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I built my first laser cutter in 1996 and learned right away that laser cutters "stink". Well, at least the fumes from cutting smell awful and are quite harmful to breath. After trying several fume extraction options, back in 2002 I found the ElectroCorp RSU filter. It was a bit expensive, I think I paid $1500, but it did a great job extracting even the worst fumes from cutting acrylic. Fast forward to 2013, I called up ElectroCorp to buy replacement filters for my unit and found out that the original company was sold and is now being run by another company. This new company claimed to supply the same replacement filters, but after almost three months of going back and forth with them, it turns out that their filters are no longer the same, cost way more and look to be much less robust. Going through this challenging and frustrating process with them got me thinking. After taking a close look at how my old unit worked, it was pretty clear that I could build a similar unit quite easily that would allow me to use off-the-shelf and readily available parts. I figured I would document the process so other people with laser cutters could try their hand at doing the same. Depending on the supplies you have laying around your workshop, you should be able to build one of these for somewhere between $400 and $450. Here's how...


 
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Testicus made it!11 days ago

i just finished building a slightly modified one, and it works perfectly. i cut six 1" dia circles in 1/4" acrylic and the only "smell" is the freshly cut material itself. i have my extractor unit sitting outside and you can't smell anything. i live in an apartment complex and a neighbor complained about the odor coming from my laser cutter exhaust. this build not only saved me tons of cash (have you SEEN how much they want for a commercial extractor!?!), but my neighbors have one fewer thing to complain to the apartment manager about when it comes to my building/making behavior when it comes to noises and smells. oh, that's the other thing, this extractor unit has "baffled" the sound of my exhaust motor. before it was nearly as loud as the air conditioner, but now you can barely hear it. awesome tutorial.

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Great job! I am having a hard time finding an affordable 29500 Honeywell filter. What did you use? I am buying the parts now to build this next week. I am so excited about the prospect of moving my 40w Epilog inside!

thank you :-)

i used this:

http://www.amazon.com/Honeywell-24000-Replacement-...

the 29500 listed above is no longer available. i had to modify the design to accommodate the different dimensions of the filter. i also decided not to attach the fan motor to the extractor. there were a couple other little modifications along the way, but overall, this tutorial is excellent. total cost of this build was just over $300.

I would love any additional details you can give me. I have ordered everything now and will begin as soon as it all arrives. Since you have worked your way through this instructable, any input or advice would be very much appreciated. Why did you separate the fan motor? Can you share pics? How loud is it compared to some other common household item.

Thanks so much!

feel free to visit my dropbox folder where i uploaded all the images i took while building this. ( https://www.dropbox.com/sh/rkmygck5f4u4ymw/AADc6e... )

the fan doesn't care at what point it's located, beginning, middle, or end, air flow difference is negligible. i'm sure you can "scientifically" calculate differences and say i'm wrong, which i probably am, but in practical use, i haven't noticed enough of a difference to make it worth mentioning, and i've tried it in all three locations. the only reason the fan is where it is happens to be by accident when i discovered it attached nice and neat to the back of my laser cutter without duct tape or clamps. just a simple press-fit and it's nice and snug.

the sound of the fan was as loud as the air conditioner, but now it's much quieter, despite being inside and the extractor unit being outside. the multiple layers in the filtering have also "baffled" the sound. an added bonus.

as for advice, i would only say to wait until you have ALL the necessary ingredients and resist the temptation to get a head start. i started with the HEPA filter and traced it out on the 3/4" plywood, then drew circles out from that. the plywood i purchased, since they wouldn't sell me a half-sheet, was two smaller sheets 2ft x 4ft. the actual width is something like 23-1/5 or something, so i made my outer dimensions as large as i could and figured out the channel between the HEPA filter and that outer edge. adding an inch for the "circles" of plywood that hold the hardware cloth and window screen.

i used this instructable as a guide, i didn't follow it to the letter. another modification was the gasket material. it's a great idea to use the neoprene shelf liner stuff, but neither lowes or home dumper had any, so i used a bead of silicone on the bottom of the HEPA filter and let it dry. in the future when i want to change the filter it won't be adhered to the plywood on the bottom of the unit.

not really sure how to explain it any better than this tutorial other than to say, take your time, measure twice, cut once. dry-fit your parts to see how they all behave BEFORE gluing or using the silicone caulking. an awl works wonders for starting screws. and resist over tightening the screws into the wood. sometimes a power tool limits our sensation and doing things by hand is better only in that you can "feel" the torque you're applying to the hardware. power tools are faster, but this isn't something you're doing on a production line. speed is less important than accuracy.

let me know how else i can help :-)

dw

I got most of the parts and I am cutting today. I just wanted to ask you if feel like you wished you had vertical supports. How snug can you get those wingnuts before things start to crush - or is that not an issue at all?

Thanks again!

also, my fan goes full blast, no rheostat controller. just plug it in and let it go. it was an added detail i didn't feel this needed. but that's just me. (whispers: it's also cheaper without it)

Thank you so much for your added input. It is fully appreciated!

np.. freely i have received, it's only fair to freely share. good luck and lemme know if you need anything else ;-)

JonW320 days ago

Would you consider posting the vector files for the wood cutouts? I have a big enough laser to cut that.

Also, in an effort to contribute to the thread it looks like Fantech may have upgraded their unit as the CFM rating is now considerably higher than the one from Amazon. I also talked to a FanTech rep and they said not to order them through Amazon as they are not an authorized dealer and they will not support the warranty. That could just be hot air because they are sold through Amazon by distributers. Regardless here is the link to the FanTech FG6XL... http://www.supplyhouse.com/Fantech-FG6XL-FG-Series-Round-Inline-Exhaust-Fan-6-Duct-483-CFM

Could you please get in contact with me I would like you to services lasercutting devices
superbenny3 months ago

Hi,
May I ask what wattage your laser cutter is? I'm looking to build this, or tweak the design a little for a DIY laser cutter that I hope to make this year for my final year project and am wondering if it could be made smaller for a say, 25-40W laser cutter. Or how large of a filtering system you might recommend for my requirements.

Zach (author) 5 months ago
With acrylic it really only takes a tiny leak to let the fumes out. I found my motor housing leaked a little as well as between the top two pieces of wood. For me a combination of caulking and some extra foam tape sealed it.
bratan Zach5 months ago

Thanks, that's useful piece of information! I'm off to Lowes to get some 1/4" ply, going to laser cut brand new top (as per "bar2" comment) with tighter motor housing hole. Having thinner top will help motor housing to go deeper into the pre-filter (I might even add small piece of pipe on the inside). And definitely more weather stripping, thanks for the suggestion! Another idea I had is to add some gaffer tape on top 2-3 inches of the outer ring. Carbon seems to settle which leaves empty gap there... Not ready to give up on my $570 investment just yet :)

bratan bratan4 months ago

Just wanted to post an update. Duct tape on top of the inside of the outer ring stopped most of the leaks. I suspect it might have leaked thru holes in the plywood (layers had some gaps) as well as thru less dens layers of carbon. I get just hint of the smell now, so it's not totally gone, but lights years better :) I now realize the circular is probably not the best design idea mainly because carbon compacts toward the bottom, and layers do not saturate evenly... Once I use up HEPA filter I'm going to try and make a box type filter.

P.S. I measured wind speed generated by the filter, and it's pretty good 210 CFM inside the laser cutter!

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bratan bratan4 months ago

Something else worth mentioning. There are apparently different compositions of acrylic which affect smell. I was blaming it on the filter, but last night I tried cutting some 1/8" white acrylic, and to my shock there was NO smell at all in the room! Even freshly cut piece had only faint odor when I smelled it directly!

formvisionse4 months ago

Great ide,

Unfortunelly for me we cant get that HEPA filter in sweden, they wont ship it here!

Do you have any flow data on that HEPA filter and are you running the fan at 392 CFM, can the filter handle that and still be working correctly.

Anyway great instructable using it for inspiration over here just need to design a solution from the materials I can get over here!

I have found a pre filter F9 class and HEPA H13 that has capability of 2000 CFM, for a good pricing, and then I will make the carbon filter part my self!

bratan made it!5 months ago

Just finished building one, and it seems to work great! What a great instructable!

It was hard (especially since I lacked some tools and experience) and took me almost a month to do (weekends mostly). As I mentioned earlier you going to need more than 5 feet of metal wire cloth (just get two packages) and blue post filter is really a must. Also interestingly enough my carbon came in 2 buckets instead of sack (cost shipped was $165).
I couldn't figure out a good way to make small 6" hole on top (router jig doesn't work for such small diameter) so I drilled it out and then used router to cut it freehand. It came out pretty bad, so I had to use a lot of calk to seal gaps near the fan base. Also since I didn't have plunge router, I managed to do all cuts with fixed router, it just took longer (do it outside if you can, and watch out for wood dust getting set on fire! I almost started one). At first I didn't think I need casters (since it will be placed on carpet) but I glad I did add them, as this extractor is EXTREMELY heavy.

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Zach (author)  bratan5 months ago

Awesome! Looks great.

bratan Zach5 months ago

It seems that I jumped the gun when I said it works great. Now that I finally had a chance to cut acrylic I must say, it maybe filters out 50% of the smell, rest goes straight thru all the filters and carbon and it stinks, really stinks :( I checked and double-checked, there are no leaks. Smell is coming near top layer of carbon. I opened top cover, topped off carbon, shook it added some more until it was even with all sides, closed tightly and... nope fumes are still getting thru :(

bratan5 months ago

I'm 98% done with the build! :)

It probably depends on screen mesh size, but I'll tell you folks, that post filter is NOT OPTIONAL as I found out the hard way ... As soon as I switched fan on, it started to snow fine carbon particles :O

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bratan5 months ago

Quick question. In the supplies you list both two 3M foam filters and Duck brand filter. But it's unclear if Duck Brand one is every used for anything?

Zach (author)  bratan5 months ago

bratan - In step 9 I used both... Duck filter on the inside of the mesh cylinder and both 3M filters on the outside.

bratan Zach5 months ago

Thanks I see that you added description of filter now! :)

I'm in final stage of the build, it's coming out great.

One more thing I wanted to mention is that one roll of wire cloth is simply not enough. I was about 5 inch short on the outer ring, but fortunately I had just enough size piece left from inner ring so I patched it up. However I had none left for the pre-filter. If you did manage to construct all 3 pieces from same 5 foot roll of wire cloth, you must have got an extra length in the package somehow...

Once again this instructable is simply EPIC, I can't wait to finish up my build and post some pictures.

bratan6 months ago

Very very impressive! I'm going to make one after I get laser cutter. Thank you so much for instructions!

I'm curious have you considered an external enclosure for it? Maybe some kind metal with lots of holes rolled into a cylinder... :)

Zach (author)  bratan5 months ago

I haven't needed that, but if you build one, please post a picture of it

wentzele6 months ago

How many times can you replace the carbon with a 55lb bag?

I am planning on building one of these. Great project, I live with neighbors close by and still plan to exhaust outside by adding another other container which would then duct outside.

Zach (author)  wentzele5 months ago

You can fill it twice with a 55lb bag.

TonK17 months ago

This is awesome. I have been looking for a fume filtration for my laser, and this fits the bill perfectly. I definitely plan on making one. I do have a question.

How is the blower attached to the filtration system? Is it just set there? Or is there something securing it in place?

- Ton

Zach (author)  TonK17 months ago

Hi Ton - I cut the hole so that it would basically be a press fit. I've fixed the few minor leaks with silicone caulking. Guess that could also hold the blower in place if your hole was a little large.

TonK1 Zach7 months ago

Perfect. It seemed like it was just a pressure fit, but wanted to confirm. Out of curiosity, how far a run are you making with the hose? Are you using a reducer when it reaches the laser cutter (unless you have a 6" exhaust on your laser). Also, did you use the entire 55 pound of charcoal in the unit?

I also have a small airbrushing booth, where I spray water based paint. I think I will make a manifold, so I can also extract fumes from there.

This is a great tutorial, cant wait to build it.

bar27 months ago

Made one and it works great!

You can use your laser cutter to make the top and bottom pieces if you split them into multiple sections. I've attached the .DXF file, they are intended to be cut from 1/4 inch wood, then stacked two layers thick to make 1/2 inch. The top and bottom layers should be rotated or flipped so that the joints do not line up.

Thanks for the project!

elincango1 year ago

thanks. today start construction. good luck for me and amazing work friend Zach

elincango1 year ago

tanks

soundgod061 year ago
With the carbon being the final step, what prevents the fine carbon dust from blowing all over your shop? Also I'm surprised you didn't pirate some parts off your old extractor, namely the blower and speed control.
Zach (author)  soundgod061 year ago
Ha! I had the same thought, which is why I turned it on the first time outside. I imagined a cloud of black dust, however, there just wasn't much dust at all. However, adding a final layer of filter mesh on the outside to catch any stray dust is probably not a bad idea. The original ElectroCorp had this.
Zach (author)  Zach1 year ago

You're original question about dust got me thinking about it... So, I just updated the instructible and my filter to include the final blue poly filter. Just like the original unit. This should catch any seen or unseen carbon dust.

What about why you chose not to pirate parts off your old unit?
Zach (author)  soundgod061 year ago
I wanted to see if I could duplicate the performance of the older commercial unit with completely off the shelf items. I also might try my hand at making a custom sized HEPA for the old unit. Then I'll have TWO fully functional and serviceable filter units.
chipkona1 year ago
How long does the carbon last.How do you know when to replace it?
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