Slim line chuck.

[JagerParticipant @jager]

Good morning.  I am going to purchase a 100mm, 4 jaw independent, front mounting chuck for use on the rotary table on my Sieg 2.7L mill.

As there is not a lot of headroom under the quill if I use a ‘standard’ chuck of around 54mm depth I  searched around and found a light slim line model which is only 28mm deep.

From on-line photos it seems they come with two sets of jaws and have an unusual means of adusting them which does not look over robust.

Do any members have experience of these and would they recommend them.

Thanks in anticipation.

David.

 

[roy entwistleParticipant @royentwistle24699]

A photo or the make of chuck would help

Roy

[peak4Participant @peak4]

A couple of things to consider here.
Some lightweight 4 jaw independents are primarily intended for wood lathes, so not ideal for metalworking ones, however, they might be OK for a rotary table.

How many T slots, and what size is your rotary table?

Some 4 jaws mount from the rear, whereas others bolt through from the front/jaw side.

If your table has 4 T slots, have a look at the Burnerd Lightweight ones, often marketed for Myfords and similar sized lathes. Expensive new but maybe affordable second hand, they have 4 through holes, whicl might line up directly with your table’s T slots; It depends on the hole spacing of course, and whether the inner ends of the T slots are close enough together.

Here’s a 6″ one as an example

Bill

[peak4]

On peak4 Said:

If your table has 4 T slot

That chuck could be made to work on a table with three slots by re-drilling the securing holes. Unlike a scroll chuck, there is nothing in between the jaws of a four jaw independent. If the table slots are at 0, 120, 240 degrees, you arrange it so the chuck jaws are at 15, 105, 195, 285 degrees.

The other option, if height is an issue, is to make faceplate jaws, similar in concept to how stuff is held on a vertical lathe. I think Harold Hall shows a set on his website. On the same website, there are a few designs for clamps to go in the T-slots of a mill and there is no reason these could not be arranged in a circle on a rotary table.

[DC31k]

On DC31k Said:

On peak4 Said:

If your table has 4 T slot

That chuck could be made to work on a table with three slots by re-drilling the securing holes. Unlike a scroll chuck, there is nothing in between the jaws of a four jaw independent. If the table slots are at 0, 120, 240 degrees, you arrange it so the chuck jaws are at 15, 105, 195, 285 degrees.

The other option, if height is an issue, is to make faceplate jaws, similar in concept to how stuff is held on a vertical lathe. I think Harold Hall shows a set on his website. On the same website, there are a few designs for clamps to go in the T-slots of a mill and there is no reason these could not be arranged in a circle on a rotary table.

I didn’t immediately go into too much detail, as we’ve not heard back from David yet, but bear in mind those chucks are hollow with not much metal in front of the voids; photo from the same listing.

David was seeking a 100mm one;
My 4″ has an approximate PCD of the mounting holes of 55mm, and my 6″ one about 70mm, so if we wish to re-drill on the same PCD to miss the voids, then the T slots need to extend quite close to the centre of the unknown rotary table.
I have the same job to do myself at some point, but I sometimes find it handy to use a Myford screw adaptor on my table, so I can move a part completed workpiece between the mill and the lathe without disturbing the setting.
It does of course make it less rigid on the rotary table, but carefully placed blocks and shims under the outer edge of the chuck can help to a certain extent.
I’ve been meaning to make some blocks to slide in the T slots, both the support the chuck and also to prevent it unscrewing whilst milling, but that’s still on the projects list

Bill

[DiogenesParticipant @diogenes]

Jager – knowing what kind you are referring to would be useful..

..a very good 100mm 4J/I is the Pratt-Burnerd Light-Duty which is about the same depth as you describe but comes with reversible jaws; they are no longer as easy to find (at the right price) as they used to be, but light, shallow, robust, and very nicely made – worth keeping an eye open for..

If I get to the workshop later I’ll post the ‘series’ / model number..

[Roderick JenkinsParticipant @roderickjenkins93242]

Rotagrip have a version of the slimline 100mm 4 jaw

https://www.rotagriponline.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=11389&category_id=239&option=com_virtuemart&Itemid=29&redirected=1&Itemid=29

Rod

[JagerParticipant @jager]

Good morning everyone and many thanks for your responses.  The Rotagrip was the only slimline chuck I could find and on reflection decided that from the pics it would lack robustness.

I have decided to make a fixture plate and use clamps and cam clamps for the time being but in the event I still feel the need for a chuck I will go for a standard 4 jaw independant and use R8 collets in place of the present R8 ER32’s to give the extra headroom required.

Thanks again for your inputs, it’s always good to bounce ideas around!

David

[Jager]

On Jager Said:

I have decided to make a fixture plate and use clamps and cam clamps for the time being…

A sensible decision; when I first acquired my rotary table I also bought a small 3-jaw chuck. But I never fitted it, and in 15+ years have never missed it. For most of what I use the rotary table for a chuck wouldn’t be much help anyway:

Andrew

[JasonBModerator @jasonb]

Some simple table clamps would act much like a 4 jaw assuming you have 4 slots in your table, this sort of thing on Harold Hall’s site or the ones second from left. A vice on the table will also allow square and rectangular work to be held and the bottom of the opening will be lower than the face of a chuck. I’ve never felt th eneed to put a 4-jaw onto any of my rotary tables.

I have a 125mm 3 jaw and 150mm rotary table almost permanently fitted to the SX2.7 and use it a fair amount as it saves having to mount it on the X3 and then put the vice back afterwards. This has a 58mm thick body + backplate and I have been able to do most things with the ER25 chuck without resorting to R8 Collets or sidelock holders.

At 100mm dia you are not going to be able to hold particularly large items in a 4-jaw so height should not be too much of an issue unless you are doing something that can’t better be done with a 4-jaw in the lathe such as boring large holes.

[JagerParticipant @jager]

Jason,

Many thanks for pointing me in that direction.

David

[Jager]

On Jager Said:

Good morning everyone and many thanks for your responses.  The Rotagrip was the only slimline chuck I could find and on reflection decided that from the pics it would lack robustness.

I have decided to make a fixture plate and use clamps and cam clamps for the time being …

Coming late to to this … I would just add that I think that’s a wise evaluation

I have an original Burnered version of the little 4” [100mm] 4-Jaw which mounts via a thick steel adapter plate onto the table of my BCA … it serves very well for holding small items, but is far from robust. … Nice to have, but limited in its application.

MichaelG.

[old martParticipant @oldmart]

The Soba 6″ RT that I bought has four tee slots which make fitting the lightweight four jaw independent easy, but I have also drilled and tapped three holes at 120 degree spacing to hold a 5″ Pratt without the extra thickness of an adaptor plate using front mount holes. The holes in the chuck are 1/4″ and the SHCS are 6mm, allowing lining up the chuck exactly before tightening the screws. I just use a MT2 test bar in the table and lightly close the jaws to get within 0.002″ tir. When planning the screw holes, it is possible to get them spaced safely between the tee slots, and after using the table to get the spacing, I just spot drilled the hole position before removing the table top for the drilling, tapping and washing. Be careful to check whether any oil holes are near the drilling and choose a different starting point if there are any. The holes have screwdriver slot grub screws in them when the three jaw chuck in not fitted to keep swarf from entering.

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