Backplate adapter for 4" chuck

My cnc lathe was originally equipped with a 4" chuck and a separate 2-1/4"-8 threaded backplate adapter.

Unfortunately the chuck was missing when I got the lathe so I need to purchase a replacement.

My question is whether I need to machine my own backplate adapter using something like this (I can't find one specific to a 4", this is smallest I've found) https://littlemachineshop.com/produc...ProductID=1923

Or whether I will get sufficient accuracy with a pre made one such as this (https://allindustrial.com/all-indust...-lathe-chucks/) which seems to match the chuck I'm looking at.

If anyone knows of alternatives I'd love to get a URL.

Thanks

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Both routes would be ok depending on your skill level. I would think you could skim cut the prebuilt one on your lathe to correct most issues.

Quote:

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Originally Posted by Fastest1

I would think you could skim cut the prebuilt one on your lathe to correct most issues.

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That's what I was hoping. The prebuilt is cheaper and I have so many projects already that I'm looking to simply things.

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There is no shame in getting it done quickly ;-)

Go with the finished one. Either way, you should install it and then check the runout and concentricity. If it isn't perfect give it a skim cut as fastest1 said. You should also then check the runout of the chuck after it is on the plate and true it up.