Myford ML7 - Convert from Imperial to Metric

Hiya

I hope this hasn't been done before but I coudn't find it.

As the title suggests, I would like to convert my new lathe to metric.

Has anyone done this ?

Hi Chris,

You would be looking at replacement feedscrews and nuts for crossslide and top slide, plus the dials of course. For screwcutting metric threads, a new leadscrew and clasp nuts, plus a leadscrew handwheel, if your lathe has one, plus the relevant changewheels.

You might be better off looking at a cheap DRO setup - then you could switch between metric and imperial as you require?

James

Edited By James Burden on 06/07/2012 12:45:20

Edited By James Burden on 06/07/2012 12:47:13

That's not a bad idea, what would one cost whould you think ?

Aren't the leadscrews and clasp nuts all imperial, regardless of the lathe's metric/imperial status?

Martin.

I don't see the point. You can cut metric threads with the appropriate change wheels. When turning to a metric size set your digital vernier to the (metric) size you want. Zero it, switch to imperial and it will tell you directly how many thou to take off the diameter.

You can make a cheap DRO setup from digital verners as well.

Russell

Wish I knew Martin

For the leadscrews, if you must you could make up new dials, on my Taiwanese lathe they are calibrated in both, but digital would be the way to go, and a metric convertion gear for screw cutting, the only thing is the screw cutting dial becomes redundant on metrics, but not a great problem. Ian S C

Do you know what the wheels I would need are, I think it's 2 x 21 tooth but I'm not sure

Just in from Myford by email

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To convert your ML7 lathe to metric, you will need:

Metric feedscrew & nut for top slide

Metric feedscrew & nut for cross slide

Metric leadscrew handwheel

Metric Tailstock Barrel

Metric micrometer dials (for the cross AND top slide)

Oh and here is the change wheel info

Link

As I do 100% metric, for my larger Kerry 1124 lathe, I just have some 0-25mm dial indicators on the cross slide and the top slide.

One of these days I'll DRO it, but it's done at least 10 years this way just fine.

The dial indicators are held on by strong magnets taken from older computer disc drives.

I only cut metric threads on it, and the change wheels for metric were supplied.

It's quick and easy - think about doing the dial indicator route for now.

Another JohnS.

Any chance of a picture of what you have done John

DRO the slides, digital calipers cost a tenner, and get the changewheel setup for threading purposes

Any chance of a picture of what you have done John

Not until tomorrow at least.

But, cross slide:

- magnet to apron, square alu section horizontal on magnet.

- dial indicator on square alu section, plunger pointing to centre of lathe, along cross slide, tailstock side (behind toolpost).

- rod, through 2 bushings and thumbscrew so it is adjustable, on cross slide, on the tailstock side of the cross slide, pointing in/out, across lathe axis.

- both dial indicator and this rod are "horizontal". dial indicator rests on end of rod. Thumb screw on rod allows for adjustment. Rod resides permanently on cross slide, dial indicator comes off if required.

compound rest:

- dial indicator on aluminum square section, mounted so dial is flat, and plunger facing headstock;

- "rod" mounted on small magnet attached to base of compound rest, adjusted to hit plunger.

So, both dial indicators are horizontally mounted, dials facing up. Both plunge onto rods on cross slide, or compound rest base.

Because of the magnets, if there is a "crash", the dial indicator comes off with magnet from lathe; so far no issues.

I realize that this is an 1124 lathe; 5-1/2" centre height. However, I have been known to do similar to my Emco Compact-8, so you should have room on a Myford.

Yes, I have only 25mm movement, but that has never been an issue so far.

Yes, a DRO would be better. But the price was right, and it's been great working in metric on this old lathe.

Another JohnS

Posted by John Alexander Stewart on 06/07/2012 15:58:21:

Any chance of a picture of what you have done John

Not until tomorrow at least.

But, cross slide:

- magnet to apron, square alu section horizontal on magnet.

- dial indicator on square alu section, plunger pointing to centre of lathe, along cross slide, tailstock side (behind toolpost).

- rod, through 2 bushings and thumbscrew so it is adjustable, on cross slide, on the tailstock side of the cross slide, pointing in/out, across lathe axis.

- both dial indicator and this rod are "horizontal". dial indicator rests on end of rod. Thumb screw on rod allows for adjustment. Rod resides permanently on cross slide, dial indicator comes off if required.

compound rest:

- dial indicator on aluminum square section, mounted so dial is flat, and plunger facing headstock;

- "rod" mounted on small magnet attached to base of compound rest, adjusted to hit plunger.

So, both dial indicators are horizontally mounted, dials facing up. Both plunge onto rods on cross slide, or compound rest base.

Because of the magnets, if there is a "crash", the dial indicator comes off with magnet from lathe; so far no issues.

I realize that this is an 1124 lathe; 5-1/2" centre height. However, I have been known to do similar to my Emco Compact-8, so you should have room on a Myford.

Yes, I have only 25mm movement, but that has never been an issue so far.

Yes, a DRO would be better. But the price was right, and it's been great working in metric on this old lathe.

Another JohnS

John, Did you get a chance to take a couple of pictures ?

How can you fit a metric handwheel to an 8 tpi leadscrew ?

And this from Myford ???

John S.

To be honest John, I don't know.

Hence the posting and asking questions.

It was direct from Myford

Chris

I have a metric super 7. The X-slide and topslide have 2 mm pitch feedscrews. The T/S has a barrel with a mm scale. As I found out to my cost one day, the leadscrew is still 8 tpi! 8 tpi is 3.175 mm, so the scale on the handwheel is calibrated in mm up to nearly 3.2 then goes back to zero! As it doesn't have a zero-settable thimble the graduation is next to useless. Even if it did it would only be useful up to 3.175 mm.

For metric screwcutting, Myford provide tables of approximate ratios that are good for some common metric threads which are just fine for shortish fasteners but obviously if you want to make a metric measuring screw they aren't and you need a 127 tooth change gear (which can only be fitted with some difficulty). However since almost all the threads we cut are for fastening the approximations are not a problem since the errors are almost certainly less than the machine accuracy anyway.

I have converted to CNC so the imperial L/S isn't an issue, it's all sorted out in the software.

J.

John, I have the same sort of fixed scale on the ML10, what I do is set the Lead screw scale at '0' and then feed in the top slide and tool to touch the work and then I can advance the Lead screw using its scale.

I appreciate the problem of the odd markings of the scale against the lead screw pitch but a '0' mark is always useful when working repetition jobs.

I have wracked my brains to see if I could make the lead screw scale a, 'slipping scale' but it would mean a complete re-work and making of a new mounting boss.

The problem is getting the scale off as a ring but then mounting it on another part to allow 'slipping'

Clive

I'm begining to wonder if it is worth the trouble to worry about it.

Perhaps change the gearing on the lead screw but leave the top and cross slide as they are and fit a DRO of some kind.

Thanks for all your replies by the way.