4" chuck on a 4" rotary table

[wheeltapper]

Hi Guys
I'm looking for ideas, as the title suggests, I've bought a 4" rotab and now I want to fix my 4" 3 jaw chuck onto it. the chuck overlaps the tee slots. has anyone done this?

answers on a postcard to here

cheers
Roy

[jim]

yes!

i just drilled the chuck to make it front mounting

[wheeltapper]

I don't think drilling through the scroll will do it much good. 

Roy

[DaveH]

Roy,

I don't think drilling through the scroll will do it much good. 
Roy

I think you may be right there.  Towards the edge of the chuck however (on some chucks) it is posible to drill through the chuck without drilling through the scroll plate.

 
DaveH

[sparky961]

I came up with a solution to this a few years back with my 6" rotary table and chuck that's a just a bit smaller.  It's a plate that bolts onto the rotary table using the T-slots, and allows bolts to thread into the back of the chuck.

Alignment is done by doing up the bolts loosely, then tapping it concentric while watching your DI.  It works, and I've used it many times.  My only complaint is that it takes a bit of time to set it up.  I've been trying to come up with a better idea for years now.

4" chuck on a 4" rotary table

4" chuck on a 4" rotary table

I think I have a picture or two showing the whole setup, but I'll need to look around a bit.  I'll post here when I find it.

-Sparky

[sparky961]

Found them...

4" chuck on a 4" rotary table

4" chuck on a 4" rotary table

4" chuck on a 4" rotary table

4" chuck on a 4" rotary table

[wheeltapper]

After a nights thought I think I have an idea.
I wont say too much in case its a flop but I'll take pics and show them if it works.



watch this space.

Roy

[DaveH]

Roy,

Go for it
 
DaveH

[wheeltapper]

O.K Here we go.
It seemed to work so now I'll bore you with it.

first I grabbed a lump of steel rod and turned a No2 morse taper.
I also turned a parallel portion to be a sliding fit in the centre hole of the chuck.
4" chuck on a 4" rotary table

I drilled and tapped the small end of the taper m8 for a drawbolt.
4" chuck on a 4" rotary table
4" chuck on a 4" rotary table

after parting off and reversing in the lathe I tidied the end up then drilled and tapped m8.
4" chuck on a 4" rotary table

now I need two washers, one for the lower end  and a stepped one for the chuck end.
4" chuck on a 4" rotary table

now to assemble,
fit taper in table.
4" chuck on a 4" rotary table


the length is just right.
4" chuck on a 4" rotary table

then the drawbolt,
4" chuck on a 4" rotary table

turn upright and slide the chuck on and retain with stepped washer.
4" chuck on a 4" rotary table

and done.
4" chuck on a 4" rotary table

this method does restrict the smallest size piece I can hold in the chuck, its about 22mm but I have a collet chuck on a backplate that will fit with no bother and that will take up to 20mm.

If I have something thats 21mm then tough.

thats all folks.

Roy

[Lew_Merrick_PE]

Somewhat of a variation of Sparky's approach, I make a set of mounting plates for my R/T that "key" to the slots using a headed press-pin.  The t-slots in my (8 inch) R/T have a precision .335 opening, so I turn down ø.375 drill rod (silver steel) for a very close (slight press) fit in the slot while leaving a ø.370/.365 head on them.  I made a ø.334 toolmaker's reamer, so all I have to do is drill & ream 3 holes which get counterbored ø.375 X .15 deep in my mounting plate.  This locates my mounting plate reliably on my R/T.  Drilled & counterbored holes for (5/16) socket head cap screws completes the attachment.  (I make the headed press pins in lots of a dozen when I start running low on them.)

I then mount my mounting plate on the R/T and drill & ream a ø.250 tooling hole at the center of the R/T.  I dress the OD of the mounting plate to (approximately) 8.75 so that I have a "lip" to pry against (using spacers and a pry bar) when I need to change mounting plates.  Having several mounting plates makes it easy to set and swap tooling.  As I have an 8 inch R/T and a set of 6 inch chucks, the interference issue never raised its ugly head at me.  I like Sparky's approach.

My "point" being that setting up your tooling is always a good idea.  Most of my mounting plates have a matrix of ø.1865 (PF for 3/16 dowel pin) and #10-24 mounting holes spaced around the central ø.250 tooling hole.  Figuring out an attachment for some locator/tooling set-up is then a snap.  I keep a CAD file set-up to drag into a design when I am making such adapters.

[DaveH]

Roy,

Well that looks done and dusted.

This is not meant as a criticism it is just an over view.

Just be mindful that it has only one fixing (one clamping point), and you wouldn’t want the chuck to move. 
 
DaveH

[wheeltapper]

You raise an interesting point there.
I think I can get round it tho.

the chuck has three threaded holes for fixing to the lathe and the table has three tee slots.
so if I make three pins to fit the slots , threaded to fit the chuck, they should stop it revolving, shouldn't they?

Roy

[DaveH]

Roy,

Good thinking

 
DaveH

[DaveH]

Roy,

Thinking about it, just one nicely fitted "pin" would stop it turning.
 
DaveH

[wheeltapper]

It's not as much work either 

Roy

[Jonny]

Sorry wheeltapper but guarantee that will move, same with any centre fixing however tight a tolerance, been there done it.

I think i know the chuck, its a backing pale jobby.
Take the chuck apart, remove the scroll etc and have a look where you can drill straight through. Usually on the side of the register clearing the scroll and jaws.
I had to do it with a Vertex four T slotted table, been permanently on 12 years.
Can be seen here.