A Chuck and a Rotary table

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A Chuck and a Rotary table

This topic has 8 replies, 5 voices, and was last updated 24 November 2013 at 11:08 by pauljames.

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23 November 2013 at 22:50 #136279
Oompa Lumpa
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@oompalumpa34302
Well following on from my previous successful requests for help, this is my latest conundrum.

I am now the proud owner of a 6" rotary table, loveky thing it is too. Now, I have a couple of chucks – a three inch three jaw and a six inch four jaw chuck that have no backplates to them and the machines they belonged to are long gone. Now, given that I need to mount a chuck on the rotary table, what is the simplest way to go about this?

I just want to centrally mount one of thyese chucks to a Sorba 6" table. It has a 2MT centre.

I thank you all in advance for your advice.

graham.
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23 November 2013 at 22:50 #17224
Oompa Lumpa
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@oompalumpa34302
23 November 2013 at 23:27 #136280
Michael Gilligan
Participant
@michaelgilligan61133
Graham,

I found it best to make an adapter plate, bigger diameter than the chuck; and fix to the tee-slots.

This would work for your 3", but obviously the 6" would be a problem on a 6" table [unless it's the front fixing type of chuck]

There was another thread discussing this question, a couple of months back.

MichaelG.

Edited By Michael Gilligan on 23/11/2013 23:30:04
24 November 2013 at 07:57 #136287
Speedy Builder5
Participant
@speedybuilder5
As Michael said, but how do you stop it unscrewing under load ?

To centralise the chuck, make up a short stub of MT to go into the rotary table with a boss that locates the adaptor plate.

BobH
24 November 2013 at 09:19 #136292
Oompa Lumpa
Participant
@oompalumpa34302
Thank you for that Michael, I read through that thread but I could not find a definitive way of centralising the Chuck.

I did read on one forum somewhere that a large ball bearing between the quill and the hole in the table/chuck is one way to centralise the actual fixture on the Mill table which I thought was quite novel!

I will of course be trying to make it a simple "put on/Take off" fixture Bob so a 2MT stub figures in my calculations somewhere. I just don't know where yet.

Finally, workholding is, by and large, a matter of common sense and having a good deal of what I call "Mechanical Sympathy" – bearing in mind it isn't going to be sympathetic towards you at all if you are being foolish

graham.
24 November 2013 at 09:42 #136293
martin perman 1
Participant
@martinperman1
Graham,

As others are suggesting I'm making a boss which fits into the the base of the chuck with an MT2 taper, you can but these soft so that you can machine them from RDG as I did recently at the East Midlands exhibition, I also have a SOBA 6" rotary table and I bought a four jaw with through bolt holes that then screw into T nuts in the table T slots. By using a four jaw chuck you will tend to fit odd shaped items in it so you will centre around the part you wish to machine so total accuracy will not be necessary.

Martin P
24 November 2013 at 09:44 #136294
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Speedy Builder5 on 24/11/2013 07:57:42:

As Michael said, but how do you stop it unscrewing under load ?

To centralise the chuck, make up a short stub of MT to go into the rotary table with a boss that locates the adaptor plate.

BobH

.

Bob,

Just to clarify …

My adapter plate effectively puts a flange around the chuck … there is nothing to "unscrew under load". The chuck [minus lathe-backplate] fixes to my plate with cap-head screws , and the plate fixes to the table with cap-heads and tee-nuts.

The obvious disadvantage is that I can't transfer mounted and centered work from lathe to mill … but; as I mostly use this arrangement for "jig-boring" small parts, that's no great problem.

The BCA has an integral 8" Rotary Table;

I use a 6" Adapter Plate to mount a 4" front-fitting 4-Jaw chuck

This lets me hold small parts without using big awkward clamps.

MichaelG.
24 November 2013 at 10:18 #136298
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Oompa Lumpa on 24/11/2013 09:19:19:

I read through that thread but I could not find a definitive way of centralising the Chuck.

.

Graham,

For the rare occasions when I need to centre the chuck …
- I have a spigot that fits the centre of the table. [note: you could make one from a MT blank]
- My adapter plate has a large central bore.
- I have a close-fitting spacer, to align these.
This will easily centre the chuck on the table, within a few thou; and final adjustments are done with a DTI .

To centre the Table under the cutter ….
- Put that carefully machined spigot in the table
- Put a dowel pin, of the same diameter, in the cutter chuck
- Bring the two close together, and Align them, as best you can, by eye
- Measure, with a micrometer, at the "join" the apparent diameter
- Do this in both X and Y directions
- When both measure the same, you have alignment.
A simplification is to make a sliding collar for the pin … when this sldes freely across the joint, you have alignment.

Hope that all makes sense.

MichaelG.
24 November 2013 at 11:08 #136302
pauljames
Participant
@pauljanes79128
This is how I mounted a 6" 4-jaw chuck. Made a location spigot to centre the chuck and bolt directly to the rotary table. Centre location of the chuck on the table is not that critical as the job is centred with a DTI as long as it is secured soundly. A 4-jaw chuck is more accurate than using a self-centring 3 jaw and also allows the holding of odd shapes.
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