Myford ML7 Cross Slide adjustment

[Alan CulpittParticipant @alanculpitt14314]

Hello, I now have my 66 year old Myford ML7 level and the switch and motor are working very nicely thanks to the generous advice I've had here.

I've tried machining some round bar using new HSS 8mm tools with….mixed results.

I think the problem may be that the cross slide isn't tight. I put a dial indicator on it and it was giving .010" movement perpendicular to the lathe bed and .002" movement parallel to the lathe bed.

I've found the bit in the book about adjusting the gib strips and i guess that takes out the parallel movement, but I can't figure out how you adjust the perpendicular movement.

I'd me most obliged if someone could point me in the right direction

[Alan CulpittParticipant @alanculpitt14314]

Myford ML7 Cross Slide adjustment

[Brian WoodParticipant @brianwood45127]

Hello Alan,

The gib strips close down on the taper built into underside of the cross slide and when set to give a decent slop free fit for the cross slide that should take out some of the vertical movement.

The bulk of it will come from the saddle lifting on the bed shears. That movement is controlled by two plain flat strips, one for the front shear, the other for the rear and these are clamped up to the underside of the bed shears. Shims are installed in the gap between the bed and strip, with holes through them to clear the bolts. They are in stacks that can have individual shims pealed away so you peal off a shim on both ends of each clamping strip, tighten the bolts and test for lift.

On an old lathe in your age range the lift you have seen could well be bed wear which will have hollowed out the bed over the most frequently used section and you may not be able to adjust it out completely. It may become a compromise on what you can tolerate and a free sliding saddle up to the tailstock

A badly worn bed can be both hollowed out and worn across the bed, it is a grinding job to put right.

I hope that helps

Brian

Edited By Brian Wood on 29/12/2020 18:44:08

[Swarf, Mostly!Participant @swarfmostly]

Hi there, Alan and Brian,

Alan, I suggest that you investigate the cross-slide handle and scale. Excess clearance there could give at least some of the 'perpendicular' back-lash of which you complain. Lock the cross-slide and then examine how much free angular movement there is in the handle & screw.

Look up under the bracket attached to the front end of the cross-slide and find a way to hold the shank of the feed-screw without graunching it. Then turn the cross-slide handle counter-clockwise to loosen it. From memory, the scale and the handle act as nut & lock-nut. They need to be adjusted so the handle & screw can together turn freely but with minimum slack. Again from memory, I believe there is a fibre washer in there, simple but effective.

If you don't have the Myford User Instructions booklet, have you down-loaded the parts lists and exploded diagrams from the Myford web-site?

Also, have a look at the modifications to fit thrust bearings in that part of the machine, see Arc Euro web-site.

Another possibility is wear in the cross-slide feed-screw and/or nut. Again, you can explore this by locking the cross-slide and waggling the handle. You might need to remove the top-slide to see what's going on.

Do, please, come back and tell us how you get on – it's very frustrating to make suggestions and never to hear the conclusion!

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 29/12/2020 19:15:45

[not done it yetParticipant @notdoneityet]

I read it as both being in the same horizontal plane but perpendicular to each other. Enough slop on the gib would allow a circular motion which may be mistaken for longitudinal movement. OP needs to realise that the gibs, on a 66year old myford may be set correct for the extremities of the bed (but loose in the normal working area), if the machine is worn… Hopefully not the case.

Edited By not done it yet on 29/12/2020 19:21:00

[HopperParticipant @hopper]

Gib adjustment can affect turning finish. But movement in the cross slide screw and nut (ie "perpendicular movement" ) is unlikely to cause problems as long as you allow for the backlash when setting the dial. That is, as long as you keep winding inwards, all slack will be taken up vis a vis the cutting load.

So if you want to adjust the cross slide to turn the job say 3 thou larger than the present setting, wind it out by 50 thou or so then come back to the mark on the dial that you want to set it to. Turning the dial inwards to make progressive cuts to gradually make the job smaller is just a straightforward matter with no backing-out required.

If you are using those sets of pre-ground HSS tools, they may be the cause of some problems. Some are better than others. Best to get a hold of LH Sparey's book "The Amateur's Lathe" and learn how to grind up a good knife tool for general turning.

[Alan CulpittParticipant @alanculpitt14314]

Hello all and thanks for the replys.

Just to clarify the perpendicular movement of the cross slide is in the horizontal plane not up and down (that's a good point I haven't measured that yet!)

I tried undoing the handle then tightening the micrometer scale up a bit to take out the backlash but I think the cross slide feedscrew is bent as the scale is not parallel to the endplate and goes tight then loose and then tight again as you turn the handle. I don't think there are any fibre washers in the assembly either

I was trying a very basic turning operation on a piece of round bar. I wound the cross slide in until it touched the metal and then traversed the carriage right to left. I could see the cross slide moving back and forwards

[Alan CulpittParticipant @alanculpitt14314]

I think you can just make out here the difference between the micrometer scale and the end plate

[Alan CulpittParticipant @alanculpitt14314]

I took apart the cross slide. The feedscrew is bent at the outer end were the handle and micrometer dial attach, its out by about .020" New feedscrew? With the feedscrew taken out and screwed into the nut on the cross slide, there is a good deal of run out. Do I need a new feedscrew?

[OldironParticipant @oldiron]

You could at a pinch straighten the feedscrew. Remove it and hold the threads in a vise use some protection for the thread. Put a close fiting pipe over the bent end and pull gently on the pipe to straighten out the bend. With a bit of judicial force you should get a decent result. Make sure that the bend is close to the vise and dont try to yank the bend out be slow & carefull. Slowly slowly catchee monkey.

Good luck. regards

[Nigel Graham 2Participant @nigelgraham2]

Thank you all Gents – especially Alan for asking in the first place!

A lot of useful pointers for me too.

My ML7 sometimes misbehaves on long power-feed cuts even at very fine pitch; and its finishing-cut control is dodgy, both most likely caused by wear.

Adjustment on the shears had not occurred to me, but something I ought look at on my ML7, in conjunction with studying the manual. Maybe a New Year's Day task after ending 2010 by ruining what I had been trying so carefully to make as accurately as possible. (By milling though, not turning.)

I am considering fitting the ARC-Euro modification Swarf Mostly suggests. I think Hemingway supply a similar one – I want to cross both companies' palms with embossed plastic anyway. I wonder if they also stock legible versions of the dials.

'.

My lathe has suffered from unwitting use in the past. Most seriously, the seller had bolted it to a heavy timber bench, which might have been OK if the chip-tray had not been a rough cast-iron " sauce-boat " of unknown original purpose, lacking any machined facings. The bed is also badly notched from hacksawing rather than parting-off work-pieces.

[Jonathan White 4Participant @jonathanwhite4]

This has been a very useful thread to catch up on.

Thank you

[Author]

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