Another Hello from Essex & Jason Lathe Question

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Hi All, I have recently re started the restoration of a Jason (Pixie) lathe. To be honest it had never been fully built when I bought it many years ago.

My current question is about a suitable 3 jaw chuck. A very competent model engineer has recently tried to adopt a 65mm dia off the shelf example for me. The thread is different on the Jason, 3/4 x 20 unified. Most small chucks seem to be either M12 or M14. So he had to cut a new thread in the back, and ended up pulling his hair out.

We seem to have found that the scroll and jaw teeth are not machined to any great accuracy, and the chuck I have is of limited use. 7-12 thou run out. I dare to suggest its a chuck of Chinese origin, although available from a well known supplier.

Can anyone suggest a suitable 3 jaw chuck that could be adopted. Max 65mm diameter. Or even have a Jason chuck lying around.

[Henry BuckeldeeParticipant @henrybuckeldee88769]

[Michael GilliganParticipant @michaelgilligan61133]

Welcome, Henry

I too have a Jason lathe … but only the original four-jaw chuck.

One thing I have noticed is that [on mine, at least] the plain register diameter does not appear to be used … it relies solely on the thread !!

… This is, of course, contrary to the usual design wisdom; and may be the source of your difficulty.

MichaelG.

.

Edited By Michael Gilligan on 29/05/2017 20:39:33

[JasonBModerator @jasonb]

Would it be a better option to machine up a backplate and then mount a chuck to teh machined in-situe backplate, something like the 60mm Zither one would do.

Only downside may be the extra overhang of a backplate and keyed chuck rather than a pin type chuck with integral thread.

[David Standing 1Participant @davidstanding1]

It is amusing that Jason has replied regarding a Jason lathe

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Hi Michael, Very pleased to hear from a Jason lathe owner. Thought I was the only one. As it happens I have a set of the original drawings for the 4 jaw chuck and other parts of the lathe. The original backplate drawing shows a recess that locates over the shoulder of the nose. The same model engineer produced a nice 4 jaw chuck for me, that locates over the shoulder. He replicated the same feature on the 3 jaw chuck, but is still has the run out show above.

I am attempting to replace the original motor setup with a 24v scooter motor and pulse width modulator.

Hi Jason, Yes this is the sort of thing I am looking for. Need to look up Zither on the internet. Are there any other makes of 3 jaw with a similar arrangement. I have a spare backplate with a thread. I was however thinking of keeping that for a faceplate. As I said above I have no means of turning the lathe as sorting the motor out.

Hi David, It is amusing, but not sure if he has a Jason lathe?

[JasonBModerator @jasonb]

You can get teh Zither chucks from ARC, said to be good quality, but as you can see as they use a key they are a bit longer than the usual threaded body M14 and M12 offerings that just use two pins to tighten the chuck and there is the backplate thicknes sto add on.

A lot will depend on how your modified chuck was held when it was altered, if just gripped by the body then runout could result, I find the best way is to fit a stout bit of bar into the larger lathes chuck and take a skim cut off to true it up, then the small chuck can be tightend onto that and the fixing modified preferably with a screwcut thread rather than a tapped one

 

No I have a Warco, I did add the bit about the Jason lathe into your thread title as I knew Michael had one and hoped he would see your post.

Edited By JasonB on 30/05/2017 17:54:47

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 30/05/2017 17:52:48:

I did add the bit about the Jason lathe into your thread title as I knew Michael had one and hoped he would see your post.

.

Thanks, Jason … Moderator and MatchMaker

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Henry Buckeldee on 30/05/2017 17:44:07:

… As it happens I have a set of the original drawings for the 4 jaw chuck and other parts of the lathe. The original backplate drawing shows a recess that locates over the shoulder of the nose. The same model engineer produced a nice 4 jaw chuck for me, that locates over the shoulder. He replicated the same feature on the 3 jaw chuck, but is still has the run out show above.

.

Very interesting, Henry …

My 4 jaw has a recess, but it's too big to act as a register.

I will measure the diameters [tomorrow if possible], for comparison with your drawings.

MichaelG.

.

P.S. I sending you a P.M. regarding the drawings

[Michael GilliganParticipant @michaelgilligan61133]

I have just checked the diameters of the register; using a Mitutoyo digital calliper.

[which is near enough for demonstrating the point]

The spindle register diameter is 0.8120" +/- 0.0005"

The plain recess in the chuck backplate is 0.8345" +/- 0.0005"

As René Magritte might have put it …

"Ceci n'est pas enregistrement"

[but of course, my lathe may not be typical]

MichaelG.

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Hi Michael, From the LC Jay & Sons Ltd drawings the dimensions are as follows;

Back plate recess 0.8135" max 0.8125" min

Spindle shoulder 0.812" max 0.811" min

Henry

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for that, Henry

Looks like my backplate has had a rebore.

MichaelG.

[MWParticipant @mw27036]

Posted by Michael Gilligan on 29/05/2017 20:33:54:

Welcome, Henry

it relies solely on the thread !!

… This is, of course, contrary to the usual design wisdom; and may be the source of your difficulty.

MichaelG.

The sherline uses threaded chucks too, it's not designed to reverse but I don't seem to have noticed any detrimental effect with regards to run out.

Michael W

[Howard LewisParticipant @howardlewis46836]

If the spindle has a shoulder, you could try machining a chamfer on the outer edge of the recess in the backplate, and pull the chuck onto the shoulder. Hopefully, this will locate the chuck and improve run out.

Having said that, 3 Jaw chucks will give material a run out of 0.005" (or worse if poor, elderly or have been abused)

Howard

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Henry Buckeldee on 29/05/2017 18:39:33:

Hi All, I have recently re started the restoration of a Jason (Pixie) lathe. …

My current question is about a suitable 3 jaw chuck. …

Can anyone suggest a suitable 3 jaw chuck that could be adopted. Max 65mm diameter.

.

Henry,

It may end-up fetching silly money, but have a look here: **LINK**

http://www.ebay.co.uk/itm/201930419786?

… It appears to be in very nice condition.

I have one of these on my Pultra, and can't think of anything more suitable for you.

MichaelG.

.

Edit: you would, of course, need to remove the Watchmaker's fitting, and make a little backplate

 

Edited By Michael Gilligan on 06/06/2017 21:04:36

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Hi Michael,

Just seen this before I go to work.

The pcd of mounting screws is very small. Would I still get the Jason 3/4 thread in on a very small back plate.

Need to think about this.

Regards

Henry

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Henry Buckeldee on 07/06/2017 06:52:03:

The pcd of mounting screws is very small. Would I still get the Jason 3/4 thread in on a very small back plate.

.

I did wonder about that … but I think an 'unusual design' of back-plate would do the job.

MichaelG.

.

http://www.nielsmachines.com/en/the-burnerd-model-32p-precision-ring-scroll-3-jaw.html

 

 

Edited By Michael Gilligan on 07/06/2017 07:51:19

[Michael GilliganParticipant @michaelgilligan61133]

Further to my previous post:

For anything significantly better than the Burnerd 32 you would probably need to look at Maprox [!]

MichaelG.

http://anglo-swiss-tools.co.uk/maprox-zweifel-chucks/

 

Edited By Michael Gilligan on 07/06/2017 08:36:10

[Michael GilliganParticipant @michaelgilligan61133]

Update:

I see the chuck made £121

MichaelG.

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Yes. It shot up in bids in the last 15 seconds or so. That's good enough reason for me not to buy it. Still wondering best way to mount it. Is the next large model engineering exhibition in the Midlands later in the year? Looking forward to having a good rummage around for bits and pieces plus suitable 3 jaw. Does anyone know how many Jason lathes still around? It would be a pure guess I think. Never seen any bits on eBay.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Henry Buckeldee on 10/06/2017 07:48:42:

… Still wondering best way to mount it. …

.

That would depend on your definition of 'best'

If you need to retain the full bore diameter through the lathe spindle, then obviously it would need to screw onto the nose … but otherwise a drawbar "un-split collet" arrangement [as per the illustrations] is preferred, for the sake of precision.

Which reminds me: What taper does your [Pixie] lathe have ? … My Jason has a taper for special collets; but I think there may have been differences between the brands.

MichaelG.

Edited By Michael Gilligan on 10/06/2017 08:39:15

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Yes my Pixie is designed to take collets. I don't have an effective means to measure the taper. It seems to roughly match the drawings. 30 deg included angle. Entry dia 0.562". Small dia where it meets the counter bore 0.4995 to 0.5005".

[Michael GilliganParticipant @michaelgilligan61133]

Thanks, Henry

MichaelG.

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