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Thread: Bend radius of 1/4" (6mm) MDF

  1. #1
    Senior Member Ed Zeppeli's Avatar
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    Bend radius of 1/4" (6mm) MDF

    Hi all,

    I'm working on the design phase of a 15" woofer module which will have curved sides. I only need a radius of 27" (686mm) and am wondering if the MDF will bend to that radius. I will use a three-ply laminate and want to avoid kerfing.

    It is unusually difficult to find this information on the net.

    Does anybody here have experience bending MDF without kerfs?


    Thanks much,

    Warren
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    How thick? Your laminations?

    Good luck bending (and having it hold) any MDF of any thickness without kerfs

    I really don't think you can in a shop with any real control (can be done industrially with a press)

    Got plenty of bowed MDF shelves out in my garage though!

    Can't wet it either

    Thomas

  3. #3
    Senior Member Ed Zeppeli's Avatar
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    Well I'm pretty sure that if I purchased a 4 x 8 sheet of 1/4" mdf and picked it up by the middle there would be a considerable bow to it. Basically I'm wondering if that bow could be 27"r.

    Unfortunately my nearest supplier would have to order it in otherwise I'd just check it in-store.

    I'm planning on 3 layers for 3/4" plus veneer.

    Thanks

    Warren
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    Quote Originally Posted by Ed Zeppeli View Post
    Well I'm pretty sure that if I purchased a 4 x 8 sheet of 1/4" mdf and picked it up by the middle there would be a considerable bow to it. Basically I'm wondering if that bow could be 27"r.

    Unfortunately my nearest supplier would have to order it in otherwise I'd just check it in-store.

    I'm planning on 3 layers for 3/4" plus veneer.

    Thanks

    Warren
    Note what I actually said:
    Quote Originally Posted by Wagner View Post
    How thick? Your laminations?

    Good luck bending (and having it hold) any MDF of any thickness without kerfs

    Thomas
    Well, 1/4", sure it'll bend.

    A circle with a radius of 27" doesn't tell me anything, what's the arc's length going to be?

    Whether you can pull it off or not would be determined in a large way by the length of your sheets and grade of MDF (the really dense stuff's not going to make it obviously)

    Too many unanswered variables in your question; no one at your store that can tell you about the specific product you are considering using?

  5. #5
    Senior Member Ed Zeppeli's Avatar
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    Just regular 1/4" Medium Density Fibreboard; the thickness of which was mentioned in the title of the thread. Arc length shouldn't matter but here's a rough of what it'll look like.

    Name:  BassModule.jpg
Views: 671
Size:  185.2 KB

    The dimensions on the left that got cropped out are 23 1/2" and 9 1/2". The sides will be one piece but the dimensions indicate where the arc begins. On top will sit a SAM1HF.
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    The arc is going to matter depending on what you have in mind to jig it up to make your panels

    1/4" will make that bend degree wise but you'll have a fair amount of waste

    It's that transition point from straight to arc that concerns me; why the aversion to a light score there?

  7. #7
    Senior Member Ed Zeppeli's Avatar
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    Quote Originally Posted by Wagner View Post
    The arc is going to matter depending on what you have in mind to jig it up to make your panels

    1/4" will make that bend degree wise but you'll have a fair amount of waste

    It's that transition point from straight to arc that concerns me; why the aversion to a light score there?
    I imagine I'll attach the sides last and use the front, back and some bracing as the jig.

    I have no aversion to throwing a score at the transition point. Good idea. I just didn't want to have to kerf the whole thing to make the bend and then have a bunch of voids to fill in.
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    Quote Originally Posted by Ed Zeppeli View Post
    I imagine I'll attach the sides last and use the front, back and some bracing as the jig.

    I have no aversion to throwing a score at the transition point. Good idea. I just didn't want to have to kerf the whole thing to make the bend and then have a bunch of voids to fill in.
    Without actually holding your MDF of choice in my hands I'm not going to be dumb enough to say with certainty that it'll work like you want..............BUT, from what I can see (the drawing really helped) I think you will be just fine*

    *I did work with putting a curve in some 1/4" MDF (single thickness) for an Art project for my daughter years ago, the arc was about the same if not more and no problems with cracking

  9. #9
    Senior Member Ed Zeppeli's Avatar
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    Yeah, the radius isn't really that large.

    Have you done a project bending MDF before? I'm speculating, but I think it will work as well.

    Cheers,

    Warren
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    Senior Member DavidF's Avatar
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    I have bass enclosures where the side-rear corners are rounded at a tighter radius that you have in mind. I kerfed the 3/4" mdf stock used but left 1/4" of the material as-is (might actually have been 3/8"). I don't think you will have issues with cracking using 1/4" stock. However, the tension will be high so you need to have a jig and lots of belt clamps. The panel joints will be a problem so figure on plenty of bondo or similar means to square the work along the seams and joints.

    The seam at the transition in your drawing may be a problem. Getting the mdf to crease like shown is going to risk breaking the panel.

    Good luck with the project.
    David F
    San Jose

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    Senior Member Ed Zeppeli's Avatar
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    Quote Originally Posted by DavidF View Post

    The seam at the transition in your drawing may be a problem. Getting the mdf to crease like shown is going to risk breaking the panel.

    Good luck with the project.
    Thanks David. Yes I see what you're saying. I may be able to round that edge on the baffle or put a kerf in as Wagner suggested.
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    Senior Member DavidF's Avatar
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    What are you thing in terms of finish? Painted, veneer?
    David F
    San Jose

  13. #13
    Senior Member Ed Zeppeli's Avatar
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    Veneer top, sides and baffle.
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    Senior Member Ed Zeppeli's Avatar
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    Started today. Angles really make things complicated and I'm not even sure I'll like the looks but I do like the idea of doing something a bit different.

    Since I don't have any 2216NDs yet I'll be using ye olde 2235s. Box measures 5.4 ft cubed without porting, bracing or driver so it'll be close enough to desired volume.

    I still have lots to do but at least I got started. Next will be the fun part; bending mdf to make those curved sides. The whole appearance will be about 3/4" wider once the sides are on.

    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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    Senior Member srm51555's Avatar
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    Looks good so far, good luck.

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