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  1. #11
    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.

  2. #12
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 6-7 years. Has a total post count of 589. Received thanks 101 times, giving thanks to others 21 times.
    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).

  3. #13
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 6-7 years. Has a total post count of 589. Received thanks 101 times, giving thanks to others 21 times.
    Quote Originally Posted by Clive S View Post
    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.

  4. 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)
    Last edited by Clive S; 08-10-2019 at 05:23 PM.
    ..Clive
    The more you know, The better you know, How little you know

  5. #15
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 6-7 years. Has a total post count of 589. Received thanks 101 times, giving thanks to others 21 times.
    Okay, mixed thoughts at the moment. I'd started with the Jeffree conversion for the Z-axis some time ago, and over the last weekend knocked up a more compact X-axis...

    Z:
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    X:
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    Just for confidence and a break from the mechanics I've slaved up an old controller box (first pic) and an old XP box that had the driver for the ethernet controller for the control box from storage.

    It proved the concept, but I'm somewhat puzzled by the noise from the Z stepper...



    X is as quiet as you might expect. Z is bloody awful. I've tried fiddling with the stepper driver with micro steps from 1/2/4 and the current from 3.2A through 5A. It just sounds awful. Part of this is transmitted through the bracket onto the lathe bed, but unbolting the motor from the frame its still not great. The motor has been in situ for the last, maybe couple of years, with light manual use of the lathe (so powered traverses using the lathe gearbox) into an unpowered motor, with stripped ends to the motor wiring that may have been shorted from time to time (just rolled up and stowed under the motor bracket). To me, it sounds very mechanical and internal to the motor. I do have a smaller motor available to replace this... in fact I should have an identical one but not seen that for a while. Whilst I tidy up the shed a bit has anyone heard a stepper sound quite so bad - is it likely goosed?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  6. #16
    mekanik's Avatar
    Lives in Barrow in Furness, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 9-10 years. Has a total post count of 672. Received thanks 87 times, giving thanks to others 133 times.
    Sounds like it's the gearbox making the noise, can the leadscrew be disconnected or gears moved to a neutral position, i don't have a gearbox and can just move the quadrant out of engagement.
    Mike

  7. #17
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 6-7 years. Has a total post count of 589. Received thanks 101 times, giving thanks to others 21 times.
    Nah, I've pulled the final gear from the gear chain - it's not that. I've also pulled the belt from the motor and the motor still grinds under power. Removing the motor from the mount and it still feels aggressive under rotation, but it's the coupling of the motor to the mount that generates the awful noise. Perhaps some weird harmonics.

    Apologies, btw, for the 80's music in the background. That's my sanity aid :)

  8. #18
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 6-7 years. Has a total post count of 589. Received thanks 101 times, giving thanks to others 21 times.
    There comes a point in your life where you say "sod it!" to playing with backlash, and decide to go for it.

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    So, removed apron and acme screw - and you know what?, it all became easy from that point. Also, removed the top slide with a fixed tool post (I don't see much point for CNC and it removes some weakness from a rigidity point of view) - undersized to allow me to change my tooling from 8mm to 12mm shanks.

    I can slew the saddle from spindle nose to end-stop easily by hand. I need another pulley (on order) and to measure a new belt, but I think this was a necessary way forward.

    Will recover to an operative state when I get a belt and take it from there.

    EDIT:

    Now, where to get a swarf guard for the screw???

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  10. #19
    Get thee to a vacuum cleaner spares supplier and buy a couple of spare Dyson hoses, they are very collapsible.

  11. #20
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 6-7 years. Has a total post count of 589. Received thanks 101 times, giving thanks to others 21 times.
    I like that idea, especially as there’s a dyson repair shop around the corner!

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