Curved New Horizons: an adventure in kerf cutting

[lunchmoney]

So to round out the home theater system, I'm ditching the Paradigm 5.25" POS Series, and building some New Horizons (from the great Mike Z). He played a pair for me a while back, and they are just astonishing for how small and inexpensive they are.

Since they're going to be high passed, I decided to simply go sealed. Since that was making my life easier, I decided to then make life harder by making them curved. I've always wanted to give curved cabinets a shot.

Note that this is my first attempt. Lots of experimenting. Who knows how this will go. Deep breath, here we go...

After lots of back and forth between the table saw and Solidworks, here's the design I came up with. 9" high x 6.125" wide x 7" deep. About .1 cu ft. Tiny.



FEB 21 EDIT: Here's how I'm going to treat the edges of the baffles. I wasn't happy with the previous design.




Here's a screenshot from Solidworks showing how I worked out the kerf geometry to get the curves I wanted:




Here's a picture of the trial and error wreckage. Good thing mdf is cheap:




Finally figured out the right spacing and cut depth, here's one of them ready to be bent:




Test bend. Happy moment:






To glue them up in this shape, I decided to fill the kerfs with Liquid Nails, then clamp up, and wipe off the excess. This turned out to be way more of a mess than I had predicted. I think it will hold well, the bend is under almost no tension at all. Those clamps are barely doing anything... and the end caps will reinforce of course.





Gonna let them cure overnight. Much more to follow. Thanks for checking this out.

[tomzarbo]

Re: Curved New Horizons: an adventure in kerf cutting

Interesting looking!

How are you planning on finishing them?
I know from experience that the flat spots will show if you don't fill with Bondo or something and get it truly smooth. Veneer will be a problem since that wouldn't get glued to a panel filled with Bondo... But, if you are planning on painting, you should be able to eventually get it smooth enough with some work.
It looks like a cool project. With that one piece, you have half of the cabinet built! I see the rest going quickly.
I think using the liquid nails was a good idea to fill in the gaps. If you didn't do it now, it would be hard to get stuff in there later!

I'd appreciate more pics when you get 'em,
TomZ

[lunchmoney]

Re: Curved New Horizons: an adventure in kerf cutting

Thanks!

Still pondering how to finish them.

I might end up wrapping them with a layer of masonite after the end caps are on... this would smooth out the facets... then I could veneer them.

But I might just paint them. Faster, easier, and cheaper for me, since I have access to a paint booth.

I dunno.

[djg]

Re: Curved New Horizons: an adventure in kerf cutting

So you have .040" left at the kerfs. Hope you don't sand through when you sand them, assuming you will sand them to get a smooth curve. Might want to experiment with that before you do up a finished cab. Looks great, as always.

[Froste]

Re: Curved New Horizons: an adventure in kerf cutting

Looking good! Only problem you might have is sanding, the depth of your cuts might cause some issues when sanding. I had this happen a few times, I now try to leave 1/8-1/4" when making kerf cuts. If it's too close can always cover with bondo before sanding. Luck.

[Wolf]

Re: Curved New Horizons: an adventure in kerf cutting

Personally, I think the facets may add some character to these.
Later,
Wolf

[lunchmoney]

Re: Curved New Horizons: an adventure in kerf cutting

Looking good! Only problem you might have is sanding, the depth of your cuts might cause some issues when sanding. I had this happen a few times, I now try to leave 1/8-1/4" when making kerf cuts. If it's too close can always cover with bondo before sanding. Luck.

Yeah, for sure there's not much material left to sand. The deep kerfs were necessary to achieve the shape with one piece (reference the failure pile picture for shallower cuts :p)

Here's how I figure my options:

A. Lightly sand, let facets show, paint... Wolf, I'm with you. I think the facets are interesting. Might just leave 'em.

B. Cover with a layer of masonite, then paint or veneer. More work, but smoother curve, and no worries about the small amount of material left.

[[email protected]]

Re: Curved New Horizons: an adventure in kerf cutting

did you wet the mdf and let soak before bending?
if you have no voids in the kerfs,oversanding should only reveal another color.
i have to agree that the facets are kinda cool.

[lunchmoney]

Re: Curved New Horizons: an adventure in kerf cutting

did you wet the mdf and let soak before bending?
if you have no voids in the kerfs,oversanding should only reveal another color.
i have to agree that the facets are kinda cool.

Nope, didn't wet them first. Thought about it, but I'm pretty sure they would have just disintegrated.

Unfortunately it was impossible to fill the kerfs completely, so yes there are voids in the kerfs.

[greywarden]

Re: Curved New Horizons: an adventure in kerf cutting

I vote B and possibly your awesome paint job on top of the masonite...

[john trials]

Re: Curved New Horizons: an adventure in kerf cutting

How are you going to get the correct curve (or are they still a bit flexible, so you can match them to the top and bottom plates)? I would expect you would have to bend them on a form to get the correct shape.

Very cool project. I've been wanting to try something other than simple orthogonal boxes, too.

[lunchmoney]

Re: Curved New Horizons: an adventure in kerf cutting

How are you going to get the correct curve (or are they still a bit flexible, so you can match them to the top and bottom plates)? I would expect you would have to bend them on a form to get the correct shape.

Very cool project. I've been wanting to try something other than simple orthogonal boxes, too.

They're already very close to the correct shape (close enough) by virtue of carefully engineered kerf spacing and depth. The kerfs close all the way, so the shape is fixed.

End caps will overhang a bit, then be trimmed with a flush router bit.

[tomzarbo]

Re: Curved New Horizons: an adventure in kerf cutting

Thanks!

Still pondering how to finish them.

I might end up wrapping them with a layer of masonite after the end caps are on... this would smooth out the facets... then I could veneer them.

But I might just paint them. Faster, easier, and cheaper for me, since I have access to a paint booth.

I dunno.

That is an idea, thin stuff, so that there would be no end grain showing on the end caps. Solves two problems in one motion.

Basically what I thought of right after hitting enter on my previous post was to use a cheap unbacked veneer to wrap the cab, clamping both sides at the front of the cabinet, leaving just a bit of space, so the veneer is barely touching on the corners, and then applying liberally some polyurethane glue to foam up and fill in all voids as it expands. Then you could veneer as normal. That's hard to explain, but I hope you get the idea.

TomZ

[Wolf]

Re: Curved New Horizons: an adventure in kerf cutting

I would get some mirrors cut to fit the facets... That would look awesome!
Later,
Wolf

[r-carpenter]

Re: Curved New Horizons: an adventure in kerf cutting

Thanks!

Still pondering how to finish them.

I might end up wrapping them with a layer of masonite after the end caps are on... this would smooth out the facets... then I could veneer them.

But I might just paint them. Faster, easier, and cheaper for me, since I have access to a paint booth.

I dunno.

You can veneer them with the crosslaminated veneer. I do crosslaminations for commercial guys then clamping or cold pressing is not an option for one reason or another. It minimizes line ghosting which in your case (because kerf cuts are so close to the surface) may become an issue later on.
This was a job for a customer for example http://techtalk.parts-express.com/sh...d.php?t=217646 post 13