ML7 tight saddle

My early 50's Myford although getting a fair amount of use is generally cosseted. I use a bedway protective rubber sheet fitted to the left side of the saddle to keep the lathe ways clear of debris and always clean up and oil after every use.

Today while in use I noticed the saddle was tighter than normal to move so my simple 'clean up' ended up with a saddle removal expecting to find the culprit trapped somewhere. But no, nothing untoward at all?

After a good clean up I re assembled and oiled up resulting in the usual super smooth movement, strange but we'll worth doing.

I know people knock the old Myfords but while I agree they have their limitations, set up properly looked after they can do a good job!

Alan

Yes, looked after they will give years of good service. 80+ years out of my old M-Type so far. It pays to take the saddle off and give it a good clean once a year or so I reckon. All kinds of tiny bits of grit can get in there and build up.

The rubber apron on the leading edge of the saddle is probably the No.1 best mod you can make on a Myford, or any other lathe for that matter. But as you have found, still not 100 per cent elimination of grit.

My guess is that the carriage was not binding on swarf - which if that tight would probably scratch the bed.

I reads to me as if the gib screws had slackened very slightly, perhaps in passing over wear transitions, allowing the gib to move lengthways just enough for the screw-end and dimple chamfer to act as opposing wedges.

One symptom that might be noticed is that when using the rack hand-wheel, the carriage binds, then on reversing it moves freely but only momentarily before binding again.

Re-fitting the saddle and adjusting the gib would have cured the problem.

[This is an effect I have found on the main slide of my manual Drummond shaper, which is of course subject to strong, alternating forces. The slide would go slightly loose then suddenly too tight to move. I replaced some of the existing screws with longer ones, square-headed in keeping, but fitted with lock-nuts]

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Re the rubber sheet - I think I will adopt that for my lathe, and on the cross-slide as well as saddle front. I have already given the milling-machine a satisfactory replacement shield made from left-overs of butyl garden-pond liner.

Edited By Nigel Graham 2 on 17/04/2021 10:00:25

Building on what has been said above, would it pay the OP to dowel the saddle gib?

It may, but obviously using a separate hole, not modifying one of the grub-screw holes.

I've wondered if something similar would work on my shaper, but using a shouldered screw through one of the exiting holes, working into a close-fitting counterbore.

This is so it still pushes on the gib-strip but prevents that back-and-forth movement. Thinking about it though, this is on a gib I'd not fitted with lock-nutted screws, which may be the better choice.

Thanks for your thoughts. As I didn't find any obvious reason for the tightness I guess it could be a gib screw riding up in it's countersunk hole.

Just seems strange that in all these years it hasn't occured before? Anyway all back together and running great!

Alan

If you are removing the saddle then it's not much more work to remove and service the apron too. You could then take the opportunity to install a dowel to the gib. Here is mine:

Also visible in the photo is J A Radford's swarf-excluding ring on the half nut handle.

Thank you for that tip Ega - I'd not realised the handle can let swarf in.

Could be why that on my ML7 is sometimes very stiff and uncertain in action. (I know how it feels...)

However I have also found its stud tends to work loose in the casting, and that won't exactly help it work smoothly either.

JAR noticed that each time he removed the original cam there was "quite a lot of steel swarf jammed in the grooves". I think it would be fair to say that he worked his Seven fairly hard.

His comment was contained in a constructional article for an elaborate auto trip accessory for the saddle. To my mind some kind of trip is perhaps the one desirable feature that the Seven lacks.

A carriage trip would be desirable, but I don't think they were all that common even on larger lathes.

My Harrison L5 has no trip, though it has a spring-clutch on the feed-shaft that disengages once it's noticed the extra grunt necessary to continue the cut into the chuck.

On the other hand its feed-release trigger is very simple and much more responsive than its Myford equivalent.

My thought (for the ML7) would for a bar with an block set along it, that simply engages a pin protruding down from the boss on the half-nut handle.

Nigel Graham 2:

My comment has veered off-topic and I will reply to your interesting post via PM.

Edited By ega on 18/04/2021 14:49:07

Thanks for yours thoughts, as this was the first time I have experienced this in all the time I've owned it (35 years!) I don't think it can be a major problem, although at the next saddle service it could be considered.

Alan

EGA -

I have read your PM, and saved the drawing. Thank you very much.

I cannot reply there though. The PM function is failing to register both my reading your message, and to accept my reply.

Nigel

Nigel:

Thanks for telling me. Roll on the new site software!