Monday, 26 November 2012

Track Base

A lot has been written about the need for quieter roadbed for model railways mainly driven by the advent of sound equipped locomotives and now sound equipped rolling stock from manufacturers like Athearn and previously Broadway Limited that has raised this to a new level of importance to develop a solution.

To date I cannot say I have been personally successful but I am confident to comment on what will not work - forget foam it is like a driving on a taught drum skin and on Phil Moores layout created panic stations. Work on Phil's Moores layout has lead too the following combinations and methods that I have to decided to place a bet on with a foam on foam for track underlay.

Road-base Construction
The road base is 20 mm plywood screwed to the risers which are manufactured using pine risers screwed to the former's. 

Road Base ready for underlay - Joint for two modules - ply will be split at this location

The 5 mm thick foam is available is large sheets from Thermotec Australia, 168 Carrington Street, Revesby, NSW 2212 Tele:9771 6400The same product is also available at hobby shops in Australia from under the name Track Right. Track-Right formed road base for O scale is a new product in the Australian Market and is by luck a perfect match for the prepared sleeper base assembly's written about in previous articles.

Midwest Cork O scale track base is another alternative and may have some advantages over the use of the formed foam road base this was discussed in an article from Kalmbach in Model Railroader a few years ago. 

The adhesive from the testing on Phil Moores layout is critical and can negate the real or a perceived advantage of using foam road base which is fixed using acrylic sealant.  These sealants are marketed under the names of Parfix by Selleys or Color Seal from Bostick. The colour selected was coffee but grey would be a suitable alternative.

It's use was a based on advice from Chuck Hitchcock in the USA to Phil and has proved to be one on the great discovery's of my modeling life - It is used for every job from gluing foam blocks to track and all other items in between. It properties are just perfect for this hobby its is hi-tack, flexible, adjustable and water based.

The foam underlay is cut into suitable pieces too use the material in the most efficient manner. Position the foam at one end and press into the sealant then apply in a wiping action. 

Adhesive Application

The adhesive is applied for the length of the foam to be applied and then smoothed using a spatula. After completing this task a heavy bead is applied along the side of the road base. At this point the application of the 5 mm foam underlay can be undertaken.

The best method to apply the sealant for either of these jobs is to use a applicator gun and to spread the sealant using a metal cake icing spatula from the $2 shop not the kitchen draw. The spatula gives a perfect film thickness about the thickness of a heavy business card [1 mm]. 

Fitting Foam Underlay
The foam is simply applied to the top side of the road base and then using a scrap piece of pine it is ironed smooth. The natural tack of the acrylic sealant works to your advantage here.

The foam underlay is fixed to the side of the road base using brass thumb tacks. When dry the waste is remove and the road base is ready for application of the Track Right Track Base

Foam Underlay ready for trimming

Repeat with the next piece until the road base is fully covered then trim the excess foam off the side of the road-base using a 25 mm box cutter.

The thumb tacks will be covered with more acrylic sealant when the foam for the scenery is installed. The 5 mm foam is to isolate the scenery from the noise [resonance] created by the rolling stock running on the ply base by creating [hopefully] a flexible barrier between the road-base and scenery-base.

Track Base
Begin by marking a center line at about every 250 mm [10''] into the foam underlay. Apply the adhesive using the techniques outline above on one side and fix the Track Right O Scale Road Base along the center line previously marked. Repeat for the other side and the track base is ready for laying the prepared sleepers.

Marking Center Line

Fitting Road Base

Final Assembly Track ready

Sleepers Installation
The assembly of the sleepers is covered in detail in the articles on sleeper assembly with the finished result below ready to receive code 125 Right-O-Way Steel Rail. The construction of the sleeper base is covered in a previous article on the assembly - click here

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