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ptjw7uk
05-05-2009, 09:45 AM
Hi All
I thought I should seek the collective knowledge of the forum on my next purchase. I have a small 4" rotating table that I am in the process of motorising with a stepper motor and the problem of holding items with some degree of concentricity, so espying a er32 chuck with a small lathe mounting I thought that may be better than a small 80mm 3 jaw. At the moment I am leaning towrds the er32 chuck as that will be easier to fix to tha table although I am not to sure how to ensure concetricity yet still pndering on that one.
Any ideas, pearls of wisdom etc

Peter

lakeside53
05-05-2009, 11:07 AM
I looked using an ER32 recently and even though my table has an MT in the center, a draw bar was difficult to incorporate. And.. to tighten it down would require lifting the table (over 300lbs!) then retramming. I decided to use a 4 jaw with a backing plate that could be attached from the top.

If I stumble across a decent priced 5C "set true" collet chuck I can mount from the top, I might go that way for small work.

John Stevenson
05-05-2009, 12:09 PM
Drawbar ??

Lakeside I think he means one of these type of ER 32 chucks

http://www.arceurotrade.co.uk/imagecache/d4ef767e-8523-492a-b246-d713e0ddb5df_281x214v2.jpg

>

Scishopguy
05-05-2009, 12:28 PM
We had a little 8" Chushman chuck that we mounted on our 12" Troyke rotary table on occasions that we wanted to make a cam or some excentric cut on a shaft. It was mounted by means of an aluminum plate that had a 1/8" step turned in the center that fit snugly into the center hole in the RT. The mounting plate was larger than the chuck and we simply used 4 tee nuts and cap screws to attack it to the tee slots on the table. No fiddling around to set up, just dead on every time. ;) This solution would probably work with any chuck or collet system.

ptjw7uk
05-05-2009, 02:02 PM
Yes thats the ER part Sir John which is my preference at the moment as I almost have a complete set of er32 collets although I can see that some times a 3jaw would be quicker its just the fitting of the thing asfor some reason small (80mm) 3jaw chucks with front fixing are a lot dearer to buy.

Peter

djc
05-05-2009, 03:02 PM
...for some reason small (80mm) 3 jaw chucks with front fixing are a lot dearer to buy.

Have a look at Sir J's thread here http://bbs.homeshopmachinist.net/showthread.php?t=20653 which shows how a rear-mounted chuck on a thin backplate can be held on a RT.

A chuck with reversible jaws will grip a larger range than a collet that tops out at 20mm.

If you go the ER route, assuming your RT has a 2MT centre hole, just use a blank arbor to centre the chuck. The diameter of the parallel blank bit needs to be at least as large as the fat end of the MT so you can withdraw it. Grip the parallel bit lightly in your ER collet or chuck and then tighten the assembly down. You may need to tap the end to enable easy withdrawal.

ptjw7uk
05-06-2009, 04:36 AM
Just to say that I have jumped down from the fence and have ordered a 80mm 3 jaw chuck seeing that as DJC said it will have a wider range than the collets.

Now to see to the fixing!

Peter

lakeside53
05-06-2009, 11:28 AM
Does anyone make collet blocks for ER32? I have them for 5C, but it would be nice to use my E32 sets in the same way.

ptjw7uk
05-06-2009, 12:02 PM
wauldnt the 5c to er32 converter that Arc Euro sell!
http://www.arceurotrade.co.uk/Catalogue/Collets/5C-Fixtures

Peter

lakeside53
05-06-2009, 09:08 PM
That would work but I prefere to not stack adapters.