How to Mount Collet Closer Chucks ?

[IgnatzParticipant @ignatz]

With the recent purchase of a Myford Super 7 lathe I also received these two, spindle-mount, lever operated collet chucks and a few collets for each one.

Now, I know that I have to affix that lever to some point on the lathe to make these work and I suppose I can figure that one out on my own, but, unfortunately, there are no threaded mounting plates included to transfer the rotation of the spindle to the collet closer..

I've searched the internet for information, made a search of the forum articles here as well, but can find almost nothing that gives me a clue as to how to go about machining a spindle mount for these and then getting them mounted and aligned.

Has anyone out there got this information?

[IgnatzParticipant @ignatz]

[Ex contributorParticipant @mgnbuk]

Pratt Burnerd Multisize collets & chucks.

One of these came with my late father's Boxford CUD, though I can't recall much about the mounting – IIRC it was just a bush with the Boxford nose thread that was secured by screws in a recess in the back of the chuck (the face that yours are sat upon). When I sold the Boxford the buyer didn't want it, so it was sold separately.

Lathes UK has a copy of the combined catalogue / manual for these, but it is a bit steep at £45 link

Could you flip your chucks to sit on the nose piece & post pictures of the rear face ? Should be possible to work out the mounting arrangement from that.

Nigel B.

 

Edited By mgnbuk on 21/10/2021 15:46:26

[egaParticipant @ega]

The photo seems to show two types of collet but the chucks both look like the Myford item: £250 in 1990 with collets at £18.75.

My price list says "It is of the backplate mounting type"

I believe the short link goes to the threaded hole in the headstock on the far side of the spindle.

PS p158 of Bradley's Manual gives more information; I will scan and post.

Edited By ega on 21/10/2021 15:59:20

[egaParticipant @ega]

[IgnatzParticipant @ignatz]

Wow! Those things were expensive!

Here are some extra photos of the back side of the collet chucks.

Those mounting holes are not threaded, but simply counter sunk on the front side.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ignatz on 21/10/2021 16:38:49:

[…]

Those mounting holes are not threaded, but simply counter sunk on the front side.

.

Which would tally with ega’s : "It is of the backplate mounting type"

MichaelG.

[Martin KyteParticipant @martinkyte99762]

If you have a chuck guard fitted then the lever hole is already occupied I would think. Depending what you want to do with your lathe you may be chasing something that turns out not to be that usefull especially as you say you don't have . The colle chucks are really for bar feed when making production run parts with tailstock turrets and cut off slides. If you are like the rest of us and mainly producing individual componants then you would be better selling them and buying a good quality ER collet chuck or treating your self to a quality SC three jaw. I don't know if it's just my eyes but looks like some of the collets are for Hex bar for making nuts/bolts.

regards Martin

[Anonymous]

I'm not convinced that the OP has two complete sets of collets and closers.

The upper set don't look like the Burnerd multisize collets I have. What I assume are the metal fingers are tapered, so they couldn't slide in slots like conventional multisize collets. They look more like rubberflex collets. Same result as sliding metal fingers but different construction. Rubberflex collets were often made by Jacobs, as were the ones I use in my auto reversing tapping heads. The lower set of collets are dead length collets.

The two types of collet work in different ways. Rubberflex collets work by contracting as they are pushed back towards the headstock. So the collet moves with respect to the headstock when it is closed. A corollary is that the work also moves relative to the headstock as the collet closes. Dead length collets are closed from behind, away from the headstock, towards a fixed stop at the front of the collet holder. A consequence is that the collet does not move relative to the headstock when being closed, nor does the work. Hence the name dead length. It's a significant advantage on repetition and capstan lathes.

It would be interesting to know if the two holders work in the same way, or different ways. The internal tapers should be different as well.

I think Martin is correct that some of the dead length collets are hexagon. I can vouch for their usefulness when making batches of nuts and bolts:

Burnerd multisize collets will hold hexagons:

But I'm not convinced the upper set of collets will, as I think the rubber between the blades would get in the way.

Andrew

[IgnatzParticipant @ignatz]

@Martin, … you have a point there. Most of what I do on the lathe are bits of one-off's, so I'm not sure that I actually need these collet closers.

On the other hand, I confess to being curious and interested to try them out… even if only for a short time before selling them on if it comes to that.

I guess I'll have to machine at least one backing plate to give the collet closers a test.

I've thrown together a rough idea of what I think the collet closer backing plate would look like in my 3D program. Not sure about the over-all length, but certainly has to be long enough to allow for proper mating to the headstock spindle… and then not any longer than that to make it work, right?

Does one have to do anything special to compensate for runout? I know that with some nose-mounted collet chucks it is suggested that one leave a bit of play to allow for 'tapping in' the collet holder before snugging everything up tight.

Any feedback happily accepted.

[egaParticipant @ega]

Ignatz:

Did you compare the drawing I posted with your hardware?

Noting that the knobs are different from drawing made me wonder if you have actual Myford items. Do they not include part no 1 (backplate) as shown on the drawing. I had assumed that this would screw on to the spindle in the usual way other chucks do.

I hope someone with hands-on experience can contribute.

Lovely "rough idea", by the way!

[IgnatzParticipant @ignatz]

@ega, … I did check that drawing (thank you for posting), but the actual design of these two collet closers does not match the drawing.

If you reference the extra photos I posted (above) you will see that both closers end up with a flat face having four mounting holes. That flat face is not bolted on as an extra, but appears to be an integral part of the collet closer body. There is no threading to be seen… certainly nothing that would allow this to simply be spun onto a Myford spindle.

[JasonBModerator @jasonb]

Looks like your sketched backplates will place the unit a lot further from the headstock than the one shown in Ega's scan which looks to have the "backplate" or Myford nose adaptor as it may be better called fitted within the main body thus keeping overhang to a minimum

[IgnatzParticipant @ignatz]

Jason, … I totally agree… and my rough backplates are probably much too long as pictured.

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