Quick terrain board question

[Charlie_]

I'm planning to make some terrain boards, and have a quick question.

I'll be using MDF with a layer of styrofoam (blue foam) on top.

I was wondering if there is a generally accepted minimum thickness of both the MDF and foam?

Whenever I see people make these things they always seem really thick, but I was thinking of going as thin as possible to make storage easier. The only reason the foam will need to be thick is to facilitate deep enough rivers, and I'm thinking 15mm will be enough.

So I'm thinking 12mm or even 6mm MDF to mount the foam on. This will be for 2ft by 2ft titles, with a few 2ft bt 4ft ones as well.

Will the 12 or 6 mm MDF be strong and stable enough? Any reason not to go so thin?

Also, what's the best way of sticking the foam and MDF together? Does PVA do the job?

[Andym]

As you say the thickness is just a preference thing. If you don't want huge undulations or rivers or gorges use the thin stuff. In theory if you are doing shallow hills, you could just glue the shaped foam hills directly on to the mdf, leaving some of the flat bits mdf without foam, and cover it in filler.

The blue sea in these is just the plain wood painted. The beach is the only bit done in foam.


As for glue, pva is enough(that's what I use) Just make sure to weight down your glued foam on the board while you're waiting for the glue to dry. I usually leave mine for a day.

[kingsmt]

PVA needs air to dry. If you use it to attach foam to MDF it will never dry.

Use Liquid Nails for styrofoam. It's made to do what you need.

[NurgleHH]

I have always used PVA, had no problems with drying. The problem with midfield is, that boards become very heavy for transport. Here in Hamburg a lot of gamers use styro-boards with a wooden frame to stabilize it.

[Andym]

I've made a LOT of boards using PVA and I've never had a problem. If PVA is air drying there must be some air getting in some how.

[Steve63]

The moisture in the PVA disperses through the MDF

[SotF]

If you're covering the entire board with foam on the one side, there is a workable way to both up the durability of the bond and help prevent warping as well.

Have a regular pattern of nails up through the board and into the foam, make sure they're short enough to be inside the foam rather than protruding and mark the pattern on the top of the foam with a pen to keep from revealing it when sculpting the board.

[snitcythedog]

My two cents here.  For the MDF thickness question you need to Have a clear idea about how the board is going to be used.  If it is to be laid on a tabletop at home that will support the whole board with very little overhang then you can go with 3mm sheets and no other supports.  (this is prone to warping but it is doable)  If the board will regularly travel and will only be partially supported then you need to either add wood supports to the thin MDF or you will need thicker MDF.  For the foam thickness that is entirely dictated by what you want sculpted into the board.  If 15mm is thick enough for your rivers and ravines then go with it.  For adhesives, that is personal preference.  I have used liquid nails, PVA and wood glue. They all have pluses and minuses associated with them.  It is just what you are comfortable with and what you can afford.  Hope that helps.
Snitchy sends.

[Charlie_]

Thanks for the tips guys. I'll consider adding some nails or pins of some sort to help secure the foamboard.

My two cents here.  For the MDF thickness question you need to Have a clear idea about how the board is going to be used.  If it is to be laid on a tabletop at home that will support the whole board with very little overhang then you can go with 3mm sheets and no other supports.  (this is prone to warping but it is doable)  If the board will regularly travel and will only be partially supported then you need to either add wood supports to the thin MDF or you will need thicker MDF.  For the foam thickness that is entirely dictated by what you want sculpted into the board.  If 15mm is thick enough for your rivers and ravines then go with it.  For adhesives, that is personal preference.  I have used liquid nails, PVA and wood glue. They all have pluses and minuses associated with them.  It is just what you are comfortable with and what you can afford.  Hope that helps.
Snitchy sends.

Oh, I'm putting a LOT of thought into how it's going to be used! : )

It won't be travelling, it'll just be for home use.
I am considering trying my hand at a bit of carpentry and building some sort of a frame which the boards can be placed on / in to keep them secure. I really don't like the idea of them being sat on a wobbly table and shifting every time someone looks at them. The frame will disassemble itself or (hopefully) easy storage. So if that works out, I'm thinking I should get away with thin boards.

How likely is it that 6mm or 9mm MDF with 15mm foam on top will warp, do you think? I would hate that.

[westwaller]

I cant claim to know anything about terrain boards but back in the day, White Dwarf used to recommend using Copydex glue to glue styrene foam to Mdf. I think that it might be too expensive to use on whom boards, but it might be worth trying to find something similar as it doesn't warp mdf.

[FramFramson]

Yes, long-term warping would always be a great worry I would have...

[Khadrin Stonetooth]

According to what I've seen here and there go for 6 mm MDF and add battens on the edges. It will secure vs warping and also make seams less visible. Check this out : http://www.coolminiornot.com/articles/6397-how-to-make-modular-terrain

Cheers
Khadrin Stonetooth

[FramFramson]

Hm, never thought about putting the battens on TOP of the board before. There's an idea. Also makes it easier to pre-make irregular edges (hills, etc.) which will line up in multiple configurations.

[Thargor]

I use 9mm plywood for my 4' x 2' boards.  No problems with warping and can self-support when in use.

[Charlie_]

I use 9mm plywood for my 4' x 2' boards.  No problems with warping and can self-support when in use.

Do you know which is most prone to warping, MDF or plywood?