Has anyone bought new jaws for one of these ?

[Dovetaildave]

Hi,
I've been given a chuck (Pratt chuck 8" with Key ) and it attaches to the Harrison graduate I have at work.

I've been mainly turning bowls these last few months and wonder if it can be pressed into service if I were to buy new jaws.

Has anyone bought new jaws for one of these ?

If its not possible is there any woodturning use for it or should pass it on?

Thanks in advance,
Dave

 

[katellwood]

That looks like a four jaw independent chuck i.e. each jaw operates independently and will not self centre. engineering chucks usually are not very good at securing wood due to the jaws design,

It may be of use if you are turning something off centre but will be difficult to setup. I would suggest you would rarely use it

You can usually buy soft jaws for self centring three jaw chucks where you can drill and tap them yourself but for four jaw independent I'm not sure

try these

http://www.chronos.ltd.uk

they supply soft jaws for chucks however if they will fit yours I'm unsure

or these

http://www.rdgtools.co.uk/acatalog/4_Ja ... iece_.html

they supply Pratt Burnerd four jaw chucks

 

[woodpig]

He's right, If it had been a self centering chuck and you could get soft jaws for it you could use it but not much use for an independent. Nice chuck though and worth a few quid if it's in good nick.

 

[graduate_owner]

Not being a self centring chuck means you have to adjust each jaw individually ( well, in opposing pairs actually) until you get the level of concentricity you need. Usually you would 'clock it' using a DTI. However whilst metalworkng jaws are not great for holding wood ( limited contact, plus they crush the wood fibres which then put things off centre again - I've tried it) I can see some potential here - you could hold a number of woodturning accessories in the jaws provided you take the time to centre them. Some suggestions include a wood screw (to act as a free wood screw chuck) or an actual screw chuck insert intended for wood jaws, a home made pin chuck (piece of steel rod with a flat filed on it, and a shortened masonry nail for a pin), a length of threaded rod on which you could mount accessories such as ply or mdf discs holding various sizes and grades of abrasive paper to make a scary type sharpening disc for woodturning and other tools, or holding ply / mdf cylinders to make bobbin sanders of a size to suit your individual needs. If you only want to use one of these suggestions, say the threaded rod, then you could leave it permanently mounted in the chuck and so would only need centreing once. Be aware that nuts on a threaded rod will tend to unscrew as the lathe rotates so a second nut to act as a lock nut would be needed. Also to grip the disc / cylinder really well you can use pronged nuts (not sure of the correct term for these). Of course you could use your faceplate for holding discs, and a 2 or 4 prong centre plus tailstock support, but this gives you an extra option.
Things would be much easier with a self centreing chuck but personally I would hang on to it for a while to try things out and then sell it on if the effort is not worth the advantages.
The thread on the graduate is 1 1/2 x 6 tpi (1 1/2 x 8 would fit South Bend and probably others) and I don't know what metal lathe that would fit as I'm not well up on that. If your chuck has a removable back plate then it would be a saleable item. An ebay browse will give you an idea of value. Hope this gives you some ideas.

K

 

[SVB]

Pratt are a well respected brand in the metal tuning / hobby engineering world. In your place I'd be o it with the ooo wire wool, tidy it up and the offer it here followed by ebay and put the money towards a unit designed for wood.

Either way, great gift!

Simon

 

[Dovetaildave]

Thanks for the prompt replies, much appreciated.

Shame it isn't self centring, ahhh well.

I could make use of a dedicated screw chuck, as the one at work doesn't have a screw for it.

It has a removable back plate, I presume then I can attach any brand of chuck I may buy to fit onto the union graduate lathe ?

Thanks again chaps =D>

 

[graduate_owner]

You can unbolt the existing hackplate and bolt on a new one with a different thread, in theory. You would need to measure up the existing backplate- not the thread but mounting hole size and location, then check with firms like Chronos, RDG etc to see if they can match it. Use the old backplate as a faceplate tor the graduate, or attach a disk and make a sander / tool sharpener as previously suggested. If you can get a match for the backplate then an 8" chuck would be a very saleable item to metalworkers ( sell it without a backplate but tell them they are available ). I think you could easily get £20 for the old backplate too as graduate extras are not cheap.

K