MDF or PLYWOOD

Ply.

Mdf will absorb dampness (and paint)

"Edward Bray" wrote

What's a biscuit joint ? I've not come across this before ? Please enlighten me ?

Have you not considered 6mm MDF ? About £3 for 4x2ft sheet ? (B&Q) or is someone going to tell me that I'm making a mistake with this ?

Andy

"Trev" wrote in news: snipped-for-privacy@pipex.net:

...

The MDF I've installed in my garage is fine and it's a lot more damp in there than any loft. The real issue with MDF is the dust created when cutting/sanding it is a health hazard. Nevertheless if you have a way of dealing with that I much prefer it to ply.

"Edward Bray" wrote

If your loft is totally dry then I'd be inclined to go for chipboard - it's pretty robust and cheaper than the other options you've suggested. It's heavy (as is MDF) but in a fixed situation that shouldn't be an issue.

John.

Also called flat dowels. Oval shaped disc's of compressed beach fitted in to a slot on both boards with PVA which then swell the compressed disc giving a firm grip. Like a double ended tenon joint tenon. But you would be hard pressed doing 9 mm ply. I thing the Router and finger jointer would be a better bet

Ummm why is price an issue on this, its a job you will only do once if you get it right and the figures above are of the order of 1 good quality rtr loco, go for the best material, not the cheapest. As to what the best is, where is it going, is it subject to temp changes, will it need to be movable at any time etc?

Hi,

Cost is not the main issue, but there is no point in spending money needlessly. The loft is completely dry at the moment and I had new roofing felt fitted 18 months ago, so I suspect in should not leak for a number of years.

We are in the middle of winter here (Plymouth, UK) and there has been no time so far this year that I have needed heating in the loft whilst up there. I have not been in the loft for any length of time in the summer yet, but as our external temperatures are usually between -5 or so (coldest) and about 32 or so (hottest, although on rare occasions it has been hotter) I do not think the temperature is a major factor.

As I previously said, weight is not an isuue.

MDF is easier to machine than both PLY and Chipboard.

As my loft is not likely to be flooded by seawater (live on the top of a hill about 400 ft above sea level) major Tsunamis excepted, I do not think the additional expense of Marine Ply is warranted.

So, my reason for asking the questions was to get an insight into what other people had used and what if any problems they had encountered with that material, once bitten twice shy.

Eddie.

Hi Andy,

Biscuit jointing is a means of fitting two pieces of wood together in alignment using a biscuit jointer (small plungecircular saw type tool) that cuts a semicircular slot on both pieces to be joined and you insert a compressed beechwood biscuit into the slot. This is usually glued using a PVA type glue which causes the beechwood biscuit to expend and lock the joint together as well as giving an extended glueing surface. Very strong joint similar to a mortice and tenon joint. But considerably easier and less time consuming to make. In kitchen worktop fitting, biscuit slots are usually cut along any joints and dry biscuits are inserted, this acts as alignment security and prevents the joint from bowing in the future. This is how I proposed to use the jointer. You set the jointer to cut at a certain depth, mark a small line on both boards at a numer of spots along the edge to be be joined align jointer to mark and plunge cutter into the edge, remove cutter, fit biscuit. Took longer to type than it does to do. see under biscuits at

As for buying wood, never, ever buy from DIY shops like B&Q unless its Sunday and you are desperate. Your 6mm MDF from the local wood merchants is under £6 for an 8ft x4ft sheet, less than half the DIY price.

Eddie.

I am using 6mm MDF for my portable layout I am building ATM. It looks as if it will be light and strong, and with appropriate framing will not warp either.

Hi Trev,

I can cut slots in 9mm ply as I have a jointer/blade that does cut smaller thinner slots for making picture frames. I also intend to fit them dry as an alignment aid/security, rather than use glue and have them swell up and split the ply.

I like the idea of a finger joint on the router though, as this would ensure alignment over the whole joint. Would still probably fit dry though.

Eddie.

Eddie,

I've used chipboard, MDF and plywood in baseboard construction and they have all worked.

But I found that chipboard needed a bit more support than you would reckon. I built one 6' x 4' baseboard using 3/4" chipboard as a top and I think I had it braces at 18" centres, and it eventually sagged between the centres. And the whole thing weighed a ton :-)

I used 12mm MDF as a topping on two medium sized baseboards for an S scale layout and that worked well. The layout never got finished due to lack of time and the baseboards sat in my unheated garage for a few years until I sold them on to another S scale modeller and the MDF looked to be in good condition when they were sold. My reservations with MDF is that it is a bit more difficult to cut, the dust has possible safety concerns, and it weighs quite a bit - the last a major consideration for me since my layouts have to be portable.

I'm now using 4mm and 6mm plywood for baseboards and open plan track as in the following web sites

although I do agree that the emphasis on light weight maybe doesn't concern you at the moment :-)

Jim.

Hi Jim,

Many thanks for your thoughts taken from your experiences.

I have bookmarked your site and shall visit often to see how things should be done.

I have all but decided to use 12mm MDF. I am used to using it and much prefer it to ply for machining. It will mean me having to route out a few

3mm hollows where the point motors will be, but this will not take too long, I will make up a jig and use that for them all. I will buy 3 sheets, 2 cut into 3x 32"x48" and one cut into 4x 24"x48. This will give me 6 sheets of 32"x 48" and 4 24"x 48". This will be more than enough to replace and in a few places extend what is already there (I feel some room for a turntable and fiddle yard coming on).

Thanks to all who replied. It will be nice to get rid of the insulation board, bloody horrible stuff to work with.

32" is the largest size I can get through the loft hatch. and just happens to divide nicely into 96".

Eddie.

Edward,

I used 6mm MDF as the baseboard for my sons N gauge layout. The reason I opted for 6mm was that the layout is no wider than 18" and all the frame work is bolted to the wall. - To be honest, I don't think it matters if you use 6mm, 9mm or 12mm MDF, ply or chipboard. The strength of the baseboard is in the frame work. Using good quality straight lengths of 50mm x 30mm timber, with braces glued and screwed at no more than 500mm centres (I used 300mm centres on our layout) is the key to how well the baseboard top works.

Malcolm

Right, bought the 12mm MDF, now the hard work begins, No, not changing the boards, getting it up into the loft. :o)

Eddie.

There's never anyone around to help and climbing a ladder with both hands occupied holding a weighty piece of wood can be a bit dicey! I know.

Adrian

"Edward Bray" wrote

Your 6mm MDF from the local wood merchants is under £6 for an 8ft x4ft sheet, less than half the DIY price.

Eddie.

But does it still fit in the back of a Vauxhall corsa ? No...

By the time I have paid for delivery I'm at the same price anyway.!

Thanks for the advice on biscuit joining .

Andy

Hi Andy,

No I suppose it doesn't, but my local timber merchant offers a cutting service for 50p cut.

Up to 30mm thick can be cut in one go so upto 5 sheets of 8x4 cut into 4x2s equals 2 cuts £1.

I did this today, I had 2 sheets of MDF cut into 6 of 32"x48" and 1 cut into

4 of 24"x48" this cost me an additional £2 but a) meant they fitted into my hatchback and b) saved me the hassle of cutting them when I got home.

But if you only want a 4 x 2 and B&Q is more convienient, it makes sense to pay the extra.

Mind you I bought a 4x2 offcut of 3mm Oak faced ply for a £1 and a 4x2 offcut of 6mm Chestnut faced ply for £2 whilst I was there.

I have already started replacing the boards along the side walls, they were

18" they are now 24", I will mark where the points are to go on these boards (as they are easier to move in and out) and tomorrow I will route out the hollows for the motors.

The main boards will be a bigger task, and I will use new point motors for the points on there. I have not yet tried the boards with a cork layer yet, but they do not sound very much noisier than the insulation board at the moment, and I have run a couple of trains around the track at top speed.

Anyway, I digress, thanks for your advice.

I'd go with ply. But proper birch throughout ply, not the rubbish most DIY emporiums and many timber yards try to sell as birch (having a cheap birch face, and then "no name plus some filler" interior mushy wood).

Proper birch ply is expensive, has alternating thin dark and light bands through it. Worth it in the baseboards I've built. One can use thinner sections, it doesn't splinter and split on you (provided you cut it correctly), etc..

- Nigel

In message , Chris Wilson writes

I have just been assisting with the construction of a loft layout which was started some four years ago and which involved the use of flooring grade chipboard throughout, of the type which is interlocking and comes in packs. Due to family illness the baseboard and its cork overlay was left unattended until just before Christmas this year. We found that it was in pristine condition, a little dusty on the top surface but flat and level. The butt joints had no sign of movement or lift at all. The cork had curled a little on the edges here and there but the rapid deployment of the glue gun soon cured that. The stuff is as hard as iron to cut out the holes for the under board point motors, and driving pins in it might be fun, but so far all is going well.

Our initial happiness at the state of the baseboards was however somewhat tainted by the discovery that European wasps [bloody great things] had decided that spring had arrived early. We had put a couple of heaters on to warm up the work area. Fortunately I was not the guy who stood on one and got stung :0) Who takes his shoes off in the loft? In the event we killed a dozen at the time and then fumigated the whole loftspace completely. No sign of invaders since.

Cheers.