cork underlay why?

[spenny19]

can anyone enlighten myself as to why and what the advantages of underlay or laying cork.

 

 

thanks

Brian

[34theletterbetweenB&D]

The long term common use of thin cork to model the ballast bed, and specifically the shoulder, probably arose from this material being both available and readily cut and shaped, and possibly with some thoughts of sound deadening too.

 

Back to basics, if you want your track to reasonably approximate the appearance of the real thing, then the ballast bed needs to be raised above the general surface of the track bed. Adding some shaped sheet material above whatever baseboard or strip support that forms the track bed of the layout is the easiest way to represent this. There is now a larger choice of materials: foam sheets, tackymats, preformed inlays; but in cork's favour it must be said that it is proven for long term stability and durability.

[spenny19]

The long term common use of thin cork to model the ballast bed, and specifically the shoulder, probably arose from this material being both available and readily cut and shaped, and possibly with some thoughts of sound deadening too.

 

Back to basics, if you want your track to reasonably approximate the appearance of the real thing, then the ballast bed needs to be raised above the general surface of the track bed. Adding some shaped sheet material above whatever baseboard or strip support that forms the track bed of the layout is the easiest way to represent this. There is now a larger choice of materials: foam sheets, tackymats, preformed inlays; but in cork's favour it must be said that it is proven for long term stability and durability.

 

 

thank you that answers my question, I had an incling that it was to do with sound deafining,but the tips regarding ballast heights helps.

[Kenton]

The sound deafening? is a bit of a myth. Most of the "drumming" effect is caused by the boxy drum like nature of the closed baseboard. The effectiveness of cork then tends to be mitigated by ballasting with granite or sand.

On a large layout there is something quite pleasing about the clickity-click of trains going past.

[HLT 0109]

if you want your track to reasonably approximate the appearance of the real thing, then the ballast bed needs to be raised above the general surface of the track bed. Adding some shaped sheet material above whatever baseboard or strip support that forms the track bed of the layout is the easiest way to represent this.

 

But, what is the correct height for this underlay? When I started my 00 gauge layout I decided on Wickes cork floortiles (as recommended on this forum) because it was cheap. I have often wished I hadn't bothered; they are 3.5mm thick, have no effect on noise and, in my opinion make scenic work more difficult. Once you've started with it though, it is difficult to stop unless making an incline. Making the ballast shoulder can use a lot of material as a result. I have since read on this forum that thinner cork sheeting (which is also readily available) can be a nightmare to lay because it wants to curl. If I were ever to start another new layout, I think I would lay the track direct on to the baseboard.

 

Harold.

[Coombe Barton]

Tried using Depron? Recommended by another poster on here. http://www.depronfoam.com/ Lots for not much cash by mail order. Goes flat and deadens sound, especially if you glue down and glue track and ballast down with Copydex.Try the 3mm dark grey stuff.

[bike2steam]

thank you that answers my question, I had an incling that it was to do with sound deafining,but the tips regarding ballast heights helps.

 

It sez 'ere in this technical book in front of me;-

Main-line depth of bottom ballast (to underneath of sleeper) - 9 inches.Width (of single line) - 11 feet. Top ballast (to top of sleeper), distance from rail - 3 feet 3 inches.Maximum size of sieve - 2 inches.

Hope that helps, cork underlay is essential for correct track bed profile, but ignor the urban myth about noise reduction .

Ignore the others, but the best cork to use is Charles Cantrill (Quality Cork Supplies). http://www.charlescantrill.com/model-railway/index.html

[Gwiwer]

Cork alone doesn't seem to reduce the sound but rather alters it. It cushions the track and the trains running upon it making for a resilient and robust underlay. Some of the foam products will not last nearly as long.

 

I agree it is a bonus to hear the right sort of clickety-clack as trains roll through our stations and yards and that can also help us to learn the right scale speeds as well. I also found another bonus to using cork underlay. If over time your boards get that sag in the middle and noticeably raised edges resulting in your track having uncomfortable "peaks" it is possible to then remove the cork from beneath the affected section, smooth the track out and reballast without major rebuilding. You can do that with some of the foam underlays as well but you can't do it with no underlay!

[HLT 0109]

It sez 'ere in this technical book in front of me;-

Main-line depth of bottom ballast (to underneath of sleeper) - 9 inches.Width (of single line) - 11 feet. Top ballast (to top of sleeper), distance from rail - 3 feet 3 inches.Maximum size of sieve - 2 inches.

Hope that helps, cork underlay is essential for correct track bed profile, but ignor the urban myth about noise reduction .

 

Paul,

 

Not being sure what is meant by Bottom Ballast and Top Ballast, I have done some searching and come up with a nice diagram at the following website; http://www.tpub.com/content/armytransportation/tr06708/tr067080029.htm. Anyway the diagram suggest a top ballast of 4-10 inches plus sub-ballast of up to 8 inches - so, 3.5mm cork underlay looks to be about right!

 

Harold.

[bike2steam]

Paul,

 

Not being sure what is meant by Bottom Ballast and Top Ballast, I have done some searching and come up with a nice diagram at the following website; http://www.tpub.com/...r067080029.htm. Anyway the diagram suggest a top ballast of 4-10 inches plus sub-ballast of up to 8 inches - so, 3.5mm cork underlay looks to be about right!

 

Harold.

 

Harold,

'As it says on the tin', bottom - below sleeper bottom, top - above sleeper bottom, I'm quoting a very useful book in my possesion 'Railway Permanent Way,Dimensional Theory, and Practice' by Hepworth & Lee (1922), a book written as a manual for Engineers, Inspectors,Foremen,etc, and includes many useful dimensions, I should have realized I had this book when a few months ago there was a thread on this forum as to the dimensions of engine pits. But your right 1/8 cork is right dimensionally, but because of the location, I use 1/16 on my current layout.

Paul

[craigwelsh]

Paul,

 

Not being sure what is meant by Bottom Ballast and Top Ballast, I have done some searching and come up with a nice diagram at the following website; http://www.tpub.com/content/armytransportation/tr06708/tr067080029.htm. Anyway the diagram suggest a top ballast of 4-10 inches plus sub-ballast of up to 8 inches - so, 3.5mm cork underlay looks to be about right!

 

Harold.

I think A would be the bottom ballast in your link http://www.tpub.com/content/armytransportation/tr06708/tr067080029.htm with the 6" being top ballast.

[Captain Kernow]

The terms 'top' and 'bottom' ballast are still in regular use on relaying jobs on the national network.

 

As for cork, I find that for branch lines, byways etc., with a less pronounced ballast shoulder (or perhaps even none at all), then the rolls of 1/16" cork that I can get from a good model shop perfectly satisfactory.

 

I was cautioned to avoid cork floor tiles like the plague, because there can be small inconsistencies in height between individual tiles, which may not mean much to floor enthusiasts, but make a big difference in track quality on a model railway...

[Gwiwer]

floor enthusiasts

:lol:

 

The more seams there are the more potential for curling at the edges. Despite cork floor tiles being much cheaper in many cases than railway underlay in rolls I only use the latter.

[BR60103]

50 years ago, in North America, there were 2 choices in ready-made roadbed: cork or milled wood (Tru-Scale). Both were about 1/4" thick. Milled wood had an extra option as it came either flat or with ties (sleepers) milled on it. Cork was used partly for flexibility as the wood only came in true circles or straight. (Possibly there was some that came with slots cut from alternate sides.)

On Noise: We visited a layout where the train ran silently round most of the room but became very noisy through the station. The station was the only part of the layout that had been ballasted. I think that hard glue in the ballast running from the track down to the baseboard conducts all the noise and defeats any sound-deadening in the cork.

[bike2steam]

I think A would be the bottom ballast in your link http://www.tpub.com/...tr067080029.htm with the 6" being top ballast.

 

Correct.

[Pete the Elaner]

You can raise the track bed with any thin material. Cork is preferred because its softness cushions the sound of running trains.

Works well unless you fix your ballast with a hard resin such as PVA.