Indexing for making longer pieces

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This topic contains 8 replies, has 5 voices, and was last updated by  Bill 1 week ago.

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  • #109540

    Stan
    Participant

    If you want to make a 12″x 24″ sign on a standard 24″x24″ build (13.6×13.6″ work area), how effective is indexing for repositioning the piece? In one dimension, you can use a rail, in the long dimension do you just use pencil marks for a new zero, or do you plunge in a shallow hole to reposition zero? Is any of this good enough or do you just need to go for the larger build?

    Thanks

    #109545

    Dalton Porter
    Participant

    I’ve done it by using something already cut as a reference point.

    Assume I was cutting the text “Billy The Kid”

    That entire text would be in estlcam, but on the first cut, I would put the zero at lower left of work and only put cuts up to maybe the “T” so it would cut “Billy T”.  Create the G-code for that and cut.

    Then I would would create the paths to follow only “he Kid” but now set the reference point to the upper right corner of that “T” that I already cut.  Of course, I slide the piece to the left to where that corner is near my left most cutting position.  Next, manually align the cutter to that point, then start the 2nd cut of “he Kid”.

    You will need some kind of fence that allows you to slide left/right without moving the piece up or down.  I clamped an extra board to my table.  It could be on top or bottom side.

    This method worked for me, but I would like to hear if there is a better method.

     

     

    #109658

    Ryan
    Keymaster

    If you need higher precision than that you can use pins.

    #109662

    Stan
    Participant

    Thank you, I understand how to use the pins for flipping a part over. How do you use the pin to precisely move the part in the X direction.

    #109682

    Bill
    Participant

    Drill for the pins at one end of the piece (outside your work area) and use pins in those holes to position the piece for the first cuts. Use your CAM and gcode to drill another pair of holes a fixed distance down. Once that cut’s done move the piece so the pins are in the second set of holes. Step and repeat as needed.

    1 user thanked author for this post.
    #109737

    Stan
    Participant

    Thank you Bill, I guess in that approach the piece needs to be oversized in Y on at least one side to accommodate the pin hole.

    #109738

    David Walling
    Participant

    Or, you can flip the piece over and put the pin holes just in the back.

    Cut all the pin holes, two at a time using the previously cut holes as your index pins to cut the next pair of holes.

    Flip the part over and index to the first set of holes. I’d use two index pins. One on top, one on bottom.

     

    I’ve typically indexed off of the existing cut like Dalton mentioned, but as mentioned, each cut can be slightly off depending on how well you center the bit over the point on the letter.

    I’ve also just used a pencil and a ruler to make small marks for my 0 point all over the board where each 0 point starts the cut for a different part of the sign.

    #109742

    Stan
    Participant

    I wonder if mounting, at a known offset, one of the cheap laser diodes that generates a thin cross hair or line, and aligning it on either a feature or a pencil mark could substitute for the pin(s), if you also use a rail for the Y axis.

    #109877

    Bill
    Participant

    The nice thing about using pins is that it’s very repeatable. Pencil marks and such can easy end up slightly non-square, which throws the back end off.

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