How to Make and Use a Pot Chuck for Your Lathe




Here is my finished pot chuck.

A Pot Chuck is used to hold work which does not match up with the jaws on your Lathe Chuck. Here is the finished pot chuck with a piece of 0.5" stock.

Step 1:

Step 2: Pick a Piece of Round Stock a Bit Larger Than Your Work Piece

In this case I want a pot chuck for 0.5" square stock. I am using a 1" diameter bit of Aluminum for my pot chuck. This is a little thick, but it turned out fine.

Step 3: Drill an Initial Hole on the Lathe

I used a 1/2" bit to remove the bulk of the material.

Step 4: Use the Boring Bar on the Lathe to Finish the Hole

In my case I needed a 0.71" diameter hole for my 0.5" stock.

Step 5: Check for Fit

My stock fits snugly. Yay.

Step 6: Cut a Slot Through the Edge of the Pot Chuck

I used the mill, but a bandsaw would work fine.

Step 7: Complete Pot Chuck in Use

Make sure that your jaws are all getting grip on the pot chuck. Especially, don't have a jaw come down on the slot in the pot chuck.

And have fun!



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    10 Discussions


    This is a handy way to grab square stock in a 3- jaw chuck that most metalworking lathes use.


    4 years ago

    Milling the slot like shown in the pictures is a bit risky , better to hold across the vise . Raising the job so your cutter does not hit the jaws ... This stops the job gripping the cutter as you break thru

    2 replies

    Reply 3 years ago on Introduction

    thanks for clarifying the terminology. I was wondering how this was like the pot chucks I have! Nice 6 jaw chuck, BTW ?

    This project really falls under Fixturing. There are some brilliant ways devised to hold very thin objects (think coins!) that are projects in themselves. You've given me inspiration to go to the basement and finish my tool to non destructively open up combination locks. Why I want to do this is beyond me!


    4 years ago on Introduction

    The times I could have used this! To address the slot, cut it first, then put it in the lathe. I would mill it to the Finish Depth (OD-ID), Drill a smaller hole, about 0.050". Bore to size (Will clear the temp bridge.) Use light cuts at end, about 0.010". With it still in lathe, check that bar will slide into hole. Adjust as needed, small cuts! Now with the bar in the jig, tighten the chuck and it should not move! This also would allow you to leave the jig in the lathe while changing the part for batch work or bar machine work. It is basicly a split Collet.

    4 replies

    Reply 4 years ago on Introduction

    My friend Steamboat Ed tells me that I got it wrong, a 'pot chuck' is something different, he calls this a split bushing...I should fix the name :-) But regardless of the name, or how it is made, this turns out to be a really useful and easy to make accessory!

    Ed often says 'yet again, making a thing to make a thing.'


    Reply 4 years ago on Introduction

    We both used the wrong term! :-) Just a thought on your excellent idea, how about adding a shoulder on the front to allow for repeatable length setups for batch process? This could be turned before milling the slot? Just a thought. Terminalogy has gotten me in trouble more then once!


    Reply 4 years ago on Introduction

    Ikmccann wrote:

    "how about adding a shoulder on the front to allow for repeatable length setups for batch process?"

    Yes, making bushings with flat bottom cavities or a pin installed instead of setting up some kind of back stop is common in production environments when holding non-standard shaped parts, even castings and highly irregular shapes previously milled and requiring a turning op. Regarding the trickiness of slotting in the manner shown, a band or hack saw would probably work. I generally bevel the OD of one side for identification purposes and cut it into two pieces on the band saw. Then if more material needs to be removed where the pieces meet due to irregularity in part size when clamped (would have to be alot), a bench vise and file can be used or hold it in the milling vise 90 degrees rotated from what's shown to mill some more off.


    Reply 4 years ago on Introduction

    Heh. I've got a drawer full of these things. I use 'em with 3- and 6-jaw lathe chucks to hold square stock; they work a treat. Just don't make 'em too thick or they won't squeeze well.