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IndustryArena Forum > MetalWorking Machines > Uncategorised MetalWorking Machines > Vertical Mill, Lathe Project Log > CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock
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  1. #21
    Join Date
    Aug 2005
    Posts
    129

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    Nice work Roadside! cant wait to see it come together!
    Andrew Abken
    www.drewtronics.net - PCB Cutters

  2. #22

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    Still working on the machine - no end in sight as it seems . I'm making the frame and everything else, to prepare it for operation. The headstock situation is still troubling, but i'm sure I'll get it sorted out by the end of the month.
    Attached Thumbnails Attached Thumbnails WP_20170103_18_56_38_Pro_LI.jpg   WP_20170103_18_56_46_Pro_LI.jpg   WP_20170103_18_56_52_Pro_LI.jpg   WP_20170103_18_57_00_Pro_LI.jpg  


  3. #23
    Join Date
    Aug 2005
    Posts
    129

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    Looks beefy! Perfect size machine. Nice work.

    Andrew
    Andrew Abken
    www.drewtronics.net - PCB Cutters

  4. #24

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    More pictures - added some additional braces to the lathe base frame, made the chip pan/ coolant sump for the lathe. Do you think it would be a bad idea in addition to the computer and coolant tank/pump also have a compressor in the cnc frame? I'm guessing it can cause some wicked vibrations when it starts working randomly.

  5. #25
    Join Date
    Oct 2012
    Posts
    393

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    I would not keep compressor in frame of machine

  6. #26
    Join Date
    Sep 2005
    Posts
    322

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    Roadside, I'm going to expand a bit on what Eldon suggested.

    Because you're welding the metal (and machining it) to create your lathe, you're creating internal stresses in the metal. I'm assuming you're using various forms of mild and alloy steel since you mention that you're using found/spare materials. Note that steel is strong, but not very dimensionally stable... for example if your bed heats up in one spot it will expand more than a bed made of e.g. cast iron would, which may cause inaccuracy or binding.

    With regard to the stresses created by welding and machining, if you do not stress relieve the metal it will "creep" or move later. It does not matter whether you design the lathe to be rigid/strong or not, the creep happens because the metal the lathe is made up of changes size, and it happens with enough force that the distortion is very hard to stop. In your case, the problem will be amplified by the use of slightly different metal alloys that are being welded together, because the individual alloys will have differing amounts of stress and different directions and magnitudes of creep.

    It's not possible to avoid this creep except by choosing dimensionally stable materials (which you aren't) and by processing techniques (like stress relief) and careful limits on where/how you machine the material.

    When steel is used in machine tool construction, it's almost never welded because of the problems and additional processing steps this creates. If you want confirmation of this, do a Google search for pictures of machine tools being manufactured and machine tool designs. You'll see lots of bolted joints, but very few welded ones.

    It's up to you whether you need to avoid future warping of your lathe, but you should at least understand that not taking it into account is going to potentially create a permanently inaccurate machine.

  7. #27

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    ErikJGreen and Eldon - i have an update just for you. I did the unthinkable and stress relieved the frame and re-re-re-machined the surfaces(as it's the third time machining the surfaces). I read through the comments here and after not having time to work on the machine (about 1 month had passed), i decided to check the frame for accuracy- the whole frame had twisted about 0.09mm over 400mm distance. I decided to add some additional material into the frame and after that I threw the thing into a big bar-b-que for about 4-5 hours. It change it's color to very dull gray and checking the color chart, the frame was between 427 and 515 degrees celcius. after that I re-machined the frame.

    I do read all the comments and take all advice in - so it is very much appreciated .

    I am almost ready to mount up the machine on the housing frame - got that triple coated with primer/paint. Next up - painting the lathe frame

  8. #28
    Join Date
    May 2013
    Posts
    480

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    So that's about .003" of an inch per foot twist, Interesting.

  9. #29

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    Did you expect more? or less? I want to know why you find it interesting

  10. #30
    Join Date
    May 2013
    Posts
    480

    Re: CNC lathe build, steel frame, HIWIN rails and epoxy granite headstock

    I didn't have any idea what to expect, how many kilograms of welding rods did you use?

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