The Z table arrived a few days ago and I got a chance to install it thanks to the Holiday. It was pretty straight forward, but I do need to remake the air assist because the frame interferes and the gantry can not reach the home position.
I just put some countersunk through holes in some 2″ x 1/8″ aluminum flat bar I had and tapped a matching holes on the frames of the Z table and and laser bed.
The bed on the K40 is terrible. There is a spring clamp (which is not very accommodating to begin with) in the center to hold a work piece, but it’s only a fraction of the travel area of the head. After spending a good deal of time trying to align the mirrors to be able to cut consistently across the entire area, I realized that since the bed was connected to the bottom of the case with standoffs rather than joined to the frame of the linear rails, the height on one side of the table varied by .8cm depending on which direction the diaphragm of the sheet metal on the bottom was popped. So, all of it came out.
On a forum that I spend a good deal of time looking at there is a regular that has a quote in his signature: “I used to spend my time to save money but now I’m willing to spend my money to save time”. As I began to think about designing and building a motorized Z table, that quote came to mind. Rather than reinvent the wheel and spend more hours designing, purchasing parts, and building my own.
LightObject.com has a bed made for the K40. The hours I worked to earn the $155 it costs is fewer than what I would spend designing and building my own. Plus, it will be here in a matter of days. Another A4988 driver on the RAMPS board and a few settings for the motor should all I need to get it operational. I will need to figure out how to mount it properly to avoid the issues of the case not being ridged, but that should be rather simple.
Distilled water is cheap (especially when you make it), but having to change the water frequently is a pain. Up until now the coolant for the laser has consisted of a bit of distilled water in an open aquarium. Bacteria and algae grew fast and changing the water was needed every couple of days to keep it from getting slimy.
Ideally, at some point in the future, I will change the coolant to Dowfrost. Or maybe I’ll be convinced that RV antifreeze is okay to use, but I can’t say for sure what is in whatever brand they have at the hardware store, or even what concentration of propylene glycol. If it is mixed too weak you won’t be dehydrating the micro organisms anymore and the glycol will just bee a food source.
I found a couple people using a low power inline UV sterilizer and straight distilled water with good results. I’m not sure it will work indefinitely, but if can keep growth down and allow me to do water changes after a month or two I think I’ll call it a success.
I opted for a 3 watt UV-C sterilizer from JBJ Lighting, the Nanozapp JB7356
I purchased an 8 gallon plastic tote from Lowe’s that seemed like it would be structurally sound when filled with liquid. Holes where drilled for the power cables and tubing. The plugs of the UV sterilizer and pump needed to be cut off and replaced to feed through the grommets.
The silicone tubing is clear, so to help cut down on light and growth I ran it through some 1/2″ black polyethylene tubing I had. I put some tubing connectors for the black tubing on the reservoir and made a nut/spacing washer with PVC conduit female adapter to fit the pipe thread.
It runs. We’ll see if it works.
Update: 2019-12-01
Water is still clear, I haven not had to change it yet.
