Pretty good deal for High Merv Griffen rated filters 
(cut em in half, you get two filters for the GF filter)
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I have not had any luck cutting filters in half and using them.
Air (like most things being pulled through a filter) takes the path of least resistance. If the filter doesnāt have that strong edge, the air just goes around the filter.
Do you have a way to prevent that after you cut it?
(This is just my experience with trying to do something like that in the past. It didnāt work.)
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interestingā¦ I lay them cut end over solid end (lower piece faces left, upper piece faces right)
I am still in the testing phases of it all, but I have a pretty decent air pull - I guess a dry ice smoke test will really give me a definitive answer.
one of the filters is a HEPA grade air filter sized for the box, I will see if that gets more contaminants then the rest.
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If you had a high-power high-volume fan, I think it would be a simple matter to find the filter set and build the container to fit the available filters. In the case where you already had a GF filter the situation would be different. I already have a Blu-Dri so the adapting means I need a 4"-12" adaptor and I can be sure I will handle the CPM, as they already sell the three different filters that need to fit.
One of the problems I see with the GF filter is that it is marginal when empty and then likely to fill up fast, while the Blu-Dri is overkill so should fill up slower with the same use. The other advantage is that there are three similar filters, the first and cheapest is the prefilter which can need to be replaced three or more times as often as the expensive HEPA filter (according to their data) with the vapor (charcoal) filter on a different time table depending on what you are filtering (If the need is abundant vapors like smells or damaging chemicals then the HEPA and prefilter will provide little help and may not need to be replaced as often as the vapor filter might be used up fast depending on the situation, but is way cheaper than the HEPA filter.
By having all the filters in one box the HEPA filter might make several rounds when all that needed replacing was the prefilter.
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Are you referring to resistance of air pull, or lack of resistance? Because if the air is going around the filters there would be little resistance.
But you are absolutely right, testing is the best way to find the truth. Theory can only get you so far.
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Is the reason for the filter, the prefilters are to protect the HEPA filter from having to deal with what they can remove so the HEPA does not fill so fast. This is why I was suggesting an open-cell sponge type filter as it would take up most of the burned wood gunk and simply washed instead of even needing to be replaced.
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āmind the gapā
the current layout is:
(intake)
(carbon sheet - prefilter)
CARBON
HEPA FILTER
HOME DEPOT CUT FILTER
HOME DEPOT CUT FILTER
HOME DEPOT CUT FILTER
HOME DEPOT CUT FILTER
(output)
Iām actually thinking the cheap home depot should be the front line filters and the HEPA should be the last - since the Home depot ones are by far the cheapest)
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Like the chess computers if you can not bother checking the obviously stupid solutions taking up 90% of the possibilities testing can be a lot more efficient and possibly only verify what a good hypothesis shows. Actual Theory provides the solution even when the most detailed verification is not possible. (like the theory of Gravity or fluid physics)
well said
Yes!^^^ A filter that grabs part of what passes will improve with duplication. Their job as cheap pawns is to protect the expensive queen HEPA ! Having queen HEPA take hits to protect the pawns approaches silliness.
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yea my thinking too, canon fodderā¦
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I did an unscientific smoke sniff test
and WIN! - nothing detected!
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So are you talking about reversing the stack of elements in the listing?
(intake)
(carbon sheet - prefilter)
HOME DEPOT CUT FILTER
HOME DEPOT CUT FILTER
HOME DEPOT CUT FILTER
HOME DEPOT CUT FILTER
HEPA FILTER
CARBON
(output)
This makes better sense to me from a users perspective. I had the frustrating experience of putting the cartridge in the case upside down (small round holes up, vice fan fold paper side). The filter plugged up very fast.
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my layout is, sacrifice the cheap filters first, and save the hepa / carbon for the real nasty stuff, the cheap filters are $5.00 a piece (hepa was 9) carbon is $60 - this is on my repack, not the sealed glowforge filters
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Iām going to try this out. How do you plan to identify the status of the filters? Will you be taking the box apart to check on the cheap filters if you notice a slowdown on the evacuation of smoke from the GF?
I also want to see if the cheap filters can just be swapped on some sort of schedule - pull the top one when it starts to look clogged, add in a new one at the bottom of the layer, etc. Let us know of any updates or results you get from your ānew unit.ā
I made myself a ādualā unit with both an infinity fan and a air filter and I select which one I use,
the revised filter is all screwed together (i drilled and tapped threads) and I took the carbon and put it in a mesh bag so its easier to handle, I can take it all apart in < 10 mins and inspect the filters, if need be. - if you will be doing this, I think you can get a good baseline by materials you are using ā MDF - every week, Wood - every 2 weeks / Acrylic ā same
remember this is PURELY unscientific ā like anything else you need to get a feel for it
but with that in mind, IF YOU SMELL SMOKEā¦ check the filters
Jonathan
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Did you change the tap size and screw size as you had hinted in one of the earlier posts? Would 8/24 (or thereabouts) be a better fit for tapping?
Also, have I said thank you for all the information and help youāve offered on this topic? I meant to start out with that. This is a really big help for me.
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8/24 is a perfect size, but the rivet hole may be slightly larger, so you wanna drill one rivit out with 8/24 drill bit and make sure before drilling em all out - CAUTION only drill the border of the top case rivets - not any on the side
Jonathan
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Thanks for the suggestion. Iāll give 8/24s a try first, then see what I need to do.
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