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    CNC boat kits...?
    by DodgyGeezer ๐Ÿ‡ฌ๐Ÿ‡ง ( Chief Petty Officer 1st Class)
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    DodgyGeezer
    Chief Petty Officer 1st Class
    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 3 hours ago
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    Yes - and you want to balance out the current available from your power supply to go to all drivers equally. I have 1/8 microstep on X and Y axes, but 1/2 on the Z axis. You usually want that one to go faster with less resolution...
    Nickthesteam
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    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    Current is set via DIP switches from 0.2 to 5 amps, mine are set to 2.5Amps to match the current rating of the motors. Microstepping is also set via DIP switches, I have set mine to 1/8. Each driver has it's own 24V input so higher current is handled by the driver and not the CNC shield. I will try and video the results when I fire it all up (not literally I hope), I only have my phone camera, which isn't very good should be good for a laugh....
    If it don't fit, use a hammer to make it fit....
    DodgyGeezer
    Chief Petty Officer 1st Class
    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    Do you have to set the limiting current to 'low' via a pot on each driver before turning on first? I am using Pololu drivers, and they suggest calculating your max current per stepper, then setting each driver to low and gradually increasing. There is a little adjustable pot on each driver board for doing this...
    Nickthesteam
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    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    I don't get 100 grubscrews at a time, I meant all sorts of screws. I have been fiddling about with wiring this afternoon, getting the drivers hooked up to the CNC shield. Just got to connect PSU to driver and CNC shield and it will be either Whoopee!! it works or a look at my on line banking for funds for more circuitry.... I am going to prove the wiring with just 1 motor/driver set up first....
    If it don't fit, use a hammer to make it fit....
    DodgyGeezer
    Chief Petty Officer 1st Class
    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    Ah well, grandmothers and eggs... ๐Ÿ˜Œ Still, I did say that the collet was cheaper than 1 grubscrew - not 100...

    I found that mine worked first time, so you probably won't need the platform. You seem better equipped than I am for the rest of it ๐Ÿ˜‰

    I can, however, report that holding balsa sheet in this way is very effective. It is a sheet of ply bolted to the base, with another sheet of ply 4" wide on top. The sides have hard balsa edges rising about 1/4 inch above the ply, which are held in with a spruce strip. A 4" sheet of yellow correx is there to provide a soft base for under cutting. If I cut outside the workpiece the cutter just goes through the balsa sides, so no damage done.

    4" or 100mm sheets of balsa drop into the 1/8th recess on top, and are held by the side balsa, which is slightly sprung inwards. If necessary they can be packed around the edges, but the recess is sized to hold them tightly. They are firmly held against the cutter, do not move at all, and the workpiece can be removed and replaced precisely in the same position if necessary. If you want you can put a weight on top of the sheet during cutting to hold it perfectly flat, and move it when the cutter is going to go over it.
    2
    Nickthesteam
    Master Seaman
    ๐Ÿ“ CNC boat kits...?
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    Cable managment all sorted. Electrics mounted on base, drag chains on X and Y axes part of the design, I will print them myself. I always get a shipping order for screws, usually a few hundred at a time, postage still the same. I have 20mm MDF and 20mm ply to hand for the spoil board and loads of milling clamps to go toward work holding kit, clamping arrangements will depend on what I am doing. I have also built a little platform for me to jump off in case I have to jump up and down on it in a rage when it won't work. I have several DTI's, Dial gauges, Depth gauges, and Height gauges lying around so have all I need to get her clocked in when the time comes. I am looking forward to seeing it burst into life. Many thanks for the tips...
    1
    If it don't fit, use a hammer to make it fit....
    DodgyGeezer
    Chief Petty Officer 1st Class
    ๐Ÿ“ CNC boat kits...?
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    ".......I am on a bitof a learning curve at the moment........"

    A few lessons I learned:

    1 - Get a good, solid base-board which isn't warped. The local timber yard may have off-cuts of 3/4" ply. You will want to assemble the mechanics on a proper base, and it helps to have it available first. You will want to paint it anyway, so it will need time to dry.

    2 - Get a dial indicator. An easy way to check for precision in assembly is to attach a dial indicator to the end of the Z axis and run it over the base board. It's good for other fault-finding and calibration as well. There are cheap ones on Ebay.

    3 - Plan out all the wiring. I put my limit switches in as an afterthought, and found that I had wires which couldn't go in the places I wanted them to go.

    4 - Wiring loom control. Consider Drag Chains, Heat-shrink tubing and Braiding. All items are very cheap from Ebay. If you don't put the wiring in at assembly you won't be able to put it in later once everything is connected up...

    5 - If you use a drag chain for the USB connection, you will either have to make sure that it's wide enough to take a USB plug passing through it, or cut the plug off, pass it through and re-solder it afterwards. If you do the latter, note that the shielding in a USB cable is aluminium, and won't solder. So you will need to use a connector plug which has a physical connection to the shielding, because interference can ba a problem on these machines....
    1
    DodgyGeezer
    Chief Petty Officer 1st Class
    ๐Ÿ“ CNC boat kits...?
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    "....Good cheap screw supplier...."

    I looked there for grub screws. There were 58 entries. Of the cheapest orders of these, only 12 were cheaper than the Chinese mini collet set. And not by much.

    Once you counted in postage, the cheapest grub screws you could get from a good, cheap supplier in the UK, at ยฃ3.20, were about twice the price of a complete mini-collet set from China, which comprised a shaft, locking head, selection of 8 different sized collets, two grub screws and an allen key....
    1
    Nickthesteam
    Master Seaman
    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    Oak or Mahogany for stable signs, I do plan on fitting limit switches at first anyway. I am on a bitof a learning curve at the moment. Once I have the machine up and running I will no doubt get the hang of it.
    Good cheap screw supplier..
    https://www.gwr-fasteners.co.uk/m3-socket-cup-point-grub-scr...
    https://www.gwr-fasteners.co.uk/m3-socket-cup-point-grub-screws---high-tensile-17166-p.asp
    ๐Ÿ”—
    If it don't fit, use a hammer to make it fit....
    DodgyGeezer
    Chief Petty Officer 1st Class
    ๐Ÿ“ CNC boat kits...?
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    "How is the cutting tool held in place? Do you use just a rigid coupler with grubscrews or a minature collet system?"

    A miniature collet system. Cheaper than one grub screw (if bought in this country!). Here is an ebay link to one for ยฃ1.28. You have to get one with the right hole size for your motor shaft, of course. There are several standard sizes. This one is 2.35mm ... Go to ebay and search for 'mini drill collet'. You can see a picture here...


    https://www.ebay.co.uk/itm/8Pcs-0-5-3mm-Electric-Drill-Bit-C...
    https://www.ebay.co.uk/itm/8Pcs-0-5-3mm-Electric-Drill-Bit-Collet-Mini-Twist-Drill-Tool-Chuck-Set-Golden-BE/332680957934?hash=item4d75548fee:g:vJ8AAOSwGUBaRQRg
    ๐Ÿ”—
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