Myford Super 7 cross slide gib adjustment

[NickM]

Hello Gentlemen,

I have just fitted a DRO to my lathe which required removal of the cross slide to machine the underside to take the magnetic strip. All went ( reasonably) well until trying to adjust the gibs. Try as I might, I cannot get the cross slide as smooth as it was before removal. I am getting a bit of binding as the tool tip approaches the centre-line of the chuck, such that I can't get a smooth feed by hand. If I loosen the gibs to give a smooth feed I get too much left-right slop. Your expertise would be much appreciated.

Thanks,

NickM

[dscott]

I have one of these as my Seventh lathe! I also took mine apart to check and polish and clean.
Unlike many other lathes the 7 has screws into the jib from above. To help mine I removed the screw which gives you instant
movement for the whole length. You can also bed it in better on a light tightening of the strip.
I prefer allan screws and nuts as you seem to get a better adjustment.

Best regards
David and Lily.

[jackrae]

If you have a surface grinder, cleaning up the gib faces can be advantageous but failing that lapping the faces on very fine wet-and-dry lying on a surface plate will ensure there are no 'pimples'. Ensure all sliding surfaces are spotless, then lubricate all before assembly. Gib adjustment requires a delicate feel and touch, setting individual screws for elimination of both nip and slop at all positions of the cross-slide. Nipping up the adjustment screw nuts tends to upset the screw settings requiring further adjustment to achieve correct setting.

[NickM]

Thanks for the replies. I don't intend to do anything to either the slideways or gibs because it was perfect before I took it apart. I realise that adjustment is an 'a bit at a time' process but I am respectfully asking for a bit more detail on the actual 'how to' rather than the principal.
The Super 7 has two gib strips on the cross slide, each held vertically by two set screws. Each gib strip then has three grub screws, no lock nuts like on the top slide; a short one at each end and a long one in the middle. I assume the short end ones are for adjustment, the long middle ones for locking the cross slide.
Adjusting the 4 end grub screws I can get a easy, wobble free feed on all the movement of the slide, except the last bit as the tool tip approaches the centre of the work piece where it starts to bind up.
Where should the cross slide be when adjusting the gibs, front of travel, mid travel or back of travel?
Should the 4 set screws be loose or tight? I can't see they do much except to stop the gib strips falling out.......

[uuu]

Just nipped up, so the grub screws can still move the strips.

Wilf

[goldstar31]

Is the top of the bring table flat?

Norman

[NickM]

Nov 10, 2019 16:08:50 GMT goldstar31 said:

Is the top of the bring table flat?

Norman

Not sure what you mean?

[simplyloco]

Nov 10, 2019 17:23:42 GMT NickM said:

Nov 10, 2019 16:08:50 GMT goldstar31 said:

Is the top of the bring table flat?

Norman

Not sure what you mean?

I know nothing about Myfords, but is there an 'o' in 'b*ring'?
John

[goldstar31]

You have a boring table. That's the funny thing with slots in and you are having problems.
So run a straight edge along it length ways please and tell me whether is is flat- flat.
Regards
Norman

John

I have macular generation hence not being able to ensure my typing.

I am almost blind in my left eye and have regular hypodermics stuck in my right one.

However, I have raised an interesting question which might assist the guy.

I've been in Myford Super 7's a very long time and -well, let's see what his answer is, eh?

Regards

N

[simplyloco]

Nov 10, 2019 18:16:03 GMT goldstar31 said:

You have a boring table. That's the funny thing with slots in and you are having problems.
SNIP
I've been in Myford Super 7's a very long time and -well, let's see what his answer is, eh?

Regards

N

Norman

No aspersions were implied or cast. It was a light hearted way of possibly pointing the OP in the right direction!
John

[NickM]

Hi Gents,

Sorry Goldstar, I genuinely didn't know what you meant; I didn't know it was also known as a boring table, the manufacturers of the DRO refer to it as the cross slide.

I haven't checked that it is flat because I am trying to remedy a problem that has arisen since I removed the table/cross slide to fit the DRO. Before I did that the feed was silky smooth and everything was tickety-boo.

So......

I wondered if I had possibly fitted the front gib strip to the rear and vice versa so I took the slide/table off again to see. The clever people at Myford made the two gib strips different lengths so it is impossible to get them the wrong way round.
I gave it another good clean (to be honest it was pretty clean to start with) re-assembled the gib strips but this time I lathered everything with loads (and I mean loads) of slideway oil, then re-assembled the slide/table to the apron(?).
I left the 4 vertical set screws a quarter of a turn loose and then adjusted the 4 grub screws until they were just tight on the gib keys. At this point the table/slide would not move.
I then backed off the grub screws 1/6th of a turn (one face of the allen key) and tightened the set screws just enough to stop the gibs moving.
Ta-Dah! Silky smooth all the way across the travel and not a trace of wobble! I am now one happy bunny!

Ain't oil a wonderful thing?

Thanks for your efforts, regards,

NickM

[goldstar31]

I wondered whether you had released some stresses in what is accepted as a very weak design of boring table and perhaps, it had been pulled out of shape with the wrong use of tee bolts.

So I'm glad that - you didn't hit the same problem as I got when I bought a Super 7 B years ago. Unfortunately, I can't read George Thomas's Model Engineer's Workshop Manual but I'm convinced he makes refrence to it as well as pinning gibs and using round ends on gib screws.

Oddly, I was given a top slide which had had its spigot broken. Yes, it isn't isolated.

Regards



Norman

using Seeing AI on my Ipad

[dscott]

On my home made lathe based on a Myford I went for mild steel for the vee and flat bed.
Cast iron for the saddle. and a rough machined mild steel cross slide which was heated to red
and slowly let cool in the Schools furnace. Then surface ground.
No trouble from it for the last 40 years. 1977 when I did it all.
Being mild steel I can bolt stuff down very tightly which is useful.

The machine is now permanently set up for cutting slots in forks and the slipping belt clutch
is on its second Z section belt.

David.

[goldstar31]

Thanks David for the information.

For those who have a copy of Martin Cleeve's Screwcutting in the lathe will note that his ML7 has no 'peg' to attach the topslide. He had the Big Bang and Myford( then) made a steel cross slide for him.

The previous owner of my S7B seems to have run it on mahogany dust. Well that was what was in the gear box. Anyhow, the two gears to the box which can be reversed were stripped. It's quite a pricey thing

Perhaps one reason for for their non standard tee slots???

Norman