Small Projects #53: Walnut Air Filter Stand

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Blog entry by Madmark2 posted 08-25-2021 02:01 AM 679 reads 0 times favorited 7 comments Add to Favorites Watch
« Part 52: Steampunk Unity Weather Station Done! Part 53 of Small Projects series Part 54: More steampunk (don't read until finished - actively editing) »

We have pets and with pets comes pet dander and allergies. We bought a Grizzly G0738 two stage (5um & 1um) filter.

Grizzly G0738 two stage, three speed air filter w/ remote.

It really makes a difference but it’s not the most attractive box in the bedroom. It’s been sitting on a faux walnut MDF stand that’s falling apart. I decided, and SWMBO agreed, that something better was needed.

Completed top is gorgeous!

I came up with a design for a real walnut (& walnut A-A ply) stand. Here it is after the first coat of MS thinned 50%-50% poly and waiting on the top (which will have a live edge but isn’t built yet.)

Cabinet with lower storage.

I had to CAD the carcass. It is built out of four panels with 3/4” walnut ply base and middle shelf. The base is 32” tall by 24” wide x 22” deep. The top is 28” x 24” with 2” overhang on the live edge front and sides. The top will be flush to the back.

Construction started with the two raised panel doors. I have the Grizzly H5553 reversable rail/stile and panel set with the classic ogee profile. This was the first project that I used this on and the doors gave me an opportunity to dial in the reversable rail and stile set. Being anal (engineer) I had to draw up the stacks in assembly order locating the various thickness washers, bearing, and cutters. After cleaning, all the washers and cutter spacings were mike’d with my digital caliper and noted on the drawings to insure accuracy.

Stack for stile dado.

Stack for rail tenon.

By cutting the dado’s first, the finished face is used as a reference. The 1/4” dado position becomes a reference for cutting the rail tenons.

Alignment Diagram.

The 4/4 S2S walnut from Craftsmen Supply (Ybor City/Tampa) came in at ~7/8”. Rather than plane down the extra thickness into dust, I used it as-is. The only issue this caused was some extra tweaking of the ply deck and the face frame was too thick for the hinges. To get around this the sides of the door frame were undercut with a router and rabbeting bit to exactly 3/4”. The hinges fit perfectly and the rabbet is essentially invisible.

I used one piece of 1×6x28 walnut per door with sawdust left over. The doors were given a slathering of wax as a “shop finish” to protect them until the rest of the cabinet was ready. The thinned poly went thru the wax like it wasn’t there during the actual finish process.

UL: Panel cutting jig,
UR: Botched rout on rear,
LL: Test fit,
LR: Under clamps.

Before and after waxing.

The doors were set aside until the front frame was built. The hinge positions were verified against the frame opening and door size before drilling the 35mm hinge cups. I set the centerline stop on the drill press to 13/16” and just drill at the marks for perfectly positioned hinge cups. I set the panel flat on the drill press table and set the depth stop flush with the surface. A piece of 1/2” scrap under the stock raises the stock the thickness needed to drill the cups. Then I use the self centering drill bits in the corded VSR hand power drill in a hinge set in the cup to pilot the two mounting screws. This perfectly aligns the mounting holes with the cup using the hinge itself as the jig.

Next came the two side panels, these are traditional rail and stile frames with 1/4” walnut ply panel inserts.

These went together easily because of the CAD analysis allowed me to set and reset the extra thickness rail and stile pieces with precision.

Four L’s form two panels

The side panels are the strength members. The middle deck 3/4” plywood is supported by 3/4” sq cleats biscuited into the rails of side panels. The bottom of the sides have another biscuited cleat in the bottom rail. This cleat is glued to and rests on the 3/4” ply base, transferring the load down to the legs.

The cleats were positioned self referentially so the ~3/4” walnut decking would sit flush with the edge of the side, hiding the plywood grain. Setting the stock and biscuiter flush on the saw top “zeroed” the slots in the cleats. Then I used a cutoff from the ply as a spacer to lift the biscuiter up and cut the slots in the sides. Without measuring, the biscuiter cutter height, or the ply thickness, I was able to blind glue the cleats and it came out dead flush.

Self referential parts fit perfectly flush.

I hadn’t fully thought thru the front face frame design. I had sketched it as two full height stiles with top, middle, and bottom rails. The bottom was to have two euro hinged doors and needed a flat 3/4” mounting surface. The top half was to have flat panels in rabbeted stiles and tenon edged rails. There was no clean way to transition one piece from flat to rabbeted so a different answer was needed. The rails were run full width with the stiles tenoned instead. The bottom was done with biscuits on the butt joints. The center rail was flat on the lower edge and rabbeted on the top. This solved the problem but leaves exposed end grain on the sides. I may make some trim to cover it.

The top panel looked boring and too wide so I added a center stile. This made the inset panels almost square. I mis-cut the panels 1/4” too narrow but they fit well with the spaceballs in the rabbets. I was careful to orient and sequence the panel plys consecutively.

The back also had three full width rails but was easier to make as everything was rabbeted in one go. As luck would have it, I cut the bottom stiles 1/4” too long. Better long than short and a quick trim brought everything back in spec.

The bottom had holes drilled for the screw on legs 3” in from each corner of the base or 3-7/8” from the outer edges. For some reason the screw studs were over an inch long and, with no way to trim them down, they project completely thru the 3/4 ply lower deck. The legs had small plastic protector caps on the screws that I trimmed and used to cap the exposed ends inside the lower shelf. Its not the best solution, but it’s neat and better than leaving the studs exposed.

3×3x6 pyramid legs.

The top plates were installed using the supplied #6 hardware directly over the 3/8” hole for the studs. The inverted pyramid feet were set back to prevent the puppies from using them as a fire hydrant. The tops were recessed slightly to hide the mounting plates.

5/16-18 top plates.

The sides are biscuited into the front and back. The panels were set up on the saw in the same assembly corner I use for small boxes. The deck ply was fitted but not glued while the sides were glued to the back. Once these had set up, the front was glued on and the deck was glued down and weighted.

Finally the cab was inverted onto the floor and the bottom, feet and all, was glued in place, weighted and left to set overnight.

The completed box was sanded to 120 all round. One thing about gluing on the saw top is that all squeezeout in contact with the iron turns black and is easy to see where sanding is needed (LOL).

After sanding, a flood coat of 50%-50% MS-Poly mix is applied everywhere. The ply and end grains drank the poly up almost instantly. I reapply until it appears slightly wet.

I use 3” and 1-1/2” disposable foam brushes for streak free and easy application. Disposable brushes are easier on the environment than cleaning good brushes with a pint of MS. It took a while, but I got every square inch (except the top edge where the top will attach) inside and out.

The doors are mounted and the knobs attached. SWMBO selected and ordered nice real crystal round knobs with dark bases. These pair nicely with the walnut and, being round, can’t be misaligned. The holes were drilled with a simple stop block on the drill press for perfect alignment.

Doors closed, open, and closing .

I haven’t dialed the hinges in yet, but they self close with less than 1/8” gap between them.

The top was supposed to be 28×24 out of a 5 board glueup with 2” overhang on the front and sides. As I sorted and squared I came up with a really good grain match across four pieces that was great but only 23-1/2”. Guess what?! The top is now 28×23-1/2”! LOL I’m not a slave to the plan and I’m more concerned about yield than having to hit an arbitrary dimension.

  • After all, how much overhang on a top is “right”? 1/2”?, none?, 2”?, 6”? I’ve seen tables with dimensions all over the place. 2” was a nice, round number, but 1-1/2” will work too. None of you would know if I didn’t tell you. LOL

Anyway the four pieces were laid out and cut for #20 biscuits in three places and glued up as two pairs, I-II and III-IV. Both pieces came in under 13” which is the limit on my planer so that’s good. I was hoping to use the new scraper set that came today instead of planing.

The two halves are under clamps now.

Halves clamping.

As luck would have it I just bought (arrived today!) a six pack of assorted shape scrapers, Grizzly D3294 (yes, I do know how to use hand tools!)

The scraper made quick work of the squeeze out.

Before and after. Sharp scraper curls. Nice clean seam.

Finally both halves are biscuited, glued, and clamped to final size.

Final top glue up. The color sequence helps hide the seams. This will be beautiful when finished.

The plan is to wire brush the live edge to remove any loose material, then round the corners and rout a profile on the sides.

One of my (many) pet peeves is pointy corners. I tend to carom off things and have been gouged by pointy corners furniture and the like my whole life. So the two front corners will be radiused and the edges profiled as an architectural detail.

Looking great!

  • Joinery Aside:
    Some insist that a jointer is mandatory for getting glue edge seam. The seams on this top are tight and straight off the saw with my favorite blade, the Freud LU83 combo. The lumber was all S2S and some was slightly bowed yet the seams are straight and tight. It gives glassy crosscuts and glue line rips. This is why there’s no joiner in my shop. I just haven’t found the need.

Because of expansion I’m going to biscuit the top to the back but let the front float on clips.

I’ve been kicking around the thought of milling some cove for under the table lip but wasn’t sure I’d have enough walnut left. The savings on the top gives me a 1×6x32 board to spare so I’ve got the material. The only secondary woods are whatever is inside the walnut ply and the biscuits. Everything including cleats and supports is solid walnut.

Completed project.

  • 4/4×6 S2S walnut — 21bf @ $12/bf ~ $252 (includes top)
  • 3×3x6 pyramid 5/16-18 screw on legs — $40/set of 4
  • 5/16-18 top plates — $15/set of 4
  • 1/4 A-A walnut ply, 2×4 sheet — $40
  • 3/4 A-B walnut ply, 2×2 sheet — 2 @ $20 ea ~ $40
  • knobs — 2 @ $2.50 ea ~ $5
  • biscuits — 20 @ $0.05 ea ~ $1
  • glue brushes — 8 @ $0.50 ~ $4
  • foam brushes — 8 @ $0.50 ~ $4
  • poly, 1 qt @ $12
  • soft close euro hinges — 2 pr @ $14/pr ~ $28

Matl. Total: ~$440

Labor: 20 hrs @ $20/hr = $400

COGS: ~$850

-- The hump with the stump and the pump!

7 comments so far

View pottz's profile


20624 posts in 2224 days

#1 posted 08-25-2021 03:39 AM

mark i gotta say some guys give you a lot of crap here but they cant say honestly that this isn’t a damn nice piece of furniture.pretty good for the hump with a stump and the pump. ;-)

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

View Madmark2's profile


3093 posts in 1828 days

#2 posted 08-25-2021 04:33 AM


-- The hump with the stump and the pump!

View Foghorn's profile


1289 posts in 626 days

#3 posted 08-26-2021 03:45 AM

Looks great Mark. The tip on the wax before thinned poly finish is interesting and something I’ll consider for some things. For guitars, I usually give everything a coat of shellac and then sand it all off before spraying lacquer.

-- Darrel

View therealSteveN's profile


8832 posts in 1814 days

#4 posted 08-26-2021 11:00 PM

Nice build Mark. So the air grid shown on the CAD drawing in green is open to the back? Is there any other air flow?

I have the same units (2), and use them in the shop, not hung, but placed atop of counters, work tables and such close to where I am creating the dust, and by looking out windows I see MANY less floaters, floating around when I use them. I always place them on top of blocks of wood to allow for air flow all around mine, it seems they do much better like that then just flat on a surface. That is why I asked about your airflow on the enclosed cabinet.

-- Think safe, be safe

View Jimarco's profile


67 posts in 2347 days

#5 posted 08-26-2021 11:15 PM

That came out great, good job. Thanks for the details.

View Madmark2's profile


3093 posts in 1828 days

#6 posted 08-26-2021 11:16 PM

Both sides are fully open. The air filter unit can be rotated 180° and there is about 1-1/2” on either side and maybe 3/4” at the top.

-- The hump with the stump and the pump!

View gdaveg's profile


359 posts in 442 days

#7 posted 08-27-2021 12:41 PM


The grain of the wood is awesome. Nice build.

Thinned poly over wax, would have never thought of that.

-- Dave, Vancouver, WA & Tucson, AZ

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