The Defiants - InDIYana 2019 Build

[tomzarbo]

Keith,
What I mentioned in my last post up there /|\ was something strange that happened to me when gluing up the fronts to a set of speakers I'm working on.

I don't want to hijack your thread, but there is a lot of good information about gluing up laminations in your thread already, I hope you don't mind me adding this.

What you did with these speakers is use 2 sheets of 1/8" HDF per side. As you know, getting those "I wanna stay flat" sheets -- even only 2 per side -- takes a bit of muscle to conform to the curve you're asking them to bend to. That's because they are wide... the height of your intended speaker plus a little for overhang.

I did 4 layers of 1/8" HDF (a full 1/2" thick) for the fronts of this speaker...



… and it bent rather easily since it was only 6" wide or so. I poured glue on each layer as I go, probably a quarter cup of glue maybe? I dunno, but it was a LOT, it seems like way too much and I was feeling like I was going to take a bath in it, but after your incident, I decided glue is cheap, dump it on and scrape it off afterwards. I rolled it out with a veneer glue roller.

So I did this for the three layers and popped the top layer on. I smacked the 4 layers to try and get them nice and friendly with each other as the layers sat on the table for a few minutes. I take my time with this because I don't want to apply a ton of glue only to literally squeeze it all out again by clamping too quickly... 'let it soak in a bit' my Father would say. So when I finally applied the gorilla polyurethane glue to the speaker carcass and put the 4 layers of HDF on it and clamped it up... I was surprised to see almost no squeeze out. Most of what you can see oozing out is the polyurethane glue, and just a few drops of the wood glue.

So thinking about it for a minute, I realized that it didn't take much effort to get these relatively narrow pieces of HDF to conform to the frame, light hand pressure did it. The many clamps were just to make sure things stayed snug, I didn't crank down on any of them... a quarter turn and the were almost loose when I removed them.

Here's where it gets interesting. The top had about 3 inches or so of overhang that I tried to cut off with a newer sabre saw with a carbide tip blade. This same saw/blade combo cuts through 3/4" MDF almost as fast as my 10" Rigid table saw, no lie. Well this thing really had a hard time cutting the scrap piece off. I thought I accidentally was cutting into the cabinet itself it was so slow (heart attack!) But no, it was just the 1/2" HDF layers. I took another piece of the same type of glue up that I had saved from another speaker... same 4 layers, but this one even had a slight curve in it... and the flat scrap I just cut off had a much higher 'plink, plink' to it when tapped. It seemed harder and more rigid... almost like concrete or something.

I think the fact that the curve was kind of shallow combined with me not cranking down on the clamps too hard allowed all the glue to really absorb into the textured back of each layer, stay in the wood, and make the whole arrangement super-hard. Hard to cut, and really really rigid. I was kind of amazed at just how hard it seems to be. Yeah, I'm getting all worked-up over glue penetration and hardness in scraps of wood, but I thought you and others may find it interesting from an engineering standpoint.

I'm seriously considering using this technique to make up some flat panels to make a small speaker with in the future as an experiment. No curves, just flat... use a ton of glue, let it really soak in, and use minimal, even clamping pressure just enough to have things contact one another, but not squeeze all the glue out. Then cut it up and build a speaker with it, just to see how stiff the stuff really is.

Anyway, sorry for the hijack, I hope you don't mind me burping out a few thoughts here in your build thread, but it's interesting material, this laminated HDF stuff.

TomZ

[Jake]

Lots of good tips on using this HDF technique. What tool do you guys use to get the angle frame cuts for the "shell" of the speakers? Jigsaw?

[KEtheredge87]

Hey tomzarbo, That's crazy! I've always heard that glues in general are hard on saw blades. It sounds like your HDF is quite willing to soak up all the glue and transform into something more rock-like than wood-like. I wonder what the thickness of that stack would measure with a pair of calipers. Did your 1/2" stack expand to 9/16" or 5/8" after all that glue?

Though it may be sturdy, I'd almost be afraid to make a speaker out of it just because of all the sawblades I'd have to buy!

Now... Jake , when you say angle frame cuts, I assume you're talking about the curved pieces that make up the skeleton of these cabinets before any HDF layers get applied. There's a few ways you could do this...
1) Jigsaw and sand-to-line
2) Bandsaw and sand-to-line
3) Manually operated router with an appropriate length trammel (i.e. a giant compass) to make the curve radius you want (lots of setup involved here)
4) Ask a buddy with a CNC router to cut a template out for you!

I opted for #4 in this case, but I could have done any of the other 3 as well. Some folks think CNC is cheating... I say smoke 'em if you got 'em!

Hope that helps!

[Jake]

KEtheredge87 thanks for the info. I like to try this method in the near future. Square boxes get boring, but it's still about the sound. 😉

[tomzarbo]

Hey tomzarbo, That's crazy! I've always heard that glues in general are hard on saw blades. It sounds like your HDF is quite willing to soak up all the glue and transform into something more rock-like than wood-like. I wonder what the thickness of that stack would measure with a pair of calipers. Did your 1/2" stack expand to 9/16" or 5/8" after all that glue?

Though it may be sturdy, I'd almost be afraid to make a speaker out of it just because of all the sawblades I'd have to buy!

I just measured the old and the new... There was only about 1/4 of one mm in thickness difference between the two... the newer denser lamination being thicker. The other one had been in the basement for a year or so, I'm not sure this is an accurate comparison, though.

It is interesting what happens when layers of this stuff are glued up.

TomZ

[KEtheredge87]

Hey Guys,

A video is coming to better detail this update, but in short - the cabinet top curve is complete! Or at least... one is complete and the other needs a little more work. The router curve method worked out great, just like it did in the past... but my tooling must have been set up incorrectly on the second cabinet, as it actually came out with a slightly different angle, and the rear of the cabinet was about 1/8" taller than the first one. Not satisfied to leave it like that, I reset my tooling and tried again, but something was still off, as now the cabinet has an odd slant to the top if you view it from the front.

At this point, I'm thinking I'll need to disassemble and rebuild my tooling setup from square one, carefully checking to make sure the heights of both runners are exactly the same at the front and the back. I'll also need to slather on a layer of bondo to the top to rebuild some of the thickness that I've kinda messed up. That way I can make sure my cuts stop at the right height to match the front of the other cabinet. the Bondo brand might be a pain to work with on this large of a repair, so I might invest in a quart of that Rage brand filler that gets marketed to actual autobody shops rather than DIY guys. We'll see on that.

Anyway, here's some pictures of where I'm at right now. And GOOD LORD those cuts made a lot of dust!

[jhollander]

If your router sled is wide enough could you cut both speakers at the same time?

[KEtheredge87]

If your router sled is wide enough could you cut both speakers at the same time?

Hey John, that's a great idea. The sled should be capable of that span, and that will let me set the template up to match the curve on the cabinet that worked well. I bought some Evercoat lightweight body filler during lunch to build up the goofed cabinet, so I can put some icing on that cake tonight and try getting my setup addressed.

I just need to make it through a few more hours of work shenanigans so I can really put the brainpower into solving THIS problem. I woke up this morning still thinking about this issue.

[tomzarbo]

Keith,
I'm thinking that the only guarantee of getting exact results would be to have the sled setup go all the way to the table surface that the cabinet is setting on... otherwise it's a measuring game and there may be a chance for inconsistencies. I KNOW you measured and lined things up super carefully as is your custom. It looks good anyway, I'm sure you'll nail it on the re-do!
Thanks for posting the process, I want to try this in the future.

TomZ

[Kevin K.]

The curved tops look great Keith! I'm with Tom, work from the table surface up. If your fixture and cabinets are both indexed from the same surface, should yield consistent results.

Looks like Tom won't be the only one borrowing your curved top method in the future. I'm envisioning the sidewalls of my Royale's with your curved top, should look pretty cool. KEF did some Coax's that look similar to your cabinets but their top curve was too subtle IMO, I like yours better. Keep plugging away man, looking forward to seeing these finished.

[jhollander]

Kevin, I was thinking couldn't you do some cnc curved tops? I was thinking like a curved MDF wig I can glue on and trim the sides flush?

[Kevin K.]

Kevin, I was thinking couldn't you do some cnc curved tops? I was thinking like a curved MDF wig I can glue on and trim the sides flush?

Hey John, hope you are doing well. Yea, I cut a curved top on the Mystiques, just a different method. Keith is layering blocks and cutting the outside curve only. I cut the curve on both sides to maintain the same material thickness throughout. A bit of a pain to do though. The curved sidewalls of the Royale's were CNC cut as well, they started as 1-1/4" MDF and yielded 3/4" after the cuts, again, cut from both sides. I'd really like to build some jigs to vacuum bag the panels from 1/8" material. And then fixture cut them to size with the CNC. Hoping to have some time to play around with that later this year.

[KEtheredge87]

Alright Gentlemen... I give you the full video version of my curved router sled extravaganza, version 1.0. I've taken jhollander, Kevin K. , and tomzarbo 's comments into consideration and have started version 2.0 in order to correct my mishap with the second cabinet. I'll do a follow-up video on that one when I've gotten it all together!

General setup and nerdery for the first 10 minutes or so. Sawdust flies at 10:30. Enjoy!

[Kevin K.]

Cool video Keith. You are a natural YouTuber and hopefully you'll make more videos in the future for the "up and comers" to watch and learn from.

It's time for that next piece of equipment man, they call em bandsaws. I'm a fan of the Delta saws since they offer an optional riser block for taller cuts. You could knock some serious time off what you just did by rough cutting a big chunk of the material before routing. But hey, you made do with what you had to work with, kudos. After seeing the mess, I would recommend this be an outdoors only type project in the future. There's really not going to be a good way of capturing all the stuff flying around and who wants to spend an entire day cleaning up the shop afterwards. Awesome work so far man!

[KEtheredge87]

Cool video Keith. You are a natural YouTuber and hopefully you'll make more videos in the future for the "up and comers" to watch and learn from. It's time for that next piece of equipment man, they call em bandsaws. ...Awesome work so far man!

Thanks Kevin!

"... they call em bandsaws" <-- that was awesome! I had the image in my head of you revealing a magical land hidden inside Rockler and Woodcraft stores where all the best tools were kept at the absurdly low prices.

If I make a habit of this video thing, I should invest in a GoPro or something rather than put all that stuff on my phone's SSD. Also... yeah... I would LOVE a full size bandsaw! The little 10" WEN bandsaw I bought does most of the bandsaw-style things I need, but there's definitely room for improvement. You're right... If I could have fit this cabinet into the bandsaw saw AND confidently held it to cut a chunk off it would have saved a whole lot of time!