ML7-R tumbler gears

I have fairly recently acquired a Myford ML7-R and so far I've been very pleased with it. When I got it, the tumbler gears were missing teeth so I'd assumed someone had done something silly. The lathe came with a set of Myford branded replacement tufnol gears which I finally fitted this afternoon.

I initially turned the gears on their own by hand and they were a little stiff engaging, but nothing too alarming. I then engaged the tumbler to the headstock and again turned by hand. Again a little stuff, but it then jammed. I turned it back and noticed one of the tumbler teeth had just fallen off. I did a little more turning having removed the offending tooth, but the gears were just shedding teeth. This was gentle hand turning and not under power.

I appreciate these parts are designed to be the first point of failure to prevent a really bad mess, but I expected them to be a little more robust. Are these know to be very fragile?

I looked at another replacement set from Myford, but at £40 for something which will fall apart in seconds I'm reluctant to part with my money.

My guess would be no clearance between the teeth

First examine the first gear in the geartrain with which the tufnel gears engage. Check that this has no missing or damaged teeth. As a comparison , I've had my old Myford for over fifty years and it was previously in a small factory. Still has the gears it came to me with.

Maurice

Mark,

I don't want to cast aspersions upon the supplier, but that sounds remarkably like the sort of failure that occurs when Tufnol gears are wrongly made, from rod rather than sheet material.

Any chance of a close-up photo ?

MichaelG.

Too late to add to my previous post: **LINK**

https://www.tufnol.com/technical/tufnol-gears.aspx

Thanks for the replies. I did check that there was no debris in the gears before running anything. Michael's thoughts are quite interesting.

Here is a picture of the teeth which came away complete very easily:

Pic1

Pic 2

And a side view of the gears:

Pic 3

Pic 4

I achieved this damage by hand turning and I can assure you I'm not that strong. They just sheared off with considerable ease.

Edited By Mark B on 17/03/2019 18:59:02

Edited By Mark B on 17/03/2019 19:31:32

Mark,

Michael G has very likely given you the explanation, Tufnol gears must be made from fabric or better still paper lay ups so that they have strength in the radial direction. Rod form is made from rolled up material, useless for gear purposes, but excellent for insulation spacers for example.

Were these gears supplied in a properly sealed Myford pack? My thought here is that they were fakes that may have been passed on in good faith [or not of course]

I think from the speed of failure you were getting this can't be explained by pressure angle mismatch. ML7-R lathes with the S7 headstock were fitted with the 30 T spindle gear, tumbler cluster and the next 30 T gear all in 20 degree PA. This fact only emerged when Graham Meek was designing his reversing clutch to take the place of the 3 gears running in engagement with the 30 T spindle gear

I'm sorry you have had this setback, if you have the kit to make your own I will happily post you a suitable one inch thick blank to make two f.o.c Send me a PM if that appeals

Regards

Brian

Definately look like they were cut from rod as MG suggests you whould be able to see the weave of the cloth on the sides

Edited By JasonB on 17/03/2019 19:15:53

.

... Myford

What's in a name these days ?

MichaelG.

Thanks all for the replies. It's pretty clear why they failed now you point it out.

I can confirm that they were in sealed "Myford" packets, but I've no idea where they came from. Could be fake parts as suggested. The packaging my gears came in are not the same as I can see on the Myford.co.uk site which makes me suspicious. I can however see similarly packaged items for sale on eBay. To be clear I can't say where they came from so I don't want to hit out at any supplier.

Making my own is certainly an option but I don't have the correct 20DP cutters (looks like I'd need 2 sizes) it's probable cheaper to just buy them assuming I don't destroy any more! I've never damaged tumbler gears on other lathes!

So where can I get genuine Myford spares? I know the original Myford company isn't in business any more, so I guess I need to be careful where I get parts.  Maybe I should just invest in cutters to make my own?

Edited By Mark B on 17/03/2019 20:08:21

Mark,

I've just seen the pictures. The sideview confims what Michael G suggested, you can even see the rolled up fibre lay up in those.

I don't know if Myford themselves will be interested in your experience, I rather suspect that they are being supplied from the Far East now, having exhausted the stock of spares they brought over from Beeston and they have been sold duds in fake packaging.

Regards

Brian

Edited By Brian Wood on 17/03/2019 20:14:01

The photo I posted of the correct sheet cut gear was from Myford's site so worth giving them a call to check what they have as it may just be a generic photo and if no good you can send them back.

The ones Myford Ltd have listed on e-bay do look a bit like they are from rod but not the best photo to be sure.

Edited By JasonB on 17/03/2019 20:18:52

.

Thanks for the clarification, Mark

... I certainly hope that they are outright fakes : In which case Myford should be very interested !!

Please; for all our sakes, contact them ... and let us know what they say.

MichaelG.

So where can I get genuine Myford spares?

Home and Workshop list them as Genuine Myford bought before their closure at Beeston.

Home Workshop

Edited By ian j on 17/03/2019 20:38:27

Other possibles will include Myford breakers, but be sure you are getting the tumble cluster for the S 7 headstock, The similar looking ones for ML7 were fitted with smaller wheels and those would have been cut at 14.5 degree PA

Regards

Brian

These are 'aftermarket' items ... but appear to be correctly made: **LINK**

https://myfordsolutions.com/collections/ml7-r-headstock-assembly/products/myford-tufnol-gear-28t-for-super7-or-ml7-r

MichaelG.

I've emailed Myford.co.uk (who also have an eBay shop) to see what they say.

I have also contacted Home Workshop to check what stock they have.

If all else fails, I'll invest in some gear cutters and make my own. Thanks all for pointers, I'll report back on this one!

Hi Mark, if you should decide to make your own, I'd suggest forgetting about tufnol and making the new ones from Nylatron or from Delrin (the grade with 10% glass fibre fill plus PTFE).

It could be worth checking the gear-train further downline and the gearbox and leadscrew etc to make sure nothing is jamming up and causing the weakest teeth (tufnol) to strip off.

It seems a bit too co-incidental that your original gears were stripped and now the replacements have done the exact same thing. You would think there might be a common reason.

Edited By Hopper on 17/03/2019 23:23:31

But the weave on the gears in the pic certainly does look wrong. Later tumbler gears appear to be made from red Delrin or similar rather than the now generally obsolete Tufnol. Might be worth getting the modern gears/material.

Plus, those tumbler gears should spin freely when installed on the rocker arm. Any stiffness indicates too tight a mesh. You should be able to pass a strip of paper between the meshing gears with no binding. Ditto all the other gears in the train.