Latest mod: Mist collector

Thought I'd share with you all my latest machine modification. Without boring you with the thought process behind why I wanted to do this, I decided some form of mist collection would be good to have. After a brief bit of head scratching and a whole lot of desire to not spend thousands of dollars on an off the shelf unit that I would have to modify to fit the machine anyway, I came up with what you see in the attached pictures. The filter is a 20x20x2" aluminum filter for oil/water mist and the fan is nothing more than a $20 hardware box fan for those hot summer days. Add a big hole in between the two and viola, mist collector. The airflow it creates is actually quite impressive and (so far) the only permanent modification to the machine is the giant hole I had to cut in the rear access panel. Should I later decide this was a bad idea I will have to somehow patch that hole or replace the panel but neither option should be all that terrible. My only real disappointment is my total lack of color matching. The original intent was to weld coupling nuts to the panel that would be used to clamp the filter in place. Unfortunately, that didn't go well so everything is just bolted on but the welding attempt, as well as the cutting, caused just a bit of damage to the paint, hence the need for a new coat of rattle color.

The next challenge is power. Because the power into the machine doesn't have a neutral leg, getting 110 to the fan becomes a bit more difficult. However, because I recently upgraded to servos, my controls cabinet now has a large empty space where the stepper drives used to be. That gives me room to add a 220-110 transformer to provide power. That will feed the switched side of an off-delay relay which will get it's signal from the coolant pump. When the pump powers on, the fan relay will kick on to start pulling air. When the pump shuts down, the relay will keep the fan running for whatever time period I determine to be appropriate before shutting the fan back down. All the electrical components are ordered and should arrive by the middle of this week so hopefully by the end of the weekend it will all be installed and cleanly wired in.

Total cost when this is done, including all parts and shipping should be about $250

That's neat! I was considering doing something like that for my shop that has my G0704 conversion. The top of my enclosure is open and on long runs, sometimes 8 hours or more, the shop really fills up with mist. The windows drip, everything gets damp. Not cool.

I assume the collected coolant is returned to the machine?

If that will separate oil from the air I would be interested! I use diesel/oil mix for coolant and the larger cutters produce lots of mist in the air, in the summer its not a problem, just leave the doors open in the garage but when its closed up in the winter its a bit of a problem.

The working theory is that as the air/mist is drawn through the filter, it will come in contact with the aluminum mesh. The mist, be it oil or coolant, should condense out of the air upon contact. With sufficient buildup, the condensate drips off the surface and works it way to the bottom of the filter. At the bottom of the filter are a few large holes (easier to see in the picture where it's not yet in the machine) that should allow the condensate to drain back into the enclosure. Other than the fan providing airflow, it's a completely passive system. I'm not expecting anything like perfectly filtered air on the far side of the fan but it should pull quite a bit out. Putting it to use will be the real test to see if the majority of the mist condenses out in the filter or if it gets pulled all the way through and ends up on my garage door on the other side of the fan. Right now I'm working my way up to a couple new jobs on the machine but I don't think I will be running anything for at least another week or two so it will be a while before I have a real report of it's effectiveness.

If this works, I'm in on a smaller version for my lathe. There is an access panel on the right side that would work perfect for one.

Not the update I had hoped to post but progress has been made. Step-down transformer, off-delay relay, and a pair of 110 panel mount sockets have been installed and wired in. Unfortunately, the bi-directional nature of AC power meant my planned wiring arrangement caused all sorts of odd behaviors between the pump and the fan. The solution will prove fairly easy but requires one additional relay (on order, should arrive wednesday) and some reworking of the factory wiring. Short version, the relay output on the ECM that used to directly power the pump motor now serves as a signal only to a pair of relays, one to run the pump, the other an off delay to run the fan. The positive side affect of this is I now have a discrete relay to burn up instead of the ECM should I ever decide to up the HP of my coolant pump.

The dual outlets was sort of a last second decision that in hindsight I'm happy I decided to throw in there. One outlet is tied to the time delay relay for the fan operation while the other is simply connected to the 110 side of the new transformer and will be powered as soon as the machine is taken out of reset. While I don't have it yet, that "always on" outlet will eventually serve to feed power to a tramp oil skimmer so I don't have to deal with plugging that device in separately. In a couple more days when this is for real done, I will post a few more photos, part numbers, and a wiring guide for anyone interested in replicating what I've done.

Update revival! Any progress on this one Soofle?

Did you use an off-the shelf replacement filter from Sentry Air or similar? Or some other product?

Very interested to hear about the performance test of your unit after a few months.

Something like this? https://www.hoodfilters.com/20-x-20-...-aluminum.html

I guess I did forget to post a follow up. That is essentially what I used, though off hand I can't remember the actual source but ultimately it doesn't matter as they seem to all be the same thing. My results are difficult to quantify. I can say with certainty that the smell of coolant is hugely reduced ever since installing the filter and fan. My garage used to have a light aroma of coolant anytime I ran the machine and more so if I was using my superfly or had the nozzles pointing to far up on an ER tool holder as both would result in a lot of misting. With everything in place, I can obviously still smell coolant when I open the doors of the machine for tool changes or at the end of the cycle but the garage has no detectable smell anymore. I am still not happy with the electrical behavior though. My original intent was for the fan to keep running for a period of time after the pump shut down but the complexities of an ungrounded 220v AC system never allowed that to happen. I have since decided that at some future point I will replace my time delay relay with a 24V version which will require a bit of a rewire in the control cabinet but I believe that isolating the relay power from the pump power will solve my issue and allow me to get the behavior that I wanted. The fan itself pulls enough air that I can feel a current moving past me when the doors are open so I think it will be a further help to get that finally working.

Overall, I'm pleased with the results, especially given my relatively minimal investment. My original estimated budget of $250 seems to have been accurate though I will end up spending slightly more to replace that relay. Now that you've reminded me of this thread I will have to really get the updated wiring diagram and parts list put together for anyone else who wants to do this.

Well thank you for the inspiration! I ordered that unit from hoodfilters.com. I think I am going to add a pleated paper filter after the aluminum one. I'm just going to plug it into the wall when I want it on :banana:

The paper filter shouldn't be necessary really. My machine is positioned about 18" from my garage door and I have a few brand flags hanging from that door that the fan blows directly on when it's running. So far I have seen zero indication of coolant making it past the filter and onto the flags or the garage door.

edit, posted this in the wrong thread. Got my smartcool clone running though!