# Advise on Myford leadscrew



## Basil (Dec 6, 2020)

I will be doing some thread turning soon, Is this leadscrew for the scrap bin. As a thought could this 4 1/2 inch bad section be moved by shifting the leadscrew towards the gears and extending the other end with drill rod? I cant see I will be ever threading down that far to the tail end. The clamping nut half's are shot so will definitely be replacing them. Thanks


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## fcheslop (Dec 6, 2020)

On My previous ML7 I turned it end to end . I did have access to another lathe so altering the ends of the screw was possible. I dont think the screw will go through the head spindle


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## goldstar31 (Dec 6, 2020)

RDG Tools should have the smaller diameter leadscrew of 8TPI but I recall 'martin Cleeve( mentioned at some length today) actuall took the less worn tailstock end and it al was joined up again. It was described in model Engineer. But______________________-

How have you  determined that it is 'shot'?   It may well be that the clasp nuts can be re furbished enough to give the old machine a new lease of life. I've forgotten what the clasp nut material is.  If it is iron or steel it can possibly be retinned with metal from car/van/lorry main bearing shell metal. I've done this on a well worn feed screw of a Pools Major- which no one now has the foggiest knowledge. Otherwise the advent of Turcite and Moglice have changed the art of reconditioning othr wise worn out bearings, spindles and feed screws.  I recall once that I had the top of a ML7 bed  'Blancharded' for say £25 or £50 I built up the worn  first 6 inches of Number One front shear and scraped the Loctite in this caseand apparently a filled ceramic powder, all was well.  I finished the job( I'm digressing a bit)but came off the un-used Number 4 shear. 
Respectfully, you have to move into a new technology. I had an absolutely clapped out Super 7B  - undrthe saddle on the narrow guide principle 'Turcited almost as new. Mine was done by Blue Diamind at Shildon, County Durham on an Italian slide ways grinder and the cost for what was beautiful slideways grinding of the vbed and building up and maching the saddle was £250.

Do have a re-think and intrigue us on your progress.

Norman


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## fcheslop (Dec 6, 2020)

The nut is the same monkey metal as the other feed screws and will be worn


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## goldstar31 (Dec 6, 2020)

fcheslop said:


> The nut is the same monkey metal as the other feed screws and will be worn



 So the two clamps could be 'blued' and fairly esily scaped to take the slop out?

Meantome of a personal note- how are you coping?

Regards

Norman


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## fcheslop (Dec 6, 2020)

Hi Norm, becoming stir crazy . Just keeping out of the way until Vlad the Impaler calls
The half nuts could be made to fit with a bit of ingenuity . I turned the screw around and made a new tail end and just made a different coupling at the head end. It was not a big job and on my old banger of a machine made a big difference when screw cutting . The rest of the machine was badly worn and my ancestry prevents me from spending that illusive stuff to often.
Although I did buy a factory refurb when they closed down. The place looked like a retirement home for fitters
Keep well all
Frazer


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## goldstar31 (Dec 6, 2020)

fcheslop said:


> The nut is the same monkey metal as the other feed screws and will be worn


I've just got a Christmas Box9 sorry, bottle of Monkey's  Shoulder Malt whisky.


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## Basil (Dec 6, 2020)

Not sure what they are made of. Seems heavier than aluminum but not steel? Is it really pot metal?


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## goldstar31 (Dec 7, 2020)

It will be a zinc alloy but having a metallurgy discussion isn't going to cure what is showing up as a sloppy situation that you will be wise to attempt to eradicate.  you need to fashion  scraper to get into the bits that  show up when the nuts are 'blued' then scraped, then blued and scraped until they fit the best part of the lead screw which probably is at the extreme end of your screw. I can't recall it in 'Connolly' but that is my opinion without my examination.

Best wishes

Norman

If you have a bit of car body bodge, it might be possible to  add a smear of resin into the suspect threads and see what is wrong It's a bit like taking a dental impression.  Yea, yea my daughter is a consultant orthodontist like her late Mum -- and has Covid-19 along  with her senior consultant husband who is down with it- and I'm feeling that bit 'testy' but it is worth a try. Use a candle to soot up the lead screw to act as a release agent.  Sounds a bit barmy but I did something like that to a feed screw.
Let me know your findings


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## skyline1 (Dec 7, 2020)

The leadscrew on my old Myford was in similar condition It was ACME type thread at the ends as it should be but more or less Whitworth at the worn bit I ended up having to scrap it but luckily a friend had a spare one he was willing to sell at a reasonable price. 

Older Myfords have a slightly smaller leadscrew (5/8") than more modern ones BTW.

I think you might still be able to get one from RDG tools but it is going to be expensive (VERY expensive like everything else Myford they sell, asset stripping racketeers !)

Dressing the claspnuts down so they grip tighter does not work I tried it you end up with a very small range of movement where they are tight enough to be accurate but do not bind.

I think the Myford principle was that the claspnuts being made of Zinc Alloy wear before the leadscrew does and can be easily and cheaply replaced.
However it doesn't seem to work in practice as the nuts seem to go on for ever and the leadscrew wears. 

The claspnuts can also be had from RDG but once again they are not cheap.

Best Regards Mark


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## steveastrouk (Dec 7, 2020)

We never had problem with our leadscrews on our production used Myfords- but we would replace the halfnuts every couple of years. Its a long time since I used a Myford, how expensive are the nuts these days ?


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## goldstar31 (Dec 7, 2020)

Mark,  You may be right but I have  double Acme threads on my slightly exotic small  but I have a perfectly norma versatile 'normal 20TPI. Whitworth vertical screw thread on my Stent T&C. In fact it is no more than standard studding.
Again, I have a 3mm leas screw on my Sieg- that looks like Whitworth form- but isn't. After all we are simply discussing screwcutting and  I have truncated Whitworth screw bed bar on my Quorn nand Cleeve in nhis wisdom  made screws professionally as well as writing his excellent book but wrote to his customoers whether they minded having the Whitworth screws without rounded crests- and the did not reply but continued to order from him. 
I therefore conclude that once the poster gets his clasp nuts to fit the worn leadscrew albeit with the necessary gap of oil it doesn' t matter a hoot.



Have a nice day


steveastrouk said:


> We never had problem with our leadscrews on our production used Myfords- but we would replace the halfnuts every couple of years. Its a long time since I used a Myford, how expensive are the nuts these days ?


Have been in the Pricing Game recently and bought a  ;as New Super7B with Power cross feed, I had checked the price of  a non- gear box machine that had been  reconditioned by the successors to the now Defunct original company. The price  of one with no motor or any v=centres chucks or whatever is a cool £3000 and then transport to be added.
Myford continue to be made with power cross feed and it would seem that to start building a  Myford(RDG) having bought the Myford name,  people are having the think of £8000. Yes!

Now n old clapped out ML7 CAN be resurrected to be factory fresh about b6 times which begs the question of not going the whole hog and approaching either RDG Tools for a quotation or  douing as I did with an old grey 'softer gear box Super7 with a saddle that looked like a cattle grid run over by a tank and being slideays ground and Turcited at a local machinery restorer . I did the rest of the work but the bed etc was  'slid in to the normal proper work and therefore was competitively and acceptably priced.
It depends on what an owner of what must be a basket case but has great potential if  the owner is prepared to go . I was an accountant and cannot predict that
I hope that this helps?

Norman


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## deverett (Dec 7, 2020)

A guy called Tony Crowe - a member of the Myford io group - used to sell bronze half nuts.  At least I think they were for the main leadscrew, or was it for the cross slide? !

Dave
The Emerald Isle


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## skyline1 (Dec 7, 2020)

Norm

Nothing wrong with Whitworth feedscrews or other thread forms for that matter. 
The feedscrews on the Z axis of one of my 3d printers are nothing more than lengths of M8 studding and they work fine (and hold very close tolerances).

The point I was trying to make was that the leadscrew was so badly worn that it's thread on the unworn ends was it's normal trapezoidal (ACME) form but on the worn centre section the flanks were worn to such an extent that the thread form was approaching that of a Whitworth on the same leadscrew.

I tried dressing down the half nuts to get a snug accurate fit on the worn section but found that I could only get a few inches of travel before they started binding on the less worn parts.

Dave

I remember seeing these too and IIRC they were actually cheaper than the zinc alloy Myford ones. Hmm something amiss there

Best Regards Mark


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## goldstar31 (Dec 8, 2020)

Mark
         No one but the poster has an inkling of actually what is wrong with his lathe.  Nothing is wrong with my lathes that I cannot fix .


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## skyline1 (Dec 8, 2020)

Quite so Norm

There is an Air Force saying you probably know off by heart.

"Nothing is beyond repair but some things are beyond economic repair"

Best Regards Mark


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## goldstar31 (Dec 8, 2020)

two expressions
Nil Illigitimi Carborundum
and 

Per Ardua Asbestos

And the other ones are quite unprintable

Take Care

Norman


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## redhunter350 (Dec 9, 2020)

Basil, have a look at this thread on another forum for supplies of Acme threaded bar UK Supplier of Imperial Acme Threaded Bar? | Model Engineer 
As for the half nuts they are as far as I am aware made from Mazak , your do look well worn so I would bite the bullet and purchase replacements, if you look after them they will last a great many years. 
John


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## ALEX1952 (Dec 10, 2020)

IF it is Mazak which I find suprising given the wear it will take, It would be possible to use the unworn end of the lead screw as a pattern and cast a replacement. Mazak has a very low melting temp and lends itself to complex castings and is cheap hence its common usage.


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## abby (Dec 10, 2020)

I used white bearing metal to cast new "teeth" onto my worn half nuts . 
the set up is pretty straight forward and doesn't really need a description other than to say that most of the original threads are removed , leaving just the outers for location , and holes are drilled through the castings for pouring access. The bearing metal can be purchased online and the repair lasts .
Dan.


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## Mike Ginn (Dec 11, 2020)

I think I would buy one at £31.  It would be an interesting project to cast one (I would use lost wax) but quite time consuming!  How do you value time??


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## abby (Dec 11, 2020)

Mike where can you buy the replacement nuts for £31 ? the cheapest that I can find are £64 . It would be a simple project to cast them using lost wax ,I have done far more difficult jobs but for one set it would cost more than the £64. I estimate that commercially it would cost around £90 for tooling to make silicone rubber moulds (given that a pair of good originals are available) a nominal charge for producing the wax patterns , say £1 per pair .
My smallest flask would hold around 15 pairs of nuts and charge at £100 plus metal cost. These were my charges at retirement 2015
So to produce a one off or 15 pairs the cost would be almost the same , but can anyone sell 15 pairs ? I


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## goldstar31 (Dec 11, 2020)

Hi Dan!
   Good c(o)sting. 

best Wishes

N


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## Mike Ginn (Dec 11, 2020)

Hi Abby
I looked up the cost on the RG Tool site which was on eBay.  After your posting I looked into the detail only to find that they were not available  when I tried to purchase.  I guess I jumped the gun so to speak - sorry.  I think I would machine from an aluminium/brass/gun metal block and cut the acme thread.  I would finish the thread using an acme tap/tap set which is available from several suppliers.  I just don't fancy casting!  I would cut the thread keeping the stock round for simplicity and then s solder to the sliding bars.  The final action would be to split the nut.

I have made several acme nuts in gun metal using this method - usually making my own acme tapered tap!


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## skyline1 (Dec 12, 2020)

Hi all

Compared to some of the highly complex engine components we see produced  here these clasp nuts  would a fairly simple item to either cast or machine from solid in a better mat'l, (Gunmetal for example or even Aluminium).

I agree with abby that in small to medium quantities they would be commercially viable and profitable whilst undercutting RDGs prices by a significant amount.

As far as I am aware RDG are not producing any new components merely selling off the existing Myford stock (at exorbitant prices) so this mat be our only choice in the future.

Best Regards Mark


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## goldstar31 (Dec 13, 2020)

With Tongue in Cheek, maybe there is the arrival of a 'Mysterious Myford' 
I was penning a few idle thoughts in the seemingly endless Parting Tool saga when I discovered some wrong sized tee nuts which I bought  hoping to fit my modern-ish Myford Super7 B with the Mk2 Gearbox and designated PXF( Power Cross Feed).  One of my even older Myford-ites of 94 years suspects that these RDG tee nuts of mine have a place in the  model engineering world--- perhaps of even more horrendous cost of things from the successors to the old Myford firm.

Me?? Merely 

Norman at Ninety


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## Mike Ginn (Dec 13, 2020)

I notice that myford.co.uk are selling S7 leadscrew half nuts for £64 and also lead screws for around £185


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## redhunter350 (Dec 13, 2020)

ALEX1952 said:


> IF it is Mazak which I find suprising given the wear it will take, It would be possible to use the unworn end of the lead screw as a pattern and cast a replacement. Mazak has a very low melting temp and lends itself to complex castings and is cheap hence its common usage.


Alex, point taken, however as you point out Mazak is great for complex castings which this item is and you will find it is more wear resistant than you imagine. For a great many years Delapena used this material for replacement shoes on honing mandrel’s and I can vouch for their longevity, indeed they outlasted the bronze ones also available many time over plus they were much less expensive. They no longer supply them in Mazak so now I make my because the bronze ones just Do not last, why Delapena have discontinued them I have no idea? 
Cheers John


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## goldstar31 (Dec 13, 2020)

Mike Ginn said:


> I notice that myford.co.uk are selling S7 leadscrew half nuts for £64 and also lead screws for around £185


But Mike you are missing the point A 1953 ML7 is vary different machine to a Super7.
I have worked and overhauled both machines and if a  Super7 Mark2) leadscrew etc was purchased it  will NOT fit without a great deal of further  'modifications'
Now until failrly recently, I had a Super7B- a grey one and with the Mark1 leadscrew and the softer Mark m1 box and  'possibly' altered to fit the ML7.  I doubt it but could be wrong.  Again, the bed changes for a second time-or more.


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## ALEX1952 (Dec 14, 2020)

Delapena that's a name from my distant past, do you think the shoes take the same wear as half nuts? I suppose at the end of the day regardless of material its got to be better than worn ones. I screw cut internal and external multi start square threads as part of my training in the  Lucas Cav apprentice school, once was enough! just grinding the tooling on a bench grinder was a nightmare. I still have it along with all the tools made during that 2 yrs in the school, once that was completed you were allowed on the shop floor under the close supervision of a tradesman for the next 3 yrs. If you were successful you got offered a job if not you were on your bike. People are complaining about parting off they need to try this, if you broke the tool not only did you have to remake it but also pick up the thread.


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## Mike Ginn (Dec 15, 2020)

Hi Goldstar31.  Points accepted.  I usually get hold of the correct manual to get the part numbers and take it from there.  With all the Myford variants, identifying parts is tricky.  I have phoned the "new Myford" several times to identify parts.


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## Basil (Dec 21, 2020)

Thank you guys for all the advice. I thought I would first replace the leadscrew nuts but found after ordering they were out of stock. Oh and the leadscrew is out of stock also. Both items not sure when they would be available. I saw online that someone had re-tapped the nuts and ordered a LH Acme 5/8 tap from America. It arrived with no bother. After aligning the nuts and using different drill bits as spacers to creep up on and inspect how the threads were reforming this  is the finished product with 1/16" between the nut halves. I could clean up more but the pegs that pull the nuts into mesh will come close to bottoming out. I'm very happy with the results so far so it is onto modifying the leadscrew.


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## Mike Ginn (Dec 21, 2020)

Thats a great result.  Always much better to purchase an Acme tap than try to make one.  Good work.


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## goldstar31 (Dec 21, 2020)

Yes, I expect great improvement but this is an old and obviously well worn machine.
I would reasonably expect that once you have sorted the leadscrew- at the clasp nuts, it would be prudent to replace the rear bearing too.  Two options are either to do the refurbishing yourself but mybe consider a new bearing and ArcEuro Trade has something suitable. I have no 1st hand experience of that! However, unless someone has already tackled issues, your  lathe bed is one of the narrow guide variety and the guide at the numbers 2 and 3 shears will be worn too, You CAN  scrape the curvature out or  build it up or  you can go off the number 4 shear which just might be  unworn.

You will find this if the number 4 shear is running 'in the air' and is still at the factory fine milled finished state.
A bit of it is described by such worthies as Martin Cleeve and Jack Radford and the obvious wear on Number 1 shear  is likely 6 inches from the spindle.

I'm going off my own experiences which part appeared some where in Model Engineer( I have sort of Forgotten when) but none of it is insurmountantable-- and the result frees a fine lathe for s new lifetime of plesure

Best Wishes

Norman


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## skyline1 (Dec 22, 2020)

Looks like they cleaned up nicely, they are much better than before. Well Done !

Now you have the tricky bit refurbishing the leadscrew.  I am not sure if it could be built up and then recut (there are some amazing techniques available nowadays) or you will have to make a new one. The latter option could be a bit tricky as you would need access to a larger lathe to do it.

If RDG are out of stock now they will probably always be. As far as I'm aware they are not actually manufacturing any new parts.

As Norman says If the leadscrew and nuts are that badly worn then the bed will undoubtedly be similarly worn and unevenly (mine was) They usually wear most in the same area as the leadscrew is worn (as you might expect).

"New Myford" (RDG) were planning to offer a bed regrind service but whether it actually happened I don't know. 
Slideway Services Slideway Services Ltd may be able to help contact is Brian Caddy.

Best Regards Mark


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## goldstar31 (Dec 22, 2020)

Thank you Mark for your contribution as I am somewhat 'out of date'.
As far s my memory is concerned, I recall \Martin Ceeve- wrote i Model Engineer of  adding to the smaller diameter of the Vertival Slide and ,-- I think, an alteration to the end of his own ML7.
Perhaps someone will have the relevant articles. Maybe JCSteam as he acquired a LARGE number of original magazines.
The other point of which I am now unclear is the reconditioning of Super7's and possibly 'new'Super7's albeit at a huge price. I, confess that all this is from the London Show or the Doncaster show- FIVE yearsago. So my comments merely say'it can be done'
Again , previous about slideways grinding oint to the excellent work of Blue Diamond at Shildon.
However- in an earlier existence-  I had a cheaper but more labour intensive solution in having the 'top' of the bed Blancharded which cuts down an enormous  amount of scraping cycles to level the bed- and creates a 'reference' to scrape to.  Perhaps the only unworn sections of an old Myford bed could be under the headstock and at the tailstock end.
Apologies for rambling on and repeating myself but  I 'Did' a friend's lathe in a week and he quoted 'half a thous out' on a 6 inch test bar. 

I hope that this is constructive

N


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## redhunter350 (Dec 22, 2020)

Basil, I just spotted this site ACME Leadscrew | ABSSAC
They seem to do a suitable Acme threaded bar you could use to fabricate a new lead screw from, no prices but worth a call I recon ! 
John


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## DickG (Dec 22, 2020)

It’s a fairly simple job to modify an early Myford 7 series lathe from narrow guide to wide guide running on the back shear. I wrote about this in Model Engineer way back in around 1973. My mod was simpler and easier to do do than previous ones. Shortly after Myford changed to the wide guide.
I noted that someone mentioned that the bit of the bed under the headstock would not be worn. Just remember that if you have the bed reground or scrape it back to true you must have the bit under the headstock done at the same time. If you don’t the headstock spindle and the tail stock barrel will not align.
If you are remaking the lead screw or half nuts note that, even for the metric versions, the leadscrew is 8 TPI. The diameter has changed over time and the ones for a ‘power feed’ lathe have a slot machined along its length to drive the cross slide power feed gear.


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## goldstar31 (Dec 22, 2020)

Yes I Did mention this briefly- a few moments ago. Again, I recall the Late Kenneth C Hart writing as Martin Cleeve writing  concise details of his  work in that direction.  Further more, I recalled with a deal of interest that he raised both the headstock casting and machined a new plate to raise the working height- by 3/8th of an inch( I think
Of course Cleeve  added an additional motor, a sort of gear box and a fascinating clutch mechanism.

Thank you fot jogging my memory!



What has  always intrigued me was  the fine milling on Number 4 shear on a ML7 and I wonder whether the ML7 was fine milled rather than ground in the years  that are in discussion.
Anyone care to c


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## Basil (Jan 10, 2021)

Got side tracked onto other projects but got the modified leadscrew back in the lathe today. After a few small hiccup's I'm very happy with the result. Thank you everyone for all the suggestions.


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