A personal story by Mick Steele
I bought a “bargain offer” 500mW laser machine kit on eBay in January this year, which assembled easily and worked quite well but had very little power. I decided to take the leap and buy the Endurance Laser 10Watt Invincible model, which arrived just before the covid19 pandemic struck. Lasers have some big plusses compared to cnc routers, namely – they can print and engrave but don’t use ink or powder and they can cut without rotating sharp cutting tools, blades or knives – so knowledge of router bits: up cutting, downcutting, straight flute, V bit and so on, is not required. Also, there is no need to know about the cutting speeds and feed rates for these tools, for the range of different materials they can cut. For a laser, it is only necessary to choose a percentage of the power of the laser and how many millimeters or inches per minute it is to travel at to engrave or cut, and these parameters are learned very quickly.
So there I was with my 10watt powerhouse ready to go but I had no material or the first project in mind and there were no local sources of supply open due to lockdown. I found the files for a large dolls house that I had made on a big 8×4 ft CNC Router at a fab lab, on an old flash drive, and decided to make a smaller one from 3mm poplar laser ply, which I had to import and due to shipping costs I decided to buy enough material to make three houses for my grandchildren, which I did initially engraving lots of roof tiles at 1200mm/min and 50% power and cutting out the parts with two passes at 150mm/min and 95% power using the standard lens and air assist but I thought the air was not close enough to the material due to the focal distance so I added a spacer which I saw on an Endurance video and found I got nice clean accurate cuts in one pass at 100mm/min. In the course of this I fixed problems with motor leads catching and various minor problems getting my machine to cover its 500mm x 420mm area without snagging. By the time I had done all this lockdown was partially lifted here and I could get some cheap plywood from a local shop. I had bought some cnc router files in 2017 for a Ford Escort, a VW Beetle and a wild west Stagecoach so I decided to make the stagecoach with my 10W laser – the plywood is described as hardwood faced Malayan WBP 1/8” plywood and I started off by doing some tests cutting out a 25mm sq with these results – 95% power and 2 passes at 150mm/min was about 50% thro- three passes ranged from 80% thro to piece falling out, depending on the material – at 120mm/min it was 90% but it was difficult to complete the cut with a craft knife ( X-acto ) due to some very hard grain in some areas and aslo glue seemed to boil in voids and dry very hard – as I was in no hurry I decided to run at 100mm/min and four passes as the parts were 99% fully cut with minimal finishing with the knife – I found that by studying the grain patterns it was possible to identify problem areas.
I also tried cutting at a different speed for each pass e.g. 1st pass 200mm/min, 2nd pass 150mm/min, 3rd pass 100mm/min and last pass at 75mm/min/ This worked really well with 99.5% cut thro but I suspect my machine was skipping steps as the kerf was much larger so I abandoned this for another time when I improve my machine motion system. Finally, the reason for using this material is its low cost – €11 for a 2440 x 1220mm sheet giving a material cost of €4 for the stagecoach. Fortunately, the files I had were in DXF format and as I was using Lightburn, once opened they were ready to arrange and run.