Bending MDF

[regme]

Hi

I 'm is the process of doing the backdrop for the layout and I'm using 3mm MDF.

I to bend for the corners to a 300mm radius, my two options are to cut the back of the MDF to a depth of 2mm for the length of the radius at 20 or 30mm gaps.

The second option is to soak the corner with water and then bend it and let it dry out and hopefully it will hope it will keep it's shape.

I have come across ways for bending Masonite but not MDF, so if anyone has had a crack at this.

Cheers

 

[peroni]

Don't even think about water, it will just make the mdf swell up and when it dries out it will still be swollen, once it is wet it is ruined and will not shrink back, if you have an off cut try it and see what happens, mdf is not made to bend,
ply on the other hand can bend easily.

 

[Smudge617]

MDF won't bend, as peroni say's if it gets wet it comes to pieces and crumble's, a section of ply would be more suitable, but for an accurate curve you would probably need to build a jig to hold it in place till it thoroughly dries out.

 

[Selector]

MDF bends, but how easily, and without catastrophic splitting, depends on how sharply you bend it. I have made nice splined roadbed with six spline-deep 1/4" MDF strips 8' long (I had the seller rip a 4X8 sheet in 15/16ths wide strips. I think I got over 42 strips.) My sharpest curves were in the 24" range, but I think I could have gone down to about 18" without too much trouble.

I would experiment with heat and moisture, maybe one of those fogger/steamers for shirts. It's risky, though, using moisture. I would absolutely agree that you do NOT want to apply water in any amount except as a vapour. Maybe pass a steaming iron close to the outside of the curved area and see if you can't convince it to bend down to your tight radius.

 

[regme]

Thanks, I wasn't too hopeful about wetting it, I was only going to wet the area of where the curve is going to be. Seams like kerfing maybe the go.

 

[Smudge617]

Have you thought about using a section of hardboard, that will bend quite easily without needing to wet or steam it.

 

[D&J RailRoad]

There are quite a few articles on line of how to do this. google, "how to bend mdf".

 

[dave1905]

Another option is sheet styrene, used just for the curves in the corners.

 

[MikeGTW]

Don't try to bend MDF not made for doing that Like Smudge said hardboard aka Masonite comes two ways tempered (very hard finish) or the normal stuff Either one will curve easily
here's some I used around a helix couldn't find later picks I did clouds and some background lower down all gone now

 

[regme]

I'll check the Masonite out see how much that bends, the styrene also sounds like a good option.

 

[dave1905]

If you use styrene and want to minimize filling you can fabricate a splice like below. Then when you curve the styrene and put it in position it fits flush against the mdf/hardboard. The splice plate is against the wall.

 

[santafewillie]

Although I don't have any installed on the current layout, I have always had good luck with either tempered Masonite or Styrene. You can buy cheap "Garage Sale" signs at your local home improvement store for nice big sheets of Styrene.

 

[bigfoot13]

I found a 4'x8' sheet of styrene online for a reasonable price too. Would be quicker and cheaper then the signs @santafewillie mentioned.

 

[D&J RailRoad]

Have you considered dry wall for backdrop?

 

[Smudge617]

Have you considered dry wall for backdrop?

It needs to curve round the wall, not sure if dry wall will bend into a curve, does it ?

 

[regme]

If you use styrene and want to minimize filling you can fabricate a splice like below. Then when you curve the styrene and put it in position it fits flush against the mdf/hardboard. The splice plate is against the wall.

View attachment 158331

Nice detail

 

[D&J RailRoad]

It sure does. I made semi curved corners in my basement so I wouldn't have to reach so far back to the corners for scenery.
Ya bend it by laying it over a couple of saw horses. Spray water over it and let it set. It will soon begin to droop then dry. Lots of videos on YouTube how to do this.
In my application, I just cut it vertically on the backside where the studs are then bent each section so I could use screws to attach it to the studs.