Translam Subwoofers with 18" Passive Radiators - The Jedi Mind Tricks

[KEtheredge87]

Good morning Everyone,

I've got another update for you all since last night and this morning. I now have the first support dowel rod epoxied in to the second subwoofer, as well as the second support dowel epoxied into the first subwoofer. I did these most recent two dowels at the same time, so I was hustling to get the wood glue in the right spots, then smear some epoxy in the holes, seat the dowels, and clamp them down for a few minutes before repeating that process on the top half of the dowel rod sandwich.



I only have 4 more wall layers on the first sub before I'll need to start assembling the top layers of the box separately once I reach this point. I still have to curve the tops, which will be easier if they are separate and can sit on the table at the same level as the jig I'll need to make. I still need to finalize exactly how I'm going to make this jig too.

I'll keep noodling on that thought, as well as mentally working through the next steps so i'm ready to go!

[Wolf]

Delamination of the ply can become an issue. I would also consider a layer of glue on the inside wall or something else to ensure they stay together. I don't recall if this has already been mentioned, so my apologies if it has.

You move fast!
Wolf

[KEtheredge87]

Delamination of the ply can become an issue. I would also consider a layer of glue on the inside wall or something else to ensure they stay together. I don't recall if this has already been mentioned, so my apologies if it has.

You move fast!
Wolf

Thanks bud, no worries! I've been thinking about something like that as well as a sealant to make sure I don't have any tiny spots where the glue didn't spread completely. Could also see something like a 20 minute epoxy on the interior walls too. The outside will get a good coating of general finishes arm-r-seal poly as well. I know that's not exactly a glue, but I figure it ought to count for something.

[Wolf]

It's not so much the glue you did, but the glue from the manufacturer that built up the ply layers. I'm speaking of the layers of ply in the board and not your layered/glued approach.

Later,
Wolf

[KEtheredge87]

It's not so much the glue you did, but the glue from the manufacturer that built up the ply layers. I'm speaking of the layers of ply in the board and not your layered/glued approach.

Later,
Wolf

Gotcha. Good to know I'm not royally screwing this thing up! A delamination would certainly result in tears and bad words.

[KEtheredge87]

Alright Everyone,

If you've been following along, you've seen lots of posts where more layers have been added to the boxes a few at a time. Well... Here's more layers!

At least this time things are starting to get more interesting. I have started building the top of the first subwoofer box, but I haven't glued it down 100%. I wasn't sure if the top layers that have full profiles (not just walls on the side) would match up with the bottom layers that were prone to having a cumulative lean left or right. The dowel pins should have helped with general alignment, and making sure the surfaces were sanded flat should have kept any cumulative leaning to a minimum... but my worry existed all the same.

In order to somewhat address this concern, I put a layer of saran wrap between the last wall-only pieces and the first pieces of the top (no gle between these parts). This way I could try to match the connection points between the walls and the top. I glued the first few top pieces together, and have a few more top layers to go. Once these layers are glued together, I will mark spots on the ceiling for vertical dowel rod supports, then remove the top from the cabinet, drill forstner bit holes for the vertical dowels, set up a jig to curve the top with a router, then place the vertical rods and glue the completed top on to the wall pieces to have a completed cabinet. Thats only a few sentences, but a lot of work!

From there, I can start cleaning up my front baffle locations and making that as crisp as possible before engaging the guitar binding ideas from John and Kevin.

[KEtheredge87]

Delamination of the ply can become an issue. I would also consider a layer of glue on the inside wall or something else to ensure they stay together. I don't recall if this has already been mentioned, so my apologies if it has.

You move fast!
Wolf

Hey Ben, Thinking about this a little more. Do you have any experience that says I should look for something stronger than yellow / PVA glue for this internal wall coating? I've started looking at some epoxy gel coats or surface coatings from FibreGlast online, but it seems like that's going to be around $100 for that kind of material. I'd need to contact the company directly, as I'm not sure if those materials are even appropriate for the application here.

If you were doing it, what would you use?

Thanks!

[Wolf]

I've not done any translamming with ply, so it's not my area of expertise. I'm sure someone else will chime in though. My thoughts would be to back-lay the inside with thin mdf or luan ply as a binder, and roll on the glue on both surfaces and clamp the board down to the inside. This would help the seal of the material, as well as keep it in place.

Later,
Wolf

[envisionelec]

Will you name it the TranSLAM?

[KEtheredge87]

Will you name it the TranSLAM?

Hehe.... I really like that, but I think someone else already used that name on a project. I'd have to cruise through the forums again and see if anyone used it!

[filmslayer]

those are looking really good !

[KEtheredge87]

those are looking really good !

Thanks filmslayer! I'm excited so far, and I think they'll look really REALLY good once the glue has been sanded off the outside and the walnut baffles are in place

[KEtheredge87]

You guys get two updates today. Once I get a process rolling and enough free time to work it can really be hard to stop! Darn speaker building addiction. All the top layers of the first cabinet are glued together (still separated from the bottom by saran wrap). I've also layered up the second cabinet to the point I can custom cut the other horizontal dowel brace tomorrow and epoxy that into place.

Work is probably going to slow down a bit as I build the jig I need to carve the cabinet tops. Hopefully it doesn't slow down too much, but this will be a major feature of the cabinet, so I'd better do it RIGHT!

[KEtheredge87]

Hey Everyone, I did some more work in the garage today. The second cabinet is now built up to the complete wall height, and is ready to start assembling the top layers for it tomorrow. Also, I reached out to Fibreglast, Smooth-on, and West Systems today to see what they would suggest as far as epoxy as a reinforcement coat for the internal surfaces. Still waiting on Fibreglast to weigh in, but Smooth-on and West Systems both recommended standard issue epoxy in ~5 mil thickness. Additionally, they also mentioned putting a layer or two on the outside of the cabinets as well. Sounds to me like they're trying to sell more epoxy at that point. I've also heard that most epoxy resins will yellow with UV exposure and time, which I would not like. Main finishing plan for the outside is still to use some general finishes arm-r-seal wipe on polyurethane.

Another question for you guys... I plan to put some lining on the walls here, but I'm not tied down to a particular product. Anyone have a good reason for something other than mattress topper / egg crate material from walmart?

Thanks!

[KEtheredge87]

Hey Guys, Good news and bad news...

The good news is the first cabinet's top layers glued up quite nicely and is ready for me to curve cut the top.

The bad news is the second cabinet developed a difficult-to-see lean somewhere along the wall building process, and is now about 1/4" to 3/8" too small at the interface between the walls and the top layers! I guess I wasn't careful enough on gluing one of those wall layers straight, and everything compounded from there. It's really even hard to tell exactly where the screw-up starts.



The challenge now... how to fix this?

Options I've thought of so far...
1) Attempting to push the wall open with spreader clamps. This seems like a dicey move for the cabinet structure since I'd be adding a bunch of shear loading to the glue joints just to assemble the cabinet. Not to mention the cabinet never being in a state of rest. Add subwoofer vibration loading to the mix and I'm sure this would break at some point down the road.

2) Gluing the top pieces for this cabinet up separately then cutting a strip out of the middle until the fit lines up. Seems improbable that I'd get this right. Even more unlikely if I do all the parts after glue-up.

3) Buy more material and try this one again... not my favorite option!

I'm going to keep thinking about this, but I welcome any ideas!

Thanks guys.