A new type of underlay?

Not every modeller uses underlay preferring to lay the ballast directly between and around the sleepers fixing it in place with 50/50 PVA glue applied using a dropper and brushing away loose after. Warley MRC tend not to on club layouts however Halesowen MRC use cork so it even varies from club to club.

Checking Hornby Magazine some of the layouts featured have underlay and some don't. Aside from any new ideas for underlay are there any golden rules relating to whether underlay should be used or not?

I can understand why foam underlay might be used as it definitely has the effect of reducing noise which could be important if the layout is situated next to the television or the baby's cot. Foam underlay can lead to poor track laying as inconsistent track pinning of track can create a roller coaster effect which means that your HST when doing 300mph goes careering off!

Much as it would in real life!

Happy modelling
Gary

Hi Robert,

I take it that the foam underlay you are refering to is of the type made by Peco and similar. I agree that those can be quite expensive.

I have been involved in the building of several layouts recently and have made use of a foam product available here in South Africa and I am quite sure that you will find a similar product in the UK.

This product is a high density foam that comes in 1200mm x 2400mm sheets and is available in thicknesses from 3mm up to 12mm. Locally it is available in white, grey and black. This product is used in the motor manufacturing trade and the 3mm thickness is also used to make foam peak caps. The local price is about ZAR40-00 (3 British Pounds).

The foam sheets can easily be cut into strips of the appropriate width with a Stanley utility knife or similar. For HO-scale you should be able to cut about 40 x 2400mm strips and that can go a long way! Once you have cut the strips you can start laying the underlay and tracks in one motion. Put the foam underlay strip on the baseboard and put the track to be laid on top of the foam underlay strip. Now pin down the track and foam underlay. When you need to lay curves/bends simply guide the foam underlay under the track to follow the curve of the track and pin the track and underlay down. No need to halve the strips lengthwise as with cork to enable it to be bent. Cut some point templates from Masonite (hardboard) and use these templates to cut the foam underlay for the points.

I use any of the available colours as the track and underlay will eventually be airbrushed before applying the ballast. I do not glue the foam underlay to the baseboard as the ballast once glued down and dry will keep the foam underlay in place. Once the ballast is dry you can remove the track pins.

This foam is a very affordable alternative for cork and Peco or similar foam underlay and as far as I am concerned I think that this product is an improvement on the traditional track underlay.

I hope you find it and if so try it. You will be pleasantly surprised.

Kind regards and enjoy your hobby.

Johan

As a certain mexican mouse was heard to say, when boarding a train....
''arriva, arriva, underlay underlay''.......sorry.

Iain Rice puts a VERY good case for thick foam underlay when laying track. [his book, ''An approach to building finescale track'']

Sound insulation s one...providing one doesn't bridge the insulation with concrete ballasting.

But the over-riding advantage he pointed out, to my mind, is the 'floating' element?

Where this fits in the scheme of things, is ''supension.''

Iain points out that modern track and trains are 'organised' very differently to'steam' era, and after.

ie, in steam days, up until the demise of track like bullhead and chairs......etc.....because steam locos were relatively heavy and stiffly sprung, in order that the loco, the short, 4 wheeled goods stock, etc did not shatter themselves to pieces, and the track get pounded to smithereens, there had to be some 'resilience' built-in.

This was achieved by making the track smooth and supple, 'floating' is a good description.
This was achieved by the nature of the track's construction...bullhead rail and chairs....for example.....the springiness of the ballast.....the track would 'give' a little under the engine's weight.....ever watched the track under one of the preserved steam locos on a preserved line?

It bounces up and down.

I used to think it was worn and faulty, but apparently it's supposed to be like this.

Todays track is designed and laid to be quite rigid.

The stock that runs on it has much more supple suspension than of old.

So the roles are reversed.

Nearly all today's current proprietary model engines have little in the way of 'suspension', if any.

Yet, P4 modellers insist on the minimum of fitting compensation, or going for sprung chassis.

Any help the proprietary engines and stock has in ensuring a soft, smooth ride must be good for performance?

Securing the track to a 'floating' roadbed, removes the 'rigid-rigid' scenario.

With the track being allowed to move, vertically, by even the tiniest amount, seems to achieve smoother running?

Iain Rice suggests stuff like camping foam groundsheets....foamies to the transcontinentals?

Not only under the track itself..........but also, between the solid 'trackbed' and the baseboard framing!!!!!!

Of course..another reason for underlay, is to allow a decent shoulder for the ballast?

QUOTE (John Webb @ 29 Aug 2007, 21:48) <{POST_SNAPBACK}>Johan,

I take it you use the standard ballast glued down to the foam and track by the usual dilute PVA method.
Do you also put the ballast at the sides of the foam underlay to completely hide the foam from sight and form the correct shoulder on each side of the track?

Regards,
John Webb

Hi John,

Spot on!

What I also do is to use say the 3mm foam on secondary lines and maybe the shunting yards. On the mainlines I will then use 5mm or even 6mm foam as the ballast on the mainlines usually have a higher profile than those on the secondary lines. The thicknes of foam used is however a personal choice.

Kind regards.

Johan

Hi John

I take it you use the standard ballast glued down to the foam and track by the usual dilute PVA method.
Do you also put the ballast at the sides of the foam underlay to completely hide the foam from sight and form the correct shoulder on each side of the track?

Take a look at the tracklaying in the forum gallery. That is on 3mm foam with the shoulders cut at the correct 60 degree angle (the natural angle of repose for ballast). The ballasted track in the craven lime images is ballasted to cover the shoulders - it doesn't look right unless you do that.

The underlay is my own product and is sold in 100 foot boxes, ready t olay, with a pre-split line underneath so yo ucan if necessary split it for sharper curves. I lay it with neat PVA and also glue the track to it with PVA.

As far as having main lime at a different height to the main, I tend to use a shouldered underlay on the main and a solid bed under yar tracks but actually don't differentiate the level. If you wanted to do a different level, I feel it would be better to slightly raise the baseboard under the main tracks and use the same thickness foam throughout, as its easier to get a good transition that way.

Re using PVA for ballast. Do dilute it much more than 2:1 - that is too way hard and makes the ballast like concrete... we only want to hold it, not make it bomb proof

I recommend anywhere between 6:1 to 10:1, depending on the quality of the PVA. Even better, use water based latex carpet glue, as it doesn't go hard like PVA (and its cheap).

When I use this, I dilute it about 1 part glue, 1 part water, one part meths - the meths acts as a wetting agent, and it also helps the water evaporate away more quickly....

BTW for my current layout (in the gallery images) I am painting the (only slightly diluted) glue between the sleepers then laying dry ballast on top, vacuming off the excess later. It seems slow, but it makes a perfectly tidy job so what extra time is taken at the beginning is saved later with no need for clean-up. It doesn't change the ballast colour like dribbled on glue does, and it adds nothing to the track noise either!!

If anyone is interested in this alternative method, I can write it up with images and see if I can post it here....

Regards

Richard Johnson

Hi David

You asked: I noticed that busybeas is using the Woodland scenic trackbed for his new O gauge layout. It looks like nice stuff and is ready to use. It's even got an NMRA conformance seal of approval Any good reason why it might not be a good idea?

David

*** Yes - see my post above yours: I actually decided to proceed with trackbed as a product because I found inconsistencies in the woodland scenics product - I bought 12 large boxes of it for my own layout and was annoyed to find several widths and three different thicknesses of foam between them - not good enough!

So I now make and market it under the DCCconcepts "MASTERscene" range. Sold in boxes of 100 feet. If you'll E me off list I'll send you a direct copy of the blurb on it.

Show me the UK shop price of WS underlay and I'll bet we are a better price too!

As to your basic question - Closed Cell foam is excellent underlay - lays better than cork, using PVA Glue. I also stick my track to it with PVA. Much easier to cut as needed and very tidy and accurate, 60 degree ballast shoulder etc etc..... Its quieter too. Each piece has a pre-partially split centreline too, so laying it on tigher curves is easy a well.

Regards

Richard Johnson
DCCconcepts

Hi

Yes, sorry....sadly: We're so far behing with updating its getting silly!

So... I've decided to change the existing site as it holds too much info to properly mix product in it sensible and clearly

we're feverishly creating a new "start page" which will take one direction to the info pages, another to the products.

We just also finished a 52 page colour catalog master and are about to go to print with it, however if anyone wants
the full page of the catalog referring to roadbed (with lots of application info) just email me off list and I'll send a copy in PDF form.

[email protected] will get to me just fine

Richard.