After having been absent from the hobby for over 30 years, I'm jumping back in and planning a HOn3 layout. My current issue is choosing a roadbed. My constraints: - I live in Ireland. The layout will see humidity vary between 35% and 75%. - I'll be hand-laying and hand-spiking track. (I'm old-school and can't get my head around gluing track, or soldered pc-board ties.) - I'm a bit of a perfectionist. Googling madly, I've more-or-less come to the conclusion that cork isn't a great option for hand-spiking. Flexxbed looks interesting, but the ballast slopes would have to be fettled (to get from 45-degrees to 60-ish), and I don't fancy having to lay to inside or outside lines. Homabed also looks good (and they do a 60-degree slope and it can easily be laid on the centre line). But humidity may (or may not) be an issue. I have read the recommendations to seal it with Latex paint, but the curve sections will have lots of saw kerfs which won't completely get sealed, and the paint barrier will be peppered with spike holes. I've also read about using two layers of 1/8" luan ply (door skin). But that's going to be a lot more work to put a ballast slope on, and I expect the sound-deadening would be far worse than Flexxbed or Homabed. The Homabed could be glued down to a 1/2 ply sub-bed. So humidity-induced sagging wouldn't be an issue. Is swelling really an issue? It shouldn't be able to kink along its length (as it's glued down). I suppose it's going to swell more on the kerfed side -- whether sealed or not -- which could remove any superelevation I put in? Any thoughts appreciated. Cheers, Jeff.
I would think that once you have ballasted the track, ballast cement would act as a sealant to offset any impacts of changing humidity on cork roadbed. Properly applied, the ballast cement thoroughly saturates the surface and penetrates the cork so they bond once dried. Cracks in the ballast are usually a result of poorly applied ballast or track work that does not account for thermal expansion and contraction. If you paint your track and roadbed prior to ballasting this will also help seal it and counter any impacts of humidity.
Thanks, mrhedly. I keep going back and forth on whether or not to try and seal it. If you did get failures in your moisture barrier, then you'd get differential expansion rather than possibly more uniform expansion unsealed. Then again with the saw kerfs on the turns (and the consequential greater surface area), maybe you'd get differential expansion even unsealed, and you might as well try and seal it.... I did some more research on Homasote, and it's humidity expansion coefficient is <= 0.25% (from 50 - 90%RH). Mine should stay a bit drier than that, but it covers the same RH range, so we'll call that number good. That means the width of roadbed between narrow gauge spikes wouldn't expand more than 1/8" at prototype scale (about 1 thou at HOn3). That certainly sounds ignorable. The height will expand considerably less, which means superelevation changes shouldn't be an issue either. The length (contrary to my first post) might be a different story. A 32" length of Homabed could expand a bit more than 1/16". If you hand-cut your roadbed from 8' sheets, you'd be looking at expansion of up to 1/4". It's easy to see how that could cause de-lamination from the sub-roadbed and produce the horror stories you see alluded to on the net. I'd be tempted to halve the Homabed lengths and put an expansion joint every 16". It could be covered with masking tape to keep the ballast out of it. Coupled with a flexible (laytex? liquid nails?) glue to the sub-roadbed might sort out any issues? Cheers, Jeff.
might I humbly, and respectfully, suggest that a better asked question would be: what dehumidifier? sincerely Gary
So, why have raised ballast/roadbed at all ? !. Mostly all narrow gauge is straight on the ground. Why not just build your benchwork and glue wooden ties after drawing center lines, right to the homabed, on top of the ply sub. When track is done sprinkled/white-glued ballast can be added without shoulders at all. You can also use N scale cork split apart, with a center .5" open gap between and filled in with soil later. If you don't know about him, please go to Wolfgang Dudler's posts and 'how-tos'. This man (now deceased) was one of the greatest USA style MRRers ever, and all done in Germany ! ! As far as PC boards, how else are you going to build hand-made switches and crossings ? Again, check out Dudler's site....Mark
The answer to that is an Ebac CD35. I've never had any of the household ones last more than 5 years when run 24/7. However, I already run 3 in the basement and one in the observatory, so I'd like to avoid a 5th. But it is a good point, as it makes it clear the roadbed choice isn't do-or-die. If things go pear-shaped, there's a viable backup plan that doesn't involve ripping up all the track.... Cheers, Jeff.
Hi Mark, When you say most narrow gauge is directly on the ground, do you mean models or prototypes? The D&RGW line out of Leadville has a raised bed, as does the San Antonito line to Chama (now the Cumbres and Toltec). Of course both of those are still running, so maybe the roadbeds are modern additions? My plan for hand-laid switches is to use Fast Tracks Twist Ties (where the track is mostly spiked, with glue in certain critical places and a pc-board throw bar). But I'll check out Wolfgang Dudler's stuff.... Cheers, Jeff.
Myself and many people in my area use or used homasote as roadbed for HO and HOn3 in the 80's and 90's . I've never had much trouble laying flex track and others in the area used flex and hand laid track . It may swell a bit , but should not be a real problem . Just leave a bit of a gap at the joints for expansion and you should be fine . I never sealed it , but I'm sure it wouldn't hurt to do so .
JeyJey, I mean the real and the model. Sure there are areas where there may have been shouldered ballast. But If you look at some old B&W pics of logging, plantation, and mining roads especially deep into the hills, woods, and forests it's usually inexpensively laid, some even on round logs right on the ground. Also where there may have been some shouldered, usually erosion, winds, rains, snow build up the soil around the ballast making it look flat on the ground. But certainly you should keep away from the high profile main line, class 1- RR-depicting, type cork. It's way to serious for Narrow gauge. Again, N scale cork looks better, height-wise, under HO. Again, they are split apart to be wide enough for HO ties. Then dirt or anything that can sufficiently fill the trough between is added. BTW. This can be added after track has been laid.
In the USA Mid-west where I live, our household humidity fluctuates from very low (20-25% RH) in the cold winters to 60% or more in the wet springs. Multiple portable dehumidifiers throughout my house were not sufficient to keep the humidity levels in the basement trainroom within a suitable range over the course of the year, so last summer we added a whole house humidifier to our heating and cooling system. I was surprised to learn that I spent more money on portable dehumidifiers in (unsuccessful) attempts to keep the springtime humidity down in the 45 to 55% range than I spent on the whole house humidifier to (successfully, so far) keep the winter RH in the 35 to 45% range. I've used 1/2 inch Homasote panels to form the surface of my N-scale layout decks and I mount most of my mainline tracks on cork roadbed. Staging areas are unsealed, but sceniced areas are (somewhat) "sealed" by paint, glued ground foam grass, or ballast. As can be seen in this staging area pic of a 10.5x6 foot L-shaped corner on my current layout, I've had a 1/4 to 3/8 inch gap form between shrinking Homasote sheets where an 8 foot length on the right met a 6 foot length on the left. Most of the flextrack rails in this corner had to be trimmed by a comparable amount to repair the kinks in the rails caused by the shrinkage. I've presently eliminated most of my rail kinks. Since I solder most rail joiners on my flextrack, but very few of them on my turnouts, we'll see if swelling this coming spring causes curves to straighten or gaps to appear at unsoldered rail joiners, as has happened in past springs. Hopefully, the smaller difference in seasonal humidity levels will lead to less dramatic swelling and shrinking of the Homasote...and thus fewer gaps and kinks.
I hesitated to provide this suggestion because I love the stuff but I'm one of the few on the planet that does. The old product was called AMI and the new stuff is called Blac Track Tack from Scenery Express [ http://www.sceneryexpress.com/Black-Track-Tack/products/1102/ ]. There is a skill to it and if you become interested I can give you guidance on how to use it. It is great because if track move due to shrinkage there is play in the material. But the real reason I love it is I have changed track and turnouts on numerous occasions and I can't imagine doing that with the ease of any other method. I have taken out a turnout, put in another one, changed my mind and decided the old one was better, all in less than 30 minutes. I have changed track so much that I can't image trying to lift glued down cork or any other method of attachment. To move track, I grab the offending track to be moved with either a dental pick, putty knife or pliers and pull up to loosen the bond. The bond can be amazingly effective but I have never failed to get the track up. I then use a putty knife to take out the old AMI which literally takes a minute or less. Lay the new AMI in the new location, this takes about 30 seconds, then add track and press down with a Masonite roller, this takes about 2 minutes. Very fast. But you will definitely want to talk to me more if you decide to use it, there are problems which are easy to over come but you have to think up the solution which takes the longest, and some never come up with a solution. I've laid a couple of hundred feet if not more over the years, 13 years latter track is still held tight. And I've had to come up with easy workable solutions to the problems I had. When guests come over and see it, because they have never seen it before, they will think it is weird but remember once you ballast no one will know. I have a buddy who thinks I'm nuts for using it but he has the old homasote and nail solution on his layout. He is loath to move problem track and lived with work around's because he doesn't want to tear up the old homasote and go through the process again
I think you'll be okay with Homabed. I would recommend cork, but you're correct that cork doesn't hold spikes too well, at least until you've ballasted your track. Even though there are a lot of kerfs cut in the curves, if you ballast your track using the matte medium/white glue method, and soak your ballast as is recommended using either alcohol or wet-water, if you've sealed your Homabed previously with latex paint sealer, the matte medium soaking should do the trick and finish sealing spots where the latex sealer didn't get as well as sealing spike and feeder holes. It'll also seal your wooden ties, and secure your spikes even better than just raw Homasote. I've got several friends in HO and HOn3 who handlay their turnouts and some track, and use Homabed without any problems. However, we live in a dry climate, but there are several weeks in the Spring and Fall when the humidity gets up to around 70% and they haven't reported any problems with it. Cheerio! Bob Gilmore
