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]

'

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

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.

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.

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.

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

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