Wondered about that, suspect its cos track in contact with ballast makes good sound board. If could keep them seperate in some way - no dont know how, then vibration of track might not carry.
Real granite is to coarse grained for correct texture, average crystal size > 1mm, so would appear as large stones of one mineral (ignore pegmatites as rare used as ballast). Need the medium to fine grained equivalent, without checking texts would be somewhere between dolerite and rhyolite. Colours can be black and white, or nice red/pink granite from Shap :-)
Well the last time I laid ballast it was on 1/8th inch cork over a 3/4 inch MDF board with conventional open 2x1 and 2x2 inch framing supported every 12 inches 44 inches from a concrete garage floor ... running a long train could sound like a bloody machine gun at times.
I used a combination of stuff nominally scalled for OO and N, the N looked a lot better on a OO layout and looked a lot closer to scale but of course although I do confess to owning several micrometers I do tend to ajust things with a big hammer :-)
Supposedly, matte medium is quieter than white glue because it doesn't dry as rigid, but I've never done a comparison test so it may or may not be so. I can't think the difference would be major.
I'd heard that to, copydex as well remains elastic (but smelling of cats) but I was thinking of using something else for my next layout instead of granite, somthing softer.
IIRC, there was quite a discussion a while back on noise control. I don't remember if it was here or on one of the Yahoo groups like layout construction.
Seems the main conclusion reached was that the track/roadbed needed to be decoupled from the benchwork. But I don't think anyone came up with a satisfactory way to do that.
There were many attempts to reduce noise back in the 60s and 70s, reported both in the commercial press, and in the NMRA Bulletin. My main conclusion: sound is amplified when surfaces are free to move. Thus:
a) Solid-top baseboards are like sounding boards --> use open grid bases. b) Track nails and the like can couple ballast strip and sectional or flex track to the sub-roadbed/baseboard --> glue ballast strip to sub-roadbed, and track to ballast strip, using pins merely to hold it while the glue sets. c) The mass of the track structure affects its ability to act as a sounding board --> use 1/2" or heavier sub-roadbed. Fasten solidly to grid at frequent intervals, thus making the grid part of the mass that the sound generator (the motor in the engine) must move.
I've also noticed that as scenery is added to a layout, it tends to become quieter.
What's needed an inefficient sound transmitter linking track to base. That means both soft materials, such as cork, and flexible glues, such a silicone bathroom caulking.
I use an 8:1 mix of PVA bought by the gallon from a builders' merchant, and water. The obligatory British Standard Drop of washing up liquid is added off course. I make up stock, 0.5l at a time, it lasts a couple of months without settling out if kept in a closed container (I use a plastic milk bottle).
Before adding glue, I recommend spraying the dry ballast with a mist of "wet water" (water plus a drop of washing up liquid). I bought an atomising spray from Hobbycraft which is good for this, it holds 125ml of water, you pump it with the lid, and then spray. A squirter of the type used for spraying domestic cleaners and such won't be much good, the drops are too big and disturb the ballast. You need a fine mist.
I then use a dropper or for longer runs (which most of mine are, given the size of my layout) a bottle with a very fine tip. Drop close to the rails, again to avoid disturbing the ballast. You can fix minor dislodged bits with a stainless clay moulding tool dipped in water.
Actually the way I do it starts by painting the baseboard with black Gesso, then PVA, add a thin layer of ballast well pressed down, apply wet water and thinned down glue and allow to dry. This base layer of ballast stops the dry ballast from flowing away from the tracks as you place it.
Then I add the main ballast, and use a children's sponge paintbrush to brush off the sleepers, and a stiff stippling brush to clear it away from the chairs. The result is usually pretty good. It took me a while to get to this technique, with some of the older bits it took ages to get the ballast off the sleepers. Guy
Rigid foam insulation rather than wood under the roadbed... Eg replace the 'traditional' sheet of plywood (which is an excelent sounding board) with a sheet of foam insulation (which "sucks" as a sounding board).
Thanks all for the tips and advice on PVA glue, ballasting etc, getting the hang of it now.
What is the best way to remove excess or PVA glue (diluted of course) from the track after ballasting apart from emery (fine) paper? Any solutions/mixtures or tips on that?
Thanks all for the tips and advice on PVA glue, ballasting etc, getting the hang of it now.
What is the best way to remove excess or PVA glue (diluted of course) from the track after ballasting apart from emery (fine) paper? Any solutions/mixtures or tips on that?
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.