Independent 4 jaw chuck ?

[RNR107]

Hi all,
I bought recently a Denford ORAC, and (as most of them I guess...) it only came with a self centering 3 jaw chuch.
So, I am now looking for an independent 4 jaw chuck. Any body could tell me where I could buy a suitable one ?

An ER32 collet chuck would usefull as well...

Ta,
Laurent

[triac]

Hi Laurent

Check out Chronos web site, they are offering an 85mm 4j Ind chuck at £77, it is front mounted so you could likely use your 3j backplate with a stepped plate to mate with the existing recess and new 4j spigots. You will of course have to drill/tap the new fixings in the backplate for the 4j.
It would of course be better to make a new backplate with direct mounting to the spindle nose for the 4j, chuck changing is then by 3 fixings.
Same would apply to an ER32 collet chuck, they are available in backplate mounted form,
check Arceurotrade for 2 different recess sizes
If you are going to a much larger than 100mm chuck size give due consideration to the speed of spindle with often unbalanced parts in the chuck.

Rgds, Emgee

[RNR107]

Hi Emgee,
Thank you for your help!

I would love making a new back plate to mount various chuck.
The problem is, on the ORAC the spindle nose has a kind of male taper used to locate the back plate.
therefore the backplate has to have a tappered hole in the center and....I don't know the angle!
Any body could provide this piece of information?

Ta,
Laurent

[triac]

Hi Laurent

This question has been asked on the forum before but nobody has the absolute answer, it seems by the diameter to be a size smaller than any of the ISO charts I have been able to locate on the web searches.
You could make the hole in the backplate to suit the parallel portion of the spindle nose, it will need to be a wringing fit for repeatable accuracy.
The other alternative is to use a good release agent (wax and PVA release agent) on the spindle nose and apply some liquid metal paste to the spindle taper and bore of the new backplate before securing to the spindle. When cured and before removal, face the backplate and create the spigot to fit the recess in the 4j chuck, finally turn the OD to suit the chuck body.
The chuck to backplate fixings can be drilled and tapped off the spindle after machining as above.
Hope this gives you some more ideas.

Rgds, Emgee

[RNR107]

Lots of ideas indeed !

Thought of something last night...
I don't really like the way the chuck attach to the spindle... Every time I want to change chuck I need to go throu the process of removing the 3 nuts, then tap the chuck from the back. Not really a good system is it?
So.............What about making a new spindle with a threaded nose (a bit like Boxford or Myford manual lathe)?

Could possibly re-machine the existing spindle, but I rather not...


What do you think ?

[triac]

Hi

My choice is the original taper nose spindle for accuracy and ease of use, don't understand why you need to tap the chuck from the back to remove, once the fixings are released the backplate and chuck fall off the taper if not supported.
My opinion is the Denford method is superior to Myfords as the spindle can be reversed without fear of the unscrewing the chuck.

For ease of use get a front mounted chuck, just 3 skt caps to undo to remove the chuck.

Rgds, Emgee

[RNR107]

Hi,
It took me a bit of time and effort to get the chuck off, but it may have been there a while... I'll try again, it maybe easier now.

L


I tryed again... It won't definitively not fall off by itself after removing the 3 nuts! It needs a few taps from the back...
Just notice something on your picture, It looks like your spindle has been re-machined, I don't have that staight part on mine...It's a tapper all the way.
That's maybe why yours comes off easly ?

[triac]

Hi

Do a search on "spindle nose taper" on the Orac forum at the bottom left of this page, towards the end you will see drawings posted by other users.

Rgds, Emgee