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Plywood vs MDF base


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Just interested to hear if there are any pros or cons for either material when it comes to using it for a baseboard or module top surface?

Weight vs strength or the like comparisons.

Thanks in advance.

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Ply cuts well, just need a good ply blade as it will shred more with a standard crosscut blade. Also a zero clearance insert also helps make cleaner cuts in all woods.

 

Mdf is dense and thus heavy. Also Thin mdf can sag with time and moisture. Also you must use screws carefully in mdf. Mdf works nicely in places you don't care about weight and are facing it with Formica or wood veneers.

 

Jeff

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Jeff's advice is good.Definitely go with ply rather than MDF. It's stronger, lighter and more dimensionally stable. Both of my club's sectional exhibition layouts are ply, and we've had no problems with them.

 

Here in Australia a lot of the timber merchants and suppliers can cut the plywood for you. My club's ply was supplied and cut to size neatly and accurately by a local kitchen building company. If you have any concerns about cutting it yourself, this is a good alternative.

 

Cheers,

 

Mark.

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Claude_Dreyfus

I use, and would recommend, ply...strong and light. MDF has been used in the past and it is heavy, as well as more susceptible to swelling.

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Since we are discussing ply vs. mdf, how about the frame for the base? Can we rip ply in length and create a frame to secure the ply top? In place of timber that is...can you share your thoughts please....

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There is a rather light construction method for modules or smaller layouts. Plywood sides with a plywood top, with pine legs and frame. For smaller modules, it's possible to glue the sides together in a frame around the leg bases, then glue it on to the top (while it's upside down), then add the strenghtening frames between the leg bases. If it's slightly larger, then add any cross bracing in the middle between the side bracing and it's done. Leg bases can be anything, like a block of wood with a metrical screw socket for screw in (office desk) legs or an open box made out of thicker plywood for a slide in wooden leg.

 

For plywood cutting, many warehouses will cut the plywood (or any other wood) to size on a cnc table saw if you have a cutting plan. Then you just have to glue everything together.

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Thanks all for the advice, I'm definitely sold on the ply to begin with. Will head to the local hardware centre tomorrow and have a good hunt around. The idea of asking them to cut the pieces to size certainly sounds tempting too. Will see how willing they are!

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Since we are discussing ply vs. mdf, how about the frame for the base? Can we rip ply in length and create a frame to secure the ply top? In place of timber that is...

Yes, you can. That's how we built the sections for our club layouts, and that's also what I used to build my home tramway layout. See the links in my signature, or have a look at my thread in the tramway section of the forum.

 

The problem I've found with timber is that good quality dimensional stuff that's well seasoned, straight not warped, free of knots etc is very expensive and by no means easy to source. The advantage of using ply is that none of these problems exist, and you can build a frame of adequate depth to protect your wiring, point motors and any other equipment without excessive weight or amounts of timber.

 

I'd post the links myself, but I'm posting on a new iPad, and I have'nt worked out how to do that yet!

 

EDIT: I'm back at home on the desktop machine, now I can post some photos. They show the base I built for my tramway layout. The links show how we built the clubs sectional layout bases. My tramway has simplified bracing, when I get a chance I'll post a photo showing how I did that. The tramway is 1700 by 800mm, and is light enough for me to easily lift it on my own. All of the pieces required to build it were cut from one 2400 by 1200 sheet of 12mm ply. The total cost was $60.

 

13422522463_80ebe2d0d1_b.jpg

 

13422520783_788675a4a2_b.jpg

 

http://www.imra.org.au/kellyconstruction.html

 

http://www.imra.org.au/waterfallconstruction.html

 

Cheers,

 

Mark.

Edited by marknewton
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Yes ply can do framing quite well if you use cabinetry grade plywood and not the cheap sand plys. Just need to get a good taper screw drill with counter sink if using screws. Also can work well with 18g air brads and glue or even nails if you predrill pilots. 3/4" ply can make frames down to about 1.5-2" wide and function well, small bracing blocks as kvp noted in strategic places can really make quite a strong structure (that goes for mdf as well).

 

Ply or mdf is not suitable for legs unless you are making some quite beefy legs in an L cross section.

 

What sizes are you talking about for your modules or layout. Construction materials and techniques will vary in size and use a lot.

 

For track modules folks just use 3/16" ply and glue them up. This is all that needed for the size and stress needed of them. Larger modules like ntrak require beefier framing for support and clamping interface.

 

Modules do tend to get overbuilt most of the time and if weight is a consideration, things can be reduced quite a bit if you use some joint techniques and good bracing. Wrack issues tend to be the biggest concern when you get to larger modules as well as sealing things up well to prevent warping due to moisture changes (even with solid wood).

 

Jeff

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Why not isolation foam? The blue/pink stuff most people use for terrain building (and regular people use, well, for house and wall isolation). 

It is extremely light, but strong and if supported on a wood open frame does wonders.

There is only one issue with isolation foam, you need to use double sided tape to secure the tracks in place. 

 

I have my "table top" set up that way. 

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Folks have successfully used pva (white glue) and caulking to attach track down onto foam as well.

 

Yes foam in a wood frame is a pretty durable and light module structure. The old JRM layout foundation/base (it was all set up on the fly, nothing glued down) was made from 10 2'x4' foam modules with 3/4" x 2" white wood frames (two small cross braces as well 1/3 in from ends). We had some interlocking plates that held the modules together and were used for the saw horses to meet up on. They survived many years of getting bashed around to and from shows and they stayed very flat and true! One person could pickup and move the whole brick of modules. I still have 4 of them in my wood shop screwed end to end to make two 8' tall racks to hold small, long moulding and such lumber!

 

Jeff

Edited by cteno4
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Thanks all for the advice...as Mark mentioned, good timber is hard to come by and quite expensive in my part of the world...I do a little woodworking as a hobby too and lately, I am happy using ply for most of my work...the layout is still in early design stages. I am going to go modular cause that is the only way I will ever start work on my layout...thanks again!

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Step resistant insulation foam for terrain in an open frame is good, but most modules i've seen built with foam terrain had a strip of plywood under the tracks, glued to the end plates and supported by the cross bracing. This is a good way to avoid the track getting ripped off when connecting modules. Most of these modules were assembled with PVA glue, including fixing down the tracks on cork roadbed and ballasting. On the still work in progress HJMTC modules the unitrack was also glued down with PVA. (the current modules have a plywood surface since it's a city layout and it's easier to fix buildings on it, but any non concrete surface will be done with foam)

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Mark makes a very good point about finding well dried dimensional lumber that is true these days. It's been getting harder to find and more and more expensive! We get lots of whitewood from Scandinavia and Russia (it's some form of pine but less sap than the North America pine and lighter) that most of the cheaper lumber is of. I will spend 10-15 minutes and dig thru the big pile at the big box store for the best i can find. I've even taken now to looking each time I'm there to see if there are some true ones to just stock up on as it's been getting harder and harder to find decent ones when you need some at the store. It drives the service guys nuts, but I alway leave the pile neater than I found it.

 

One of the best materials to use that kind of splits the difference between regular plys and dimensional lumber is to go for Baltic or Russian birch ply. This stuff is usually 7 equal ply layers so you don't have paper thin veneers on the outer sides that regular plys do (sneeze even with an orbital sander and you will go thru many the veneer!) it's also a much better laminated product and real resists de-lamination and takes screws well into the edge of the plys. The outside layer edges are also pretty tough and resist edge splintering pretty well. It's a bit more expensive and a tad denser than regular plys and dimensional softwoods, but it's worth it as it really resists warping well, takes screws really well and is super strong. It's better stuff than the better cabinetry plys we get here and the same price. Many times it's sold in 5'x5' sheets but also in 4'x8' sheets. The edge is actually quite nice looking with the 7 even plys. The edges can also be run thru a jointer or vertically in a planer w.o splintering so you can make super clean edges.

 

Plus it comes in many thicknesses from 3/16" up to 1" so you can easily make various thicknesses of your own dimensional ply lumber w.o having to mill down boards! It's also knot free on one side usually and the other may only have eye plugs that are usually well done and not horribly visible. Careful planning of your cuts can give you very clean exposed surface that look nice. It's not super rich hardwood grain, but clean even wood train that takes well to stain or painting. It works super well with wood dyes that can be very fun and colorful and a nicer effect than paint, but make things pop more than stain.

 

The Baltic birch ply is a tad more than the whitewood dimensional lumber, but in my mind worth it. I love the stuff and am slowly chucking using dimensional lumber on products when ever I can I made some big pullout pantry shelves last year out of it and they came out great and hold up well with the bug loads of canned goods, jars and bottles they carry. I also decided to not finish them other than a very nice sanding to see how they would look after a bit and they have held up well and have a nice natural feel and no warping and we get some humidity swing here in the house.

 

Down side to using ply to make dimensional type lumber is you need to have access to a table saw to really rip up your pieces. Can do it with a circular saw and a good guide, but it's tricky getting good clean cuts this way. Some lumber supply places will do free cuts or for a fee mill up what you want, which can be quite reasonable compared to buying a table saw!

 

There is also Finnish birch ply that is usually the same but higher grade stuff and bit more expensive. Then the ultimate is marine birch which some are 9 or 11 plys and those are super strong and flat, but really expensive and can be hard to source. I've built some furniture out of marine ply that needed larger flat areas with little support and they have held up amazing well for over 25 years! Beautiful stuff but way overkill for modules.

 

cheers,

 

Jeff

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Hi mate,just read your post on mdf or ply,firstly let me add that I m no expert having only started serious modelling about three years ago,but in my opinion I prefer to use mdf.I use 6mm(1/4 inch) for the actual base and I make the frame and cross braces from 25mm(1 inch)by contructing it this way it is reasonably strong and it keeps the weight down,it also gives a natural void underneath for wiring and power supplies.this is the underneath of my tram layout,post-2329-0-50902200-1420544781_thumb.jpg

My board is 1400mm x 700mm,any wider and it will probably need to be braced along the length aswel.One thing to remember is to give it a coat of water based paint just to seal it up.hope this has been of some use to you,regards,paul

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I've seen folks use a hollow core door and take a router to make some slots on the underside panel to run wires in.

 

Jeff

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Or - you could face the edges with something like 1" X 3" stock, or quality ply (birch) cut into strips to provide even more stiffness, and space for wiring underneath.

 

Major benefits of a door are that it's cheap, light, stiff, and ready made.

 

The major drawback is the limited range of sizes, along with more difficult access to the space just under the tracks.

 

However, it beats setting up on a floor.

 

You could attach a handle to one long edge to make it portable to take to shows.

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