The Defiants - InDIYana 2019 Build

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Looks great so far man. Looking forward to hearing them.

Cheers!.

[KEtheredge87]

Tonight I was able to glue up a replacement layer on the poor, poor cabinet that got the chisel treatment. I took time yesterday to apply bondo to all the deep (relatively speaking) gouges that I made while removing the initial 2nd layer. All the bondo was sanded smooth with 80 grit ROS work in prep for more glue. The surface itself was not perfectly following the contour any more, but I made sure I only had barely-there depressions rather than mounds of bondo sticking out. My assumption is that the following layers of HDF will restore the proper curvature, and all will be well.

I remember TomZ's video mentioning that gluing up only one layer at a time wasn't ideal since the HDF is so thin and relatively flexible. To account for that on this single layer glue-up, I included a second layer without any glue and a good saran wrap shield to keep glue off of it for use later. This way I got a little more clamping force distributed by using that dry layer as a caul of sorts, and the overall curvature was maintained. I am much happier with this glue-up because there was actual squeeze out! No way this one is going to delaminate later. Now I feel secure in a job well done.

Also tried the Kevin K. nail method for keeping my glue-up panels from sliding around and it definitely did the trick! Thanks for the helpful suggestion bud!

Tomorrow I will inspect the repair glue-up results and get the repaired cabinet caught up to it's brother. With any luck I'll get flush trimming done on the 1st and 2nd layers and get layers 3 and 4 glued up and drying overnight.

[Kevin K.]

Also tried the Kevin K. nail method for keeping my glue-up panels from sliding around and it definitely did the trick! Thanks for the helpful suggestion bud!

The nails are a wee bit bigger than I had in mind, lol. But I'm glad it worked out for you. Looking good!

[tomzarbo]

Nice work Keith.

That second pic looks just like the same amount of coverage I use on my panels nowadays.

Thanks for posting your boo-boo and resulting fix.
Reading this hopefully helps someone else avoid the same issue in the future.

And just like me... I betcha' you won't make that mistake again!

TomZ

[KEtheredge87]

Hi Guys,

It's been a few days, and I have another "boo-boo" to report and share a fix. Working on cabinet "B" I did a two layer glue-up and was having a hell of a time with the panels trying to slide backward as I clamped them down. This time it was both panels on each side shifting as a unit (yay nails!) rather than one layer shifting relative to the others.

I had the idea to apply a clamp to between the front cabinet panel and the rear cauls to keep things from sliding backwards. I think I went a little too overboard with this clamp, or had my clamping forces unbalanced, because I actually made a thin but deep void on the edge of one side. Maybe 5" wide and 6" deep at the worst point! Rather than ripping those panels off, I decided to fill the gap with some 5 minute epoxy.

I think this worked out pretty well. I made little hot tub for the resin and hardener to warm them up, thereby reducing the epoxy's viscosity as much as I could before pouring it into the crack. It still didn't flow as easily as I would have liked, so I used a popsicle stick as a ram-rod and stuffed it all down into the crack. From there I gave it a good few hours to totally harden, then trimmed the cabinet as normal. Technically, that side of the cabinet has a slight difference in the radius of the curve from that point forward. However it's not noticeable in the final product. The curve really hides the minor error that got introduced this way.

Since this point, I've finished Cabinet B's side panel glue-ups and trimmings completely. Tonight I will be finishing the same final trimming on Cabinet A. Using 6 layers of 1/8" HDF makes this sucker HEAVY and really non-resonant. I'll post a YouTube video in a moment that shows a knuckle test of 4 layers vs 6 layers in the final product. Next on the docket I'll be moving on to front baffle work and top-face curve toward the rear of the cabinets!

[KEtheredge87]

Here's a YouTube video showing a knuckle test on the walls of The Defiants.

[4thtry]

Nice fix on your boo-boo. I had some "wavy-ness" on my Kowaxial curves too, but no one mentioned it at any of the shows. I really doubt that anyone will ever see this. Once they are painted, that small, little mistake should disappear. I could hear a slight change in pitch on your first knuckle rap test, but the 2nd test sounded the same on both cabs. I had 6 layers too on my Kowaxial curves and I was amazed at how strong HDF becomes when bent and glued like this.

Good luck! Can't wait to see and hear these in Indy,

Bill

[KEtheredge87]

Nice fix on your boo-boo. I had some "wavy-ness" on my Kowaxial curves too, but no one mentioned it at any of the shows. I really doubt that anyone will ever see this. Once they are painted, that small, little mistake should disappear. I could hear a slight change in pitch on your first knuckle rap test, but the 2nd test sounded the same on both cabs. I had 6 layers too on my Kowaxial curves and I was amazed at how strong HDF becomes when bent and glued like this.

Good luck! Can't wait to see and hear these in Indy,

Bill

Thanks Bill! Your SideTowers are quite unique as well, InDIYana never disappoints!

[KEtheredge87]

Tonight my speakers are teaching me more about patience.

had hoped to finish the flush cut and sanding work on cabinet A, but I found two more gaps in the panel glue-ups. These are much smaller than the last one, at only 1.5 to 2.5" deep and ~3 inches wide. Some of the Titebond II glue also wasn't 100% set inside the cracks. My makeshift depth gauge hit the bottom of the voids with a squishy, not-quite-cured-yet feeling.

The cracks are even smaller than before which is great... but difficult all the same. I expect my Devcon 5min epoxy will be too thick to cram into these cracks, even with the hot-tub treatment to pre-warm / reduce the viscosity of the resin and hardener. I also worry about working time with these smaller cracks, as any added heat accelerates the epoxy chain reaction and thus shortens the already small 5 minute window. I also considered a few drops of acetone to thin the mixture, but that also negatively impacts the holding strength of the finished epoxy, with the risk of it just getting rubbery instead of curing solid. Finally, I also thought of just putting more Titebond II down there, but that won't really be a strong joint, and glue is not meant to be a gap-filler!

Ultimately, I think the best option will be to go buy some 30 minute epoxy tomorrow and heat that up to a pourable / wick-able consistency. Best to do it now before final flush trimming to cut down on added spot sanding later on.

[Nismoron]

Super interesting build. I'll be following. I'm thinking of building something very similar.

After a 20ish year hiatus from speaker building, I'm trying to decide whether to finish a previous build that I bought all of the parts for (but tweeters damaged in storage and are now NLA) or just buy a Wolf Nephila kit. The previous speaker was going to be constructed much like this except was a 40inch tall tower with a bit more curve to it. The widest part is about 1/3 way back from the baffle. But it is only sliiiiightly wider. I found the Nephila kit by accident and it really intrigues me. But I cant find much info on how it sounds.

Anyone have a link on the alleged video about building curved cabinets? I would love to see it.

Not trying to hi-jack with my comments. I'll actually be starting a thread about it soon. As soon as I do some more reading and thinking on it.

[a4eaudio]

Keith, thanks for running into all these problems now, I'm about to start some curved cabinets this weekend.
What do you think is causing the gaps? Do you just need more clamps, or something different like strap-clamps, or is it just the nature of the HDF?

[KEtheredge87]

Super interesting build. I'll be following. I'm thinking of building something very similar.

Anyone have a link on the alleged video about building curved cabinets? I would love to see it.

Thank you sir! Tom Zarbo has his videos on YouTube for curved cabinet construction. That's the method I've been following here. He's got 3 parts to the video, here's the link to part 1: https://youtu.be/Yeczz85R8tc

As for Wolf's Nephila, He's a very active participant on these forums. I'd imagine you could send him a PM or just start your thread and tag him with the @ symbol to get his attention.

[KEtheredge87]

Keith, thanks for running into all these problems now, I'm about to start some curved cabinets this weekend.
What do you think is causing the gaps? Do you just need more clamps, or something different like strap-clamps, or is it just the nature of the HDF?

Glad to be of service ;) The more I practice with these glue-ups, I start to conclude that I am the problem causing those gaps. Warning: Engineering nerdery ahead...

During each glue-up I've been fighting with the HDF to keep it from sliding backwards when I tighten the rear clamps against the angled wall. By adding those two front-to-back clamps, I'm trying to pull all the panels forward / counteract that backwards slide. That front-to-back clamping force is acting at 90 degrees to the front clamps that just want the panels to smash against the wall, so the HDF layers are the weak links caught in the middle. Without a solid glue line to support them in the shape that I want, they give way and flex a bit to help the whole system reach a force balance.

For this build I decided going 1/2" larger than the cabinet walls on all sides would be sufficient overhang for the HDF during glue up. I did not anticipate the sliding issue though. While it may be more wasteful, next time I would make my front and rear overhang something like 1" or more to give myself more margin for sliding error. It all gets trimmed off anyway.

On the number of clamps... I think the 5-6 harbor freight clamps I've used on the front and back is probably OK. Strap clamps would be good if I had a big spacer or something to keep the straps from crushing the overhang on the HDF layers. In my head I can see those HDF layers cracking or crumbling when the strap tightens around the corners on the front/rear. I could be overthinking that though...

A better method would be something like vacuum bagging or having a bunch of special cauls that match the curved profile exactly. That would apply a pressure evenly across the whole HDF sheet rather than only on the edges. Of course proper vacuum bagging would be a glue squeeze-out nightmare. I don't know how you'd pull that off without having to clean all kinds of dried glue off your good surfaces between each layup.

Hope those thoughts help you plan your own curved cabinet build!

[jhollander]

Vacuum bagging the HDF should be like veneer where the glue squeeze out is below the edge as the bag wraps the edge. I add tape on the edge to protect the already veneered side, that would probably not be required to protect the MDF frame. I would probably add some breather/ batting to capture the glue and protect my bag.

Fibre Glast usually has their bagging film on sale. I'm going to try the thin composite bag for my next veneer project. I got about 3 uses from my $30ish diy vinyl bag.

[Kevin K.]

I think the strap clamps would yield more consistent pressure throughout but as you pointed out, the ends would have to be protected from crushing. A scrap panel of 3/4" a little smaller in width than the front and rear panels would probably do the trick. Also thinking with the strap clamps, you'd see less of an issue with the panels sliding around since the pressure would be pulled down consistently on both ends. Not sure how often one would need a strap, maybe every 4"-6" or so? Start with a strap in the middle and work your way out would be my approach. Suspect I'll be building a pair of curved cabinets this next year, will report back with how it works out for me, good or bad.

You're getting there man, hang tough.

To clarify, vacuum bagging the panels would be better but that's an expensive approach (bag and pump) unless you plan on numerous cabinets.