Hardware Mods to the Lasersaur

The Lasersaur build guide gives you a well-performing machine that can control your laser beam and put it anywhere on the cutting bed that you need it. But it conspicuously leaves out instructions for hooking up a lot of the auxiliary equipment needed to run the machine, and for designing a solution to pumping out the smoke that is generated when vaporizing wood. How one wants to do these things an exercise to the builder. So, here are the solutions I came up with, along with some other hardware mods that I did. Also check out a tour of my machine, a cost breakdown, and my software mods!

Control and Power Distribution Panels

To power the machine and its accessories (exhaust fan, air assist, and chiller), most people have plugged everything into a common power strip, and used that to turn everything on and off. I wanted something tidier, where I could control the power to all the different equipment from the same place, have the emergency switch accessible, and monitor current through the laser and from the wall at a glance. Thus, the front control panel was born.

Lasersaur front Control Panel
Front Control Panel

I arranged the switches so that you turn them on from left to right – the driveboard and chiller should always be on, the red dot goes on next to see the laser path, and the air assist and exhaust start before you give power to the laser. The current for the laser is measured through the high voltage return line, which I routed from the laser tube up to the front ammeter, and back to the laser PSU. You do not want to do this with the high voltage supply line, as that is a serious 18 kV safety and sparking hazard. Measure the current after the voltage has dropped through the laser tube. 

Once you do this, the current meter works really well. You can see it flick up to about 25 mA when I do a test firing here during the build phase, which causes my wood target in the background to burst into flames. (As expected!) During normal operations it will swing back and forth as the laser pulses on and off over its cutting path. And if it goes over 35 mA or so, I know something is seriously wrong and to shut the machine down.

Test of the Laser Current Meter

For mains current, during peak power cutting I’m only seeing about 8-9 amps for the whole ensemble (cutter, exhaust, air assist, and chiller), so pulling from one 15 amp outlet is just fine. The white light below the Mains ammeter is on when the Emergency stop is letting power through, and switches to red when it is pressed and blocking power. All the switches except the exhaust and laser usually stay on, and I use the E-stop as the regular master on-off switch. This is good since it trains your muscle memory to go right for the stop if you need to power down.

In order to have the switches on the machine be able to control external equipment, I needed to have them connect to the machine in some fashion. So, in the back right corner of the machine right above the inlet holes for water/data/power, I made a power distribution panel. Power comes from the wall, through the E-stop and Mains current meter at the front, through the switches for the relevant external equipment, and back to the internal electronics and these plugs for the external equipment. The two Auxiliary outlets here are just overflow not hooked up to any switches, in case I need to plug anything else in.

Power Distribution Panel
Power Distribution Panel

Exhaust and Air Flow

The exhaust setup on the machine is likewise left as an exercise to the builder, and people have come up with quite a few solutions.

For the air inflow, I cut a long rectangle out of the left side of the machine at bed height. Some simple air filter fabric went over that to keep particles from flying in. That air flows across the cutting bed to a hole on the right side of the machine, where I 3D printed an adapter to transition between that hole and some 8″ diameter ducting. I originally had an air filter over this, but it got clogged super quickly from the smoke, so I left it open. This ducting attaches to an 8″ 735 CFM inline fan, which pushes the air through more ducting that dumps out the window. I don’t have a filter on the end of it right now, but the neighbors aren’t that close and haven’t complained yet. I originally tried using a bouncy castle blower as the exhaust fan, and that worked okay, but it was super loud and also burned out after about 20 minutes of continual use (I think they’re built to run at slower speeds with a lot of backpressure). The inline fan is working really well right now, and I get good airflow that clears the smoke quickly.

3D Printed Parts

Having a 3D printer was invaluable for building this machine, since occasionally things didn’t line up quite right and you needed some brackets or adapters that would be tough to make otherwise. Considering you can pick up an Ender 3 (what I use) for under 200 bucks, I’d go so far to say that you should just consider it park of the baseline BOM. It was invaluable for making brackets and adapter when things on the machine didn’t fit quite right.

In addition to the exhaust port adapter, there’s a couple other pieces for the machine that I made. First is new brackets for the magnetic door switches, since I was having trouble getting them to line up close enough to reliably sense door closure. Second is two inserts to close the gaps on the door between the two translucent acrylic panels. I didn’t like that there was an optical path out of the cutting volume that a rogue laser beam could bounce through, so those sealed those gaps up. Third, which I don’t have a picture of after being printed, is a little cover that fits over the test button on the laser high voltage power supply, so it doesn’t accidentally get pressed somehow. It’s a bit redundant now that the back area of the machine is sealed up, but it was a good peace of mind when I was in the build phase. Lastly are some guides that I mounted to the bed, so that I can frame up my sheets of material in the same (0,0) origin position each time. That’s been really useful so far.

Misc

The only other “mod” I should mention is that I used a 1:3 ratio of normal automotive antifreeze to distilled water as my coolant. This room is in a cold part of the house, and I don’t want to worry in the slightest about the water freezing and cracking the tube if the power goes out in the winter. I also put in a bit of green dye, which looks cool but also lets me see any bubbles in the coolant lines a lot easier. 

Filling the laser tube with dyed coolant

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