Hi Now that my long overdue OX is up and running I want to cut some acrylic parts for my eleksdraw writing machine. I broke two pieces by accident and can't find any replacements on the net. So I'm going to cut them on the OX. I'm sure the router will cut these parts out, but I wanted a really fine edge to them so decided to get a Laser cutter to do the job instead. At some point I would have added a laser, but because the writing machine is down I've decided to buy the module now. Actually the two parts are 7mm thick, but getting a module that will cut 12.7mm (1/2") will save me upgrading for the time being. I want a complete kit including the mount for the OX to save time running around trying to find bits and pieces later. Thanks a lot. Fabian.
I sometimes work on a commercial 8x4 150W CO2 laser. It struggles to cut 12-15mm clear acrylic at a speed that doesn't result in the plastic melting. It cuts through black acrylic at 15mm like butter, though. The general rule of thumb is that for every 10 Watts of power you will be able to cut 1mm / 0.04 inch of absorbent material (in other words, a colour of acrylic that is absorbent for your laser frequency). You would therefore need a CO2 laser of around 40W to easily cut 12mm of dark acrylic, and even then it may be a slow and melty process with inferior edge results. A diode laser would struggle to cut 7mm-10mm acrylic, even black, cast, high-quality perspex and you won't easily fit a 40W CO2 laser on an Ox. That being said, you CAN cut thicker acrylic by multiple passes and refocusing the laser at each pass - easy enough with a movable Z-axis. But that would still require a diode laser at the top end of the scale. You will be really disappointed with a cheap Chinese laser as they are nearly all lying about their specs or are cranked up to a higher-than-recommended voltage which shortens their life. There is a solution that fits - Endurance Laser sell a 10W laser that they say will cut 8mm dark acrylic in 2 passes without setting it on fire. 10 watt (10000 mW) super powerful diode laser attachment from Endurance It's close to $800, though. For a one-off job like that, I would send it out to a bureau for cutting. If you intend on doing a lot of cutting and engraving, it may be worth the buy. If you are committed to doing it yourself, use black cast acrylic and run some sample cuts on a test piece to get your speeds and feeds . For thick acrylic, (15mm< ) we normally use a CNC router, its quicker, cleaner and gives a superior result, although it does need edge treatment afterwards.
$800, A year ago that would have sounded like a fortune, but after paying out for the OX and all its odds and ends that go with it I didn't bat an eye when I read your reply. I really appreciate your full and frank reply, but I'm going to end up cutting the acrylic with the cnc router. I've already got that and it would have been ideal to get the parts I wanted with those finely cut edges you get with a laser. I'll have to settle with a more robust cut instead. I could, as you said use a bureau, but this is going to be a production run (hopefully) for a new design of Robo Writing Machine that I've designed and patented (Applied for) and doing it myself would be the most economical way at this point in time. Thanks again for you reply and I hope I haven't wasted your time here.
Heck no! No time wasted at all. What I will do is to try and cut 6mm dark acrylic with my new Endurance 5.6W and see how it goes. Damned postal service in the tropics is making me antsy... I would also recommend you drop George at Endurance a line and ask him what he would recommend for 7-12mm - I suspect he has a lot more experience than me and can give you better advice. Just as an FYI, I originally contacted him about his 10W diode, but he convinced me that I really didn't need it and that the 5.6W was the right unit for my needs - not many vendors will willingly sell you less kit than you were wiling to play for! If you are handy, I see he has his 10W DIY (solder, etc) kit, for US$395 right now. There are some new devices from Coherent just released that offer 30W of diode in ~800nm IR, with or without fibre tail, that would eat 10mm acrylic for breakfast, but I have no pricing other than 'more than $500' And look into flame-finishing your edges after CNC - its easy and you get a shiny, flawless finish.
