How do I identify chuck to find jaws to fit ?

Hi all,

I need a set of outside jaws for my chuck but I don't know how to identify what I need. It's 4" but there are no distinguishing marks although it looks like a Pratt Burnerd (see photos). All I have is the current inside jaws code which is 36956.

Any advice very gratefully received !

Many thanks,

Neil

This info sheet from Thame engineering may be useful, unfortunately I don’t think they supply all the jaws in the document but it may be helpful in identifying what you have.

Mike

Rotagrip sell some PB jaws but they are not at the budget end of the scale!

Rotagrip list outside jaws for 4" Pratt Burnerd chucks here currently on offer at half price - £124.20 inc Vat per set. There is a link to a specification sheet for the jaws on the page linked to.

Alternatively, you could get a complete new 100mm K11 3 jaw chuck with both sets of jaws & a chuck key for £41.88 delivered here Not a Pratt Burnerd, but a new unworn chuck and, if it wasn't up to you required standards, subject to Ebay's money back guarantee. I have a similar Chinese chuck awaiting fitting to my S7 to replace a rather worn direct mount Pratt Burnerd, bought on the back of positive comments about them on this and other forums.

Nigel B.

Jeez it beggars belief how the Chinese can knock out stuff that cheaply and delivered!

Tony

That's how I'd approach the problem. The Thame catalogue gives the A,B,C,D, J dimensions of jaws for various sizes and makes. What A,B,C,D, J relate to is shown not very clearly on the soft-jaw image.

So, remove a jaw from the chuck, measure it's A,B,C,D and J dimensions, and then look for a match in the catalogue. If Thame don't have a match, look for other chuck jaw catalogues and wade through their dimensions.

Dave

If you can find a set of outside jaws then you will find that they will cost an arm and a leg. Unless you strike VERY lucky and find a second hand set. I have been there and got the T shirt.

I once got lucky with a 3" PB grip true, but that was a near miracle. Do yourself a favour and do as Nigel suggests. It isn't as though your chuck is near new. In fact it looks a bit on the tired side.

Andrew.

I wouldn't contemplate a new set of hard jaws for an elderly PB chuck at ~£125 but I recently bought a set of soft jaws for my 5" PB 3-jaw from Rotagrip. Cost about £30 and seem good. They could substitute for hard jaws for light use, but a cheap far-eastern chuck is likely to be more satisfactory at not much extra cost.

Many thanks all, new Vevor ordered. Can't believe the price tbh !

Far less bother and the Vevors are plenty good enough for home shop use. Judging from the size of the backplate you might have been able to fit the next size up. There is a probability that you will have to drill new holes in the backplate to line up with the new chuck threads, and possibly adjust the size of the register on the backplate. There will be plenty of room for any modifications fortunately. The numbers on the jaws are serial numbers and are of no help in identification.

Edited By old mart on 21/11/2022 17:49:13

Quick thank you to all for your advice.

I've got the new Vevor chuck installed. Quality is absolutely fine for my needs & great value for money. As suggested the original backplate was the right size so I've turned & drilled it to suit the new chuck & all running nice & centred. So I finally got to start my first (very basic) project, a new shaft for an egg chair, and it all got a bit much for the old Hoover motor it was running on ! New TEC motor now ordered which I need to make a baseplate for and bush out to take original pulley. So my £300 lathe has now cost me another £150 so far - perhaps I should've spent more on a better one to start with but it's all an interesting learning curve & hopefully there's not much left to go wrong with it (famous last words) !

Cheers,

Neil.