Nice one - what laser are you using? I bought a wickedlasers Arctic Spyder (1W blue) a while ago, but it's too heavy and too huge. Mabye I will disassemble it?
Or do you have a source for the laser diode and driver?
I have been selling a 1.7W 445nm Diode Laser head that works in conjunction with the 3D extruder with no need to swap out for laser cutting. We have a Makerbot 3D printer that we use for laser cutting solder stencils and other things. We have sold upgrade kits to people with RepRap and Felix printers as well.
nice driver and even more nicer tests with the balsa. I would believe 1/8balsa can be cut so nicely.
but I would consider your driver a little bit overengineered . Lasers are diodes as LEDs. And because of a big interest in LED drivers, you get all kind of nice current limiting sources for quite cheap.
for example AMC7135 chip gives 350mA and can be parralled meaning 4 in a row give you 1.4A (your supply voltage should not exceed 6V though, the 5V input of the regular ATX power supply is fine)
pt4115 can be driven up to 1.25A and can be adjusted with a simple potentiometer and can be supplied with more than 30V input.
and all these cost not more than 2-3 euros to make
Thanks! I am going to try and cut birch plywood and ABS plastic next. It really does a pretty nice job of cutting things that just a few years ago it wouldn't with the 1W lasers.
I would agree that the driver might be a bit over engineered for most folks doing hobby lasers. I sell this to research labs and industry and they really need the 0.001 resolution and holding accuracy, which is not really needed for this application.
To drive these lasers you need more than 1.25amps, you will need at least 1.7amps for the 1.7W and we are coming out with a 2.6W that needs 2.2amps. It gets a bit tricky when you get to sourcing 2 amps or more, especially dealing with the thermal issues.
It uses three 1.1amp regulators in parallel to dissipate the heat generated from the voltage drop and current sourcing. I tried using real cheap LM317 variants in the beginning, but they would thermal shutdown in just 20 seconds of near full current draw. I then went to a larger LT1083 design (7.5amps) and it still only gave about 40 seconds of on time before thermal shutdown. Putting normal regulators in parallel can be tricky to get them balanced. You might not need the isolated input, but then again you know you are not going to blow up the driver by plugging in a 24V relay switch to it from an old CNC computer. Anyway, you can get cheaper drivers out there for sure, especially if you look towards the LED market instead. You might just be having some trade-offs for performance and features.
... my first (and most reliable) drivers with currents up to 5Amps (5x LM317) or 9Amps (2xLM317+3xLM338) use parallel LM317 (for 1Amp each) or LM338 (until 3Amps each) without any issues - I'm selecting the max. current with jumpers to sum the needed count of LM's and then switch the current through the LM's to the diode with a MOSFET ...
@jtechphotonics birch plywood would be an awesome test. you encourage me to finally finish my laser cutter (based on a 2D mendel90) which is muddling for the last 3-4 months.
I wont argue about the needed resolution and accuracy, for some people its essential. But allow me to disagree on the laser drivers. While PT4115 is limited to 1.25A, AMC7135 are designed to work in parallel.
So by using jumpers (my cheap solution) or a microcontroler you can set your current pretty accurately to 350mA increments. Drivers with 8 AMC7135 and selectable power outputs are available for LED flashlights and that means 2.8A, for around 5USD . AMC7135 wont complain as long as you feed it with less than 6V (5V would be definitely better). And the simplicity of the circuit is such, that nearly nothing can go wrong for you. The AMC7135 is a driver on a chip solution no external components needed.
Im sure you can scale this up even more with no heat issues as every AMC7135 chip will only provide 350mA so heat is distributed among the chips. have a look and why not a try. You can find AMC7135 chips quite cheaply for your tests.
@waste. I checked out the AMC7135 and it does look like a very simple and nice solution. I will get some and try it out for a cheaper driver. I guess my holdup has always been the desire to have a fully adjustable current source. I like to test my lasers when they get in and make a current versus watts graph in 50ma increments. The downside is on these they are only in 350ma increments, but for 1/10th the price it will be worth it. Thanks for the info!
Just tried cutting ABS and boy what a mess. I need to get a air assist going to keep the fumes down... Cut through 1/16 inch though after 4 passes. The trick is not getting it to catch fire. It definitely needs some tweaking. I think the birch is a better idea for the next test.
There is a small 5V fan output on my driver board, so I hooked it up and printed out a holder to connect it to the XY table and it seemed to do the trick. No more fire, but the fumes are still horrible. What I really need is to close up the printer/laser and put a vacuum on one side with a filter in the path and exhaust it outside.