearest at the time.

[egaParticipant @ega]

Presumably oxidisation of the oil is unlikely to occur if the air is excluded as it would be on a well-fitting chuck.

[John BaronParticipant @johnbaron31275]

FWIW the Myford S7 lathes have a spindle lock !

Its that pin at the back to the left of the spindle change gear cover.

Since I don't seem to be able to attach anything I can't post a picture.

[egaParticipant @ega]

John Baron:

I've been hanging my handbag on that pin and did wonder what it's real purpose was!

Seriously, however, I do invariably use the spindle lock for removing chucks that are willing to come off but in the case of a stuck chuck would prefer to immobilise the spindle as directly as possible; as you no doubt know, the pulley into which the lock pin goes is connected to the spindle via the bullwheel ie indirectly.

Is it the case that the ML7 doesn't have a spindle lock?

Posting pictures on the site is rather like treadling a lathe – clunky and hard work but good for the soul. I believe the drill is to put the pictures in an album and then use the camera image to insert into the post. If you discover how to put text into the post *after* the picture please let me know! It does seem to help to size photos appropriately.

Edited By ega on 12/12/2015 15:25:03

[Ady1Participant @ady1]

A picture of the Drummond system I use

The block of wood sits on the ways and catches a jaw a 3 O'Clock while the thin bar in the pulley oil hole can be seen

With backgear engaged the bar turns the chuck backwards(clockwise) and the chuck easily unsticks from the spindle nose

[LambtonParticipant @lambton]

Take great care when using any method of locking the bull wheel on a Myford Super 7 whilst using force to free a stuck chuck as there is only a small woodruff key (item H22 on the exploded diagram) that secures the spindle and bull wheel together. Keyways, especially in cast iron or heat treated steel are stress raisers and excessive force or shock loading could easily cause serious damage.

Take precautions to prevent the chuck getting stuck e.g. lubricate the spindle end with anti seize compound and never "spin" the chuck onto the spindle at speed or with any undue force.

[egaParticipant @ega]

Lambton:

Good point – although my understanding (and reading of the diagram in the S7 manual) is that it is the bullwheel that is keyed to the spindle by the woodruff key (H22); the pulley is connected to the bullwheel by the backgear key (H5).

So, ideally should we be looking for a method that doesn't involve the pulley, the bullwheel or the backgear? Perhaps by gripping the spindle tail in some way?

Incidentally, the manual does stress the need for cleanliness and to oil the spindle register.

[RobboParticipant @robbo]

The Myford Super 7 has already got a spindle lock, at the left hand end of the headstock, at the rear, a "bolt" that slides in. Part no A2751 – Pulley lock assembly item H32 in the diagram

[Author]

Posts