All,

I bought my ML7 about 13 years ago, and did a light refurb on it (basically stripped, cleaned and painted):

I've only really started to use it properly this year, for building a Stuart 10V.

It works fine overall, but there are some foibles, such as the cross slide dials are stiff and aren't re-settable, and the saddle stiffens up at each end of its travel, with a free spot about 1/3 of the way back from the chuck (as is common on old lathes I suppose). I've adjusted it to allow me to work in the region of the ways that most often get used, but on the occasions I need full travel, if just feels too stiff, and is just not very nice to use. A few questions:

1) How do I determine the amount of wear I've got in the ways?

2) Is there any way to compensate of the variable wear, or is it a re-grind?

3) How much wear (as measured in 1) makes a re-grind impossible?

4) Where, and how much would it cost to re-grind and re-fit the saddle?

I'm just after preliminary info at the moment, so I can make a decision on whether to put up with it, or get it done. I am planning more steam engine builds in future, but I'd like to get the lathe sorted out first.

Thanks.

Thanks Dave.

Do you happen to know what the dates of the relevant magazines were?

Thanks everyone. I'll re-measure the ways at lunchtime. BTW IIRC my lathe was built in 1957.

I will try to get hold of all the articles as back issues.

Hopefully I can improve the feel of it without a regrind. I think it's always nice to have something 'perfect', but the real question is "how perfect does it have to be for the work I'm doing?" Obviously cost has to be factored in as well.

I'm really enjoying building the 10V, and all being well it won't be the last engine I build. The other factor therefore is the time spent trying to fettle it so it's as good as it can be (something I'm always fiddling with) vs. time spent turning parts and wondering what proportion of dimensional error is my fault (probably all of it to be honest).

So I just found the aforementioned article by "R. A. Ganderton" on correcting wear on these lathes. From what I can make out, in simple terms he suggests milling back the short face of the saddle – the bit that apparently wears the most and causes the corresponding wear on the front slide – to give a clearance fit. You then use the rear face of the rear slide as the bearing instead?

Is that basically what the method is? If so I will go ahead and get the back issues and have a go – especially since the method outlined in there is simplified?

Are there any issues with subsequent alignment of the leadscrew split nut, or is it adjustable?

I do have an SX2P Mill, so I guess any machining could be done on that?

Cheers.

I bought the back issues online and printed the relevant bits out:

I'll re-measure the ways (although I know they are worn), and get on with the modification once the 10V is finished.

Ganderton seemed to say (and I may well have mis-interpreted his method) that the apron could, without modification, be moved back enough to compensate for using the rear of the saddle without adding a strip. If so, it seems like milling the short saddle bearing is a much easier way to do the modification. Even if the leadscrew bearings do need milling, you've still avoided having to dowel a strip to the saddle.

I think the gap quoted is 0.035", so why not combine the two methods and pin a 0.035" strip to the rear saddle bearing, relieve the short saddle bearing to give clearance, and avoid modifying the brackets altogether; is a 0.035" thick strip too flexible to attach reliably?

I'm no expert on lathes, so I'm curious to know what the relative advantages/disadvantaes of the two methods are? Have I missed something in terms of accuracy in terms of what the various methods will give?

Cheers.

OK thanks.

I just measured the gap, and it's consistently 0.022" all along the bed and at each end of the saddle.

Shim Steel seems to be available in that thickness, with a +/- 0.001" thickness tolerance.

Could a strip be bonded to the rear face of the saddle, compressed by the gib strips until it set? I guess it could be scored, bent and screwed around each end of the saddle ends as a backup fixing, and the lower kepper plate would prevent it from falling out? Might cause some bowing at the ends though.

I wonder if going to 0.025" shim would allow the saddle to move out of contact with the short bearing, and compensate with the gib strip. I'd have thought the leadscrew half nut could cope with a 0.003" misalignment – or the apron could easily be moved by that amount?

Is that a total bodge, or is it viable? Guess there's not much to lose by trying, assuming I'm comitted to converting to the wide-guide concept anyway.

OK great, I'll think about it some more.

I was just thinking that in your article, you Loctited your 1/32" strip (and of course dowelled it). I know that good bonded joint design means putting the joint primarily in shear, which of course this would be exclusively. Quite a large surface area too, and it's always clamped. I'd say it ticks all the boxes for a purely bonded joint. Even so, "glue" just seems a bit of a short cut, even though that's not necessarily true.

Milling the short bearing isn't an issue for me if it needed some more clearance, it was avoiding machining the leadscrew bearing housings if at all possible that I wanted.

Cheers.

Yep, so many options I forgot that one. Use the 0.022" shim steel to make shims for the bearing blocks I guess.