# Purchasing a new chuck for my supermax 1338



## sasanifab (Oct 23, 2020)

Ive watched alot of videos but im still slightly unsure as to what im looking for. My lathe has a d1-3 spindle, Id like to purchase a decent 4 jaw chuck for alignment purposes. Shars makes a variety of chucks and backplates. Looking at the chuck I can see a few features that need to match up.... the chuck needs 3 cam locks of the correct size, the backing plate need to fit the chuck and the register on the spindle need to match the backing plate.  Is this correct?  I notice that some backing plates have different diameters. This measurement needs to be spot on correct? This isnt just a through hole.


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## Nogoingback (Oct 23, 2020)

It is possible that Shars has a chuck and backplate combo that will simply bolt together and will be
good to go, but commonly, some machining will be required.  As you said, the backplate has to be correct
for the spindle on your lathe and would usually be the same diameter as the chuck.  As for the register, 
it is common to machine that to match the recess in the chuck.  It also may be nessessary to drill and tap the
backplate to mount the chuck.

I recently bought a collet chuck and backing plate combo from Shars.  The bolt circles matched on both parts, but 
I still had to re-machine all the machined surfaces on the backing plate to ensure a proper fit.  Unless you can find
a chuck with the d1-3 mount as part of the chuck itself, you are likely to need some "fitting".  Fortunately, there's lots
of help around here if you need it.

Oh, and welcome to the group!


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## mksj (Oct 24, 2020)

They do make 4J independent chucks that are direct mount D1-3, although pretty uncommon. Otherwise you would need a plain back 4J independent chuck (I am assuming 8"), and an 8" backplate in a D1-3 mount that has the same bolt pattern as the chuck. Typically they will both be listed on the same page or section, or some notation as to the type of backplate to use. In the lower price range,  a fully machined backplate should fit or may need a skim cut yo true it up. Shar's and a number of other vendor's are out of a lot of stock, the cheaper 4J chucks may not be made very well, the one I had was very poorly balanced and jaws were pretty rough.

As far as direct mounts, you might look around, Bison makes a 200 mm (7.8") direct mount, they aren't cheap. You can purchase from the UK and save quite a bit, I have ordered from RotaGrip previously. The Bison 200mm Bison 4 Jaw D1-3 Independent Chuck Part Number 7-850-203    4344-200-3 is about $450 plus shipping. (You do not pay the VAT which is 20%). Cost comparison to Ajax. They also come up on eBay occasionally.





						Rotagrip - 200mm Bison 4 Jaw D1-3 Independent Chuck
					

Rotagrip, Bison 200mm 4 Jaw D1-3 Independent Chuck




					www.rotagriponline.com
				







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						Bison Independent Lathe Chuck - 8" D1-3 Mount, 4-Jaw  7-853-0833
					





					www.ajaxtoolsupply.com


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## tjb (Oct 24, 2020)

It's always been a bit of a mystery to me why most mid-sized lathes come equipped with a 6" 3-jaw scroll chuck but an 8" 4-jaw independent.  I'm sure there's sound logic behind it; I'm just not aware of it.  I have both and use the 8" occasionally but in many instances have recognized that a 6" 4-jaw would be more practical.  One was recently located by trolling eBay - I got a great deal on a 'New-Open Box' made in England Pratt-Burnerd 6" 4-jaw independent chuck.  Only challenge was that it had a D1-3 back plate.  My lathe takes a D1-4, and since I had an extra one to replace the D1-3, the purchase was a no-brainer.  If you happen to end up with a 6" chuck and need a D1-3 back plate, I can be talked out of mine for a very reasonable price.  Modifying a back plate to fit a different chuck is not difficult.  You just need to go slow and think all the way through the process before you start.  And as noted above, there's plenty of wise counsel floating around here to help you with the process.  I had loads of help doing my conversion.  And if I can do it, anybody can do it.

Regards


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