johnsmachines

First the new toy.

I mentioned to Pat, an expert model ship builder, that I needed to sand the linings of the gunports on my model HMS Bellerophon. He loaned me his Proxxon Pensander to try out, mentioning that he intended to buy the new model. It worked quite well, so I suggested that he order an extra new model for me.

The new model is a Proxxon Pensander P13. It is 12-18 volts via a supplied transformer/controller. There is an on/off switch on the handpiece. The head has a linear movement sideways (which is not always convenient) of 2.5mm. There are 8 heads to accept different shaped pieces of sandpaper. It is about twice the price of the older model at $aud170, but Pat says that it is substantially more powerful which is a big plus.

It has a quality feel and appearance. The included 3 pieces of sandpaper each have 20 pieces of self adhesive sanpaper shapes.

Unfortunately, none of the included heads would fit into my Bellerophon gunports.

So I 3D printed one of my own design, to take a piece of sandpaper 5mmx12mm. Printed on its side for maximum strength.

I had a roll of 120 grit sandpaper with adhesive backing, and cut the piece in the photo to try. It worked well!

But I really do not like to cut sandpaper with scissors, sharp knife etc because it wrecks the scissors/knife cutting edge.

Then I woke up this morning with the solution obvious. Laser cut the sandpaper!! But I wanted to cut the sandpaper and adhesive but not the backing paper. That required a fairly exact setting of the laser.

So I used Lightburn to generate the G-code for multiple settings of speed and power, and produced the following test cuts. During the laser cutting the sandpaper particles produced a nice sparkling display.

The vertical axis is the various cutter speeds between 600 and 18,000 mm/minute. The laser power 10% to 100% is the horizontal axis. The black holes are where the laser cut through all layers and the chads fell out. (remember “chads” guys?) The rest are partial depth cuts. I chose to use 1000mm/minute at 70% power to cut the following pieces….

1000/70 might have been a bit excessive, but the pieces are useable and it is easy to peel off the backing. With these 112 pieces of sandpaper I should be able to make gunports for several more model ships.