S7 saddle shims

Does anyone know how thick the front and rear saddle shims are on a super 7

Myford want silly money for little spacers....

Thanks Mark.

They provide laminated shims and layers are peeled off to suite. They are a real pain to use easily wrecked by peeling too much off. If the saddle is loose some can probably be peeled off the ones that were fitted. That might make up for wear on the plates but if you also try and adjust to suit the bed it will be loose by the headstock or tight at the end of the bed.

The other option is a selection of shim brass or steel and cut your own. That's not easy either especially trying to get a hole in them to clear the bolts.

John

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I think the peel-off shims are 0.002" thick.

If you make your own the necessary holes are easily made with a suitable wad punch on hardwood block.

The photo on Myford's page isn't very helpful

... Note the descriptive labels on the bags.

**LINK**

MichaelG.

Having wrecked a few I reckon that they are a lot less than that - if the thinnest layer can be peeled off. A scalpel or safety razor blade might help or maybe there is a knack to it.

John

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Thanks guys

Ive got a set of wad punches so making my own is easy.

Cheers Mark.

Ajohnw:

Yes, I do remember having difficulties with the peelable shims when I overhauled my own saddle some years ago. I'm pretty sure I ended up making my own. I have just located one of the discarded shims and measured it at about 0.0025". I agree that this seems an unduly large increment and it may be that I was measuring two (or more) unseparated laminations.

This construction looks to have been adopted for convenience in manufacture.

I concluded that either there are various sizes in the stack or they go a lot thinner.

When people have mention having beds reground by Myford I usually say pay for the saddle fit too. It's a really fiddly job. I had some 0.0005" feeler stock around which proved useful. Feeler gauges might turn out to be the cheapest way to get small quantities of shim material. I bough a shim pack from RS Components years ago and also have various thicknesses of brass scrounged from work.

One of the plates that bolts up against the bottom of the rails can be turned over. The other has to be reground. Only problem is that if there is wear on these there will be some on the bed rails as well but fixing them can make a difference.

John

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Edited By Ajohnw on 25/02/2016 23:46:05

One of the plates that bolts up against the bottom of the rails can be turned over. The other has to be reground. Only problem is that if there is wear on these there will be some on the bed rails as well but fixing them can make a difference.

Indeed the back gib plate can be turned over but the front one can only fit one way. On my S7 the bed had been reground before I bought it but the saddle hadn't been ground, so there was a huge gap which even with the laminated shims completely removed was still too sloppy. Myford states the shims are 2 or 3 thou each, there seems to be some confusion here depending on who you speak to. The new shims I purchased from the old Nottingham works were definitely 2-thou as I still have the odd bits here now.

To touch up the bottom of the shears is not a difficult job if you turn the bed upside down. I measured my bed all over and found the outer edges from headstock to tailstock was about +1.5-thou at the tailstock end and about +0.6-thou on the underneath slides both front and back at the tailstock end. Using a fine slipstone and some oil I was able to get the slides within 0.2-thou after a few hours of careful work, which is good enough. To set up a bed to take just a tiny bit off it is not economic. It would entail some very careful setting up and then the grinding would take 30s max on each slide, the grinder barely touching the slides. In any case after grinding it is the hand scraping and finishing which is the important bit. If the wear is really bad then a fine file will take off the bulk of the metal required and finish by scraping and lapping. That's how they were made originally!

Incidentally a word of warning about grinding the ML7R and S7 beds.

If the top of the bed needs grinding then it is essential that the top of the headstock pad is also reduced by the same amount. If you just grind the bed portion then the headstock sits too high! In other words the grinder must traverse the entire length of the casting to ensure the top slideways are absolutely level. And remember it is very easy to take a bit off but almost impossible to put it back on again.

Edited By John Fielding on 26/02/2016 12:36:46

Some years ago I bought some colour coded plastic shim material from Radio Spares. Dead easy to use, just trim with plain scissors. The sheets are of differing colours for each thickness and start at 0.002 inches

Whether R S still supply this useful stuff I don't know but they are easy to separate as well, no curled up edges as you tend to get with metal shims. I imagine they are virtually incompressible as well, at least as good as metal in that respect.

Brian

The bed scraping on lathes even old Schaublins is purely cosmetic and wouldn't be as accurate as a slideway grinder in good order anyway. The same is also likely to be true of an old style bed planer.

I've never seen a Myford with a scraped bed. What can be done to a brand new lathe is a bit of very mild lapping to titivate it a bit especially the cross and compound slide but I very much doubt if Myford did that.

It is possible to have beds lightly skimmed but it can be difficult to find some one who will do it. A lot of the problems with doing it can be got round by standing the bed upside down on parallels directly under the feet and grinding the feet first. Then turn it over, feet where the parallels were and then clock it up etc. On some machines the saddle can be set up on a sub table - for prismatic beds.

My ML7 bed was hardened making work on it a touch more difficult. One thing I did find was that shimming up was speeded up by initially using a pair of sets of feeler gauges. It gets things close quickly.

I suspect that the Myford shims have varying thickness's in them - that would explain what I found anyway,

When metal shims are cut I found the best way of curing edge problems especially with brass was a tack hammer. I don't think I would use plastic shim but each to their own etc.

John

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I had to adjust mine when I found the saddle did not have any in it. The cap heads were just left loose...

Anyway, I ended up using polythene bags (4 tho) folded over to get the required thickness. If that didnt work, I found other materials (food container tops etc) were other sizes. So combining the different materials, I made it work.

To find the gaps, I used feeler gauges.

This made a great improvement to accuracy, funny enough!