Advise on Myford leadscrew

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Mike Ginn

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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??
 

abby

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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
 

Mike Ginn

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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!
 

skyline1

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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
 

goldstar31

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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 :p

Norman at Ninety
 

Mike Ginn

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

redhunter350

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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
 

goldstar31

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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.
 

ALEX1952

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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.
 

Mike Ginn

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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.
 

Basil

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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

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

goldstar31

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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
 

skyline1

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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
 

goldstar31

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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
 

DickG

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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.
 

goldstar31

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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
 

Basil

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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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