Laser Filtration

Laser cutting filtration cabinet:

Preface,

I recently moved into an apartment with my Fiance and unfortunately had to leave my big machines at my families house (Tormach 1100, CNC masters lathe, Smithy 3 axis mill). I was able to bring my MaxNC desktop mill and once I finished an enclosure to make it apartment friendly i set out to build a 3D printer capable of making resin cast ready parts. I decided that a laser cutter would come in handy to build my inkjet style 3D printer, so i purchased a full spectrum 5th generation laser. Between my MaxNC 4 axis mill, laser cutter, and Makerbot I should be able to make any of my smaller projects in-apartment.

Project Background: Now that I had a laser cutter on the way I had to provide a stand, air filtration system, water cooling for the laser tube, and an air assist system. I decided to combine all of this together in as tight a space as I could, while also making sure it was apartment safe and visually pleasing.I know you all look at the pictures first so here is an image of the finished product.

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And the internals:

Laser Filtration Internals

 

DISCLAIMER: I lack carpentry skills, I am at home working in a machine shop but I’ve never been good at working with wood; Do not expect professional carpentry.

I wanted to share this project in case there is someone else out there who is in a similar situation.

The following project log will be broken down into these parts:

1. Bill of Materials
2. Tools required
3. Filtration Unit Construction
4. Blower installation and connection
5. Water cooling installation and support structure
6. Air assist connection

And here is a pic of my milling enclosure:
Milling Machine enclosure

I would advise anyone attempting this build to locate the nearest friend who owns a table saw and a jig saw as it will make your life drastically easier. Feel free to substitute the MDF for plywood if you have it available, the only reason I went with the MDF was because I had it on hand from a previous project. My main limitation with some of my material choices was the space available to work, most of the work had to be done on my coffee table in a small apartment.

Bill of materials:

1/2″ MDF Sheet (2′ x 4′) x 2 –> $10ea at Home depot [SKU# 279388]
1″ SQ wood segments x 4 –> ~$2 ea at Home depot [Used to build exterior stair railings]
Chicken wire 25′ –> $13 at Lowes [Item# 92679]
Fiberglass screen 25′ –> $6 at Lowes [Item# 15542]
4″ to 6″ Duct fitting –>$8 at Lowes [Item# 127823]
4″ 90 Deg Elbow x 2 –> $4.50 at Lowes [Item# 36400]
4″ Flex Duct (4′ Lg) –> ~$10, local selection varies
1″ Grey Iron Pipe (36″ Lg) x 2 –> $13 at Home Depot [SKU# 438274]
1″ Grey Iron endcap x 4 –> 2.50 ea, Local selection varies
1″ Grey Iron Coupler x 4 –> 3.70 ea, Local selection varies
2 gallon Bucket and Lid –> $5.50 at Home Depot

AC Blower Unit –> $75 at Harbor Freight [item# 97762]
Air Assist Pump –> $69 on Amazon [Item# AAPA110L]
Kobalt tool cabinet –> $157 at Lowes [Item#: 19801]
Activated Charcoal (90 Oz) x 3 –> $12 – $20 on amazon [Accurel “Black gold”]

The above list comes out to about $459, the only things left to add are the cheap pleated filters, some angle braces, and a few eye bolts. This list was compiled with NO shopping around, I had to get this whole build done in a week and didn’t have too much time to look around for good deals, my laser came with a submerged pump for the laser tube. If you have time to wait for things to go on sale you can easily bring the price down, for instance the Harbor freight blower can be had for 20 dollars less if you catch them at the right time; I purchased my charcoal for $12 on sale at the time. Taking a trip to your local contractor supply house for the HVAC components will bring the cost down as well now that you have a list of what you need. You can go with a smaller air assist pump (60ish Lpm) if you don’t plan on cutting anything thick, but for ten extra dollars I went with the 110 Lpm just so I had the available capability. If you don’t have a hardware store in your area McMaster sells most of the plumbing and HVAC components. I would not be surprised if you could bring this build down closer to 300-350 mark if you substitute the Kobalt Cabinet with a reclaimed housing and shopped around for the hardware (Or used salvaged components).

Tools:

Sheet Metal shears
Needle Nose Pliers
Hammer
Drill – Cordless preferred
Spade Drills (7/8″ and 1/2″)
Table saw or Jigsaw (I used a jigsaw)
Staple Gun
Miter Saw and Miter Box
Standard Hand tools (Hammer, hacksaw, screwdriver, etc..)

DISCLAIMER: I will be neglecting specific dimensions for areas that I feel are up to interpretation, When in doubt start big and work your way down. This is an exercise in stuffing 10lb work of stuff in a 5 lb box….. so to speak.

Step 1:

The first step of this journey will be to prepare the cabinet to accept all of the equipment. Learn from my mistakes and DO NOT widen the pre-existing hole in the back of the cabinet; I did this late at night without thinking and it is not even remotely where it needs to be for the main duct to pass through. Start by tracing an outline, I used the pre-existing mounting hole in the back of the cabinet as my center mark. The easiest way to trace this circle is to just trace around the end of one of your ducts.

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Next get your tin snips and elbow grease out because this is the part that SUCKS. Watch your fingers as the edges on this steel will be sharp and jagged, I hooked myself twice doing this and had to spend time picking metal splinters out of my fingers…. wear gloves. Start from the center and try your best to cut a “piece of the pie”, when you get a slice cut out just bend it towards you can use your tin snips to cut it as close to the back wall as possible.

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This template was made using a protractor and compass. After bending the finger up snip it as close to the root as your snips will allow you to.

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Now this part is a bit tricky, use a good pair of needle nose pliers to roll the remaining material into a rolled edge. You can very well just fold the remaining material flat if it is easier, this step is optional.

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As you may notice by the above picture I got lazier about rolling the edges as the process when on. The reasoning for this style of notching is so that the aperture opening can be adjusted without requiring additional cutting. If your duct is too large to fit (mine was) just continue to roll the offending segments which will tear the metal rather than having to get the tin snips back into such a  tight spot. You will need to do this again for the blower opening, I recommend making the opening larger than the blow to allow the use of a duct in the future (See below for duct).

Blower and opening:

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If you made it this far congrats…. the easy part is done! So go grab a drink and get ready for the smell of MDF. Kidding aside this is the most labor intensive part of the build, once you finish preparing the cabinet the rest is a cakewalk.

Step 2:

Now we move onto the filter stack which is the major volume hog of this system. The path of the exhaust travels first through two coarse filters, then two fine filters, after which it is forced through 12 lbs of activated carbon, and finally through the blower unit and either into your apartment or out a window or screen door. Lets start off with the first set of parts:

  • 4 Angle braces per tray (12 total)
  • 2 (3/4″ x 2″ x 12″) Sections of hard wood (6 total)
  • 2 (3/4″ x 2″ x 10.5″) Sections of hard wood (6 total)
  • Finishing nails
  • wood glue

I recommend using a 90Deg angle clamp to make sure the joints are held in place during nailing. Obviously this is optional but I highly recommend it unless you have a sturdy work bench.

Parts and tools:

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Clamp one 12″ length section to one 10.5″ section:

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Drive two nails into the corner after clamping (glue is optional but advised):

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Repeat with the remaining 12″ and 10.5″ sections. Then install a angle bracket into each corner to reinforce the frame:

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Ready for the screen and chicken wire!

Cut a section of screen that is about 3/4″ larger than the frame:

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Fold the screen up on one side and staple several times on each side:

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Make sure to secure the corners cleanly:

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Repeat this process with the chicken wire, keep in mind you will be putting approximately 4lbs of activated carbon on each frame.

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Now cover the outside with duct tape or foil tape to help keep your hands off the sharp chicken wire edges:

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Now flip the frame over and apply the weatherstrip seal around all 4 sides, you only need to do this on the bottom face:

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First frame finished! Now you just have to repeat this process 2 more times! Re[eat the sealing process on the 2 coarse and 2 fine filters.

Part 3:

Now that you have your filter stack all sealed up and ready to go we can get started on the housing for the filters. I apologize that I cannot post the drawing at this time, they were made in a hurry and need to be cleaned up before posting; they will be posted shortly!

[Drawings go here (PDF, DXF, and IGES). ]

This matter aside lets gather the materials, start off by marking your two sheets of 1/2″ MDF:

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Next you should cut the 2 4″ DIA holes, I was fortunate enough to find a 4″ hole saw however that is rather large for a hole saw and you might need to use a jigsaw instead (Or a chisel if you are a maniac):

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I used a guide and a jig saw to cut the rest of the parts out, this however is not an ideal solution and I would highly advise using a table saw if at all possible. The cleaner you make these cuts the easier it will be to assemble. Lets start off with the main body components, the top and bottom of the filter stack housing are identical so just follow these steps twice:

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Start off with the top of the lower housing (Or bottom of the upper housing…) and drill four 1″ diameter holes in the positions from the drawing. These holes can be slightly oversize without effecting the stack, I used a standard spade drill bit:

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Next you will assemble the filter housing using more finishing nails, glue would be a good idea if you can spare the extra time:

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Repeat this one more time and you are ready for the upright supports. You will need to cut the 1″ DIA gray pipe sections in half, I used a band saw but a hacksaw would suffice as well:

 

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Now that your pipes are cut (AND DE-BURRED!)  you will need to also grab the 1″ short nipples, end caps, and couplers. You could very well also use pipe to flange fittings and screw them down to the MDF, however each flange is $8:

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Now thread the coupler into the nipple, slip the nipple through the hole in your MDF, and tighten the endcap onto the nipple to secure it:

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After you secure all 4 assemblies to the MDF go ahead and thread on your pipe sections, make sure you have everything square before your pro cede (well… kinda square…) and pay no attention to the attached ducting elbow, we will get to that next!:

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 Have to call it quits for tonight, it’s 2:36 am and I need some sleep. I’m hoping to finish this part and part 4 tomorrow!