Friday, 29 July 2011

Laser splash back

A few weeks ago we tried cutting some miniature guitar shapes from MDF with mixed results. At best it could be described as a partial success. With our swanky new LS3020 laser cutter, however, cutting such shapes is a doddle!

Like most laser cutter users, we've had to spend some time with different materials of different thicknesses and types, finding out which settings to use for the best cut rate.

For 5mm acrylic, we're cutting 15mA at about 8mm/sec.
For 3mm acrylic, we're using 15mA and cutting at about 18mm/sec.

These values give an incredible performance, far better than we'd hoped, especially considering how slow and difficult the laser cutter at BuildBrighton has been. We've tried cutting slower, with less power, and faster with more power - but 15/18 gives a nice balance between speed and power use (apparently, cutting with less power makes the CO2 tube last longer; I guess it's a matter of time before we find out how true this is!)

However, whatever speed/power settings we use, we're getting a bit of what can only be described as "splashback" on the reverse of each piece. It's more obvious on some cuts than others, but on the back of some pieces, the pattern of the honeycomb bed can be seen in relief. It's particularly noticeable when cutting black acrylic:

After removing the protective film, small pits can be seen on the back and on the edges of the piece:

Yet the "front" face of each piece is cut perfectly, with a smooth, straight polished edge:

We've had conflicting advice on how to correct this - some people say a faster cut with more power gives a better finish. Some people have told us that we need to turn down the power and cut more slowly. In our experience, both approaches still create this "crazing" on the back. Maybe it's something to do with the bed. Maybe it's time to put in another appearance on the LaserScript forums to see what advice any other users can give. Those guys have been so helpful and supportive getting us up and running - we can't be the only people to have experienced this problem. Other than this little niggle, we're absolutely thrilled with the laser cutter and can't wait to start making "proper" stuff with it!