ER 32 Collet Chuck for SB 9"

[Shawn]

I got started on an ER collet chuck today. Got the internal threaded side bored out and the thread relief front and back cut today. Hopefully I'll have the threads cut and the part mounted on the spindle by tomorrow night.



Welded a short piece of HSS to a bar to cut the thread relief at the back if the bore, worked great.



Hard to see the two relief grooves, my phone didn't want to focus on the bore?



Shawn

[Shawn]

I couldn't wait till tomorrow to cut the internal threads I'm only a couple hours past my usual bedtime so not a huge deal It was a pretty exciting operation as I didn't leave myself much room to stop the cut. Took me an hour of intense concentration but the fit is pretty tight with no noticeable slop once I get a few threads engaged. The chuck butts up against the back of the spindle nicely which is where the accuracy comes from anyways, if I understand correctly?





Shawn

[DaveH]

Looking good

DaveH

[Shawn]

Thanks Dave, so far so good, I'm still hoping that cutting the taper goes alright. I need to get some transfer fluid I guess

One of the next steps will be to cut the metric threads for the collet nut. I bought a set of metric change gears for my SB lathe a few weeks ago but haven't had a need for them till now. Since my motor isn't set up to run in reverse and I will need to keep the half nut engaged all the time, I will need to turn the spindle in reverse by hand. So this afternoon I built this reversing handle. I already had the handle, it came in a box of odds and ends I got with a milling machine. I did have to cut my first key way though so that was kinda cool.



Shawn

[Shawn]

Starting to take shape. I realized tonight that I'm going to be about .3" undersized on the length of the bore for the collet, I'm hoping that won't effect its gripping strength by too much? I thought I had measured everything out quite carefully?





I couldn't measure any discernible runout on the chuck body tonight, the needle had just a slight vibration to it which I'm chalking up to surface finish.

Shawn

Edit: hey guys how bad do you think having the bottom .3" of the collet hanging out past the tapered bore will be? I was thinking last night that I could always change this to an ER25 collet chuck as I have one of those in the shop as well. That would shorten the collet by a little more than 6mm and would fit the length of the bore perfectly? Thanks in advance for your advice.

[marfaguy]

It would probably work fine but I would probably change it to a ER25 anyway. Then make another one for ER32.
It's good practice and the material cost shouldn't be too much. I really like having mine and use it a lot.
If you haven't watched Doubleboosts you tube video series on making the ER32 holder you should. Very informative.
Best take away I got from it was to make sure the collet was expanded a bit and that your dial indicator is dead on
at lathe center height when you're dialing in the bore angle for the collet holder.

[Shawn]

Your right Marfaguy, why build something and not build it right. I can always build another one for ER32 collets if I feel the need. I'm still scratching my head over how I lost .3" but live and learn I guess.

Shawn

[f350ca]

Must have measured it HOT and it shrunk as it cooled down. I'd stick to that story.
Nice work.
I'd be tempted to take it on and off the spindle a couple of times to see if it stayed true. If not you may have to play with the shoulder it registers on before you cut the taper. Just a thought.

[Shawn]

Thanks Greg, I have taken it off the spindle and checked it again a couple times now and it checks out each time. But...It needs to be tightened slightly to register next to no runout so I'm thinking it might need a bit more clearance but I'm now worried I will mess it up? As long as I spin it on and hear it clunk as it hits the end of the spindle it seems good?

[marfaguy]

(12-11-2013, 12:42 AM)Shawn Wrote: Thanks Greg, I have taken it off the spindle and checked it again a couple times now and it checks out each time. But...It needs to be tightened slightly to register next to no runout so I'm thinking it might need a bit more clearance but I'm now worried I will mess it up? As long as I spin it on and hear it clunk as it hits the end of the spindle it seems good?

Yep. That's how mine works. If I just let it very lightly touch the back it will register about .001 out. With just a bit of snugging it settles out to less than .005 every time.