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Baseboard planning - advice sought


aleopardstail
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I've got an "N" gauge layout planned, 4'x 2'6", will be a single board, idea to hang on the wall when not being used, eventually.

 

proposing 9mm plywood for the deck and for the side frames which will initially be probably 4" deep below the board deck (I want a road underbridge at one point so part will go below the deck). three sides will eventually get a second layer, possibly 6mm, glued on to carry a basic backscene but won't be more than 6" high to keep the overall height of the model manageable.

 

my concern is torsion forces and the board warping, adding some cross bracing is in the plan, outlined below, my question is would the diagonal bracing shown be enough? this would be a mix of screw & glue construction with every bit of wood touching wood getting glue. the Inner frames will be probably slightly shallower, maybe 3", with holes for cable access and weight recution.

 

does this look reasonable (bracing positioned to clear servos under the points, could adapt if it would help though)

 

A second possible design has a double "X" of bracing, not sure if this would be better or worse

Dingleberry mk6-baseframe.png

Dingleberry mk6-baseframe-X.png

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The lower, double X style has a weakness across both the central axes. But with a combination of 9mm ply and sides 4" deep, presumably from 9mmply as well although you don't say, it will be quite rigid to start with, although it would be better to use PSE timber say 44 x 21 inside the 9mm ply, carefully fitted so the sides of the box can be screwed and glued. There wont be much movement from that and while you and some others would feel safer with some cross bracing it might be rigid enough already. If you wanted a brace I would put one across where the upper one is, avoiding as you placed it any point motor locations. I wouldnt worry with the extra diagonals, really overkill in my book, and adding to weight while hindering cabling.

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I think plan A looks the best. I would avoid PSE and use ply throughout as that has much less tendencny to warp.... Unless you can get some really good quality PSE.

For the crossmembers and framing, you will find it more stable if you use 6mm ply and laminate three layers together, the middle layer need only be ends and the middle. If you look at my layout thread, you will see what I mean.

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7 minutes ago, RobinofLoxley said:

The lower, double X style has a weakness across both the central axes. But with a combination of 9mm ply and sides 4" deep, presumably from 9mmply as well although you don't say, it will be quite rigid to start with, although it would be better to use PSE timber say 44 x 21 inside the 9mm ply, carefully fitted so the sides of the box can be screwed and glued. There wont be much movement from that and while you and some others would feel safer with some cross bracing it might be rigid enough already. If you wanted a brace I would put one across where the upper one is, avoiding as you placed it any point motor locations. I wouldnt worry with the extra diagonals, really overkill in my book, and adding to weight while hindering cabling.

 

Yes plan is 9mm ply for the sides, there will be some PSE ~ 25mm square but only in the corners so the sides can be screwed to it as well as the glue, then the deck screwed down to it as well as glued, one of the ends will also get some PSE as a batton, to hang the thing from.

 

only thinking to diagonals to aid with twisting, hopefully won't be a massive issue

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6 minutes ago, ikcdab said:

I think plan A looks the best. I would avoid PSE and use ply throughout as that has much less tendencny to warp.... Unless you can get some really good quality PSE.

For the crossmembers and framing, you will find it more stable if you use 6mm ply and laminate three layers together, the middle layer need only be ends and the middle. If you look at my layout thread, you will see what I mean.

 

"A" is probably also a darn sight easier to measure up and make, which given my tendencies with "accurate measurement" is good. I think I know what you mean with the lamination stuff, seen it before as a weight saver.

 

I've made layouts before, a while back, but the "fixed PSE & Chipboard and don't worry about the weight" type, I want to be able to lift this when its done and move it about, probably not too often but to at least be possible.

 

9mm is on order already, not averse to getting some 6mm (well 5.5mm from what I see locally) and laminating, as it is the outer frame will likely get a layer of that laminated to it anyway at some point to go above the board

 

 

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Diaginal bracing wont stop twisting as it would lie along the axis of the twist not across it. You will be fine as described.

 

Light ply has certain problems, not as a base material but because its thin for screwing anything into it. Its OK but additional board for mounting point motors for example is needed - this happens to be how I do it but it wont be for everyone.

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16 minutes ago, RobinofLoxley said:

Diaginal bracing wont stop twisting as it would lie along the axis of the twist not across it. You will be fine as described.

 

Light ply has certain problems, not as a base material but because its thin for screwing anything into it. Its OK but additional board for mounting point motors for example is needed - this happens to be how I do it but it wont be for everyone.

 

this is something I was pondering, plan is servos in "U" channelling, but obviously still needs to be fixed to something - the ply is going to have something on top of it, its possible I may use further 9mm play in small rectangles glues below where the point servos need to go so there is a bit more to screw into, it may or may not be ideal, but everything at this size is a compromise anyway

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Looking at the track plan it looks like you are planning to use set track points. If you are be aware that these may not be compatible with all locos and rolling stock. 

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I am neither a carpenter nor an engineer but I think this is being over-thought.  The board will be only 4' x 2'6"; if good quality, birch ply is used for the top, and there is a a 4" deep frame frame on all four sides, I believe that a simple cross bracing from top left to bottom right, and top right to bottom left, will be more than adequate.  As far as i can tell, it would also avoid all locations for possible point motors.

 

Harold.

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2 minutes ago, HLT 0109 said:

I am neither a carpenter nor an engineer but I think this is being over-thought.  The board will be only 4' x 2'6"; if good quality, birch ply is used for the top, and there is a a 4" deep frame frame on all four sides, I believe that a simple cross bracing from top left to bottom right, and top right to bottom left, will be more than adequate.  As far as i can tell, it would also avoid all locations for possible point motors.

 

Harold.

 

That is possible, there is a bit of flexibility on the exact track position, my concern was that leaving larger areas unsupported, presumably thats based on 4" deep cross bracing (with a few holes obviously), may be some scope for a few more blocks of PSE glues here and there along the joins.

 

I've got 8'x4' of 9mm ply arriving (basically having other stuff delivered and figured why not, avoids the deck being in parts mostly which I think will help a fair bit here.

 

only turnout that is potentially a problem is the one off the upper loop into the to sidings (which will be a parcels depot), there is space to shift that along a bit if needed anyway.

 

given this is a bit of a learning exercise anyway this may well be the way to go - will be building the board a while ahead of sticking stuff done, the only "fixed" bit will be the loco shed as there will be two pitted roads. the "underbridge" was going to be the grey road bit, that can quite easily be shifted to sit alongside that length of bracing (or flipped to the other side)

 

the lack of a scenic break in the loop is something I'm accepting for practicality due to where its possible the signals will end up

 

 

overall, many thanks all, plenty of food for thought

Dingleberry mk6-baseframe-Xx.png

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15 hours ago, Kris said:

Looking at the track plan it looks like you are planning to use set track points. If you are be aware that these may not be compatible with all locos and rolling stock. 

 

There is also a facing point.

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5 hours ago, TonyMay said:

 

There is also a facing point.

 

There will likely be many more sins on this line than just a facing point, that inner loop, and the bit of track linking it to the two crossovers at either side will be bidirectional...

 

Yes its all set track, the idea is to have a layout thats pretty simple to build to experiment with the digital control logic side of things before planning anything larger, also to allow a home for a collection of rolling stock as its slowly built up.

 

I'm specifically trying to avoid a situation I had last time I built a layout where I had a ton of space, a really long twin track oval and storage sidings but only ever really had one decent train to run on it.

 

this is a mix of 1st & 2nd radius PECO set track, I'm aware that may restrict some stuff to the outer loop, and even then only with the points set for straight running, at this point I'll accept that, though my thanks for pointing it out.

 

the two longer sidings are set as trailing, mostly so trains can back into then let the loco escape from them, the bit in the middle is a loco depot, hideously oversized for a layout like this but thats intentional. the two sidings with a platform are intended as a parcels depot, probably limited to either a pair of Mk1 full brakes or a few covered vans, otherwise its coaches and watching trains chasing their tails (trains probably two, maybe three coaches normally though there is space for four or five)

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On 17/04/2021 at 21:53, aleopardstail said:

presumably thats based on 4" deep cross bracing (with a few holes obviously), may be some scope for a few more blocks of PSE glues here and there along the joins.

Dingleberry mk6-baseframe-Xx.png

 

I have been developing a 009 gauge layout over the last 2-3 years, which is about 2m x 1m; it has four boards (all different dimensions!) and the bracings are all 2" x 1" softood whilst the outside frames are 3" deep ply sandwiches.  Admittedly, whilst at home, the layout sits level on a table but there has been no warping of any of the boards.  The carpentry is not particularly pretty with inaccurate butt joints and everything is PVA glued and screwed.  The top is 6mm birch ply but the ply-sandwich frames are of cheap ply.  I have had it set up on legs several times at the club without stability or alignment problems. 

 

Harold.

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sorted, I hope, the 9mm ply for this (and some other stuff, like securing my work desk etc) arrived today and its a lot more rigid than I expected, the side bracing and a central "X" I now suspect will be fine.

 

hope to make a start on Sunday

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On 17/04/2021 at 20:44, aleopardstail said:

 

this is something I was pondering, plan is servos in "U" channelling, but obviously still needs to be fixed to something - the ply is going to have something on top of it, its possible I may use further 9mm play in small rectangles glues below where the point servos need to go so there is a bit more to screw into, it may or may not be ideal, but everything at this size is a compromise anyway

9mm depth of ply on baseboards is fine for point motors in my opinion as the fixing lugs on MP-1's and SEEPS as two examples will only take a 3/8 inch screw anyway. I use 6mm and the screw heads come through without an extra 3mm mounting board which you shouldnt need.

Edited by RobinofLoxley
typo
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