[webgeek]

While waiting for my conversion kit from CNC Fusion, I decided to create an enclosure for my mill to keep myself busy. While working on it, I realized that if I made it nice and waterproof, I'd have a good set up for using flood coolant which seems to be really helpful in general. To that end, I've come up with what I think is a pretty slick system I thought might be of interest to someone here. I started by looking at what others had done and quickly realized how similar the whole thing is to an aquarium sump system and decided to take it from there.

The first piece of the system is a bucket. This holds the coolant but to keep things self contained, it also holds the filter for the return coolant as well. By keeping it all in one container, there are less chances for leaks and it's also much more portable if needed. I hated the thought of ruining the bucket and making it less water-proof so everything needed is done through the cheap lid.

The filtering is easy because we only need mechanical filtration and what we are filtering is heavier than the coolant itself. Because of this, I used another aquarium trick. The filter "tank" is just a square plastic Planter's Peanuts container I had sitting around, anything else with a screw on lid would work. I simply used some bailing wire through some holes in the bucket and container lid to sure it all in place. This makes it easy to screw the square container onto the bucket lid to secure it.

The return fluid comes down the tube and then has to rise up past all the filter media (fiberglass from a remodel project in this case - poly-fill batting would be even better) before draining out the holes drilled in the top half of the container. Any sediment has to go vertically through the media and because the container is quite a bit larger than the down-tube, the fluid moves much more slowly coming out than going in - providing far less force to rise up. Cleaning the filter is easy; unscrew the container, pull out the batting, dump out the sludge, put in the batting, screw on the container.

Getting the coolant out of the bucket is handled via a 500 GPH pump I had from a previous project. This pump is way too strong so I created a bypass valve to bleed off pressure. The idea is that fluid goes from the pump up to the three-way connector and then has to go either back into the bucket, to the barb (more on that in a sec) or up and out to the mill. Since the path of least resistance is back to the bucket, the valve on the return line lets me control how much pressure gets to the mill without touching the pump. Generally, it's a bad idea to cause a pump to strain by restricting it's flow. This lets me regulate pressure with a minimal change in the pumps flow as I simply control how much goes straight back to the bucket. I'd have rather used a true bypass valve but I didn't see anything at Home Depot for 1/2" PVC that would do that. This trick is used by the DIY gas turbine folks for oil pressure to keep it constant when the temperature changes.

The 1/4" barb is an idea I stole from Hoss. In one of his videos he had an air blowgun hooked up to squirt coolant. This seemed like a great idea since I didn't want to bring my compressor indoors and I'd still like to be able to clean off the machine and parts at times. It seems to work great. It does bleed a little pressure off the coolant line but it seems minimal as the blowgun is only capable of a small stream.

Finally, both PVC lines leaving the bucket are attached with PVC couplings. This allows the entire bucket mechanism to be removed from the enclosure without breaking anything. I personally prefer solid, glued PVC connections over flexible tubing. I feel it's less likely to leak or become detached. It's also kink proof and I think it looks better than running tubes everywhere. In this case, I'll simply attach the PVC directly to the frame with conduit straps.

Anyways, that's about it. Nothing too terribly amazing but I thought it might help out other newbies like myself in building a self-contained flood coolant system. All told, it was between 50-60 dollars in parts (not sure the exact number, I had the pump and some of the PVC already but still cheap) and should work great. It only took about 2 hours to put together. Everything is available from Lowes or Homedepot except the poly-fill (Walmart or a craft store) and the plastic return tank (also Walmart - look at the food stuff to find something that would work ).

Have fun!

Mike