Lightweight MDF?

[inblackandlace]

Ok, so I just finished my war axe project and I'm itching to start something else. I'm really curious about MDF, but when I went to pick some up at Lowes, I realized that my weak little girl arms couldn't even pick it up. I know I can get it cut down, but if I'm going to be carrying said prop around with me at a con, I'd like for it to be at least somewhat lightweight. I've worked with floral foam, but I'd REALLY like to try something else. That stuff was a nightmare. Also, (I know this is asking for a lot, but) if there's something that's lightweight AND formaldehyde free, that would be AWESOME. I have a respirator, but my dog doesn't.

 

[TheSt.LouisKid]

Look into Sintra from a store that sells sheet plastics. Also called "foam ABS".

 

[inblackandlace]

Look into Sintra from a store that sells sheet plastics. Also called "foam ABS".

Haha I looked up foam ABS and I got a lot of pictures of fake foam abs
As far as the Sintra, that looks really promising. How do I shape it? I have a collection of rasps, sandpaper, and a hand saw. I work out of my kitchen, so I don't have access to anything more complicated than that.

 

[TheSt.LouisKid]

You can draw out parts on the sheet Sintra and score them lines with an xacto knife using a strait edge as a guide. You may have to make a few passes depending on how thick the sheet is. If it is 1/2 and inch then you need to saw it. If you get thinner sheet then you can stack it to make a thicker part. You can cut it with a saw but it leaves a cleaner edge if you use the xacto.

Call or visit your local plastic supplier. They should probably be able to give you a sample to play with. Tell them you would like a sample to see if it will suit your needs. I know a place that would cut sheets to size for some clients and throw away the rest even though it was perfectly good(2x3 foot pieces at times).

Actually visiting a supplier may not be a bad idea. If you have plans to make more things then becoming familiar with materials firsthand may not be a bad thing. Don't be discouraged that you are an individual and not a big company.

Sintra is nice for medievily armor sections. You can heat it easily with a heat gun or even over the stove and shape it without the distortion that you get from styrene. I made curved wall sections for the master pattern of the Grinch Who Stole Xmas toys back when I worked for Mcfarlane Toys and it shaped really well. It routers well and you can cut designs into it with a rounded end dremel bit. Work with it outside if you use a dremel type tool0

I am going to make a small console with some here soon. Always liked the stuff.

 

[PaulMmn]

Other sheet goods along the same lines are Gator Foam / Gator Board, and Ultra Board. Both are extruded dense foam sheets. Gator' is faced with a plastic-impregnated wood pulp on both sides; Ultra with a plastic sheeting. Both are smooth-surfaced, rigid (at least in the 1/2" and thicker-- thinner may wobble a bit, but I've only used the 1/2"), can be painted with latex or acrylic paints. They can be glued with Gorilla Glue (as long as you clamp the joint until the glue cures). You have to watch anything solvent based-- solvents can eat away at the foam core.
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These products are used by sign makers for light-weight signs-- look overhead in WalMart, Kroger, or other stores-- those impressive signs are often Gator/Ultra Board. Look at the edges and you can see that they have a foam core.
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They're both light-weight, each to cut with wood-working tools. Drilling can be temperamental-- twist drills don't do well in the foam core. You need drill bits with a 'spur' around the outer edge-- like some spade bits and Forstner-style bits. You need to drill a small pilot hole through the board, then use the bit with a spur to score the facing along the outer circumference of the circle ON BOTH SIDES! Then work carefully through the foam core.
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I've never tried heating and bending these products, so you're on your own as far as that is concerned!
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Pricing is more than an equal thickness of plywood, but your arms and back will be ever so thankful that it's not plywood that you'll forget the price! If you play your cards right you may be able to talk the manager at some of these stores into saving any seasonal signs that they're about to discard for you!
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--Paul E Musselman

 

[Fizbin]

What about the 4'x8' pink (or blue) ridgid foam insulation sheets found at any Lowes/Home Depot? They come in a few different thicknesses and are very light weight. I think they're about $10 a sheet.

 

[BAK55]

Have you ever considered using cardboard? I've used it for lots of builds. It's readily available from stuff you would normally throw out, so costs are reduced, and PVA glue (White glue) is far more friendly to the human body than a lot of other chemicals needed to coat foam.

I'd create the core of your axe with corrogated cardboard, and add a veneer of regular cardstock -like cereal boxes- to create a smooth surface. After sanding to blend edges, a coating of a mixture of PVA glue and water lightly painted over the entire surface will seal the project. Use as many coats as needed, with sanding between coats, until total absobtion of the moisture is achieved. Another step could be spraying on a coat of polyurethane or acrylic (available in spraycans) to give the project an added tough skin, and also creates the illusion of the project being made from something other than cardboard once it's painted. The end result is a lightweight, convincing prop.