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Thread: one corner of rectangles bad/ splayed out

  1. #11
    Join Date
    Dec 2005
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    Pro Signs, Coal CIty IL
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    302

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    If that's a 3/8" cut it makes my point even more valid. It looks like the cut has gone at least the width of the bit past the corner in that photo. That's .375". Where did that much play come from? Also sounds like it's just the "4th corner"? If there's play, why is it only showing up in one place and not every corner? At least the common axis corners? I don't have an answer either, so I'm asking?

  2. #12
    Join Date
    May 2014
    Location
    MA
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    487

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    Scott, "sharp corners" mode just moves in one direction into the corner (so a command like MX 12) and then another move command to get out of the corner (so MY12) So essentially the machine will move into the corner, ramp down to a stop, and then ramp back up when it goes out of the corner.

    With that option unchecked you get a super tiny arc at the corner. This causes the machine to ramp down less, and keep some load on the tool.

    If there's some mechanical slop in the machine these two corner cutting methods might show different results. If there isn't, they should look the same.

    Austin, if you can post either the VCarve file, or your SBP cutting file we can see if the problem is in the file for you.

  3. #13
    Join Date
    Jun 2001
    Location
    Austin, TX
    Posts
    409

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    Do you have “Lead In, Lead Out” checked? I think that that might give you that result in the one corner if that is the start point.

  4. #14
    Join Date
    Jan 2008
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    Hobby-Tronics, Chiloquin Oregon
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    “Lead In, Lead Out” and that combined with "inside / outside" gives all kinds of differences. Russ
    AKA: Da Train Guy

  5. #15
    Join Date
    May 2014
    Location
    MA
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    487

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    Both good suggestions, but don't try to fix a hardware problem in software

    Aluminum framed machines (SB and non SB) can flex if you push them hard. A common example of this is when you aggressively cut plywood you can get a part that's a bit out of square. If on your last pass you switch directions you can solve that problem. Lead and lead outs can help too. but again, if you've got a sloppy machine you've got to solve that first, and then dial in the cutting techniques.

    I really think what we're seeing here is some worn pinions/gearboxes.

  6. #16
    Join Date
    Jun 2001
    Location
    Austin, TX
    Posts
    409

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    The splay is probably hardware slop but the size of the over-cuts and being only on one corner sure suggests like lead in and lead out.

  7. #17
    Join Date
    Mar 2004
    Location
    North Plains, Oregon
    Posts
    473

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    If this were Mach 3 these exact symptoms would be linked to constant velocity settings. The only way I have been able to combat the issue is to slow down my cut speed...goes from one rounded corner to all four being identically straight. As an aside, I don't think Mach3 ever did cure this issue.

  8. #18
    Join Date
    Oct 2000
    Location
    Willis Wharf, VA
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    1,680

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    Do your parts turn out correct other than the bumps on the corners? The correct size, corners square, etc? If so then trying some changes to optimize the toolpath like lead-ins or lead-outs or ramping into the cut seems like the sensible and easy first shot at fixing the problem.

    Bill

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