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Baseboard thickness

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7 minutes ago, Derekl said:

Much helpful advice on the need for bracing above, but not much on exactly how much. Say you use a 9mm board  of 1.2 by 0.6 metres (or 4' x 2') supported around the edges, what bracing are we talking about intermediately - traditional one every 300 mm or something else? And what bracing for similar sized 6mm board? 

 

To support the deck well enough to make a flat surface without dips and bumps, I reckon about 250-300mm c/c for 9mm hardwood ply (Builder's merchants ply). For 9mm Birch ply 300-400mm c/c should be OK.

 

For 6mm hardwood ply, I would guess that 200-250mm c/c would be about right but I don't have direct experience of that yet.

 

As Nearholmer says, cross-bracing is important to prevent twisting.

 

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Posted (edited)

Yes, any interfaces where alignment dowels and/or NBW are fitted for joining boards need a bit more meat, so sandwiches of ply and softwood or, better, some thicker good-quality ply.

 

As regards distances between supports/braces, I think I must be a bit more daring than harlequin. My view is that the loads imposed by a model railway are trivially small, so I would accept larger spans, provided everything is solidly glued. 6mm birch ply on a grid of support at 200mm centres could probably support a clog dance :-).

 

 

Edited by Nearholmer

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Sorry, I overlooked wood quality. I am using 9mm birch ply so I will go for 400mm or so. When you say "cross-bracing", do you mean a ladder effect (looking from underneath) or something diagonal?

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Just a quick aside here. Imperial measurements are normally 'downsize' when you come to metric sizes. so 1/4" ply (6mm) is normally 5.5 mm, or 5mm 1/2" ply is normally 11mm, and 3/4" material is 18mm. Sorry to be pedantic, but there's nothing worse than a blessed big gap, when you're trying to make a decent job. 

 

 

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Whilst not immune, ply is much less prone to sag between braces over time than the various particle boards (mdf, chipboard, insulation board etc.), so I tend to agree with Nearholmer about the reduced need for support. I think I'd still not want to see more than a couple of square feet without something under the surface, though. 

 

My first experience with plywood baseboards was with the test track of the Somerset 0 Gauge Group some 40 years ago. The boards were, from memory, about 6' x 1'6" or so, and constructed entirely from 1/2" ply, with side and cross members maybe 6" deep. Crossmembers were at maybe 1' intervals. There was no diagonal bracing, although the boards for the end curves had diagonal ends to form a thrupenny bit shape when erected. These boards weren't especially light, although a pair bolted together were a reasonably easy two man carry. They were, however, massively strong and survived several years of exhibition use and general rough handling without sign of deterioration.

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Posted (edited)
5 hours ago, Derekl said:

Sorry, I overlooked wood quality. I am using 9mm birch ply so I will go for 400mm or so. When you say "cross-bracing", do you mean a ladder effect (looking from underneath) or something diagonal?

A diagonal lattice is more difficult to make but resists twisting as well as bracing the deck. It's probably simplest to do it square for ease of construction and then see if you need to add extra diagonals to resist twisting.

 

My "Vanilla Minories" build topic might be of interest. Because the boards are only 305mm wide I just added just three diagonal braces under each 9mm ply deck, adjusting the angles to avoid point motors. (No need for a lattice.)

 

 

4 hours ago, tomparryharry said:

Just a quick aside here. Imperial measurements are normally 'downsize' when you come to metric sizes. so 1/4" ply (6mm) is normally 5.5 mm, or 5mm 1/2" ply is normally 11mm, and 3/4" material is 18mm. Sorry to be pedantic, but there's nothing worse than a blessed big gap, when you're trying to make a decent job. 

 

 

 

I'm not sure that's always the case. I've just measured some sheets of 12mm birch ply and they are on average just over 12mm thick. I think there are other reasons why manufacturers make the thicknesses they do. The message is really to measure the actual material rather than believing what the manufacturer or supplier tell you!

 

Edited by Harlequin
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6 hours ago, Nearholmer said:

Yes, any interfaces where alignment dowels and/or NBW are fitted for joining boards need a bit more meat, so sandwiches of ply and softwood or, better, some thicker good-quality ply.

 

As regards distances between supports/braces, I think I must be a bit more daring than harlequin. My view is that the loads imposed by a model railway are trivially small, so I would accept larger spans, provided everything is solidly glued. 6mm birch ply on a grid of support at 200mm centres could probably support a clog dance :-).

 

 

It possibly does depend on whether you are building for home or exhibition use. For exhibition use a board  benefits from being light but is more prone to damage or twisting. Catch 22?

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Posted (edited)

I honestly don't think there is a contradiction or tension between lightness and strength.

 

As an example, I built a US H0 exhibition layout c25 years ago, three baseboards from basic quality 6mm ply in box form - 100mm deep sides and ends, with a bottom to the box with lots of access apertures cut in it.  There were some fairly complex shapes, because it had a dropped foreground for a harbour, plus a raised line at the rear to serve coal drops.

 

Each board was 1500mm x 500mm, had a 300mm above datum back-scene integral with it and could easily be lifted and carried with one hand. That got toted around in the back of my then estate car and remained rigid and robust. It was often stored in the loft of our three story house, so the boards had to be easy to handle by one person (me) up and down three flights of stairs and a loft ladder, and survive knocks, but ..........

 

Don't ever build baseboards 1500mm long!!

 

The above layout boards eventually got junked not because they were heavy or fragile, but because 1500mm is an unwieldy size to handle. 1200mm is the sensible limit for one person going up and down stairs where the board has to be carried upright IMO.

 

That having been said, for a static home layout lightness is far less of a consideration and, depending upon what it is supported by, the rigidity may come from the support rather than the board itself. My present essay is decidedly static (apart from a portable mini-terminus) and was knocked together from all sorts of odd-sized bits of wood and board that I had left-over from other things, including two stupidly heavy 1200x600 baseboards that I built from 85x25 framing and 9mm ply tops when I was having a fit of insanity  - they never got used for portable purposes because lifting them practically pulled my arms out of their sockets! Interestingly, they are less rigid that a lightweight ply box of the same dimensions.

 

Of course, if super-lightness with rigidity is the prime consideration, you will go a long way to find something better than a slab of insulating foam, skinned with 3mm ply to resist knocks. 100mm thick high quality floor insulation weighs c4.5kg/m^2, so c3.35kg for the typical 1200x600 layout board.

 

 

Edited by Nearholmer

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Posted (edited)
2 hours ago, Harlequin said:

A diagonal lattice is more difficult to make but resists twisting as well as bracing the deck. It's probably simplest to do it square for ease of construction and then see if you need to add extra diagonals to resist twisting.

 

My "Vanilla Minories" build topic might be of interest. Because the boards are only 305mm wide I just added just three diagonal braces under each 9mm ply deck, adjusting the angles to avoid point motors. (No need for a lattice.)

 

 

 

I'm not sure that's always the case. I've just measured some sheets of 12mm birch ply and they are on average just over 12mm thick. I think there are other reasons why manufacturers make the thicknesses they do. The message is really to measure the actual material rather than believing what the manufacturer or supplier tell you!

 

 

Hi Phil,Yes, you're probably right. I've just spent the last couple of weeks messing about with 4x2" timber, only it's not 4X2, is it? No, it's blessed 95x 45mm. 1/2" ply is, as you say, 12mm. The latest 'dodge' is to sell timber in 4.8 metre lengths, only you can't get 2off  8' lengths: Oh dear me no!  

 

I'll stop griping now....

 

Anyway, what's all this about 'Diagonal Lettuce?

 

Oh.....

 

Ian.

 

 

Edited by tomparryharry
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9 hours ago, Harlequin said:

 

I built 3 identical boards and a bridge section for a test oval using 9mm ply. All the joints in Board 1 were glued and pinned or screwed. The pins often missed and split the ply on the other side.

I gradually used less and less pinning because I realised that it was taking time, doing more damage than good, making the structure look worse and because I realised I could trust the glue.

The last part I made, the bridge section, used no pins or screws at all and it's been absolutely fine.

 

(To use glue alone your edges need to be straight and square, and just before gluing you should make sure the surfaces are clean by sanding them a bit and removing the dust. Then you needs lots of weights and or cramps to hold the parts together while the glue sets.)

 

Thanks for that info.  However I think the last paragraph counts me out for that option. Cutting straight and square edges is not one of my strong points. :)

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2 hours ago, rab said:

Thanks for that info.  However I think the last paragraph counts me out for that option. Cutting straight and square edges is not one of my strong points. :)


I can relate to that.  Having got through O level Design and Technology (Woodwork) on the strength of my design work and because the specialist subject in my year really was the new-fangled idea of ‘flat-pack furniture‘ (ironically called ‘knock-down furniture‘ if I remember the syllabus correctly), I still struggle to persuade a saw that my pencil markings are more than just a suggestion.  The baseboard solution I’ve therefore followed is a bit different.

 

If the experts, the competent and those qualified to do more than follow IKEA instructions could please look away for the next few moments...


8DBB4A2B-7E22-4A75-B39D-EF2359A52EA7.jpeg.897c1169cef1a2d1443f430cc5705572.jpeg

 

463A975F-FEF8-4647-87B1-0E63849EE4C0.jpeg.6e33402735584920d5eb7faa7820a50d.jpeg

 

4’ x 2’ boards in 12mm plywood framed round the edges with 2 x 1 softwood.  Two of the four boards stacked here are now 20 years old, one is fifteen and one nearly 10.  Until a couple of weeks ago they hadn’t even been painted.  Despite being in vertical storage for most of that time, only one shows any sign of warping, and that is just a little at one edge.

 

All fixings are drilled and screwed, not pinned or glued, which has (until I painted them) allowed me to undo or redo the combinations to suit over the years.  The plywood has never been cut (I’ve never actually yet needed to try).

 

Downsides: I’ve never got as far as drilling holes for wiring, nor fixing proper legs, so can’t comment on how the boards would perform if properly erected in a permanent layout.  

 

Upsides: trouble free fun laying track and running trains when I’ve had the opportunity.  Easy to modify the combination of boards as just screws have been used (NB: quite a lot of screws, but drilling is easier than sawing I find).

 

I’m not saying I’d recommend this approach for others without thinking carefully, but it has helped me enjoy the hobby.

 

Others may now open their eyes, sigh and move on...

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I too am rubbish at what might be termed "freehand woodwork". However, I do quite a lot of wood fabrication on a professional basis (I'm very definitely not a carpenter/joiner/cabinetmaker, just a general "maker" of assorted stuff), so I've learned various ways of getting around my chronic inability to do things properly. Mostly it's by using assorted jigs, fixtures and fences, and quite a bit of staring at the job and scratching my head. Calling the things I use jigs and fixtures is probably a bit grand. They tend to be a couple of bits out of the scrap box, held in place with a clamp or two. 

 

I do have the advantage of plenty of space to work, though, along with a fair level of equipment (though I do most stuff with a small, handheld circular saw, a tenon saw, lots of clamps and a good orbital sander, so nothing terribly exotic or expensive) so I'm a step or two ahead of more occasional woodworkers. 

 

For those without the facilities to do the fabrication, I think the laser cut baseboard kits offer great value for money. Certainly cheaper than setting up to do the job from scratch to the same standard.

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On 04/07/2020 at 18:18, johna said:

Hi

Would 6mm plywood be too thin for making a oo gauge  baseboard.? I haven't been able to get out due to Covid-19

 

Once again, I would appeal for a dedicated area on the forum onfor baseboards. It is such an important element in the success of a layout.

 

To answer the OP, 6mm ply is plenty thick enough to make the framework of the baseboard if you use the right design - but you may end up using more of it. It is probably too thin for the trackbed though, even with a lot of cross-bracing pieces.

 

It would help if we could see what is to go on the baseboard. If just a length of plain track, you could construct something very lightweight with the trackbed supported along its whole length by a length of ply on its edge. I only recommend this approach for plain track as the "beam" will get in the way of any point motors mounted below the trackbed. If you have surface mounted point control, that would not matter. 

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Posted (edited)

We built all our large O gauge layout baseboards , 20 baseboards , some as big as 5’ x 2’6” from 6mm high quality moisture resistant Scandinavian  or Russian birch ply. We use 6mm 120mm deep sides and Centre longitudinals as well as diagonals , no screws or nails , hot glued initially , then PVA and fiberglass tape to all joins. Extremely rigid and light for their size 
 

end cheeks carrying pattern maker dowels are 12mm birch ply 

 

three years later and several exhibitions , it’s bomb proof , we tested each board by placing a 9 stone man sitting in the middle of the baseboard supported on its outer end , maximum deflection was 2mm 

 

All major dimensions were CNC saw cut. 

don’t use the cheap “ dark “ far eastern or Asian ply , it’s junk , birch ply is nearly white. 
 

and definitely don’t use MDF ( except in a enclosed stove) 

 

it takes track pins and screws very nicely 


ps. We investigated fully laser cut , but we wanted the ability to move the cross bracing based on the track diagram to ensure point motors could be fitted , so we have asymmetric box sections underneath busy track work boards 

Edited by Junctionmad
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I built my loft layout using 6mm and regret now that I didnt use slightly heavier material. My loft has structural timber everywhere and getting the sections into place was seriously difficult, so i wanted the sections as light as possible. They had to be braced underneath, which I elected to do using planed timber battens screwed from the top surface, so the screws had to be countersunk into the ply. I was careful but over time some of those screws bit through the ply. Building boxy sections in the garage to slot into place would have been beyond my skills!  I then found that just jobs like tapping in track pins would be problematic as the ply would 'bounce' transmitting shocks along previously laid track. Bad enough to bounce out point bearers, those little bits of plastic that maintain the gauge of the track on the moving part of the point. I needed quite a bit of bracing and found that some of it interfered with point motor positioning; it shouldnt have but you only need the track to shift a few mm during laying and there you are. 

 

Theres a big difference between what professional modellers can achieve and what you can do as a beginner.

 

All my track (well 98%) is down now and the operational side is ok, there is nothing in the operations that is compromised by the choice of 6mm but I think it took me longer to build than it should due to all the work arounds I had to do; and in the future I will have troubles with bowing and flexing of the panels, and then having to do repairs and shore-ups forever. I dont want to be crawling around underneath the layout when I'm 80!

 

If I could do it again, I would change a lot of things and that would included going up to 9mm ply .

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I've found that many plywoods are sufficiently soft that I don't need to tap in track pins, as they can be pushed home with a small pair of pliers. It does vary from material to material though. The various S-E Asian produced "hardwood" plywoods are best for this. The locally produced cruddy pine has rather too hard a surface (and I wouldn't light fires with it, let alone use it for baseboards anyway), as has the (also local, lovely and, sadly, expensive) hoop pine stuff.

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