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Tool Hardinge Dividing Head 5C Drawbar

Tool

SightlessSeer

Super User
Last fall, I picked up a Hardinge Dividing Head along with a Hardinge branded Buck Adjust Tru chuck (no external jaws) from a gentleman near Montreal. It only came with one dividing plate, but there was another gentleman in Lachute who was selling a set of 7 Hardinge Dividing plates, so I picked those up on the way back. Since I picked up that head, I've wanted to find or make the 5C drawbar for it to add a couple more work holding options. I was able to pick up one of the original Hardinge dividing head pin wrenches from Cardon Tools, but he didn't have the drawbar that it mounts into. After a bit of searching for the drawbar came up empty, I set to work coming up with what dimensions I could.

The 5C threads were the easiest part. I found a thread on Hobby Machinist, where somebody had posted some Hardinge Factory drawings for the drawbar threads, so I more or less lifted those dimensions directly into my model.

For the drawbar itself, I looked everywhere that I could think of for dimensions, but the best thing I could find were these two pictures from a Practical Machinist thread, which I had to go to the Wayback Machine to find non-dead links.

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That gave me a rough estimate at the length and diameter of the flange, but in the end, I derived most of my dimensions from the two mating pieces. I based mine off of the top version of the drawbar.

This drawing isn't the one I was working off of when making it, but I updated it so the important dimensions matched up with what I ended up with.

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Now that we're past the design phase, into the build.

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The part was machined out of hot roller 4140, which I bought specifically for the purpose
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Here I'm roughing out the piece from 2" down to size.
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I used a vertical sheer tool to bring the part to the final outer dimensions.
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With the outer dimensions finished off, I setup for roughing out the bore.
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Because the part was relatively short I couldn't setup the steady read with the carriage in the usual location, so it got shunted to the end of the bed to make space
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I brought the bore up to 1" using a set of cheap reduced shank drill bits.
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In between drilling, while waiting for the part to cool off a bit, I put the precision flat stones to some of the surfaces to polish them up a bit. This turned out better than I could have imagined.
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Once the bore was brought out to final diameter, I set up for threading. Notice that I pushed the steady rest back a bit to make room for the compound.
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After threading, the collet fits nicely. I compared against the drawbar for my horizontal spindle to get a similar fit.
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There's a bit of visible chatter on the threads, but it's super slight. You can't feel it when threading in the collet. I think I got this because I did the threading at 28 RPM. I think that if I ran the lathe slightly faster I could have gotten a smoother finish here.

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After a quick test fit in the dividing head, I flipped it and faced the flange down to the final 1/4" thickness.
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Here's a quick mock up before I drilled the wrench holes
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With the lathe work done, I setup the drawbar in the dividing head and got it running on axis (that is an adjust tru chuck)
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Once the drawbar was setup in the dividing head, I setup the loaned vertical head. This is a copy of a setup from a Hardinge bullitin that I found on Vintage Machinery (see below at the bottom right)
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I think that's my picture limit per post, so I'll continue in a reply.
 
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With the "vertical head' setup, dialed in horizontal, and centered on the drawbar, I used the DRO to setup the offset for the wrench holes and spotted them with a center drill.
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After bringing them up to final dimension, the handle fit nicely and the drawbar is finished.
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The handle is a nice friction fit into the draw tube. It holds firmly, but can be pulled out without unreasonable force.
 
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