The wtf-ridden chinese laser engraver/cutter adventure
Out of curiosity i bought one of those very cheaply built K40 china laser engravers/cutters from ebay. I knew that the machine will probably have terrible shortcomings, and i never expected the software coming with it to work. But it would be a nice project to tinker with.
Warning: I have CO2 laser protection gear. Your eyesight is at risk with this machines, so the first thing you should buy are good CO2 laser googles. be careful: those goggles with red glass that are sold on ebay are not laser safety goggles!
My machine arrived with multiple defects: laser tube broken, pulley of the y-axis broken, software not working.
there should be no water in the outer tube
20.000 volts arcing, yeah
The merchant told me they have no technician in germany, so they cant repair or diagnose anything, and i cannot return the machine as the shipping would be too expensive. So i did my best to get a very good deal for the broken machine:
| bought for | -600€ |
| got back | +400€ |
| sold controller | +100€ |
| new lasertube | -100€ |
| 200€ spent, yay! |
Safety problems
more than you can count. these machines are inherently unsafe and the ce sign on them is (obviously) fake.- iec connectors earth pin is not connected at all.
- earth cable runs to an extra earth connector, which is isolated against the chassis. WTF!
- no safety switch for any door, you can open the machine while the laser is operational.
- the isolation tubing for the high voltage cable was dangling somewhere. it was added but not moved to the correct position. high voltage arcing anywhere possible.
- Laser sometimes turns on when homing. WTF!
- If the lasertube goes bad, the power supply will happily arc to the chassis and release magic smoke a short time later. no fault detection at all.
- US-Style 2-prong power plugs with 220V output for fan/pump.
- All (metal) covers have no earth connection to the chassis, despite 220v cables dangling all over the place.
- acrylic access door window (which this laser can easily cut thru, so invisible eye-popping laserbeams in your lab, yay)
- several (unused) openings where laserlight can escape the chassis. firehazard, etc.
Product problems
if you ignore the highly problematic safety problems it's still a shitty product. at least mine has a newer laser power supply, with digital power settings and not the older analog gauge (which is in-line with the 20kv anode, wtf)- The corellaser software for the lihuiyu controller always simply crashed, poking around with an debugger was highly entertaining (super crappy software)
- Lasertube had a water leak to the outer hull. The tube is undamaged, it was probably produced with this defect and never tested
- Lasertube is rated for ~31 watts, product description claims 40 watts. this will lead to a short tube lifetime
- The fume exhaustion fan is underpowered and you have to tape it to the chassis because it just dangles loosely in it's mount. if you mount the internal propeller backwards the output nearly doubles ^^
- The fume extraction slit is not wide enough and covers only part of the cutting area.
- No air assist. This will quickly deteriorate ZnSe lens and mirrors
- No cooling fans. Power supply gets very hot.
Fixing it
- Fixed/added all wiring (earth, insulation, ...)
- Added safety switches to all relevant doors (not software controlled)
- DRV8834 drivers (for the steppers), an arduino and two mosfets (for internal fans) are all thats needed for a controller.
had to hand-solder new connector to the flex cable (leading to x-axis) because of missing connector - Uses Slightly modified lansing marlin firmware
- a small but powerful fan (near cutting nozzle) acts an air assist replacement
Done!
Thats about it. Now it's working and i only invested 200€ plus a few evenings worth of awesome tinkering time. It's now a valuable tool for me, but i'm still cautious around it: invisible lasers beams at 40 watts are extremely dangerous.
electronics (mostly only an arduino and 2 stepper drivers)
warning label with hilarious spelling (and power panel with added emergency cut off)
