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  1. #1
    Though I'd start a log to have somewhere handy to put random notes etc...

    Copying from [ame="http://www.mycncuk.com/forums/showthread.php?t=1030"]my intro posting[/ame] with a few updates:

    Plan is to add a removable CNC sub-table (X-Y) to my existing milling machine, a Deckel FP1. The CNC table would simply be clamped to the existing worktable. As the vertical head is easily removable on this machine I plan to make a new head which will incorporate the Z axis slide.

    Beauty of this plan is that there is no need to create floor or bench space for a new machine and in a few minutes of heavy lifting (ideally crane assisted) the mill can be back to its normal manual use, and the CNC bits tucked under a bench. Or for simple profiling I could just use the X-Y CNC subtable with manual Z and existing machine spindle if I can't be bothered changing over the vertical head.

    As the mill also has a DRO, this can effectively be used to add travel i.e. if I have a Y axis travel of 150mm on my CNC subtable then that can be effectively doubled (at least some of the time depending on the part) by CNCing the frist half, then using the milling machine's original Y slide to move exactly 150.000mm via the DRO and then do the rest on CNC, no reclamping required. Assuming that it's all aligned perfectly... which may not be entirely trivial.

    If it doesn't work out as an add-on (I suspect it may just be too much hassle changing it over and aligning it each time) all I have to do is clear some space (ha!), make up a beefy frame, and bolt on all the bits to make a stand-alone CNC mill.

    Will be machining mainly lumps of alloy I think, plus doing random bits of engraving.

    Anyway what started me actually getting on with it was more or less impulse-buying this on ebay:

    Slide/ballscrew assembly on Ebay

    Got it a few days ago and looks pretty good, slides are in great shape. Ballscrew (16 x 5) is rolled and has a few tiny bits of pitting but it'll serve for now.

    Current plan is to use that as an X axis. It will sit on 400 mm slides (just bought from Ebay USA - he's got some more BTW:

    Slides on US Ebay

    (Cheaper than any UK ones I could find, and even 15mm Hiwin stuff new is almost twice the price. Incidentally German Ebay also has loads of slides which seem often cheaper than UK - search for "Linearführung". Also some cheap alu profile e.g. this seller)

    Anyway those NB slides will sit under the X axis Airy points on a 20mm+ thick alu plate which will be the machine baseplate (approx 350 x 450). Will be trying to find an affordable bit of flat tooling plate type alloy for this as my milling machine only has 250mm or so of travel so I can't easily accurately machine flat the 400 mm Y slide bases.

    Ballscrews for Y and Z are yet to acquire. Z slide blocks (or may use 25 mm rails) also still to acquire. Not sure either yet what sort of spindle to use - will probably build one around a straight shank ER32 collet chuck. Not sure re spindle motor either - will see what comes along.

    As for the electronics I'm planning on getting the 3Nm/5A system from www.diycnc.co.uk as everything I've read has been super positive about his stuff and I'd rather spend a few quid extra and get the UK support than buy drivers etc from China.

    Power supply will be three 350W computer power supplies (free from a mate) in series for 36V, 20ish A :-). More than required most likely... but price is right. Will build in some nice analogue panel meters to show output.

    All of the electrical connections (steppers, limits, e-stop, spindle) will be plug-in via XLR or similar plugs so once unplugged, the control box and computer can just sit under the bench too. Have yet to decide on controller software and CAD/CAM options.

    Will use belts to gear down the motors by 2:1 or so (assuming other ballscrews also end up 5 mm pitch). Looking like 220 mm X travel and 200mm or so Y travel currently.

    ***********

    My general way of working is to get all the various bits and pieces required in my hands and only then do a detailed design in CAD. This lets me scrounge around for the cheapest bits and bobs then adapt the design to suit.

    This log will be a bit random note form... will do some pics later too.

  2. #2
    Latest additions - got 4 x 15mm Hiwin carriages cheap off Ebay USA and a 500 mm C7 ballscrew from Marchant Dice via Ebay auction - £43 + post ...

    Also got the steel enclosure as per here to house the electronics.

  3. #3
    And BTW you can download all of the Hiwin rail, carriage etc CAD files in 2D and 3D for free here.

  4. #4
    80servo? Yup he's got loadsa nice kit and pretty good prices IMHO. And he's one of those sellers who never sleeps and answers emails ridiculously fast...

    Just had the DIYCNC kit delivered and also the MD ballscrew - looking forward to playing with it all after work!

  5. #5
    Just got four Hiwin 15mm blocks from 80servo (for Z axis) - took just a week to get here, and no customs hit. Brand new for about £15 each all in. Will order some rail from MD at some point...

    Still waiting for the Y axis slides also from him...

    Also, anyone needing XLR connectors should check out this UK ebay seller. Just got a load off him - really nice quality and he does deals and combines shipping

    Picking up computer PSUs from my mate tonight - turns out 200W not 350W each but should still be more than ample with three in series.

  6. got 4 x 15mm Hiwin carriages cheap off Ebay USA
    Are they the MGWs ? I was after them myself for my bed-top cnc lathe conversion. ;)

  7. #7
    Mmm, must be different ones, mine are just HGH15C carriages: linky.

  8. In that case, I'll off the fatwa ;)

  9. #9
    Minor progress last night - opened up one of my donated Dell ATX PSUs and armed with a multimeter started looking around for the ground-to-case connection as per the various instructions around e.g. here. Aiming to link three PSUs to give a 36V 10A supply.

    Turned out to take about ten seconds - just follow the black wires back down to the PCB and there was an obvious jumper (J23) over to the case via a screw. Bit awkward getting in to cut it so ended up desoldering and pulling it out with needle nose pliers. Checking after with meter revealed it did the trick, so I did the second one as well.

    Still a bit of wiring to sort and need to get some power resistors to provide a bit of load for them to go at but that's the main hurdle over I think as far as the PSU goes.

  10. Quote Originally Posted by bikepete View Post
    Minor progress last night - opened up one of my donated Dell ATX PSUs and armed with a multimeter started looking around for the ground-to-case connection as per the various instructions around e.g. here. Aiming to link three PSUs to give a 36V 10A supply.

    Turned out to take about ten seconds - just follow the black wires back down to the PCB and there was an obvious jumper (J23) over to the case via a screw. Bit awkward getting in to cut it so ended up desoldering and pulling it out with needle nose pliers. Checking after with meter revealed it did the trick, so I did the second one as well.

    Still a bit of wiring to sort and need to get some power resistors to provide a bit of load for them to go at but that's the main hurdle over I think as far as the PSU goes.
    Doesn't need much of a load. 100mA on each +5V rail is usually sufficient (50 ohm, 2W).

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