Myford Super 7 Bed Wear

I have uploaded two photos of my Super 7 bed, which show some rather nasty wear near to the headstock. My question is, does anyone know what this might have been caused by?

I had seen several Super 7's before buying this lathe, and they had significant wear. I have nipped up the saddle gibs with the saddle near the headstock and the carriage only starts to tighten when moved to within 4" of the end of the bed, and even then it is still movable. Would you consider this average wear?

The saddle has no movement when I try to lift it at the rear, so the shims seem to be doing their job. However, there is movement when I lift the saddle at the front, even at the very end of the bed. Is this normal? Do you think I should fit additional shims to remove this movement?

Once again, many thanks in advance,

Mike

Looks more like abuse than use to me. Previous owner had an angle grinder, or hammer, and wasn't afraid to use it? Looks like said owner also had a triangular punch which he "tested" on the bed.

Andrew

Andrew,

You beat me to it---my thoughts were on the use of a coarse file on the front shear especially.

The other marks may well have been made by chuck jaws as he dropped them on the bed with the sudden weight from unscrewing the chuck from the spindle nose. I think Mike would be well advised to check the lathe over carefully to see what other liberties may have been taken with it.

Brian

Edited By Brian Wood on 27/03/2019 16:18:35

Looks more like cleaned-up corrosion damage than wear to me.

Quite a lot of materials attract water. Possibly the lathe was left for a long time with something like a heap of damp sawdust on the ways, or a chemically treated cloth was braced across that edge and the lathe did nothing but polishing. It's a bit odd.

The novel Black Beauty is really about lathes, not horses. The machine starts off as a pampered show thorough-bred, is ruined by an inconsiderate owner and then sold-on for hack-work through a series of kind and cruel owners. After much mistreatment Black Beauty is saved from the Knackers Yard at the last moment by a benefactor, and has a happy retirement.  I hope this old girl is restored to full performance.

Dave

Edited By SillyOldDuffer on 27/03/2019 16:31:28

Mike,

I looked again at your specific questions concerning shims and saddle lift. From what you say, the wear across the bed doesn't seem to be so bad, I would expect it to get slacker near the chuck end though and you might find the saddle slewing on return under power which will give another cut on a boring tool as it is withdrawn.

If you know that is a feature of the lathe wear you can allow for it accordingly. At my last place of work I had to allow for a lot of that on an old DSG lathe but even with the degree of wear that had it was still possible to bore accurate bearing pockets.

Lift on the front of the saddle is reduced by removing shims from between the flat strip bearing on the underside of the front shear and where it is bolted up to the saddle with two cap head screws. Test the result over the full length of the bed.

Brian

A friend had a similar problem on his old S7. The wear was on the rear vertical face of the front section of the bed. The saddle is guided by the the front and rear vertical faces of the front part,(the "shears". I overcame it by inserting a piece of ground steel, of the minimum thickness that would fit, between the unworn rear face of the REAR part of the bed, and the rear "flange" of the saddle. Small pieces of brass were screwed on to prevent the new piece of steel from moving sideways due to friction. The adjustable gib on the front was readjusted to give the correct about of clearance for the saddle to move smoothly, at the same time ensuring that the original short face on the saddle was just clear of the bed. Ideally, this face which is now redundant, should be milled back a little to ensure that the saddle is in the correct front to back position, for the alignment of the half nuts. We did not have the facilities to do the last bit, but that lathe is still doing its stuff forty years on.

Maurice

I have just read your original post again. As Brian says, you reduce lift by removing shims; actually, in the case of the S7, the shims are soldered together in a stack and my be pealed off one at a time. The can be tricky to start; I seem to remember resorting to an old fashioned razor blade. I can't remember how thick each layer is I'm afraid.

Maurice

Many thanks to you all for your help. The lathe was bought at a relatively low price for a powered cross slide model with a gearbox and being my first metal lathe (I've done plenty of woodturning) it was a risk I took to get me started in metal turning and lathe milling. I'll adjust the shimming of the saddle over the next few days as I assume this may help with milling..

Always keep the carriage locked when milling. And arrange job so cutting forces are downwards.

My Spidey sense is saying to me ground out hacksaw marks from parting off with a hacksaw.

It is sad to see this abuse on any lathe bed....a simple wooden "chuck" board laid across the bed to protect it during chuck changes - or hack sawing whilst job is still in the lathe would have saved all the "dings" and dents to the bed...

Regards

Del

I cant remember if it was on this site and cant remember its name. I read about an epoxy like compound that is designed for repairing slide ways.

Maybe someone who is not having a senior moment knows of it.

Like it! I wondered last night if it might be due to something like metal spinning, with the bed edge being used to support a long lever-like tool. We may never know.

How much does wear in that position matter on a Myford? Most of the bed top and sides look reasonable and, depending on the design of the saddle, the missing edge might not be essential to accuracy. Mike's other alignment problems could be due to more normal wear, perhaps fixable with shimming or a regrind.

Dave

Nah, that'd be on the far side of the bed.

As someone else said recently - don't ask me how I know...

I think it's also true as others have said that the bed wear itself and the bruise marks as shown aren't especially serious - it's whatever else there may be that's not so conspicuous that could be worrying.

Not at all really. The carriage rides on the full width of that flat surface so the 1/8" missing will not alter the path of the carriage at all. Main guide when turning, however, is the vertical surface of the shear, the one at the rear, away from the operator. The pictured damage/wear does not impact that surface at all.

Dings and dents don't matter particularly either, as long as the resulting "bump" of displaced metal is filed or stoned down flat. A 10" flat file, fine cut, will do the job in a couple of strokes.

The individual shims in the laminated shim packs are 0.003" each. I measured them about 6 months ago when I was reassembling my S7 after a bed regrind.

i would have guessed repeated use with a toolpost grinder without protecting the bed

That was my guess too, Russ. Perhaps even a grinding fixture for grinding tool bits? It looks almost as if sparks have eaten away the metal over time. Is that possible?

If that's so, all the more reason for a critical examination throughout, and a thorough washdown to get rid of the abrasive grit that could be in any and all parts of the machine.

Yep, first thing I did before using the lathe was give it a thorough clean and oil, especially under the saddle. The lathe had no felt wiper or plate when I bought it, so this was also fitted after cleaning and oiling.