Wolf Jahn 6mm Lathe Headstock problem

I have a Wolf Jahn 6mm watchmakers lathe. Today in removing a stuck 3 jaw (smart rap with heel of hand on drawbar) instead of the chuck coming out, the spindle did!

Once the chuck was out I removed the spindle to see what state the bearings were in. However that left me with two queries, and I wonder if someone who has one of these can help.

The spindle shows no sign of anything that might be designed to hold it in place in the bearings although there are two loose split brass dust caps on the front bearing.

The pulley does not appear to be designed to bear against the back of the front bearing (at least that is not how it was aligned), and there is no evidence at the back of the headstock of anything which might pull the spindle into the bearings.

Question 1 - am I missing some part that should retain the spindle in the bearings? If not, how is the bearing loading set when reinstalling the spindle in the headstock - and what keeps it in there?

The front bearing appears to have rotated. The oil hole in the bearing is misplaced from the oil hole in the headstock, the rear bearing has the holes lined up.

Question 2 - any suggestions on how the front bearing comes out , or suggestions how I can rotate the bearing in situ to realign the holes.

There are further pictures in my album entitled Wolf Jahn lathe.

Thanks in advance for any help.

Edited By Peter Cook 6 on 08/06/2021 17:24:12

It looks like the main bearings are both tapered, so there should be some way of altering the spacing of the bushes in the headstock, as well as some type of adjustable thrust bearing at the left hand end. The thrust bearing would be vital to keep the spindle adjusted fir minimum play, but free running and also to prevent an accident as you have just experianced. The bearing that has moved would likely need to be removed adr replaced using suitably turned tubes, washers, nuts and studding.

There is a WJ listing in Lathes UK which might have pictures of yours, and hopefully show whether yours has any parts missing.

**LINK**

Thanks old mart. I agree that there ought to be something of that sort. But there is no obvious sign on the back end of the spindle of any threads or other attachment points that would allow the bearings to be adjusted.

I've seen the lathes site. The last WJ lathe on page 2 ( the one with orange wood in the background) looks identical to mine, but unless there is something under the brass dust cover between the pulley and front bearing, I can't see anything in those pictures to suggest the sort of adjustment I was expecting.

The two grooves in the front end of the pulley are suggestive. I wonder if there is supposed to be a brass(?) bearing keyed to the slots that the pulley would have pressed against the back face of the front bearing. I was hoping someone had a similar device and would know.

On the NAWCC website there is a brief description of adjusting a Lorch 6mm WW late which says "The pulley has a bearing surface at the front end that should run against the back face of the front bearing. There should be no end play and the spindle should run just a bit stiffish when lightly oiled. I use light machine oil in the holes on top of the headstock bearings."

The box it came in is marked as a Clarkenwell Lathe, and it could well be a Lorch clone with some Wolf Jahn bits ( only the foot and the tool rest are actually marked Wolf Jahn.

I think what I am looking for the detail of the bearing. I will start looking at Lorch.

PS I clamped the front bearing between spacers and twisted. It moved - so I simply aligned the holes and cleaned them out. Hopefully that will be sufficient.

I am almost sure that the pulley provides the necessary surface

... You will, of course, have noticed that the front bearing is ‘double taper’.

This is the classic arrangement for Geneva lathes.

The steep front taper is non-locking, so the very shallow taper behind it should never be able to lock-up.

... Normal use would never impose the force that you put on it whilst trying to remove the chuck.

MichaelG.

Thanks Michael,

However if that is the case, then looking at the nose of the pulley

I think there is a bearing plate missing. Now to find out the shape of, or design, a suitable thrust washer.

It sounds like the front bearing could be gently tapped out with a soft drift. Then the bearing and headstock bore could be degreased. I would then refit the bearing halfway with the hole lined up and put a couple of drops of loctite on the part of the bush which is still exposed. Loctite 290 is a wicking threadlocker which would hold the bush well, or you could use any thread/retaining compound you have, as long as you could be sure of pushing the bush home in a few seconds.

How is the pulley fixed to the spindle? Is there a keyway and or grubscrews?

If you fit the spindle in place without the pulley, what would any thrust washer bear against? With the pulley fitted, is the belt alignment going to be a problem? Also with the pulley lined up to suit the belt alignment, is there room for a thrust washer?

Edited By old mart on 08/06/2021 20:50:22

Edited By old mart on 08/06/2021 20:53:08

Edited By old mart on 08/06/2021 20:57:40

This is not the spindle configuration that you have ... but it’s interesting viewing anyway:

**LINK**

https://youtu.be/DL6oKA8vXs0

MichaelG.

I had not noticed the double taper until you mentioned it, the steep angle is also obvious on the head of the bush.

There is something dramatically wrong with your spindle. The link that MichaelG posted is exactly like yours should be (except for size) There should be double angle opposed bearing at each end of the spindle. Does the taper bearing at the rear on yours slide off? It is tapered the wrong way.

Edited By david bennett 8 on 09/06/2021 02:23:54

Edited By david bennett 8 on 09/06/2021 02:24:34

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I agree that would certainly be the more standard arrangement, David

But if anyone is likely to have devised a clever alternative, it would be Wolf Jahn.

I wonder if Peter’s lathe is an attempt [previously unseen by me] to produce a satisfactory bearing arrangement without the need for opposed double-taper assemblies ... It looks like this might be a master-stroke of Production Engineering.

MichaelG.

UPDATE

I have just found this:

.

.

**LINK** http://www.terrysutcliffe.com/?p=378

... It may be worth contacting Terry Sutcliffe for an opinion.

MichaelG.

Re the oil hole, have you tried putting oil in the hole to see if it comes out in the bearing? Might be a recess around the bearing to act as an oil reservoir.

Adrian

Thanks everyone. Some diligent searching online has revealed several images of identical headstocks. One (withdrawn from sale) at

Wolf Jahn Watchmakers Lathe Headstock For Sale in Glasnevin, Dublin from steve2011 (adverts.ie)

shows the headstock disassembled and the shape of the spindle is identical to mine. It also shows the same nose to the pulley and has one of the dust caps. I think Michael is (as usual) correct and the intention was/is for the pulley nose to run against the back of the front bearing. Bearing preload is simply by squeezing the pulley up against the front bearing while holding the spindle in the double taper - then tighten the four grub screws. That would also explain the groove inside the front bearing from the oil hole to the back of the bearing (see the picture in the original post). At first I assumed this was damage - but now it seems more likely to be designed to lubricate the faces where the pulley bears on the back of the bearing.

As Michael also suggests this may be clever production engineering for a low cost product that could be badge engineered by wholesalers and suppliers. My headstock has no markings on it, only the tool rest and foot into which the headstock fits have the Wolf Jahn mark.

I have fixed the alignment of the oil hole, so I guess I should trust the quality of Wolf Jahn's engineering design, and reassemble it the way it was made.

Thanks again for all the ideas and thoughts - as always dialogue with someone else clarifies things.

Edited By Peter Cook 6 on 09/06/2021 13:39:14

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An excellent find, Peter

MichaelG.

Wow ! something new to learn every day.

Edited By david bennett 8 on 09/06/2021 20:31:51