Laser engraved plaques

[Rich Kruyer]

Having an issue when engraving multiple plaques on a 12" x 24" alum. plate. What is the best practice to engrave all the plates on the full 12 x 24 sheet and then use shear to cut the plates to the correct size. Or is it best to cut the plates to the correct size and then place the plates in the laser and engrave?

I have have had issues when shearing a full sheet after engraving as some of plates don't appear square with the graphic. I have tried adding cross hair lines outside the plates to line the shear up with and still seems like the images are not centered in the plate.

Thanks in advance.

[Chris DeGerolamo]

Why not sheer them in advance and place them in a fixture [of your making]? This would weed out any bad units and still allow you to engrave multiple units at a time.

[Kev Williams]

What size plates? Using 1 x 3" for example, what I do is square one end of the sheet (they never seem to be square from the mfr), then cut the sheet into 3" x 12" sections. To verify the edges are 3" and straight, I cut two pieces of 1" wide or so scrap to exactly 3", place one at each end of the shear blade, then tape a straightedge to the shear table against them. Your cuts will be 3" from end to end...

To further verify square, I rotate the material for each cut, as in, first cut from the masked side of the material, rotate and make the second cut from the back. If there IS any variance from end to end, doing this cancels out the variance.

Then just matrix the 3" sheets across on the laser table. Verify that the total length of the 3" sections adds up, I do this with the red pointer. If the last edge is what it's supposed to be within a few 1000/ths, run it. But if for example your 24" comes out to 23.96" actual, then all I do to fix that is (in Corel), I group the whole sheet to be engraved, change the length (only, not width) from 24" to 23.96", then make sure it's parked in the home position. Now everything will engrave exactly where it's supposed to.

And cutting the 3" strips to 1" wide is cake....

[Ross Moshinsky]

There are so many ways to tackle this problem and it really depends on what your equipment is. For example, my shear can cut 24". Many can only cut ~12".

I'll give a few hints.

1. Square the material from the mfg. As Kevin stated, it's not square. Sadly they aren't even giving you the extra 1/8" so sheet yeild can be tricky.

2. Consider compounding error. If you cut individual plates, are you spot on? If you're cutting 5x7 plates and it's really 5.03" x 7" and you stack 4 across your machine, by your 4th plate, you're going to be pretty far out of spec.

3. Don't be afraid to trim the plates after engraving.

4. Don't use tick marks or lines for cutting. If you're off, even by a little, it looks sloppy.

[Rich Kruyer]

Thanks everyone for the tips!