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Old 17th January 2012
Here for the gear
mtbdudex's Avatar

Been reading gearslutz for almost 1 year, kinda new at posting here.
I made these movable SSC for the rear of my Home Theatre, sharing here.
(I need access to the rear so these can't be built into place)
This was before I knew that for these big/deep ones pink fluffy was better than the OC705 I used.

removable lower corner superchunk bass trap made with 1/2-13 thd rod and OC705

Each stack is (6) sheets of 2" thick 2' x 4' OC705 panels, cut 24" x 24" x 34".
The 24 triangles stack just over 48" high, I've decided to make them removable "corner tables".

fwiw: I have some Star Trek stuff to display, the 3D chess set, some ST:TOS replica phaser and tricorder, etc, collected over 20+ years.
So, the top will be nice wood, while the bottom possible mdf or even some leftover OSB I have. The 1/2 thd rod comes in 72" size.

Now, above that display zone, which will get light w/o shadows via the sconces, will either be a 17" x 17" x 24" superchunk as shown on LH side, or a more visually pleasing triangular patch as shown on RH side, tbd.

(the boys and I watched a movie last night, sorry for the clutter)

Regarding cutting the superchunks out of the 2' x 4' sheets, I started with the big bread knife, did 4, then tried the electric turkey knife.
My experience, the manual knife was MUCH easier to get dead straight and perpendicular lines cut, the electric knife seemed to walk on its own slightly, giving a wavy edge, not style points.

Here you can see what I'm talking about.
The bottom 4 were cut by hand/bread knife, the next 4 by electric knife.
It's not that much more time for hand/bread knife, 1st pass with edge guide sets the line, then 4 more passes holding the knife at a low 15-20 degrees gives perfect straight and perpendicular edge.
I suppose a jig could be made to ensure the electric knife is straight and perpendicular, but this manual method worked for me easily.

in the garage, via makeshift paint/infra red warm booth I'm painting the thd rods......and the attach nuts/washers

-final cut/paint the OSB base.
I added a 1 1/4 perimeter of 3/4 OSB so the thd rod/nuts won't be resting on the floor directly. Painted green, same as walls.

-Final cut/sand/stain the birch top board

Maybe tomorrow these "Mikes Mondo Corner Bass traps" might get assembled and put into the room.
Each will weigh 50+ lbs, looking back at my original plan of 1 huge removal bass trap.....nope that's 100+ lbs of weight, glad I went "1/2 size" then an additional trap in the top corners

Good progress made today on these beasts, they are huge, big, and sturdy
(YouTube video clip will show that)

Layout the cut big triangles, cut back corner 3" x 3" 45 deg for clearance to rear thd rod

Stack 'em, trying to keep the leaning tower straight/aligned as it gets higher...

Me next to my the 4' stack, showing size of this beast.
However, mistake I made was NOT putting the rods in 1st before loading the triangles, so I had a PIA to get the rods in...lesson for #2
After fiddling here are the rods installed

I did NOT pre-cut the thd rod in the garage, had no way of knowing how much the OC705 would compress.
I actually can compress easily 1", more than 2", but the 1/2" birch ply top flexes too much at 2", I settled on 1" of compression, it felt very sturdy and solid.
Green tape for cutting spot, my wife held the rod top while I used a Dewalt 18v buzzsaw.
Load in room, check for ingress/egress of loading the trap etc.
No other issues appeared to prep for fabric covering time

Cut the mid-hi freq blocker (kraft paper here) for the front face, install and hold with simple 1 3/4" craft pins

Cut the 56" wide fabric (roll size), for this first one I cut just 3/4" extra top/bottom (to 50", compress size is 48.5 "), it worked but for the 2nd one I increased that to 1" top/bottom extra for wrapping safety.
I should say this is a GLUE-LESS/PIN-LESS build for the fabric, I just use pins for the top to start, put the top birch ply board down and compress/tighten, keeping fabric not attached, and tuck the fabric in at the bottom.

1st one "done", front face side


Backside looks good, needs covering

Now, the 2nd one went much quicker and smoother!
Make a 3 rod frame with base and top, gave 5" extra for loading.
This worked best for aligning the loose big triangles for flatness.

Kraft paper installed on 2nd bass trap:

Close-up showing 1" of extra material on the top before clamping down the birch ply.

2nd one done, and backside covered

Loaded into the HT room, RH side one is the 2nd one made, it came out a little better.

YouTube video showing how these can be moved around.