I have a Creality open frame laser and am looking for a DIY solution to the smoke and fumes the laser creates. I have a built-in exhaust fan in the outside wall of the small room where the laser is, which works really well to exhaust the fumes and smoke, but when it’s cold out I hate opening an outside door to replace the air.
I’m cutting mainly basswood, 1/16" & 1/8" plywood and MDF, laser board, that kind of material. no plastics, nothing thick.
Is there an economical way to DIY a system using charcoal & HEPA filters, or whatever, that will exhaust back into the room without venting the exhaust air outside?
No.
I have built a system of pre -filter, active charcoal and after -filter. All in a fine box that stands outside. After a few weeks, the system was saturated and a new filter set was to be used.
I have seen advertisements from professional companies that claim that their filter machines can handle the task, but I do not know if it is true. But the prices for the machines/filter and filter change are very high.
PS. Even in the first days, with new filters, it smells outside near the filter system, just like a bad fireplace in the neighbourhood, but not very violent.
I have a “Laser-Line smoke evacvator” that’s probably a Plymovent TK-400 rebranded for medical/surgical use.
The reason I haven’t used it is that just replacing the HEPA and active charcoal filters would set me back sweet 600€ or so. If I can source 'em that is. Not changing the filters is not really an option in this case since the unit came from hospital use, and has been stored inadequately to guarantee the HEPA filter is safe to use.
My solution so far has been to either put up with the smoke/cold, or to not cut/engrave such materials when the weather is cold.
DIY:ing such a filter-fan unit is perfectly possible, but appropriate fliters that actually do the job cost excactly the same and has to be changed just as frequently regardless of whether it’s a commericial- or a DIY unit.
There are some DIY options though, but none that will actually work will be particularily cheap and will be guaranteed to require quite a bit of work and also expertise.
And are not necessarily living quarters approved by our wifes/spouses/so’s .
The simplest/cheapest/most effective solution IMO/IME would be to make a heat (/cold) recovery unit and use easily available HVAC filters for the make up air and box it.
Or
To modify an existing (second hand?) air handling unit that already has most of the parts needed, and is housed in a somewhat practical and nice looking enclosure.
On the plus side, those units usually have heating/cooling elements and filter frames already installed.
As well as condensation pans and such.
Of course, a DIYer that has an access to a sheet metal shop can probably make all of that, but not as quickly.
The main problem/expense with the heat exchanger approach is the fact that most common cube style cross flow heat exchangers are dismally inefficient, no matter what the manufacturers claim.
So the exchanging lengths have to be rather large for the unit to work as intended, at least in the ballpark of 30cm/1ft.
In order to improve efficiency by slowing down the air velocity, the width of the unit would probably need to be ~twice of that.
Or the exchange dimensions greater and the width narrower.
And the make up air will still require additional heating/cooling, at least 50% will still be lost no matter what
While the rotating heat exchangers would be much more efficient for the same size, unfortunately those won’t work in this case for obvious reasons.
So that leaves the air-liquid-air heat exchangers and heat pumps.
Air-liquid-air heat exchangers are rather easy to make and adapt, heat pump based systems perhaps not that much.
At the simplest, an air-liquid-air heat exchanger for HVAC is just two radiators connected together with insulated pipes/hoses, and a pump that circulates the liquid of choice.
One radiator is in the exhaust air stream, the other in the supply/make-up air stream.
Older automotive cabin heater cores make perfect small scale DIY air-liquid-air heat exchanger components.
As do motorcycle radiators.
But…
Installing radiators of any kind in place of a cube style heat exchanger is impossible, or at least extremely hard without completely re-arranging the supply and exhaust chambers, filters and fan units.
Or even then.
So that kind of a modification pretty much has to be made into an air handling unit that is originally equipped with a rotating heat exchanger.
Or the enclosure has to be made from scratch.
So, it won’t be easy, nor will it be cheap, but it is most definitely doable.
I dump mine thru a hole a in the wall. The make up air is a non-issue at this volume (200-400cfm). Not dissimilar from a healthy bathroom exhaust or clothes dryer. The living space heat doesn’t even know the difference. As long as the baffle is sealed well, no cold drafts are felt even with 0F outside temperatures.
My cooktop exhaust is 1200-ish CFM and does do better with make up air. House heat still doesn’t break a sweat keeping up.
If you are lucky enough to be able to direct the air flow out through a hole in the wall, and there is no neighbor directly in front of it, then there is no problem, that is how it works here with me. I haven’t removed my expensive filters yet, my industrial extraction pulls the air through the “closed” filters anyway. At least my radial fan is very quiet.
It is just an unfortunate reality that there are no affordable solutions for hobbyists or self-employed people who would like to clean their laser exhaust
I have a 6" inline exhaust fan ducted from inside the laser bed housing (mostly sealed, but with air intake vents on one side to replenish the air, then outside via a cat flap through a homemade mdf box with two carbon filters designed for cooker hoods. It was a cheap solution, but seems to work ok. A bit smelly outside sometimes, but the neighbours haven’t complained…
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