# 5C Collet Chuck



## Hawkeye (Aug 3, 2014)

I picked up a set of 5C collets a while back, along with a spin indexer,  and there have been a few times I've seen the advantage of having a  fairly precise work-holding method for the lathe that allows the stock  to extend into the spindle.

I got the chuck finished today, so it's time to post the build. I followed Pat Ioop's design, with a few small revisions.

The back plate started out as a broken lump of cast iron, just barely  large enough for the required piece. The big bandsaw did a good job of  trimming it to an octagonal shape.



A 10 1/2" four-jaw is just the ticket for roughing out a big piece of cast...



But, when it comes time to check the fit of the thread on the spindle,  without removing it from the chuck, you have to wrestle the whole  assembly around to screw it onto the spindle. Amazingly, even with the  weight of the four-jaw hanging way out from the spindle, the register  surface inside the chuck had a TIR of only around 4 thou.



In order to make it easier to loosen the 5C chuck from the spindle, I cut four slots in the neck to allow use of a spanner.



Next, I needed a big chunk of steel to make the nose piece for the  chuck. It takes along time to cut through a 7" x 4" cross section. The  first cut gave me a 40 pound block.



By the time the block was reduced to a 5 1/8" octagon, 4" long, it was  reduced to 25 pounds. The long rod in the tailstock is my wiggler - 10"  of music wire with a collar clamped on to make a better place to  reference the DTI.



The nose piece is roughed out to a bit larger than required and a 1" hole drilled through it.



The nose piece was turned around and indicated carefully to keep it  concentric. Then the inside features were shaped out with a boring bar.  Note the stylish spiral knurling on the outside of the piece...  Oh,  alright! it's chatter! Ya happy now?  I found out I had issues with the spindle bearings.




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                     At this point, I went to the Hercus lathe to make the collet nut. I  had some  3 1/2" round stock, so I made the nut a bit smaller than the  plans called for.



The plans show both sides of the nut grooved to take ball bearings. I  used BBs, since I had a tube of them. I spent some time sorting them by  size. I ended up using 0.173" balls for the front of the nut and 0.172"  ones for the back side.



Once the nut was finished, I needed to find out how deep to cut the  groove in the back plate to allow a bit of slack between the two sets of  ball bearings. One set is only loaded when the nut is tightened and the  other set when the collet is being loosened. I loaded both sets of  bearings between the nose piece and the back plate and measured the gap  with feeler gauges. This information let me cut the groove deep enough  to allow a loose fit.



On to finish the outside of the nut. This is the first time I've used  the tailstock with my dividing head. It adds a bit more rigidity to the  setup.



The grooves were cut with a 3/16" ball end mill. Then the holes were drilled and reamed for the tommy bar.



Time to drill the holes for the bolts that will join the nose piece to  the back plate. You can see why we recommend getting the biggest mill  you have space and budget for. I needed stubby drill bits to do this  job.



Once the two halves were clamped together, the only machine I had that  could handle the height was the bigger drill press. The dividing head  just made a good vise to hold it all.



Once the drilling, tapping and counterboring were done, the two pieces  could be bolted together and mounted directly on the spindle and the  outside matched up a bit.



A major concern was how to cut away the steel on the nose piece to leave  the three gaps for access to the collet nut. I started out with the  obvious method of milling down from above, but the endmill caught in the  metal and started to unscrew the chuck from the dividing head. Swinging  the DH down to horizontal made it easier to control. I cut in on either  side of the three bolt posts with a 9/16" endmill. Then, rather than  mill away at all that steel, I drilled down a row of 1/4" holes that  allowed the three pieces to be broken out.



Once the cutouts were finished, it was time to bore the hole for the  collets to finished size. Notice the 'stepped' arrangement of the steel,  left to allow enough material for rounded fillets.



I took a lot of time boring the collet tunnel and taper. The whole  project hinges on this being accurate. I'm pleased with the result.



The key that engages with the slot in the side of the collet is held in a collar inside the body of the chuck. The hole through the collar is turned when the hole through the nose piece is bored and the key made and inserted later.



Final assembly, with a bit of grease in the bearing grooves.




The proof of the job is in the measurement of the runout. It came out at 8 to 10 thou   But then, every chuck needs to be coaxed into its optimum position. I  loosened the bolts and gave it some careful taps. That brought it down  to 0.0015-ish. I can probably tweak it a bit closer, if I take some time  with it.



Thanks for taking the time to read through this somewhat long process.  The designer mentioned that this type of collet nut is a lot faster to  use that a keyed design would be. Changing collets by turning a key  would take a long time. With the ball bearings, the nut in this style  spins onto the threads very quickly. Then the tommy bar pulls it all up  tight.


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## Terrywerm (Aug 3, 2014)

Don't know what you did with all your photos, but none of them are showing up.  Would love to see 'em!


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## Hawkeye (Aug 3, 2014)

Check it now. It looks like someone changed the software since the last time I posted a project. As you say, none of the pictures came in. I had to edit each one in as soon as I saw it.


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## JimDawson (Aug 3, 2014)

Great job!   Thanks for the pics


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## Terrywerm (Aug 3, 2014)

Yup!  They are all there now. Great pics, great project!  Thanks for sharing it with us!

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Hawkeye said:


> Note the stylish spiral knurling on the outside of the piece...  Oh,  alright! it's chatter! Ya happy now?  I found out I had issues with the spindle bearings.
> View attachment 81262



I liked it better when you referred to it as "stylish spiral knurling"!!    :laughinghard:


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## Bishop (Aug 3, 2014)

Is this from the same scrap chunk of cast iron you built the tool post from? Either way I love seeing what you can do with scrap iron, simply amazing. 

Shawn


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## Hawkeye (Aug 3, 2014)

Terry,

I was actually tempted for a little while to leave it like that. If that had happened on the nut, I would have.


Shawn,

Same source, but it might have been from a different casting. I was there on Friday, but no new chunks. I check for that every time I get to the scrappers. I need to find some even bigger pieces.


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## zmotorsports (Aug 3, 2014)

Very nicely done.  Impressive job.:thumbzup3:

Mike.


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## Smudgemo (Aug 3, 2014)

Thanks for taking the time to share this, Mike.  It's great fun to see interesting projects and how they were completed.

-Ryan


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## rick9345 (Aug 3, 2014)

*Nice work*. Just an evening in the shop?


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## LJP (Aug 4, 2014)

Very Nice Job! Thanks for posting. 
Larry


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## Hawkeye (Aug 4, 2014)

Thanks for the comments, guys.

Yeah, rick. A little more than an evening in the shop. It was spread over a few weeks, including some evenings when I was just too worn out from working in our summer heat to haul myself downstairs.


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## Knobley (Aug 30, 2014)

What a great project - Thank you!!


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