584,846 active members*
4,085 visitors online*
Register for free
Login
Results 1 to 7 of 7
  1. #1
    Join Date
    Mar 2015
    Posts
    164

    multi part fixture reference

    I have workpieces that are processed in successive cuts along a continuous piece of flat bar and then a chop saw separates them; each individual workpiece length now varies slightly.
    The next operation, multiple workpieces are mounted to a fixture plate by alignment dowels and screws.

    Since the WP edge does not reference it's prior operation, the fixture plate must provide the G54 reference point.
    Is there an optimum way to create a G54 reference point on a fixture plate?

    The fixture plate would need to be imported into the CAM with the parts (or rather the other way around) and the parts must be referenced to the fixture plate G54.
    I use SprutCam and this sounds like an opportunity for a mudslide.

    Is there a better way?

  2. #2
    Join Date
    Oct 2010
    Posts
    670

    Re: multi part fixture reference

    Yep, working out the details on this myself. However, I'm using Fusion 360.

    On my fixture soft-jaw, I machined in a .25" x .25" x .125" deep indicator box so that the soft jaws can easily be set up and aligned. Working out the details on how best to do this in the CAM section based on probing for location where the parts "actually" end up when in the fixture.

    http://www.cnczone.com/forums/tormac...980-g59-p.html
    The Body Armor Dude - Andrew

  3. #3
    Join Date
    Feb 2006
    Posts
    7063

    Re: multi part fixture reference

    I always reference to one top corner of the fixture plate, usually the left-front. When I machine the fixture plate, I bolt it to the machine, with the X/Y/Z zeroes set to avout -.020" INSDIE the left and front edges, and 0.02" BELOW the top surface. I then take a finish cut along the front and left edges, then face the top surface with a Face mill, to bring them to zero. Then, simply machine the fixture features. When making parts, mount the fixture square to the table, and zero to the same corner, and you're ready to go.

    Regards,
    Ray L.

  4. #4
    Join Date
    Dec 2010
    Posts
    1230
    Quote Originally Posted by SCzEngrgGroup View Post
    I always reference to one top corner of the fixture plate, usually the left-front. When I machine the fixture plate, I bolt it to the machine, with the X/Y/Z zeroes set to avout -.020" INSDIE the left and front edges, and 0.02" BELOW the top surface. I then take a finish cut along the front and left edges, then face the top surface with a Face mill, to bring them to zero. Then, simply machine the fixture features. When making parts, mount the fixture square to the table, and zero to the same corner, and you're ready to go.

    Regards,
    Ray L.
    ^^^ Yep ^^^

    Or if the plate is bigger than your travels plan a hole in a location that doesn't get covered up (preferably) and set as zero. Say 0.25 from home position. Drill and ream the hole just big enough for you to ref. Then REF if and THAT is the 'true' repeatable location.

  5. #5
    Join Date
    Mar 2009
    Posts
    1863

    Re: multi part fixture reference

    If I am doing one part or 4 parts I will put a tooling hole at the front left corner of each part. Then I can check against absolute X Y zero if I feel the need to check parts for location.

    If I'm making small parts, I'll make 2 fixtures so I can have one in the machine working and one on the bench being loaded.
    You can buy GOOD PARTS or you can buy CHEAP PARTS, but you can't buy GOOD CHEAP PARTS.

  6. #6
    Join Date
    Mar 2015
    Posts
    164

    Re: multi part fixture reference

    So If I understand this,
    The advantage of a fixture based work offset, oppose to a workpiece offset, is that the fixture offset has reference to a part feature, whereas the workpiece offset references itself.

    A reference point on the fixture plate (corner or hole) is set/declared for G54 work offset, for example.
    The fixture plate will have points with holddowns,stops or pins that reference G54 when built.

    There fixed points constrain the work piece parts and assumes the referenced to G54.
    Parts all reference G54 by an offset that varies according to its position on the fixture plate.

    This G54 offset absolute value is critical and must be established during initial holddown, stop or pin placement in CAM.
    The G54 offset value should be a short round number and not like 1.245824, to prevent truncated position errors.

    The CAM will permit multiple copies of the initial part; beware of truncated offset values after many copies.
    The CAM, part separation feature, for copied parts will automatically calculate the G54 offsets.

  7. #7
    Join Date
    Jun 2012
    Posts
    311

    Re: multi part fixture reference

    Sounds like you got the concept right. Perhaps you're overthinking it a little bit. When you make the fixture you will establish the relationship between the reference feature (G54 XYZ0) and the features that locate the parts. In CAM just move the XYZ0 accordingly and then pattern the part at the required spacing for your array of parts.

Similar Threads

  1. Ideas to fixture this part!
    By bob1112 in forum Uncategorised MetalWorking Machines
    Replies: 2
    Last Post: 10-24-2013, 04:50 PM
  2. Small part fixture
    By l u k e in forum Work Fixtures / Hold-Down Solutions
    Replies: 8
    Last Post: 01-31-2013, 05:16 PM
  3. Help with multi-part fixture
    By Pharkas in forum MetalWork Discussion
    Replies: 12
    Last Post: 09-12-2012, 04:07 PM
  4. Multi-part Fixture with Single Point Clamping
    By Geof in forum Work Fixtures / Hold-Down Solutions
    Replies: 35
    Last Post: 08-22-2011, 03:13 AM
  5. Multi fixture issues
    By durgam605 in forum FeatureCAM CAD/CAM
    Replies: 3
    Last Post: 07-01-2011, 01:54 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •