Another option is to buy secondhand.

A couple of months ago I bought off eBay a 160mm Pratt Burnerd 3 jaw chuck, nice condition, D1-3 camlock backplate already fitted, for £98 delivered!

Lee

I think Jason meant this link :   http://www.rotagriponline.com/index.php?page=shop.product_details&product_id=3534&flypage=flypage-ask.tpl&pop=0&option=com_virtuemart&Itemid=29 

160 mm standard accuracy Pratt Burnerd for £ 351.90. Safe to 3000 rpm which is nice. No specifications as to axial alignment, concentricity and run out tho'. Its an import of course but probably more of a warm cuddly feeling from buying via a major industrial supplier. Hafta say there was an moderately minor issue with the new PB chuck I got back in the day and that was sorted with no quibbles. Chucks'R Us shop types wouldn't have wanted to know.

With an integrated fitting chuck these need to be good out of the box as there is no possibility of adjusting thing. Theoretically a backplate fitting can be adjusted to compensate for any chuck body errors. Monumental faff if you want to get to thou' and below levels. Oft talked about but I wonder how many people have actually done it. Considerably different than getting better results from a 40 year old worn out chuck.

In a practical world its the axial alignment with the spindle that really matters and that is something readily got dead right with a backplate.

In todays market pretty much all but the stupidly cheap stuff has generally acceptable performance so there is much merit it Johns suggestion of getting a reasonable, but relatively inexpensive chuck and backplate. Maybe save £100 over a respectable integrated fitting version. But if you go for brand name equipment Pratt Burnerd / Bison / TOS et al chuck and backplate will come out more than an same chuck on an integrated fitting.

Clive

PS Slow typing.

Edited By Clive Foster on 20/06/2017 11:34:28

Edited By Clive Foster on 20/06/2017 11:35:38

Sorry, I probably got the last one that came up . I haven't seen another since.

What other chucks do you have if any? If the 3-jaw is going to be teh first one you buy then sooner rather than later you will also want a 4-jaw. Best do the sums to see what works out best either save the backplate for a 4-jaw, or use it now for a 3-jaw. It is not practical to swap chucks onto one backplate regularly so you really need a backplate for each chuck or chucks with integral mounts

Without shopping around I think it may work out most economic to save the backplate you have for say a zither or other reasonable quality imported 4-jaw. Then get a 3-jaw with integral D1-3.

One think to be aware of is the backplate you have may be fully premachined and have a short spigot on it of about 125mm, your new 160mm chuck will need a matching recess to suit this spigot.

It's really your choice, which will probably be dictated by a mix of cost, availability, and the amount of faffing involved.

If I weren't dictated by cost I would go for a new Bison with D1-3 backplate as linked above.

Lee

Boxford fitted three or four different motors. I presume you checked the motor plate first, as you may well have a dual voltage 240/415v motor.

Lee

Use your backplate unless the stud thread alignment is so poor that any of the cam position indicators are outside the 45° quarter past / half past safe fitting arc. Very rare error. As mentioned on another post I have a backplate that is marginal and can only safely be used in one position. PB precision 160 mm sitting on it and all behaves just fine.

If you are going to use your backplate then have a look at this page **LINK**. for ideas.

The Vertex at £180 looks a deal but not sure how well Vertex quality has held up over the years. All my Vertex gear has been at least outright good not just good for the price. Bought a new 125 mm version of the TOS front and rear mount chuck years ago for a SouthBend lathe now long gone and was perfectly satisfied with its performance. Not far short of my 160 mm P-B precision really.

Clive.