Flip Some Wood

[ob1coyote]

Couldn't think of a better title at the moment...
I have an XTool D1 Pro 20 watt diode laser and I prefer Lightburn.

I'll try to include as many details as I can think of.
I'm cutting out a non-symmetrical object, a keychain in the shape of the state of Arizona from 3mm basswood plywood, The way I'm currently doing it is to create an array to cut out multiple copies at once. Tonight it's 5 columns, and 4 rows for a total of 20 keychains. I just set it to Start from: Current Position so I can just move the laser to the corner of the board and hit Start. I know Rich prefers absolute coordinates and I'm sure that's going to be part of the solution.

My problem is that I would like to then flip the sheet over and use it as a jig to engrave the backs of each keychain. I can't think of a way to get the flipped board to line up correctly and with the least amount of fuss to get it lined up.
I have made the Clackshack XTool D1 jig, and I currently just use a Squaring jig to position my sheet, but I can produce a jig specifically for this project if necessary.

My initial thoughts is to make a jig for the Clackshack jig panel using absolute coordinates and cut out all the reversed keychain shapes I can fit on one board. Then I can just delete keychains from the array as needed if I want to engrave fewer keychains afterwards. Just be careful not to overwrite the master file.

Is that the only/easiest solution, or is there something better. How would you do it?

[dovetaildan]

I would try drawing a rectangle around the array, and center it on the array. To test if it flips correctly I would group everything, make a copy, flip, and then line them up along either the left or right edge depending on how you want to set it up, or probably better yet make a centerline to line them up.

If that does not work, I would set up two different positions on the squaring jig. One on the left, and one on the right. In lightburn I would keep both copies and make sure they are on separate layers. Turn one of the layers off, burn the side still turned on, switch the output of the layers, flip the jig, line it up on the other side and burn.

Hopefully this makes sense. Others may have a better suggestion, but this is what comes to mind first for me.

[Gillman]

This is where I whip out the Cheapo Chinese UV to work the other side. (Really helpful right?) I gotta tell ya, it is nice to have that sucker on standby. The galvo is nice and exact.

[JimNM]

In your array, make a front and a back image. Engrave and cut both the front layer and the back layer. Swap the pieces between runs.

Done.

[thelmuth]

Since the basswood cannot move side to side, when you go to engrave the back change your origin to top right and move your laser head to that corner. I would also do the engraving on the back side first, before engraving and cutting the front side. Cut last. Be sure to mirror your array horizontally in Lightburn so your state outline is correct.

[pbien]

On the front side, cut a pair of "X" completely through, then use those as registration marks for Print & Cut on the back? I've never tried doing something like that, but it at least sounds right.

[pbien]

This time with pictures!

Black = engrave, red = cut, blue = toolpath.

Start with the back

Untitled-2.gif

Then flip it over and do the front, using the through cuts as registration marks with Print & Cut.

Untitled-1.gif

[WillV]

Your first intuition is the best solution.

Use a jig for accurate, repeatable work-piece placement and use absolute co-ordinates. If your work-piece is in a known location relative to machine 'home' you'll be able to accurately predict where the laser will move. As thelmuth pointed out, engrave first, cut last.

Design and machining become so much easier when a common point can be established in both CAD/CAM and your CNC device.