First, an apology: my attempts at close quarters photography are a bit poor tonight, for this I am sorry. I blame the earthquakes.

Last Sunday I took the opportunity to experiment with my friends laser cutter. My experiment was aimed at producing relief detail in styrene, i.e raised details. This was my first time dealing with laser cut styrene and also my friends first dealings with it. Oh dear. I understand now why people may have mixed results with laser cut styrene models. It is a sod to work with on the laser. The main issue seems to be the amount of heat it retains and the time it retains that heat for. While "rastering" (engraving) the details in works reasonably well, if the vector cut (the actual cutting out of the component) is done immediately afterwards, the item is guaranteed to warp like drying timber. There are ways to mitigate this, multiple passes at low power, leaving the item to cool before cutting, use thinner material.

It is true that the styrene takes fine detail well, see below. Those cut lines in the 'grill/louvre' fashion are only 0.25mm wide.

What you can also see here, in the lower left of the photo is the melt back around a rectangular cut. This is only 1mm styrene, with the laser set to only just enough power to cut through.

Out of the various trial runs, the following is the most relevant here;

The larger rectangles are 25 x 12.5mm, the smaller are 12.5 x 6.25mm. All are 1mm thick. The top pair are the first cut in this size, the power was a little high. The next 2 pairs are lower power, with the last being a different pulse-per-inch setting. In the flesh, the last (bottom) pair are actually the best, but all have a mottled/lined appearance on the engraved/recessed area and all are warped to some degree, despite cooling attempts.

Now, my friend prefers to work with acrylic for his business, so using some scrap 3mm:

I was flipping stunned how well the first (top) pair came out. The setting was his standard setting for 3mm acrylic, and I must give him credit, he knows what he is doing! I tried to improve on it by increasing the resolution from 300dpi to 1000dpi, which immediately ruined it for the next pair down. After backing off the power (3rd pair down) and reducing the res to 800dpi we arrived at the last pair, which (when not poorly photographed) is as good as the first pair, but has an even smoother engraved area, with no 'tracks' visible.

What does all this blather actually mean? Well, not much that wasn't already known to some, really. Amateur-Fettler has noted similar problems and the benefits of acrylic on the blog of doom (Motorised Dandruff), I just wanted to try it out for myself. My conclusion has to be this: favour acrylic where size and strength requirements permit (it is a bit fragile under 1mm or so) and avoid relief details in styrene. 

I may try to do a Kp or similar in acrylic, time and laser owner permitting. Also, and as blatant advertising, if anyone is looking for a laser cutting service, particularly in Canterbury try: www.zebracraft.co.nz.