Myford Super 7 – Cross Slide Problem

[Alex TwiggParticipant @alextwigg67363]

Hi,

I've just bought my first lathe, a Myford Super 7. When I inspected it before purchasing everything was great there, and the guy had turned something with it proving it was good.

I've just taken delivery and there are some glaring issues that I hadn't noticed before. I know nothing about lathes except how to use them.

The video shows the issue. The cross slide has play in it. It's not backlash, it's a physical movement of the Y axis of the cross slide. The carrier and the bed are solid, but then the leadscrew for that axis moves loads.

Also the spindles with the numbers on are fixed so I can't set them to zero.

Any help is appreciated. I'm phoning the guy tomorrow or the day after and talking but was wanting a little bit of advice so I can suggest to him.

I don't think it's his fault but hopefully someone has some ideas on possible fixes.

Many thanks

Alex

[Alex TwiggParticipant @alextwigg67363]

[JasonBModerator @jasonb]

Alex you may have your video set to private a sit will not view.

[Alex TwiggParticipant @alextwigg67363]

Posted by JasonB on 22/05/2019 06:50:30:

Alex you may have your video set to private a sit will not view.

Thank you Jason. Just sorted it!

[Michael GilliganParticipant @michaelgilligan61133]

Alex,

I would first check the screws, item 31 **LINK**

https://www.myford.co.uk/acatalog/info%2d3576%2ehtml

MichhaelG.

[Phil BoylandParticipant @philboyland37326]

I wouldn't panic just yet, highly likely it will just need some of the screws adjusting.

Using the Link above, start with screws 3, 9 and 11 and see how you fare. 9 & 11 are shimmed (item 6) and the bed may have worn enough to warrant some play which can be overcome easily with thicker shims. Myford do them at a price, or you can buy a selection of thin brass sheet* cheaper and do it yourself. Let us know how you get on.

*  I did this on mine buying a pack of 1, 2, 5 & 10 thou

For the dial, undo screw 39, remove the handle and dial and give it all a clean, its probably just gummed up or been done too tight. It just spins on the cross slide screw so nothing to go wrong as such.

 

 

Edited By Phil Boyland on 22/05/2019 08:01:32

Edited By Phil Boyland on 22/05/2019 08:06:35

Edited By Phil Boyland on 22/05/2019 08:08:29

Edited By Phil Boyland on 22/05/2019 08:08:47

[HopperParticipant @hopper]

Posted by Alex Twigg on 21/05/2019 22:47:25:

The video shows the issue. The cross slide has play in it. It's not backlash, it's a physical movement of the Y axis of the cross slide. The carrier and the bed are solid, but then the leadscrew for that axis moves loads.

Check too that the cross slide feed nut is not loose on its mountings. And that the graduated collar and feed handle arrangement are nipped up to eliminate back and forth movement of the feedscrew where it mounts.

Does look like a bit of movement on your video, but it's not unusual for a used lathe to have 15 or 20 thou of movement there. It does not particularly affect normal turning operations as long as you remember to wind the cross slide out past the backlash and reset to the correct mark if wanting to reduce depth of cut etc. Even new, there will be some slack there and this procedure need to be followed.

ArcEurotrade has a kit, and fitting instructions on thier website IIRC, for a roller thrust washer to go between the cross feed screw and its mounting to eliminate all slack there. (But there will still be some slack in the nut etc as per usual.)

[Neil LickfoldParticipant @neillickfold44316]

Item 39 is a screw collar and has a little grub screw to secure it on the cross slide screw. This sets the back lash of the cross slide screw itself. If this comes loose , then the effective backlash on the cross slide becomes huge. Undo the grub screw about 1/2 turn. Then tighten it against the casting until the leadscrew does not turn. Then undo it a little bit , so that the screw can rotate. Do up the grub screw. If this clearance is correct, then it could be else where , like the screws of the casting being loose or the leadscrew nut screws are loose.

Neil

[Martin KyteParticipant @martinkyte99762]

Hi Alex

I would begin by removing the cross slide lead screw. Referring to Assembly drawing K undo the two screws (Items 13) holding the leadscrew support bracket to the slide and unwind the leadscrew out of the nut.

You will see that the leadscrew is held to the Cross slide end plate by item the adjusting collar (Item 19) which screws onto the threaded portion of the lead screw and is retained by a gub screw. Loosen the grub and it will be possible to adjust the end float of the lead screw in the end bracket by initially tightening until the leadscrew becomes stiff to turn and then backing off slightly to achive free movement without play at which point the grub may be tightened and the fit rechecked. It will obviously pay you to fully disassemble, clean and lubricate the assembly prior to adjustment.

With the leadscrew out of the cross slide the slide itself should be slid of the saddle and the ways cleaned up and relubricated. Refit the slide and adjust the gib screws to acheive free movement with no trace of shake which is so much easier to do with out the leadscrew as one can move the slide too and fro with simple hand pressure.

Refit the leadscrew by winding it into the nut ALL the way in untill the end plate meets with the cross slide. The two screws may now be refitted with the confidence that the leadscrew is in good alignment.

Have fun

regards Martin

[roy entwistleParticipant @royentwistle24699]

Hopper I think you'll find that the kit you refer to is only for the ML7 not the Super 7

Roy

[John HaineParticipant @johnhaine32865]

With an ordinary screw there will always be a little bit of play equal to the backlash. If the cross slide (conventionally the X axis) is very free moving within that then the gib may need adjusting, this isn't straightforward on the S7, but there are no shims to worry about (they are on the carriage/bed interface).

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Martin Kyte on 22/05/2019 08:53:37:

Hi Alex

I would begin by removing the cross slide lead screw. Referring to Assembly drawing K undo the two screws (Items 13) holding the leadscrew support bracket to the slide …

.

Is that [K] a different drawing to the one that I linked, Martin ?

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 22/05/2019 07:23:51:

Alex,

I would first check the screws, item 31 **LINK**

https://www.myford.co.uk/acatalog/info%2d3576%2ehtml

MichhaelG.

.

… and then the screws, item 22

MichaelG.

[ too late to edit ]

[Martin KyteParticipant @martinkyte99762]

Posted by Michael Gilligan on 22/05/2019 10:05:58:

Posted by Martin Kyte on 22/05/2019 08:53:37:

Hi Alex

I would begin by removing the cross slide lead screw. Referring to Assembly drawing K undo the two screws (Items 13) holding the leadscrew support bracket to the slide …

.

Is that [K] a different drawing to the one that I linked, Martin ?

MichaelG.

It does seem to be, where did you find it.

K is here **LINK**

Perfectly reasonable suggestion to check the screws you point out. Just thought I would sketch out the proceedure for setting the slide up.

regards Martin

 

Edited By Martin Kyte on 22/05/2019 10:54:38

[Nick HulmeParticipant @nickhulme30114]

Posted by roy entwistle on 22/05/2019 09:30:04:

Hopper I think you'll find that the kit you refer to is only for the ML7 not the Super 7

Roy

It's easily done on a Super 7 if you visit and talk to your local engineering bearing supplier.

[Nick HulmeParticipant @nickhulme30114]

Posted by Alex Twigg on 21/05/2019 22:47:25:

The video shows the issue. The cross slide has play in it. It's not backlash, it's a physical movement of the Y axis of the cross slide. The carrier and the bed are solid, but then the leadscrew for that axis moves loads.

That is backlash, that the gib strips aren't tight enough to stop you moving the slide by hand doesn't change the fact that it's slack in the axis drive system.
Strip it, clean it, lube it and assemble it and adjust it correctly and check it again.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Martin Kyte on 22/05/2019 10:50:49:

Posted by Michael Gilligan on 22/05/2019 10:05:58:

Is that [K] a different drawing to the one that I linked, Martin ?

MichaelG.

It does seem to be, where did you find it.

K is here **LINK**

.

.. on the Myford website [as per my link]

Strange isn't it ?

MichaelG.

[Alex TwiggParticipant @alextwigg67363]

Posted by Nick Hulme on 22/05/2019 12:51:05:

Posted by Alex Twigg on 21/05/2019 22:47:25:

The video shows the issue. The cross slide has play in it. It's not backlash, it's a physical movement of the Y axis of the cross slide. The carrier and the bed are solid, but then the leadscrew for that axis moves loads.

That is backlash, that the gib strips aren't tight enough to stop you moving the slide by hand doesn't change the fact that it's slack in the axis drive system.
Strip it, clean it, lube it and assemble it and adjust it correctly and check it again.

Talked to the guy who sold it. He came over and looked at it. I think it is backlash. He said he hand't stripped it down so, I will need to do it and get it all sorted. Not to worry. Might machine some parts for it at University. We shall see. Thank you to everyone for helping. If I'm going to strip it down then I can sort all the points people have made out. Thank you all for this. I will post a follow up on it, especially if I make some parts to sort out backlash. I've got a lot of learning ahead! Thank you again to everyone for all the great responses!!!

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