I'm designing/building a speaker cabinet from OSB with curved sides. I determined that the 7/16 OSB I have can sustain a deflection of 6" over a 3' span.
(By the highly scientific method of suspending a 17" wide by 4' long strip of OSB between two car ramps and standing on it, then measuring how far apart the supports were versus how deep it went. There were some ominous cracking noises but no visible damage and the piece sprung back to its original shape - more or less.)
It turns out, according to a calculator I found online, that a circle segment with a 3' chord and 6" height has some nice properties. It's radius is almost exactly 2.5' (30"), and its surface area is almost exactly 1.0 sq ft (which will make volume calculations easier later!)
I think I can bend this without a kerf, but I wonder if it would be worthwhile to use them anyway? Since it's such a long distance with gentle radius of curve, I'm thinking either it could do with shallower cuts, or perhaps space and stagger kerfs that don't run all the way from end to end? Or alternate deep kerfs and shallow kerfs?
(By the highly scientific method of suspending a 17" wide by 4' long strip of OSB between two car ramps and standing on it, then measuring how far apart the supports were versus how deep it went. There were some ominous cracking noises but no visible damage and the piece sprung back to its original shape - more or less.)
It turns out, according to a calculator I found online, that a circle segment with a 3' chord and 6" height has some nice properties. It's radius is almost exactly 2.5' (30"), and its surface area is almost exactly 1.0 sq ft (which will make volume calculations easier later!)
I think I can bend this without a kerf, but I wonder if it would be worthwhile to use them anyway? Since it's such a long distance with gentle radius of curve, I'm thinking either it could do with shallower cuts, or perhaps space and stagger kerfs that don't run all the way from end to end? Or alternate deep kerfs and shallow kerfs?
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CCM: Curves Cost Money - either time and materials, or materials and time.
Even if you can bend it, OSB would not be on my list of sheet good materials suitable for curved fabrications, and I'd certainly not want to kerf it. There are several pre-kerfed products designed specifically for such applications, and then of course you can fabricate your own curved plywood, using either rubber ply or several layers of 1/8" BB ply.
Build a ribbed skeletal frame, and apply several layers directly - the rubber ply can easily take a much tighter radius than you need. Note that its surface is completely unsuitable for direct finishing or paper backed veneers - but GP grade plastic laminate would probably be fine - providing it's only the sides you want to curve.
My favourite method for curved panels is vacuum bagging, but the time and materials required for a suitably sturdy form can be pretty steep as well - of course, once the form is built, you can pump a few perfect panels in a day.
Even if you can bend it, OSB would not be on my list of sheet good materials suitable for curved fabrications, and I'd certainly not want to kerf it. There are several pre-kerfed products designed specifically for such applications, and then of course you can fabricate your own curved plywood, using either rubber ply or several layers of 1/8" BB ply.
Build a ribbed skeletal frame, and apply several layers directly - the rubber ply can easily take a much tighter radius than you need. Note that its surface is completely unsuitable for direct finishing or paper backed veneers - but GP grade plastic laminate would probably be fine - providing it's only the sides you want to curve.
My favourite method for curved panels is vacuum bagging, but the time and materials required for a suitably sturdy form can be pretty steep as well - of course, once the form is built, you can pump a few perfect panels in a day.
Without a form, kerfs work pretty good, but have to do a test strip first to get them in the right spots. Too many and it will be difficult, too few and it won't perform to the desired shape. This trial 2" wide piece is better than risking your time and materials.
I also like to make a form and laminate thin sheets of wood, making your own plywood basically.
It is the only place where the "Gorilla Glue" really works imo.
You can buy mdf pre-kerfed, in your direction of choice, but is probably harder to find that way.
I wouldn't use osb either, too inconsistent of a material, but maybe with a huge radius perhaps, like you have described, but would be inclined to use three layers of standard, 1/4" plywood, moistened with towels. Alway make your parts oversized, then trim away to get the finished parts. The edges almost always suffer.
I also like to make a form and laminate thin sheets of wood, making your own plywood basically.
It is the only place where the "Gorilla Glue" really works imo.
You can buy mdf pre-kerfed, in your direction of choice, but is probably harder to find that way.
I wouldn't use osb either, too inconsistent of a material, but maybe with a huge radius perhaps, like you have described, but would be inclined to use three layers of standard, 1/4" plywood, moistened with towels. Alway make your parts oversized, then trim away to get the finished parts. The edges almost always suffer.
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The top and bottom solid pieces, and depending on overall height, middle brace(s), along with a rear spine and (temporary)front panel should provide sufficiently rigid skeleton on which to laminate your kerfed MDF or thin plywood.
I've worked for a commercial millwork company for over 20 years, and we do a lot of curved panels. I could probably count on both hands the number of times we've used kerf-core or the veneer ply faced Timber-flex product. For us it's rubber-ply all the way- not always requiring vacuum bagging, but 3 layers done that way with yellow glue or epoxy makes for a very rigid panel much lighter than MDF. It's also arguable that a combination of the rubber ply's composition - 2 layers of very soft meranti or equivalent veneer with an internal layer of synthetic "rubber" and the rigid adhesive between each layer of the rubber ply results in a certain degree of constrained layer damping.
I've worked for a commercial millwork company for over 20 years, and we do a lot of curved panels. I could probably count on both hands the number of times we've used kerf-core or the veneer ply faced Timber-flex product. For us it's rubber-ply all the way- not always requiring vacuum bagging, but 3 layers done that way with yellow glue or epoxy makes for a very rigid panel much lighter than MDF. It's also arguable that a combination of the rubber ply's composition - 2 layers of very soft meranti or equivalent veneer with an internal layer of synthetic "rubber" and the rigid adhesive between each layer of the rubber ply results in a certain degree of constrained layer damping.
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