I’ve noticed this before, but always wrote it off to other random things. I tell myself I should have cleaned my lenses first, or maybe I didn’t notice a warp in the board. But this time it’s incontrovertible, because I was running the same job on the 3 types of wood, and I checked carefully for warps and cleaned my lenses just before starting, because it was for a customer and I wanted to make sure it came out right.
The default proofgrade settings for walnut plywood aren’t comparable to those for other PG plywoods. I wasted a whole sheet of walnut last night because it didn’t cut through using the PG settings. As mentioned above I had just cleaned all the lenses, etc., the sheet was perfectly flat, and it detected the material correctly.
The same design cut in maple ply and cherry ply works perfectly at the standard proofgrade settings. Here’s a comparison of the cherry and walnut, to illustrate what I mean:
Note the holes for tabs are too close to the edge on the walnut because it’s been recut to get it out of the sheet. Also the etching is too light – lots of lost detail on the walnut one (specifically look at the tree at upper right, the detail in the trillium petals, and the sun, as well as the frame outline on the righthand side), whereas the cherry comes out beautifully.
We should be able to count on comparable results on proofgrade materials using proofgrade settings – I can see a slight amount of variance in etching between different wood types, but for SURE the cut settings should actually cut through the wood they’re supposed to be tuned for!