(More) Big progress on absorption panels

[jim1960]

Originally Posted by b1j

Thanks for understanding that I meant “improvements” instead of that hasty autocorrect.

Autocorrect is my worst enema!

[rick-slo]

Originally Posted by jim1960

Autocorrect is my worst enema!

Auto correct strikes again.

[b1j]

First panel is filled and fully wrapped, back and front, except the tucking in of the last two corners. Lessons learned so far:

1) Muslin is easy to cut and resists tearing if handled carefully and firmly.

2) It is translucent. Not knowing better in advance, I allowed some overlap of the backing fabric, so it came over the front a few inches around the edges. The front fabric then went on tightly and smoothly, but now you can see under it the lighter muslin perimeter over the darker brown Rockwool in the center. I’m not taking it off to redo it. I’ve learned to trim the backing fabric five or six inches smaller before stapling it in.

3) Staples — even moderately heavy duty commercial ones — work fine into pine, but do not penetrate 1/4” hardboard. I had to screw it into the pine inner frame. It was easy enough, but didn’t give me the zip-zip-zip staples would have offered.

4) Folding the first two corners of the front cover fabric went well enough, but I had to take a break when the other two bested me. I’ll return to them later. I need to put some thought into how to pre-trim the corners to take out most of the bulk. I imagine it would be even more difficult with thicker, stiffer fabric. I’m counting on the pine outer frames to hide the inelegant corners.

5) I had devised a step to screw the outer 1x4 pine frame to the inner 1x2 frame, by drilling shank holes through the 1x2 frame. I was going to use self-tapping screws and come at the outer frame from the inside out so they wouldn’t show. In my excitement to wrap the muslin, I forgot the shank hole step. Now those holes will be a little more touchy around the filled and covered frame. I’ll still be able to drill them, but less conveniently, and the screw heads will sit proud of the inner frame in the back instead of being recessed. It will still be worth it to come from inside so the screws don’t show on the outside.

I almost have my first panel!

[keith.rogers]

Double frames? That's gonna be heavy!

Yeah, the folding part I kind of remember. Kind of like making a bed with flat sheets, except you get to cut away excess on the back where you fold over the edges of the frame before stapling. Put the folded part at the top and bottom (assuming you'll mount them vertically) and nobody sees it.

I put the back cover on first and trimmed it up short on the inside of the frame so it did not wrap around to the sides. I'll get a picture up later if I can spin around one of the bass traps after I get my phone off the charger.

(edit: added pics - backing used at this point was whatever was left over, and a sloppy and neater finishing shown in the bass trap, with corner fold shown on wall mounted panel.)

[b1j]

Originally Posted by keith.rogers

Double frames? That's gonna be heavy!

Yeah, the folding part I kind of remember. Kind of like making a bed with flat sheets, except you get to cut away excess on the back where you fold over the edges of the frame before stapling. Put the folded part at the top and bottom (assuming you'll mount them vertically) and nobody sees it.

I put the back cover on first and trimmed it up short on the inside of the frame so it did not wrap around to the sides. I'll get a picture up later if I can spin around one of the bass traps after I get my phone off the charger.

(edit: added pics - backing used at this point was whatever was left over, and a sloppy and neater finishing shown in the bass trap, with corner fold shown on wall mounted panel.)

"Double frames" isn't as heavy as it sounds. I don't expect anyone to have watched the 12-minute video I linked, but in it the guy shows how to make a lightweight inner frame from 1x2 to keep the panel square, covered with 1/4" sheet material for the inner sides. That assembly weighs a pound or two. The Rockwool is 2.4 lb/ft^3, and it's 4 cubic feet per panel, so about 9.6 pounds. So, the entire inner panel, including the Rockwool and the muslin, now weighs about 11 pounds. Once I add a frame of 1x4 pine, that will probably bring the weight up to 20 pounds or so.

As to the back fabric, you're right on target: I heed to trim it after stapling so it doesn't go past the front of the inner frame. That will help the appearance.

The front fabric will be a little more complex. I stretch the muslin in one direction into stapling position along the long sides. I think that's the step after which I should trim the waste out of the corners, before I staple along the short sides. The muslin doesn't stretch nearly as much in that direction. I suspect I'll get the hang of it.

Thanks for your interest. I'm glad yours turned out well! Your bass trap wrapping is world class.