building a myford super 7 from bits ?

I have 4 super 7s, one is complete and little used on a wooden stand bought 50 years ago. No 2 is complete with QC box but has a very badly worn bed on a makers stand. No 3 Has a good bed but is in bits (some parts are missing) No4 is a a long bed, a good bed with rack and lead screw on makers stand, That's all ! The plan is to use the best bits of 2,3 and 4 to make a complete Long bed machine. No1 then lands up on the stand from No2. Gentlemen, what are the pitfalls ? Is there a flaw in my plan? Thanks Noel.

Excellent plan, go for it.

The type of bed design should make them quite economical to have a regrind. Only top, back and front.

Edited By old mart on 04/11/2019 19:52:58

The only pitfall I see is getting all the tolerances to match up. Perseverance and some fitting and a bit of scraping and it will go together like magic. Making time is the only problem I find with any project. Good luck I hope it all goes well for you Noel

regards

You can chop & change most parts at will. My friend bought seven rusty machines and is renovating them all one at a time.

https://www.youtube.com/watch?v=TCpYsAIQgxo

I suppose the unknown is how much fitting is done when the lathe is built in the factory, hopefully Myford would have chosen accurate manufacture rather than expensive hand fitting. As the donor lathes will need dismantling and you will have all the major parts for the long bed build then I would put it together and see what you have got. Many lathes seem to get broken for parts and nobody has complained on here of parts not being interchangeable. It’s got to be worth a go.

Mike

If the bed is straight and flat then the only thing that matters really is the headstock and tailstock centres are the same height. The underside of the headstock won't wear so it should be as aligned to the spindle as when it was new.

Myford 7 series headstocks have alignment blocks underneath. They were hand scraped at the factory to give the correct spindle alignment so that the lathe produces faced surfaces that are slightly concave

The spindle axis should also rise at an angle of about 0.002" in 12" as you go down the bed, so as the bearings wear, the lathe wears Into accuracy before it wears out of accuracy.

As Pete Rimmer has noted, you'll need to check that the tailstock aligns correctly, it should also be angled slightly upwards to allow for wear.

If you need to correct the elevation of the tailstock, it's probably going to be faster and safer to make a new base section and scrape it to the correct height and alignment, than it woutdoor be to risk messing up the headstock casting. You could also mill down the underside of the base section, stick turcite onto it, and scrape the turcite to get the correct alignment. Turcite works like the mythical "putting-on tool".

There were two guide systems used for the saddle.

The earlier narrow guide, that guided only on the front shear of the bed, and was prone to rapid wearing

And the later, Radford inspired, wide guide, which guides the saddle on the front and back of the bed. On the wide guide, the little projection in the middle of the saddle, is relieved, so that it does not contact or wear the inside of the front bed shear.

The saddle should align so that the cross slide travel will result in the lathe cutting a faced surface that is concave at an angle of a couple of thou in a foot.

The bearing surfaces for the cross slide were hand scraped both for fit and for a smooth moving (no stick-slip motion). It is usual to scrape the surfaces to give fewer spots in the middle of the dovetails on the saddle, so that the cross slide maintains contact at the end of the dovetails as wear takes place.

You will probably have to fiddle with the packs of shims to set the correct clearances between the saddle and the bed

And also fiddle with the position of the apron, to get the half nuts to align properly on the leadscrew and the pinion to mesh correctly with the rack.

Go for it!

But take pics and make notes so you can write it up for MEW

Neil