Hi Cai,

I agree, to me it seems that the bed is worn. On a lathe the carriage is most often used close to the chuck so the bed at that end gets more use and wear. The carriage should ,of course, move along the bed but not at 90 deg. to the bed, is that the case on your lathe?

Thor

So . How do you get around the problem without a complete re grind of the bed . First it may not be as bad as you think because you may not use all of the bed that often. Set the gibs while close in to the chuck and live with it. Also if your not using the leadscrew to feed, lock the carriage and any other motion your not using for the cut. There is info out there on the correct measurements of the 7 bed, have a look and compare to yours . ML 7s are notorious for being subject to paint-pot restorations and that's why imports are so popular.

Cai:

I believe you describe the classic symptoms of a worn bed. It is also worth bearing in mind that the saddle gib strip is not positively restrained laterally which can lead to alternate tightening and loosening caused by the ends of the adjusting screws riding up the dimple in the gib.

Once your bed is dealt with this phenomenon can be prevented by dowelling the gib to the apron. The procedure is very well described in GHT's Workshop Manual (by reference to the topslide where the same idea applies).

'Restore' is ebay speak for wire brush and repaint which is what is done for 90% of 'restorations'. Most older lathes have this movement and you just learn to live with it. As said above adjust the settings at the area of the bed you are using as most things you make are only a couple of inches long.

One of the things to be aware of is when you have taken a cut and want to move the saddle back to start another cut the slack causes the tool to move closer to the work on this return journey, spoiling your finish. So you must move the tool away from the material remembering the position the dial. Also be aware that if you do this and make 3 cuts at the same setting you may still be taking off material even though you think it should have taken it all off at the first cut. There are several reasons for this not related to the wear on the lathe so don't be alarmed.

I suggest you read every thread on the forum to do with lathes made this year as you will learn a lot as almost every problem has already been mentioned along with suggestions of further reading.

Are you referring to the saddle mounted wheel or the bed wheel being 'stiffer?

The saddle wheel runs on the rack and any change in stiffness will be only the bed wear.

Yes.

Have you checked the tailstock height? that wears the bed and the bottom of the stock casting.

The under side retaining plate is shimmed to give a nominal clearance, they should never touch such that any drag is possible. In use the pressure is downwards mainly onto the top of the shears only.

Check the shears with a micrometer, front to back and top to underside, these measurements will show where the wear is as set out in previous postings.

If a bed is reground, the carriage also needs to be done to match (reason – top of shear to leadscrew centre is reduced by grinding the bed)

A guess would be that, if adjusting the gibs bearing on the front face of the front shear, results in the Saddle being acceptable at the Chuck end, but tight at the Tailstock end, some very careful scraping at the Tailstock end, MIGHT improve matters.

How much needs to be removed will be shown by the measurements already suggested.

BUT remember that once removed, the metal cannot put on again as neatly as it was before you attacked it!

Howard

The wear in the bed of the museum's Smart & Brown model A is so great that I opted to have the saddle extremely tight at the last three inches at the right hand end. It doesn't get used there often.