jiggered lathe

After making a acme lead screw I decided to make a tap.I chose some silver steel and started to cut the thread ,the silver steel was a big mistake as nearing the end of the first pass there was a horrid noise.I have nackered the tumbler gears,fortunately they are made from a composite material and are designed to destruct under stress to save the lathes gears.Not only have I got to buy new gears but a 5/8" 8Tpi L/h tap too.Don't you just love making a fool of yourself.I hope RDG stock replacement Myford gears.

Frank

Do make sure that the gears are cut properly ... from sheet material, NOT rod

There were some dodgy ones on the market a few years back.

[ Tufnol 'Whale Brand' was the original spec, I think ]

MichaelG.

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https://tufnol.com/tufnol-gears/

Edited By Michael Gilligan on 19/04/2022 20:55:27

If you have a Facebook account, there's a chap on the Myford group who sells them, cut to the correct pressure angle.
https://www.facebook.com/groups/917590484920210/posts/4730948193584401

He also trades on eBay at a higher price, but make sure you get the correct vendor, as some of the eBay ones are the wrong angle. Not sure he has any listed at the moment though.

Bill

Thank you both for that info.

frank

A few thoughts:-

• You don't have to buy the tap. Just the replacement gears and then cut another tap.
• You need to relieve most of the thread behind the cutting edges or it'll rub and take enormous effort (DAMHIKT)*
• Either take a smaller depth of cut or:-
• Ease the load by cutting the thread initially with a V (55°/60° etc.) tool first and then finish to the ACME form.
• The tumbler gears might have been on their last legs anyway. See Michaels comment.
• Assuming that it's a short bed ML7, then just get the iron tumbler gears and try not to crash the carriage into the chuck .

*Unless you've got a Balzer hob relieving attachment (I need to make one of them).

Hi Bricky you should have no problems cutting silver steel. I made a tap for my cross slide bush from silver steel. Turned the thread to depth first then cut the cutting edges followed by hardening and tempering.

David

I wouldn't blame the silver steel. Those Tufnol gears had a limited life by nature. They used them in some GM and Holden car engines in the late 1950s for a while also, to quieten cam drive gear noise. They always failed later in life. Simply not up to it in the long term.

I am not convinced Myford fitted them as a deliberate weak point. I believe they were fitted to the Super 7 so they would run quietly at the S7's higher top rpm of 2,000 vs the old ML7 plugging along at 800rpm. The metal ML7 gears are noisy at that speed already. But new good quality Tufnol gears should keep you going for another 50 years.

When turning an ACME thread DO NOT plunge cut the tool into the work in a square cut by using the cross slide.

Instead turn the compound to a 14.5 degree angle (half of the 29 degrees for an ACME thread) and only use the compound screw to advance the cutter. This reduces the load on the tool as it is only cutting on the leading edge and 1 side, instead of 2 sides.

Lots of Youtube videos showing this method

Ford used tufnol for the oil pump drive gear, in the 50/60s for their Zephyr/Zodiac V engines. Some failed, but mostly seemed to work OK.

My Raglan has tufnol tumblers. Original ones, AFAiK. One got slightly damaged while in transit but has not deteriorated since. I might blame the silver steel if it was not in the fully annealed state - but that would really be down to operator.🙂

Not particularly added as a weak link (may have been - but why fit two of them?). Much more likely to simply quieten the gear train.

Ford and Vauxhall used tufnol camshaft gears in the 1920s. Still good in both of mine. A good long lasting solution to quietening gear drives if engineered correctly.

Ford used tufnol for the big cam gear in all the essex pattern V4 and V6 till they were superseded by the Cologne V6.

The oil pump drive came off the base of the distributor via a hex rod, which had a nasty habit rounding off the flats.

Thats good to know David,I checked the set up and as it is a left hand thread I tried the tailstock centre and it was not tight in the centre hole anymore and I think that the thread was forceing the work into the collet causing the work to ocilate and the tool to jam breaking the gears.I have sourced one gear from RDG but they say they are out of stock of the other and won't have another order for two months.

Frank

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Please forgive what might be seen by some as gratuitous pedantry, Frank

I have just been looking at the RDG website, and cannot find a single reference to Myford [or even ‘Myford-compatible’] tumbler-gears … Can you please confirm what you have sourced, and from whom ?

MichaelG.

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https://www.rdgtools.co.uk/acatalog/Change-Gears-for-Myford-Lathes.html

Edit: __ corrected typo 

Edited By Michael Gilligan on 20/04/2022 23:07:09

Michael, try the Myford site instead.
They come under headstock, rather than change gears
https://www.myford.co.uk/acatalog/Headstock-Assembly.html

Parts A2006 & A2007. @ £21.22 each.

The chap I linked to earlier on Facebook, was doing them at £25 a pair direct from him, or @ £27 via ebay
https://www.ebay.co.uk/itm/324815202954   

Bill

Edited By peak4 on 20/04/2022 23:21:05

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That is precisely my point, Bill … for which I risk being branded a pedant.

RDG and Myford are two separate limited companies.

Yes, Mr Gregory is involved in both … but they are separate entities.

MichaelG.

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Edit: __ and yes, they would correctly be listed under ‘headstock’ not under ‘change-gears’ … but, so far as I can see, RDG doesn’t list them anywhere.

Edited By Michael Gilligan on 20/04/2022 23:34:59

On paper they may be two separately listed companies, owned by the same person/s.

But in practice, whenever I order genuine Myford parts from Myford Ltd's own website or Myford's eBay shop, those genuine Myford parts from Myford themselves arrive in a box all clearly labelled and packaged as genuine Myford parts, BUT with the sender clearly listed as RDG Tools Ltd of the very same Mytholmroyd address that Myford operates out of ie Unit 7/8 White Lee / Burnley Road, Mytholmroyd.

They are for all practical purposes the same company operating out of the same premises under the same owner/s, with RDG being the dominant half or parent company according to their customs declaration as the sender of genuine Myford parts.

So if the RDG/Myford industrial complex megacorporation conglomerate or its subsidiary components at Mytholmroyd do not have any more gears in stock on either of their websites or eBay stores, Bricky's option is aftermarket or used parts on eBay and take a chance on the quality. Or use a steel gear if available and keep revs below what sounds safe. If it's an ML7, won't be a problem at its top speed. And one fibre gear will still act as a weak point if that is a concern.

It is worth checking both their company websites and their eBay stores. I have found items in the past listed on one but not the other. So you can get lucky. Usually it is the eBay store that has things that are listed as out of stock on the Myford.co.uk or RDG.co.uk sites, but it can be the other way round too.

Edited By Hopper on 21/04/2022 06:14:25

Have a look on here for some spares as well.

https://www.homeandworkshop.co.uk/browse-stock/myford-parts-new/22/

David

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That’s very interesting, thanks Hopper … and something of which I would obviously have no personal experience.

When I looked at Companies House [a while back], it seemed very clear that there were two distinct Limited Companies: and I have always assumed that this was to the advantage of both.

MichaelG.

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APOLOGIES

Dyslexia appears to have struck me

I think I should have written Dickinson, not Gregory !

MichaelG.

Not that I know much about business, but I would assume they were kept as two separate limited companies for administrative reasons. If one went bust it would not take the other down with it. And it would keep the valuable Myford brand intact and reputedly independent. It wouldn't do to have it sharing a website etc with a supplier of import mid-range gear, tainting the image so to speak. Plus I suppose would make it easier to sell the Myford brand/business on in the future if ever required.