Today I finished up my 17.03 machine and made my first cut! Excited to start making some stuff with this, and hopefully recoup the cost of the machine before too long. Who do I talk to about getting on the map?
I've been filming my whole build process in pretty good detail, and have an idea to put together a step-by-step video assembly guide for the machine. If I can find the time that is...
As a side note, does anyone have any tips on getting honeycomb to lay flat? I expanded mine by hand, and there's some area that rise up off the bed frame. I tried weighing it down for a few days, but it just springs back if you don't bend it much.
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I finally have my machine in a state that I really like, so I wanted to share some of the modifications I made!
Also - Adam, thanks for the tip on the honeycomb replacement, I picked up two of those aluminum grilles and they're working perfectly.
First off, a beauty shot of the machine in my small workshop. I built a lasersaur-sized table to size for it to sit on, with two shelves: a strong one near floor level to hold the chiller, fan, air pump, and supplies, and a thin one just under the main surface to store sheets of wood and acrylic.
The laser I ended up getting was the SPT Tr100, which is a 100W laser with a red dot sight. I highly recommend getting a tube with the red dot sight - it make aligning mirrors 100x easier, it's a safety factor so you know where your beam is pointed, and it lets you 'preview' alignment of cuts/engravings before doing it for real (very useful for engraving phones, for example). The laser cost me $435 + $400 shipping from China to the US (probably more now with this trade war..), and with a laser power meter I got I measured the peak output of the tube at 102W so I can confirm it's legit.
First up for modifications is the custom control panel on the front right. I wanted to be able to control the power to all the different equipment from the front, to have the emergency switch easily accessible, and to be able to monitor current through the laser and from the wall at a glance. Below is a close-up of that control panel. I arranged the switches so that you turn them on from left to right - the drivebard and chiller should always be on, the red dot goes on next to see the laser path, and the air assist and exhaust starts 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 18kV safety and sparking hazard. Measure the current after the voltage has dropped through the laser tube.
At 100W, my laser is drawing 32.5 mA, which put total laser power consumption at 32.5mA*18kV = 585W (meaning a laser efficiency of 102/585 = 17.4%, about what you'd expect). This means I'm dumping 485W of waste heat into the chiller. Right now I have a CW3000 chiller, which pulls out 50W/degC. The Tr100 recommends a max 5degC room-laser temperature difference, which means that the chiller will only pull out 250W under recommended conditions. All this to say, I didn't understand before buying why people said to go with the CW5000 as a chiller, and now that I did the math it shows that the CW3000 is pretty drastically undersized. If you're starting out, I wouldn't use it for anything over a 60W tube. I'll eventually pick up a CW5000, but in the meantime I'm addressing this by running at a max of 75% power (better for tube life anyway), keeping an eye on chiller temperature, and relying on the fact that the laser isn't at 100% duty-cycle during operations which will keep waste heat down.
For mains current, during peak power cutting I'm only seeing about 8-9 amps for all the equipment, so pulling from one outlet is just fine (breaker for this part of my house is at 15A). 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.
How do these switches control power to the external hardware you might ask? 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. So, I can control the power going to these outlets mounted on the machine with the front switches. I really like this setup - it's tidy and there's no fidgeting with power switches on all the equipment every time I turn on or off the machine.
For the exhaust, I cut a long rectangle out of the left side of the machine at bed height for the air inflow. Some simple air filter fabric went over that to keep particles from flying in. That air flows to a hole on the right side of the machine, where I 3D printed an adapter to go from that hole to 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.
On the topic of 3D printing, I highly recommend picking up a printer when building a lasersaur. 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. 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 bound through, so those closed those gaps up. Third are some guides that I mounted to the bed, so that I can frame up my sheets of material in the same (0,0) position each time. That's been really useful. And the last which I don't have a picture of, is a little cover that fits over the test button on the laser high voltage power supply, so it doesn't accidentally get pressed.
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.
That's about it for the hardware mods! In addition to that, I've been poking at the driveboardapp source code. I've mostly finished porting it from python 2 to python 3, and got some new bells and whistles put in. I'll send out another email with a link to the codebase and an overview of changes when I'm done, but I think the most exciting thing for the folks on here is that I've got raster engraving making cuts on the backwards pass as well as the forwards, which is cutting the engraving time almost in half.
That's all for now - if anyone has any questions about this setup, let me know!
Cheers,
Scott--
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