What Size 4 Jaw Chuck

.

I know this may be a bit like asking 'how long is a piece of string'

I am in need of a 4 jaw chuck. My lathe is a Boxford STS 10-20 that will swing 10" (it 'would actually clear 11" ) and has a D1-3 fitting and I know I will need to cater for this fitting with a backplate.

Lets say (for now) I wish to build models such as the Stuart Victoria or beam.

I imagine it would not be wise to go too big on the chuck size due to then only a small opening of the jaws outside the main body being required to then clout the bed of the lathe. But one too small may be limiting of what shapes and sizes it can hold.

So a 160mm chuck or a 200mm chuck.??? - Advise please.

Cheers, Nick

Edited By Nick_G on 07/05/2014 22:06:41

The 200 mm chuck will be a lot heavier to lift and fit, if that is an issue for you. I have one but on a 12" swing lathe and have to be careful not to drive the cross slide into the extended jaws. I suggest 160 mm for yours.

I would be inclined to play the waiting game, e.g. wait until you need a chuck rather than buy one just because you think you need one. I have a metric late AUD Boxford (5" and have a selection of chucks one of which is a large, well large for the size of lathe, 4 jaw independent and have only used it for one specific job. If I was only doing a one off I would have found another way to hold the job but I had about 30 to make. A case of time against cost.

Bob

I don't. But one is on my shopping list of purchases.

Nick

My 280 warco is a similar size with 11" swing, came with a 5" 4-jaw which was a bit small so I got a 160mm Bison for it and it seems a good size. Also have a 10" faceplate for odd shaped items.

J

I suggest you look out for the original Pratt and Bernard 4 jaw that was fitted to the Boxford. You should be able to easily pick one up complete with (or was it integral to?) the backplate from the regular second hand tool suppliers.

It will probably be a 6" and will cost a fraction of a modern chuck and be many times the quality.

I think I paid £50 for one from one of the dearer second hand suppliers two years ago so I had it available for my dividing head.

Jo

Edited By Jo on 08/05/2014 08:17:31

probably the best option would be a narrow bodied Burnerd 200 mm four jaw with direct fitting D-3 mount,they can be found ,but their popularity results in high second hand prices, the narrow body and direct fitting reduces the overhang and resultant load .on the front of the spindle, New direct fitting Bison 200 mm fitting chucks are available but their cost has risen so much in recent years that they are no longer really viable for the average model maker,

I agree with Nigel that a narrow body, light duty, 8" / 200mm Pratt Burnerd would be the ideal choice of four jaw for your Boxford. Its around half the weight of the standard version which, even if there were not more compelling reasons, would be a major point in its favour. A standard four jaw is getting close to the top end of what I care to haul out of the cupboard and heave onto the machine.

One such on a D1-4 mount is what I normally use for four jaw work on my Smart & Brown 1024 VSL. A machine of similar nominal capacity to your Boxford albeit much more heavily built and easily capable of coping with the mass of a normal 8" / 200 mm four jaw. The light duty Pratt Burnerd body is around 2" / 50 mm deep whilst the standard version is a little over 3", almost 80 mm, deep. The light duty Pratt Burnerd chuck jaws are essentially the same size as the jaws for the next size down (6" / 150 mm) four jaw so everything is that much more handleable and even small work can be conveniently held. Standard 8" / 200 mm jaws are very much on the chunky side so small jobs tend to either disappear or suffer badly from chuck-jaw-in-the-way syndrome.

My view is that in these sizes the standard style four jaw should be classed with the Chas Taylor three jaw as being for use when you need serious grip on a component. Not as a normal use resource.

Clive

As important size is, you can't beat quality. I have picked up all sorts of bits for my Boxford, some are well worn out and make the job more difficult - but possible. As said above, a nice 6" and the money saved for a faceplate.

BobH

Under drive Boxford's are quite common and have a 1-1/2" x 8tpi thread but this one has a D1-3 fitting so will need a D1-3 back plate. Buying a narrow body Pratt Burnerd is easy enough but you need add in the cost of a D1-3 back plate.

BobB

.

What about this with the addition of a back plate.? **LINK**

Can that be right for a Bison at such low 'coinage'.?

Cheers, Nick