MDF as Sub-roadbed

Model Railroader General Discussion (Model Railroader)
1

I am about to replace some cookie-cutter roadbed - cork on 1/2" plywood. My son suggests using medium density fiberboard (MDF) instead of pylwood. (He has found this a workable material in many projects, but not in HO model railroad projects!)

So, is MDF an acceptable alternative to plywood as a sub-roadbed? What do you folks think?

Thanks in advance.

Andy

2

You ask a timely question. I am in the process of building benchwork on my new layout and I had the same thought. I doubt very much whether MDF would work as a plywood substitute in a model railroad context. It is my understanding that MDF is not used as a plywood substitute because it does not have the shear strength of say a CDX product. I would be interested in hearing from any contractors or wood workers out there.

3

My concern is that the MDF possibily lacks the dimensional stability plywood offers. Call me a chicken, but if I were you, I’d stick to what’s worked well for all these years – plywood.

You might contact the American Plywood Association (www.apa.org, I believe) and ask someone there whether MDF is a good substitute for plywood in this situation.

Paul Schmidt
Associate Editor
MODEL RAILROADER

4

Make that www.apawood.org. One of the things the APA does is certify engineered wood products and sheathing.

Paul

5

I wouldn’t use MDF for subroadbed, mainly because it isn’t meant to be nailed into, or even screwed into, unless holes are pre-drilled close to optimum size. Also although it ‘machines’ well, this really applies to tablesaw,CMS, drill press and router table work. Cutting MDF shapes with a jigsaw is no fun.Plywood is best for the initial work, and any changes later.
I use MDF for general carpentry projects like drawers and drawer fronts. Only place I use it on the railroad is for bases for buildings. It’s really good for that.

6

I tried MDF - 1/2" on with supports on two foot centres. It was way too flexible.
1/2" plywood on the same centre distance to be fine, although next time i will use 16" centres.

The MDF is flexed too much. Its also very dusty when cutting, far more than plywood.

You learn by trying right?

Kevin

7

Plywood it is then!

Thank you Jim, Paul, Mike, and Kevin for responding. And like you said Kevin, “You learn by trying, right?” - true. But it is also nice to get information from guys like you who have had past experiences and can say “whoa!” to the MDF idea.

Thanks again.

Andy