Knowing what to do with different materials?

[Steve Crawford]

I'm still having lots of cool fun with my Trotec speedy 300 but does anyone else find it difficult to visualise how different materials produce such different results. For example I did a flask with a golfing image and it looked awful, so I inverted the image and outlined the characters and it looked great (see photo), but when I did the same image to a tile expecting great results, it looked bad again! How on earth do you decide whether to reverse/invert an image or not?

[Dan Hintz]

You want to know one thing... is the engraving lighter or darker than the main surface once lasered. Once you have that, choosing the proper image (or reverse) is an easy decision).

If it engraves darker, select the positive... if it engraves lighter, select the negative.

Granted, this isn't a hard and fast rule, but it will serve you well for the majority of work you do.

[Mike Null]

Steve

Besides visualizing how the image will engrave you'll also need some experimentation with substrates. In the example the tile is not really a good substrate for engraving that image and I would avoid using it. A darker wood would have produced a similar result.

Keep in mind that the laser engraves black or dark objects and does not engrave white objects. Sometimes it can be a little confusing. In the case of the flask it was a substrate that engraved to white; other substrates will darken when engraved.

[Ross Moshinsky]

Keep sheet stock around that is cheap to do testing on. It will cost $50-100 to have a stock of acrylic, plastic and metal sheet goods to run tests on. You don't need to use stainless steel or granite to do testing when silver laser aluminum (the stuff that marks black) and black anodized aluminum can mimic the look for a fraction of the cost.

Also you should be able to create computer generated previews pretty easily which will typically give you a pretty good idea how things will look.