Probably worrying for no reason but.......

[cupoftea]

The baseboard I made is 5 foot by 2foot 6 inches 9mm marine ply and has 2x1 battening. Now it has more weight on it I notice that when I pick it up it is able to flex (twist) by about 1 inch corner to corner - is this flex going to be enough to cause any problems? I cannot see a way of making it any more rigid.

Thanks for any advice.

[Tank]

An inch!  Yikes!  I use 9mm MDF, and it doesn't budge.  I think the only thing you can do to keep the baseboard is to make another frame with thicker wooden battening, or lay the plywood on MDF.     Preferably, replacing the plywood with MDF would be the best and most solid option.

[zwilnik]

Everything is flexible if you jump on it enough.

Sounds like it wouldn't be an issue if the layout's not going to be moving around. If it's designed to be placed in a room and not trekked to clubs and exhibitions for instance. 5x2.5 9mm ply with 2x1s would probably need a forklift anyway once you add scenery Is it being placed on a pre-made table or does it have its own legs? If it has legs, just adding another pair in the middle would reduce any chance it'll bend in the middle with the weight of scenery and doing diagonal cross-ties from wire would increase the rigidity of the legs and thus the whole structure.

If it's designed to be carted around, putting some holes in the 2x1 frame and building a set of box sides/ends (and possibly a lid) to turn it into a carry case would also help any issues of flexing when being moved. Bolt it all together for lifting, move to car with help of friends/forklift, place at exhibition/club and remove box components.

[cupoftea]

The layout is being placed on top of a pre-made table but i will have to lift it off from time to time.

I did wonder if when I fit the 9mm ply backdrop and sides the 'box effect' would reduce the flexing. My guess is it will always flex under torsion though.

Basically i want to make sure all is well before I start on the scenery - I would hate to have to scrap the board at a later stage..........

[poliss]

Did you put 2"x1" cross members in as shown on Brian Lamberts website at this link?
http://www.brian-lambert.co.uk/Hints%20&%20Tips.htm

[cupoftea]

Yep -   have put cross-members in.

Think I may have to cut my losses and start over with a new baseboard. I just can't figure out why it is flexing in torsion like it is. My guess is that the flexing may damage any scenery when the board is moved.

[Dock Shunter]

Hello Jon.....have you thought about maybe adding some diagonal bracing for extra strength?
something like this maybe....
http://www.modelrailways.co.uk/forum/viewtopic.php?f=6&t=128

(apologies for using posting from another forum)

[Lawrence]

It may well be worth building a new frame using kiln dried, planed timber. I used good quality joiners wood glue as well  as screws as i found it gave a more secure feel. You can also get light weight mild steel brackets from diy stores which can help too. So make up your new frame and leave it for a couple of days to settle before reskinning it. 12 mm ply is surprisingly more rigid than the  9mm stuff too!

[cupoftea]

Thanks Chaps

Have now made up my mind to start over and use a new design layout. Going to go for a three piece baseboard with the scenic centre section 5 feet by 1 foot and then two 'hidden' sections as fiddle yards. This will make it more portable and also very rigid. Going to use 12mm birch ply this time and 3 inch by 1 inch battening with a cross member every 12 inches and diagonal bracing between the cross-members. Good news is I only taped the track down so i can re-use the track. The only waste is the cost of the baseboard materials thank goodness (plus my time i suppose but being retired that is not really a factor).

I would much rather start over now than have huge problems further into the project. There is a carpenter's workshop just down the road so I am going to ask him for a quote to make a board for me. He has the tools to do a really accurate job.

[jonclox]

I used 3" X 1" planed timber framwork with 1 x 1 blocks in each corner to screw and glue into then added underboard battoning to support a  'Sundeala' topping. The result was firm and strong and shows no sign of twisting or bending. Bassically its 3ft X 5ft and mounted on 4 screw in legs.   

[poliss]

If you use cross halving joints for the inside bracing and dovetail joints on the outer bracing it will make the constuction much stiffer. Dovetails are much harder to make though.
Here's some diagrams of the different joints. http://www.diydata.com/techniques/timber_joints/frame_joints/frame_joints.php