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Any Thoughts on this?

Discussion in 'General Talk' started by GrandpawB, Jul 1, 2014.

  1. GrandpawB

    GrandpawB Well-Known
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    Here's my latest project that I'm having problems with. I'm trying to engrave the backrest of a park bench. The boards are of course longer than the reach of my CNC. So I'm trying to mark where the reach ends, move that to my start mark and continue from there. (sounded good in my head) but it doesn't come out right. Any thoughts? Thanks.:banghead:
     
  2. Tweakie

    Tweakie OpenBuilds Team
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    If it’s any help, this 2mtr piece of teak was V-Carved in 3 sections. The layout was done in CAD / CAM then the toolpath was split into 3 sections each with it’s own origin (on the centreline) and each a known distance apart. The timber was pencil marked with each origin and the job completed as 3 separate parts. Obviously you have to take great care in re-positioning the timber straight against the fixed side stops but it all joined up perfectly.


    Tweakie.


    a1.jpg
     
  3. GrandpawB

    GrandpawB Well-Known
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    Thanks. Is there a video or article on the details of how this was done?
     
  4. Tweakie

    Tweakie OpenBuilds Team
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    No, but when I do the next one I will make a video of the setting up but I have no idea when that will be.

    Tweakie.
     
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  5. GrandpawB

    GrandpawB Well-Known
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    Thanks. I hope this helps other beginners as well. I've been playing around with the idea all morning. I found if the text fits between the reach of my gantry, I need to center the text not the board. (DUH) If the text doesn't fit then I'm stuck again. But sooner or later I'll figure it out. Keep the ideas coming. :)
     
  6. steelspinner

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    One way that I have machined long parts is:

    1: Make sure that the part you have to machine has a qualified straight edge on the long dimension. (Cut this!! ie. wood on table saw. IT MUST BE AS STRAIGHT AS POSSIBLE!!)
    2: Make another part the same thickness as the one that you need to machine with a straight edge (see #1). This part is just for alignment and doesn't need to be anything special except for the straight edge. Clamp or screw this to your table and align it with the axis movement with a dial indicator (attached to the spindle) or put a drill or end mill in the spindle and use that to align at both ends of the alignment board.
    3: Put the straight edges together on the table and clamp down your work part.
    4: Before you machine your part program it to put a witness mark (a small scribed line) or ideally a hole that you have a pin the will fit at the joint between the two parts (half on each part). put this mark at your X zero Y zero location (this is the easiest can be most anywhere). Put another hole or mark past the area that you are machining, same as the first.
    5: Do your machining.
    6: Move your work part along the alignment part until the marks or holes line up. (a pin makes alignment more accurate)
    7: Machine your second section.

    Leave your XY zero at the same location for both sections and use the second mark location in your software as the zero location for your second location. You can keep going forever this way. The longest I did was 24' part on a 3' table Bridgeport.

    If this isn't clear let me know and I will put make up a drawing showing what I mean.

    Dave
     
  7. GrandpawB

    GrandpawB Well-Known
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    Thank you Dave. A drawing would probably help.
     
  8. Tweakie

    Tweakie OpenBuilds Team
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    @GrandpawB

    It may be some time before I get around to making a video but here is an explanation of my earlier posting in picture form.

    Hope this helps.

    Tweakie.

    a1.jpg a2.jpg a3.jpg a4.jpg a5.jpg a6.jpg a7.jpg a8.jpg a9.jpg a10.jpg
     
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  9. steelspinner

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    After you cut the first work area just unclamp the part you are working on and slide it until the witness mark on the next work areas are aligned and reclamp.
     

    Attached Files:

  10. GrayUK

    GrayUK Openbuilds Team Elder
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    This is going to be really unhelpful, because I have seen a Video on YouTube doing just this thing! No, I can't remember where! :banghead:

    Sorry
    Gray
     
  11. Tweakie

    Tweakie OpenBuilds Team
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    Any chance you could just have a quick look on YouTube again and see if you spot it ? :)

    Tweakie.
     
  12. GrandpawB

    GrandpawB Well-Known
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    Thanks for nothing. LOL :D
     
  13. GrayUK

    GrayUK Openbuilds Team Elder
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    I`m looking!

    Gray
     
  14. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Search "toolpath tiling" on youtube and that will lead to a number of videos.
     
  15. GrayUK

    GrayUK Openbuilds Team Elder
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    See! I knew I'd seen it somewhere. :cool: I just didn't know it was called that. :banghead:
    I knew there had to be a name for that sort of thing.

    At least I can stop looking now, I was running out of titles to look for! :sleepy:
    Cheers Rick :thumbsup:

    Gray
     
  16. GrandpawB

    GrandpawB Well-Known
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    Thanks everyone for all your help. I found this on You Tube thanks to RICK2.0.
    Machining parts longer than your machine
    [​IMG]
    CNCnutz (Peter Passuello)
     
    #16 GrandpawB, Jul 3, 2014
    Last edited: Jul 3, 2014

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