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  1. #1
    Hi,

    After recently moving to the uk I found myself without availability to a proper machine shop for the first time in years. My garage is also quiet limited so I had to chose wisely on what machine to get. Finally settled on a Hobbymat md65 with milling head attachment that I picked up the other week.


    I really like the machine so far and Iím now exploring options when it comes to either just putting DROs on it or potentially CNC converting it. Iím an engineer working most of my days in CAD so Iím not foreign to the CNC concept but have never owned/built a CNC machine myself before. Anyone converted one of these machines before? Find plenty of threads where people are looking to do so but none where it has actually been done. I guess like this one so far.

    Is it a must to convert from lead screws to ball screws in a conversion? Any guidance on the strength of steppers needed?

    Iíve found a few 3-axis kits avoiding 24v tb6560 as Iíve read many horror stories about them. What else should I be looking out for?
    https://www.ebay.co.uk/itm/392747498521

    Many thanks for your help :)


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  2. #2
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 16 Hours Ago Has been a member for 6-7 years. Has a total post count of 1,127. Received thanks 160 times, giving thanks to others 52 times. Referred 1 members to the community.
    I'm probably talking balderdash here, but this is my view.

    Firstly - I've no experience of this lathe or milling attachment, which makes this reply even less relevant. But I have CNC'd up a manual mill, and manual lathe.

    I would question firstly your motivation for CNC'ing the lathe - the dominant part of this. Lathes to me are very organic machines - very suited to the manual dexterity of a good operator, and you lose that quickly when you CNC the bugger. Now, my motivation was largely along the lines of "because I can" - and the activity was more one of a past-time than because I needed the lathe to turn out a hundred widgets an hour, and because I haven't the patience to apply the care and finesse needed to turn parts well. But, in that sense the project achieved it's objective. Compare that to a milling machine where much of the work is very man-draulic, a mill is a more obvious candidate in my eyes for conversion. But, your machine is first and foremost a lathe.

    Your first problem is understanding what you're going to do in terms of retaining manual control - if you want to do this, you're going to have to compromise on things - e.g. having clutch assemblies to disconnect your drive motors, working out how to couple (or decouple) the saddle from the drive train (a split-nut system works on a trapezoidal screw but not on a ball screw!), Do you go all motor-drive, and introduce mechanical hand-dials to drive the motors? Do you need the top slide (no use on the CNC side, but very useful for a manual lathe). And how are you going to synchronise the spindle to the lead-screw? (removing the gear train, which does this for manual - versus motor driven lead-screw for CNC) - essential for screw cutting. I think you have to silence any inner demon you may have with the CNC/Manual nature of the lathe before going too far.

    Lead-Screw vs Ball Screw - it depends. The trapezoidal lead screw will, by design, have backlash. Typically though, with turning, the majority of cutting operations are performed either in one direction on each axis - or can be. In which case you can accommodate small orders of backlash in software.It could be more challenging if your machine is sloppy. Then, back to the whole manual/CNC operation again - you probably don't want a ball-screw if you're trying to retain manual control (you need to maintain torque on the screw to avoid the screw unwinding in response to cutting forces).

    If you're looking to CNC both lathe and milling attachment, the case for replacing the screws is more compelling, but in doing so you're moving away from a recovery to manual operation.

    On my ML7 I decided to forego any manual operation (other than through MPG controls), which made my direction very easy. Replace the lead-screw with a ball screw with a hard-mount onto the saddle. Remove the top slide, motorise the cross slide, and replace the spindle with a servo under step/dir for spindle control (naughty) - previously using a VFD/3-phase motor and spindle encoder, but that was clunky.

    Stepping back, and looking at the MD65, and particularly with a milling attachment, I'd wonder if it's a good machine to modify. It's a small machine, with limited capability. The Boxford Duet's already do pretty much what the MD65 can do at a similar footprint, but affordability may be a different question. If you do adapt the MD65 you need to understand the limits of the machine and what it will be able to achieve. Of course you could, like me, be keen to pursue the conversion on a S&Gs' basis - crack on, but I'd suggest thinking carefully before you start this to understand if you're prepared to spend on the conversion, and whether the resulting Frankenstein will match your needs.

  3. #3
    I'm pretty sure the first Conect Cadet cnc lathes where based on an MD65 , before they started using a Myford ML10 as a base machine.
    If you can find photos or info on these it may give you food for thought or inspiration !

  4. #4
    I had the mill and the lathe. 2 times. Each time thought to CNC them and each time decided against it.

    Not a square column, no place for the nuts, etc. I have seen a video of someone CNCed the lathe. These are good machines for the size, but no good to make them CNC
    project 1 , 2, Dust Shoe ...

  5. #5
    Thanks to you all for your input. To be honest the CNC would be largely for the mill and for the ďbecause I canĒ factor, none of which is perhaps very good. Might need to take a step back and ask myself why as you all suggest.

    Turned my first piece of steel on it today. Very impressed on the performance of this small machine so far. Have yet to try it as a mill though which I think is where it will struggle


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