# Fitting a 4 jaw chuck to 9X20



## Stockyj (Aug 25, 2020)

Maybe someone has done this already with some tips.
I have the original 4 jaw chuck but want a more precision 4 or 5".
I am buying an extra standard backing plate for this purpose I realise the mounting to chuck may not be exactly what I need but should be able to modify.
I am looking at a  K72-100 4" 4 Jaw Independent or maybe a 5"
Any experience ideas Thanks.


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## stupoty (Aug 25, 2020)

Hello,

When you say "more precision" is it a 4 jaw scroll chuck or independent jaws you have ?


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## Stockyj (Aug 25, 2020)

As quoted Independent


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## stupoty (Aug 25, 2020)

Stockyj said:


> As quoted Independent



Sorry I was kind of asking what the improvement in accuracy you were after was.  

If it's an old chuck are the jaws damaged / worn or do you wan't a new feature like replaceable / soft jaws ?

I have a fairly cheep and cheerful 4 jaw that I got for my 9x20 , 5 inch one.  It's done well and is still quite happy.  I think it's a generic india import one.  I kind of think if the four jaw is in good condition the accuracy gain is small.

I am often tempted by chucks that can mount soft jaws though


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## Stockyj (Aug 25, 2020)

My reason for a 4 jaw chuck is to hold none cylindrical parts. The 4 jaw chuck supplied with the 9X20 is very basic with minimal accuracy that is why I would like to upgrade it. I am an ex Toolmaker so do understand the technicalities. I am interested if somebody has done this using the stock mounting plate.


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## stupoty (Aug 25, 2020)

Stockyj said:


> My reason for a 4 jaw chuck is to hold none cylindrical parts. The 4 jaw chuck supplied with the 9X20 is very basic with minimal accuracy that is why I would like to upgrade it. I am an ex Toolmaker so do understand the technicalities. I am interested if somebody has done this using the stock mounting plate.



Which spindle nose does your lathe have ? I had to make a backing plate for mine as I couldn't find a source for the type I have (face, taper and 3 bolts ).  I used a piece of dura bar cast iron.

Stu

edit ,

If quality is your goal you can never go wrong with a bison chuck.


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## C-Bag (Aug 25, 2020)

Almost all of us here have replaced the chintzy 4jaw that came with it. I was lucky the previous owner had already done it for me, but had replaced it with a 5 1/2”. A 5 would have been better. If you already found a backing plate your almost there. As a toolmaker I’m surprised you have settled on a 9x20. With some some work it can do some good work but is not exactly a revered lathe  I like mine and it fits my work envelope, small shop and cheap heart but my background is mechanic/fabricator.


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