My MDF Questions: #3 Can you BEND it?

[Tom Overthere]

MDF QUESTION 3: Is there any tried-and-true way to BEND MDF to a specific radius? If so, does it remain stable once dry?

I know MDF is very water-sensative (but then, so it wood). Is there perhaps some other soaking medium that is used?



And this point really ought to be a seperate My MDF Question (#4) but since it applies so much to this concept (fantasy?) of bending MDF, let me introduce it here:
Does MDF come in 1/4" sheets (or thinner) that could be laminated and clamped, as is done when thin solid-wood veneers are face glued to form a bowed frame member or panel?


Or hOw AbOUt i jUsT maKe A bUncHa KeRfs iN tHe bACk, aNd TRy tO BEND iT, dRy ? :D:eek::D


I know, I'm pretty far out there on this one. Be gentle...

Thanks, Tom

[glenn bradley]

Yes, with kerfs. No soaking.

[Mark Boyette]

I'd just buy some "wiggle wood" sheets. It's a 4 x 8 with kerfs already in it. The kerfs can be bought horizontally or vertically. This stuff is great for making radius cabinets/counters. Fairly cheap too.
If you cut your own kerf in MDF there is a change to breaking it depending on how sharp the radius.
We have used 1/4" masonite in 3 layers for radius concrete forms.
Mark.

[Chris Padilla]

MDF is available down to 1/8" but it may not be too common. 1/4" is a bit more common...1/2" and 3/4" are all over the place...and I've been seeing 5/8" a lot more lately.

To bend MDF and have it stay put, you would need to laminate several thin pieces of it or do the kerf trick. I think soaking MDF in water is a big no-no...it would eventually fall apart because the glue holding it together is NOT waterproof.

Are you thinking to laminate several thin pieces of MDF into some curved shape and then veneer it with hardwood? That could work fine but another way to approach it is to glue several sheets of MDF together (let's say 3/4") and then cut out the curved shape and then veneer that.

Either way, with the curved shape and veneer, you'll likely need/want the opposite form of the curve to act as a caul/clamp when you veneer it UNLESS you have a vacuum bag (but even then, you may need some kind of a caul).

[Tom Veatch]

... I think soaking MDF in water is a big no-no...it would eventually fall apart because the glue holding it together is NOT waterproof...

Not to mention the thickness change. Made a template/guide from a piece of 3/4" MDF for some oddball miter cuts with a circular saw on my deck building project. Walked off and left the piece exposed to the weather. Found it later, after some rain. It hadn't disintegrated, yet, but it had to be at least 2" thick after the soak/dry cycle(s).

[Per Swenson]

You can bend anything as long as you have a suitable form to bend it to.

You can even bend will.

Per

[John Stevens]

MDF QUESTION 3: Is there any tried-and-true way to BEND MDF to a specific radius? If so, does it remain stable once dry?

Yes, use "Kerfkore" or a similar product:

http://www.curvolutions.com/Kerfkore.html

Follow the link on the page to "Fabrication Demos"


I know MDF is very water-sensative (but then, so it wood). Is there perhaps some other soaking medium that is used?

Not necessary with Kerfkore and similar products.


And this point really ought to be a seperate My MDF Question (#4) but since it applies so much to this concept (fantasy?) of bending MDF, let me introduce it here:
Does MDF come in 1/4" sheets (or thinner) that could be laminated and clamped, as is done when thin solid-wood veneers are face glued to form a bowed frame member or panel?


Kerfkore comes in 1/4" thickness, but I believe you have to laminate two sheets together or attach them to a curved frame.

Hope this helps. By the way, if "Overthere" isn't your real surname, please re-join with your real name. Thanks.

Regards,

John

[Tom Veatch]

I'd just buy some "wiggle wood" sheets. It's a 4 x 8 with kerfs already in it. ...

Minor quibble since the effect is the same, but the "bender board"/"wiggle wood" sheet I used to make the housing for my cyclone blower didn't have any kerf cuts. It was laid up like regular plywood except the grain was parallel in all plies instead of each ply being 90° to the neighboring ply. That allows it to be very flexible in one direction and quite stiff in the perpendicular direction.

It's my understanding that you can get it such that it's flexible about the short (4') dimension or about the long dimension. Interesting stuff. I'm not used to a piece of plywood waving around like a piece of paper.

[Per Swenson]

Johns sig sez's it all.
But this shouldn't be a values compromising thread at all.

per

[Joe Pelonio]

I've come in late to this thread, but I have done curved MDF and also plywood for people using the laser. Several jobs were for an art institute student of furniture design, making miniature chairs. I merely set the laser to cut about 1/2 way into the 1/4" material, with the distance between the parallel cuts varying depending on the radius. It took some experimentation
but did result in nice smooth curves. Unfortunately, depending on the application, you would have all those grooves to somehow cover up, in the ones I did they were upholstered.

[Per Swenson]

Bondo, fiberglass, epoxy, make excellent curves with MDF
Take a hint from the fellas who do automotive speaker enclosures.

Per

[John Stevens]

I merely set the laser to cut about 1/2 way into the 1/4" material, with the distance between the parallel cuts varying depending on the radius. It took some experimentation
but did result in nice smooth curves.

Wow, I had no idea you could do that with a laser.

By the way, Lon Schleining's book on bending wood gives a procedure for figuring out how close the kerfs need to be to bend a material to a given radius. Probably more or less what you ended up doing, but for others who haven't already taught themselves, the book may be worth buying.

Regards,

John

[Tom Overthere]

Man, excellent information!

I was just kidding about kerfing the back and dry bending it...

Who'd a thunk it...:eek:

With WiggleWood, Kerfcore, bondo, fiberglass and epoxy in my arsenal--in addition to kerf-cut bending--I think I might go ahead and build a Cadillac :D