Baseboard with built-in gradient advice

[Pete 75C]

I need to construct a baseboard with a falling gradient built-in. Apart from this one gradient, everything else with be built "on the level", so I don't see the need for an open frame construction.

The gradient is prototypically quite steep (around 1:50) so I'm planning to incorporate DCC Concepts Powerbase into it to give stock climbing the gradient a little helping hand if neccesary.

I'm no stranger to baseboard construction, preferring a 9mm ply top, but I'm not used to incorporating gradients, so I'm after advice as to the best way to achieve this?

I'm thinking of using a jigsaw to cut out the gradient from a single sheet of 1800mm x 600mm ply. This can then be gently bent into the gradient to give a transition from level to slope.

The only way I can figure out how to do this is to use a sliding mitre saw with depth stop to "notch" the crossmembers, and then add risers to support the trackbed at intervals, see diagram below.

The problem I have is that I'm convinced there must be an alternate approach... I just haven't figured out what it might be! If anyone has attempted something similar, thoughts and ideas would be much appreciated.

 

 

 

[ISW]

I need to construct a baseboard with a falling gradient built-in. Apart from this one gradient, everything else with be built "on the level", so I don't see the need for an open frame construction.

The gradient is prototypically quite steep (around 1:50) so I'm planning to incorporate DCC Concepts Powerbase into it to give stock climbing the gradient a little helping hand if neccesary.

I'm no stranger to baseboard construction, preferring a 9mm ply top, but I'm not used to incorporating gradients, so I'm after advice as to the best way to achieve this?

I'm thinking of using a jigsaw to cut out the gradient from a single sheet of 1800mm x 600mm ply. This can then be gently bent into the gradient to give a transition from level to slope.

The only way I can figure out how to do this is to use a sliding mitre saw with depth stop to "notch" the crossmembers, and then add risers to support the trackbed at intervals, see diagram below.

The problem I have is that I'm convinced there must be an alternate approach... I just haven't figured out what it might be! If anyone has attempted something similar, thoughts and ideas would be much appreciated.

 

 

I have a similar situation planned, but with the majority of the tracks on a gradient, and only the adjacent sidings on the level. I was therefore thinking of building the entire baseboard section on the gradient (relatively easy) and 'build-up' the area required to be level (also should be straight-forward). Maybe that's an option for you?

 

Ian

[Guest]

Thanks Ian. I do think our situations are similar but different if you know what I mean... In my case, only one single track is on a gradient with 90% of the baseboard surface flat. I need to get a sheet of 9mm ply and cut out the gradient. Hopefully it can be "bent" into the transition from flat to gradient without deforming. I'll see how it works out.

[Enterprisingwestern]

Jigsaw out the riser strip first from the flat ply sheet, then build the framework around the gradient as normal, box sections roumd the outside as per usual practice, notched ones for the gradient.

 

Mike.

[DCB]

It depends on whether the gradient is straight to a large extent.   9mm ply is not going to bend easily to start the gradient and will probably end up a bit like a sine wave rather than an even gradient. with a gentle transition.  Far worse is if you have a curved gradient the ply wont twist and your trains will be leaning sideways at 1 in 50.   well supported 3mm ply is probably better or well supported sundela board.   Don't forget powerbase needs to extend at least a train length along the flat at the top of the gradient.

EDIT  I built a double curved ramp by cutting it from ply, probably 3mm  up and down lines are at different gradients with one curving inside the other and where I went wrong was leaving the area under the track beds open. I should have put a sheet of 6 or 9mm ply under it to provide somewhere to put the supports, On the curve because of twist the end of the support inside of the curve holds the trackbed up and does not need a screw while the outside hold it down and needs a long screw tightened firmly to hold it down. I use any old timber but have some thin strip wood formerly a venetian blind for packing, I find card compresses too easily and settles over time.    

With any gradient it is important to measure the actual gradient not calculate from an assumed level plane, to your "Professional" 1 in 100 is good enough for level and your 1 in 50 on a 1 in 100 base becomes 1 in 33.  Its why my "Bed" layout gives so much trouble as I can't keep the base level.

Edited December 19, 2017 by DavidCBroad

[NittenDormer]

Once the gradient starts curving, the height crossing the supports can get confusing - a couple of mm different from one side to the other. I use copious amounts of cardboard as test pieces to get things right, and mark the heights out along the two edges. The aim is to make mistakes with the cardboard rather than the ply. Bike shops are a good source of large sided boxes.

[tender]

Hi Pete.

I did a similar thing but with 6mm ply. Cut back like you describe then fix the lower end sides to the top underside with a couple of wood blocks. When set I then strengthened the ramp with two bits of flexi MDF strips again stuck to the sides of the ramp and top underside. The resulting U section is very strong despite only being 6mm thick.

[BR60103]

Consider turning the roadbed on its side. Cut the gradient profile into the sheet several times and fasten them together. 

This should let you work in the curves to transit from level to slope.

 

Alternately, find a soft material for the roadbed*, cut it much longer than required, and fasten the horizontal bits down securely.

 

* I use Homasote, but that seems to be a N. American product.

[Guest]

Thanks for all the advice. I must admit, the curve (although gentle) was worrying me a little. Having experimented with some 9mm ply, it certainly doesn't want to "transition" smoothly between flat and gradient. I almost always use 3mm cork tiles on top of 9mm ply, so it occurred to me that if I left approx. 6 inches of cork out on the flat part of the baseboard immediately adjacent to the top of the gradient, I should be able to fix a flexible 3mm surface material to the ply. This would make the transition easier. This 3mm material could then be stiffened along the gradient. I guess experimentation is the name of the game. Many thanks.

[John ks]

What you suggest is close to what I would do

 

2 jig saw cuts from D to C (red lines) should be the only cuts you need in the ply

 

 

Transitions from level to grade are very important & should be as long as practical.

In your modified drawing D-B is the transition A-C is the effective grade (where the grade would start if there was no transition)  & B-C is the part of the grade that is constant

 

Ideally the cross members that support the grade should bevelled at the same angle as the grade or if you are a little rough the a screw as shown will work OK (tighten it until the baseboard just touches the cross member)

 

A small piece of timber glued or screwed to the underside of the grade will keep the grade constant

 

If my maths are correct then the distance, A-C at 1/50 grade will be 1750 mm

I would allow 400mm for the transition D-B so the total length from D-C would be 1950mm

 

To keep the grade inside the 1800 x 600 sheet then the grade will need to be steeper

Allow 100mm from edge to start of transition plus half the 400mm transition length gives 1500mm to calculate the grade 35/1500 = 1/43.8

If you keep the grade at 1/50 then the -35mm becomes -30mm

 

Things that determine the minimum length of a transition are the length of your longest wagons & the effective grade

 

Hope there is more help than confusion in the above

John

[BR60103]

The radius of the transition curve needs to be monstrous compared to horizontal curves.  I used a 60" Tracksetta and there are a number of rolling stock problems with it, still.

 

You never see vertical curves in the specs in magazine reviews.  

[Guest]

Thanks again. With regard to John's post (#10), I'm thinking that in order to maintain the prototypical 1:50 gradient, getting that track from level down to approx. 35mm below datum means I will need to extend the baseboard length from 1800mm to 2400mm. Otherwise, I just won't have room for the transition. I know you cannot go from level to 1:50 instantly, but I hadn't appreciated quite how much room the transition would take up.

I have no exhibition aspirations - this project will be for my consumption only, therefore although a 2400mm baseboard is cumbersome, it will only have to be moved once or twice. If I can reduce the width from 600mm to around 500mm, it should be just about manageable with 2 peson handling. I could split into two 1200mm sections but I'd rather not have a baseboard join mid-gradient.

It might be worth pointing out that this baseboard will represent Platforms 14, 15 and 16 at Kings Cross, and the very slightly curved line on the 1:50 gradient will be the infamous climb up into Platform 17 from Hotel Curve tunnel. Extending the baseboard length will also allow me to be a little more prototypical with how many 57' Mk1 suburbans can be accomodated in the platform, which is also on the gradient.

 

The Flickr link (below) should give a reasonable idea of the effect I'll be trying to achieve.

 

https://www.flickr.com/photos/davidh73/26220378251

[Enterprisingwestern]

Plan B.

Cut out the gradient portion of the baseboard altogether and rebuild the gradient with short lengths of 6mm/9mm stripwood, each strip can be angled to maintain a smooth transition. Covered with cork it should make a decent roadbed.

 

Mike.

[RAF96]

The alternate method of grade support illustrated in post #10 allows you to cant these longer supports to drive the superelevation on the curve as necessary for a smooth transition and it will provide a very sturdy mount for the transient track bed.

 

As you are aware the top and bottom transitons of a gradient are a kind of sine wave the severity of which can be as harsh or as gentle as your worst bit of rolling stock will put up with - generally coaches and diesels have enough slop in the bogies to compensate but other locos with 6, 8 or 10 coupled wheels will struggle across any vertically wavy track to the point of wheel lifting. You can even see this on flat track curves as they transition into superelevation.

 

Rob

[DCB]

A 2400mm X 300mm baseboard is easily manageable by two people but a struggle single handed, I made up such a beast for additional hidden sidings over the new year and slotted it under existing baseboards.

I find the transitions from up to level (or level to down) can be much more severe than level to up (or down to level) as most current bogie stock has insufficient clearance above the front bogie wheel to allow it to rise enough for the trailing bogie wheel to stay on the track, or for its flange to remain below the rail head level.   Triang had their buffer height 1mm above scale to avoid this but I have been carving away bits of Bachmann current Hornby etc chassis to allow stock to cope with my transitions.   The Hornby T9 has almost no ability to cope with level to up transitions as the leading bogie wheels hit the running plate. The awkward locos going from level to down are 6 wheel and 10 wheel drive chassis without flanges on the centre wheels which derail sideways as soon as they rock on the centre axle... Unsprung 9F s and Triang Jinties with Romfords and flangeless centre drivers are worst I know of.

Edited January 5, 2018 by DavidCBroad

[gordon s]

If it helps, I try to make my vertical transitions at half the overall gradient for a length of 12" each end.  Of course I accept this may not be possible due to space constraints, but it is something worth considering at the outset.

 

Most of the gradient issues I have seen arise from unrealistic expectations of what a locomotive/rolling stock can handle.

Edited January 4, 2018 by gordon s