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Thread: Kit's Machine

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  1. #11
    Looks like you could package it and sell it as a Flat-Pack. . . . . .

  2. #12
    At least when you finally put it back together you have an instruction video !
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  3. #13
    Quote Originally Posted by AndyGuid View Post
    Looks like you could package it and sell it as a Flat-Pack. . . . . .
    Maybe I could get Ikea to stock them?
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  4. #14
    Quote Originally Posted by routercnc View Post
    At least when you finally put it back together you have an instruction video !
    Actually that was part of the plan! I was a bit surprised at how little time it took to rip apart. Fingers crossed it will go back together equally quickly.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  5. #15
    How things can change in four months!
    When last I wrote in this thread I expected it to be at least another six months, possibly 2022 before there would be anything new to report. Circumstances including the ever changing border arrangements for travelling within Australia and other issues I shan't bore you with mean I have permanently retired to Tasmania a little sooner than I'd expeceted and now have most of a 6m x 6m double garage as my workshop. The bolted together base frame of my CNC router, which sat on a rather dodgy old office desk didn't make the journey from Exmouth, Western Australia to just outside Devonport, Tasmania (roughly equivalent to the journey from Barnsley to Baghdad in distance but with slightly fewer bandits) but the essential bits all arrived safe and sound. A new more solid base was required.

    On Monday a nice man at Nubco Steel in Devonport sold me an 8m length of 100 x 50 x 4mm painted steel RHS and cut it into bite-sized chunks at no extra charge. That plus a couple of extra bits will make the new base. Yesterday and today I've been welding them together using the samel 'Bird-Poo' welding technique I perfected when I made the gantry, the only other time in my life when I have used any kind of welder.

    With no welding table and no desire to make a mess of the nicely finished and flat floor in the new workshop I had to improvise a level working surface outside using a couple of pieces of nice straight Jarrah timber shimmed level using a spirit level and suitable spacers...different sized lumps of gravel. getting the two 1300mm side beams and 820mm end beams exactly square and parallel involved lots of nudging with a rubber hammer and repeated measurements but once those pieces were fixed correctly the rest of it had no choice but to fall into place. The legs were aligned prior to welding simply by tightening two clamps. The design was deliberately intended to make it simple to construct with limited tools and facilities. I made the decision to put the machine on wheels based on experience with the very difficult to move design I previously had and being uncertain at this stage exacly how I want it placed in the workshop. The was never any hope of getting four legs to sit level on the floor and so the inevitable error on one leg was measured on the flat floor of the workshop and shims applied under the fixings for the relevant wheel.

    The final picture shows the almost finished frame with one of the rail/leadscrew/motor actuators sitting on it's mounting bolts to prove the frame is the right size! All that's needed now is to weld on some 25mm square rails above the wheels to help brace the legs and support the cupboard which will contain the controller, VFD and cooling reservoir/pump under the router base.

    In fact the final alignment of the machine does not depend on getting this frame exactly correct but as close as possible helps. The next stage is to get the fixed rails fitted and aligned with shims before the gantry goes on and the electrics and motors are put back in place. Then the whole process of aligniment using taught wires as described elsewhere on this forum will start all over again.

    I have come to the conclusion that the main cause of potential DIY router builders failing to weld together a suitable frame is failing to start. No, your welding will not be good enough for building a new Forth bridge. No, your welding will not be good enough to offer your service for paid work. But yes, you will be able to weld well enough to make a CNC router if you stop farting about and just get on with it.

    Click image for larger version. 

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    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  6. The Following User Says Thank You to Kitwn For This Useful Post:


  7. #16
    With the frame welded up it's time to fit the fixed (X -axis) rails. As described earlier, the rail, ballscrew and motor for each side are all mounted on a single piece of 65 x 65mm hollow steel, effectively forming a 'linear actautor' for each side. This is done to keep them all in a fixed alignment while the relative alignment of the rails is adjusted.

    I wasn't sure how accurate all the welding had been so made 3 of 12mm shims to lift the rails beams above the frame. The fourth corner would then be adjusted to make the rails co-planar. A first approximation was done with a standard spirit level using a stack of washers to lift the fourth corner. Absolute level is not required here, a slight tilt in the whole machine is no problem, but the tilt must be the same at both ends. This showed that a shim of about 6mm was needed at this corner. Bearing in mind the primitive setup used for the welding an error of 6mm was not too bad, though I'd have been a bit more smug at 2mm.

    Once a ballpark figure for the shim was found the precision spirit level was brought out and some pieces of copper shim used to make the rails as parallel as possible. The whole point of this design is adjustability rather than highly accurate initial construction.

    Now the gantry can be put in place and the rail spacing adjusted. This is done by simply moving the gantry to one end, making sure the ballscrews move easilly and tightening the rail beam fixing bolt. Then run the gantry to the other end, by hand to check for any tightness, and tighten that end fixing bolt.

    The fixed rails are now aligned and fixed in place ready to provide a reference plane for aligning the gantry.

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    Last edited by Kitwn; 18-01-2021 at 10:45 AM.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  8. The Following User Says Thank You to Kitwn For This Useful Post:


  9. #17
    It's coming back together nicely. There's a shelf in the base for the controller and cooling to sit on, a nice new tray for the drag chain and I'll have all the motors, proximity sensors and the spindle back in place over the weekend. With a bit of luck it will all have survived the journey from WA to Tasmania and move as expected by Monday.

    Once it's all assembled I'l be aligning the gantry from scratch using the same 'tramming with taught wires' method I described briefly in this thread last year...
    http://www.mycncuk.com/threads/13627...ut-Wires/page2

    This method uses the fixed rails themselves rather than the baseplate of the machine as the reference plane for adjusting the gantry and spindle in various axes and also uses the Z-axis drive as a micrometer for measurements, saving the expense of a dial guage etc. I'm not sure I was very clear about the method last time round, is anyone interested in seeing more details when I go through the process again? As with the rest of this machine the gantry was built with hand tools with limited accuracy so alignment and adjustment with lots of measurements and shims is required.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  10. #18
    It moves! It actually moves!!

    Sorry, got a bit carried away... In spite of being taken apart as seen in the video from last year, rattled around in a container for several thousand killometers and otherwise mistreated, there appears to be no damage to the LinuxCNC computer, machine controller or any of the mechanics, motors, proximity sensors or interconnecting wiring. It all started up as normal and homed perfectly. Once I find the USB Nintendo game controller that acts as a pendant (I had it yesterday, must do some tidying up) I can start on the alignment.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  11. #19
    The alignment with taught wires went well. Having built a more solid base than previous I was a bit more careful and took more time on this ocassion. Measurements for nod, gantry tilt and variations of nod along the Y axis (on the gantry) were made and re-made and shims placed under the gantry mounting bolts and Y axis rail mounting screws to slowly bring it all into line. These measurements are interractive but I got closer to perfect with each iteration and am very pleased with the results.

    A slight delay to progress has been introduced by the reapearance of noise-induced spurious trips but a nice man has just turned up at the door with a mains filter from RS which will hopefully fix that. I have been getting by by plugging the VFD into a mains socket at the other end of the shed to everything else but that isn't a long-term soution.

    I have fitted the plywood base and adjusted the auto-racking in LinuxCNC to get the X and Y axes exactly perpendicular and added a second layer of ply complete with an array of M8 T-nuts (the lower layer stops the little blighters from falling out!), fitted the sacrificail spoil-board and drilled it for the M8 nuts.

    For the final test of the tramming I have skimmed the MDF spoil board and examined it for tell-tale ridges. I'm smugly pleased to say that, in the right light, you can just see some faint lines indicating in which direction the 22mm tool has passed but I honestly cannot feel any ridges or bumps when running a fingernail across it for either the X or Y axes.

    All that's required now is to fit the mains filter, get the dust-extractor set up and I can actually start making things!

    Kit.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  12. #20
    Hi Kit

    Incorrect earthing can cause problems, Are all the leads shielded? the should be. Do they all lead to common grounding point ? sometimes grounding at both ends of a wire can cause earth loop issues. try just earthing them all at the control box end only.

    https://www.google.com/search?rlz=1C...fRwCjgQ4dUDCA0

    Regards
    John

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