ML7 : To convert, or not...

[Doddy]

I'm a little confused now with what I actually have. I fear a Frankenmyford (remember, it was one of the last ML7s off the production line, according to the serial numbers on lathes.co.uk)



The link to the conversion site that John provided at the head of this thread (bottom of https://cncyourmyford.com/modifications-needed/), suggests the extra bolt-hole on the left of the saddle is that of a Super-7 saddle, not the ML7. And the bore for the cross feed screw is 1/2"

[Neale]

If it was a late model ML7, was it actually an ML7R? I have a feeling that at some point the more basic ML7 adopted some bits of the S7, presumably in a vain attempt to keep manufacturing costs down by standardising on parts. In the same way, you cannot trust all threads on a single machine to be from the same family and every bolt needs checking if you need to replace or whatever - might be BSF or metric.

[Doddy]

Agreed with standardisation (sweeping the factory floor for bits) to build up the lathe. No, not a ML7R, and ironically it has the clutch (one significant difference between the 7R and the S7).

[Doddy]

I actually made a 64 slot disc with slot opto sensors. https://photos.app.goo.gl/66KmdtD7TzUziNih7 you have to be able to move the sensors around to get the correct sync

edit: if I was to do it again I might have used a rotary encoder (it would have to be low count with a PP) But its been working for at least 3 - 4 years

https://photos.app.goo.gl/JH1GWVQbhxe6Z6Yo7 This is it simulating an arc that I needed to put on a roller for my belt sander

Clive, if you don't mind I'll cross-reply here to avoid stealing too much(!) of th thin-client thread. This is likely to become something of a conversion thread.

Cheers for the photos - very interesting and useful. I do, and don't like your approach on the saddle - it's a nice design but for my purpose I think it protrudes somewhat into the user space (I've a 13' by 7' shed so have to tip-toe between benches and lathe). But I agree with the two MPGs (I've got one knocking about somewhere) - think that's a necessary solution to keeping a semi-manual mode on the lathe.

The spindle encoder?, I know mach3 needed 1ppr, heard that linuxcnc can use more, effectively. Your experience is that 64ppr is a good number?, it's as good a number as any I support. The quadrature encoding is usually easy enough - easier if you can get a twin-sensor coupler with a pitch smaller than the hole gap space, if you're not worried about symmetry on the A/B signals. That side of things doesn't worry me but good to see that you took the same approach as I'm thinking for the spindle mount.

This, just a placeholder for me to ask more daft questions as I move through the build.

[Clive S]

Not sure what you mean by this

easier if you can get a twin-sensor coupler with a pitch smaller than the hole gap space

re the 64 pp rev you you want it for threading then you won't be running the spindle fast. I think I have tested it at about 600 rpm. 64 was just the number I drew the disc in cad. you could also just use one sensor on the disc and another on a tooth some where as long as it is 1:1 with the spindle.

When I change the motor I might have a go at CSS (constant surface speed) with a VFD for the fun of it.

With the 3 sensors like mine it could do rigid tapping. Although I have never done it on the lathe.

Edit re the mpg's I used the same mpg's between the mill and the lathe with the same control box with 5 drives in it and one mesa card (using only one machine at a time)

[Doddy]

Not sure what you mean by this

Something like the TCUT1800X01,



This has 4 detectors at differing X/Y positions capable of quadrature encoding with index pulse.

Now that I've bought 10 of the little darlings I think I might need to upgrade my soldering iron. Or microscope. Or both.