New pictures of some recent progress
The 40W DC High Voltage laser tube is now mounted in place of the original Synrad. Some might view this as a crime, but the more I use this tube, the more I like it. I may switch to an RF laser in the future, but I'm a year into my first tube and have seen no problems at all.
I used Tygon tubing exclusively for all water lines. The tube has a 1/4" ID that perfectly mated with the nipples on the laser tube. My pump actually had a 5/8" nipple on it, but with careful heating and stretching of the Tygon over a cone shaped object, (tip of a tube of silicone caulk), I was able to stretch the 1/4" ID tube all the way for a nice tight fit over the pump nipple. The Tygon can also be heated and stretched to reduce the diameter. It gets soft at 190F, so putting the end in a pot of boiling water makes it easy to work.
I made my water reservoir out of 2" schedule 40 PVC. A normal cap on the bottom and a screw-off cap on top for filling the system. I drilled and tapped the side of the PVC for hose nipples. Seems strong. No leaks.
I didn't go with a flow meter yet. The pump and radiator coils are from a surplus chiller, so they should be very reliable. I tapped a third hole in my reservoir that is presently plugged. This plug can be removed and I can insert a thermister in the return stream. This is the only place in the system where there is a "fountain" stream through air as the fluid enters the reservoir. I can build a circuit that applies current to the thermister to heat it and then reads the resistance once a second, which is proportional to temperature. If the stream is present over the thermister it will be held at the cool water temp and will not self heat. If the flow stops, the thermister will self heat and trip the laser off. It isn't as cute as the spinning flow meters, but it has no moving parts to fail and should be trouble free. The entire upper section gets covered by a steel enclosure that hangs off the yellow tabs up top. This covers all electrical lines and the laser tube. The only exposed items beneath this enclosure will be the water pump, the radiator, and the bottom of the reservoir.
The next picture shows my new adapter plate that lets me put the new DSP control interface on the front of the unit. I added an E-Stop button and a 12pin keypad. The keypad can be used for a number of functions once I program a PIC to read it. A couple example applications:
1. Password entry for machine startup.
2. Press * then enter desired table height. (for stepper controlled Z)
3. Code to start or stop exhaust fan. (Fan not needed for glass, granite, rocks, etc.)
4. ??? Many other things I haven't thought of yet.
Thought about adding an LCD for this keypad as well for better PIC to keypad user interaction. Can always add this later.
I may scrap this panel later and start over. I bought an Arduino with TouchShield Slide, so I could make an interactive control panel with touch screen. The TouchShield is really nice with bright colorful OLED display. Way overkill for this application though. http://www.liquidware.com/shop/show/TSL/TouchShield+Slide