Myford Bed Regrind

I have dismantled my newly acquired Myford Super 7 to give it a good overhaul and now think that while it is in pieces it would be a good time to get the bed reground. There is a drop of .003" on the horizontal face close to the chuck and .005" on the front vertical shear. What is the recommended way of reconditioning the bed and saddle. Obviously the horizontal surfaces need to be ground along their entire length including under the headstock but what about the inner vertical shears? Should they be left alone under the headstock and the remainder of the bed be set up to be in alignment after grinding. The other way could be to grind the inner shears along the full length (which would ensure alignment) and the push the headstock against the rear shear, before locking down, with the two long grub screws. I fear the latter way would compromise rigidity.

Many thanks

Jan T

I don't see why it should affect rigidity of the machine, that's the way Myford did it.

The correct way would be to do all the surfaces in one set up. Can't see the point in leaving the headstock end 'as is', just adding complication for no reason.

Tony

If you get the bed reground, you should get the two inner vertical shears done as well as the two outer vertical shears. The tailstock runs in the inner shears and usually creates some wear. If they are not reground, you can end up with a tailstock that if set so it slides all the way to the right, will be a sloppy fit in the 'working area" at the centre to left end of the bed.

( How do I know this? Just spent the morning with my son fixing the same problem on my ML7. Ended up attaching a vertical slide to the saddle, long lathe tool bit down to the inner shear and planed it back and forth by hand until the shear was remachined, one thou at a time. Tedious!)

And you should get the ways ground full length, ie under the headstock as well. That way it will all drop back into place in good alignment.

The prices S7s are fetching these days (or at least being asked) make it worth spending the money to do the whole lot properly IMHO.

Life is more diffcult than it initially looks.

You will need to regrind of all mating surfaces as well, eg saddle and tailstock, corresponding gib strips etc.

This can be done in Mytholmroyd (where whatever is left out of Myford is located) but if you are located in Poland as your surname suggests, your option is to find a fitter who may undertake rescrapping it for a reasonable money.

Have you managed to get bedways and mating surfaces rescrapped, your machine will be superior to any ground product, possibly better than new.

IMO doing any scraping job on surface under headstock is of no use, but if you go for grinding, by all means do it as well. You will possibly need to reallign headstock with bedways after all this job. There is a lot of mythology around about supposed difficulties in doing so. Contrary to all of that I have found this task quite straightforward. You will get there with set of shimming strips, precision level, test turning bar with 2 bobbins 6 inch or so apart, patient measurments and 1-3 days of dedication. Later you may need to reallign crosslide.

I was there in the past. Still tapered socket needs correction and suitable grinding jig to be mounted on crosslide is under construction.

Martin

Thanks for the replies. It way my father who lived in Poland, I live in Scotland! At the present time without any regrinding the oblong, ground boss under the headstock is a vey tight fit between the inner faces of the rails and provides location. There are two screwed dowels in the outer face of the front rail under the headstock. At the present time they do not appear to do anything but if the inner faces were ground they could be used to force the headstock against the back rail before fully locking the headstock to the bed. Grinding the entire length of the inner faces would ensure perfect alignment. The reason I am seeking advice is ML7s do not have the dowel screws to jack the headstock against the rear rail. Perhaps this was an update for the Super7. I have spoken to two firms who can grind a Myford bed. They are Unislide and Slideway Services. They are cheaper than Myford. I have been unable to find anyone in Scotland who can do the job so will probably have to make a couple of trips to the Midlands. It is sad, at one time there would have been a dozen firms in Glasgow alone who could have done the job.

My ML7 has those two clamping screws in the front of the headstock to force the headstock into contact with the inner shear, so not just a Super 7 thing, I think. Either way, definitely worth getting the bed ground in that area to get perfect line up.

You should look at getting the underside of the saddle ground too. They seem to wear far more than the bed. EG my ML7 had 3 thou wear on the bed on the vertical shear that guides the saddle, and more than 25 thou on the saddle surface that ran on it. On the top of the bed way i had 4 thou wear but the mating area on the underside of the saddle had more like 10 thou. (Luckily I scored a recently reground saddle on eBay and solved that problem!)

Then there are the dovetails on the top of the saddle and the underside of the cross slide. Usually not so worn though. But it can go on and on ... It all depends on just how perfect you want it, relative to the type of work you will do on it, and what kind of work you want do on your wallet also.

Yes, shame about the lack of suitable regrinders these days. The nearest one to me in Aust. is about 1500 miles away. Luckily I was able to do the wide guide conversion on my old ML7 and get away without a regrind. Not an option on the later Super 7 like yours though. (Although, you could look into converting it in to a narrow guide and using the vertical shear on the back of the front bed way to guide it.)

Hello, and welcome, roughly how much are you looking at for a re-grind of bed, saddle etc on a Super 7?

If you'd rather not post the answer on here, a PM would be appreciated.

Thanks

Bill

Myford were quoting earlier this year 495 pound to regrind the bed and 165 Pounds to regrind the saddle. I'm sure the others are cheaper.

I have just had a 1958 Super 7 bed reground in northern Brisbane, Australia, cost me $80. Still in pieces as I need to take it to the Gold Coast where I can get access to a large surface plate (2mx1m) and Biax scraper.

will also do the wide bed conversion and Taper roller bearings on the headstock.

AS the Myford is a Flat bed, a solid surface grinder capable of grinding larger than the bed length should do a reasonable job. A vertical spindle such as a Churchill Sno grinder would be excellent, fofm the grind marks on mine under the headstock that is what it was ground with originally. Assuming it was not reground before I acquired the lathe in 89.

A 3 phase surface grinder is better as the motor speed is more constant. Have been told single phase surface grinders will not be as even.

Peter

When milling the shears on a new bed, Myford (Beeston) gang milled all four shears at one go, but when refurbishing used beds each shear was done individually as the wear would be different over the four shears. Cutter heads ran all the way along the shears. I seem to remember that cutters with ceramic inserts were used.

For the top of the bed, first it was turned over and the four feet ground at the same setting on a surface grinder, then the bed was turned right way up and the flat tops ground on the same surface grinder. Maximum that was removed was 5 thou (0.005" ).

Regrinding the saddle was optional, but was strongly recommended.

When I had a bed only regrind in 2008 it cost £147 incl VAT

Edited By Robbo on 09/12/2017 10:14:07  To get rid of smiley!

Edited By Robbo on 09/12/2017 10:15:09

Jan, Robbo is spot on with the method, grind the feet first then the top of the bed. A pal of mine who is a retired old school motor mechanic has just had his done by the local engine boring shop who also have a larger surface grinder for skimming heads etc so maybe worth checking this out locally.

Also consider I looked at my S7 and my pals and the centre serves only to locate the headstock and guide the tailstock. We measured the wear between the shears on the one being reconditioned and it was tiny -- a few tenths, however the outside of the shears where the carriage runs was worn by some 0.007 / .008"

My pal came up with a novel solution to solve this, I had suggested using a file and working carefully measuring with micrometer to remove the metal required, he thinking outside the box found a file that would sit in place of the gib and with this in place pushed the carriage back and forth measuring as required until one side was correct then transferred the file to the other side and did the same -- result a very uniform bed width. He has not actually finished it yet so the proof of the pudding etc !!!!
Hope this helps and good luck with the restoration

John