RFinch wrote: I agree with Jeff. I don't think cork roadbed directly on plywood will present a noise problem, especially in N scale. However, I have no personal experience with this method. I mentioned the extruded foam insulation under the track simply as an easy way to do terrain that is below track level such as rivers, etc. Some contributors to this forum have described noise problems depending on the nature of the roadbed and sub-roadbed. I think these are HO modelers. Bob
I agree with Jeff. I don't think cork roadbed directly on plywood will present a noise problem, especially in N scale. However, I have no personal experience with this method. I mentioned the extruded foam insulation under the track simply as an easy way to do terrain that is below track level such as rivers, etc. Some contributors to this forum have described noise problems depending on the nature of the roadbed and sub-roadbed. I think these are HO modelers.
Bob
Sorry I am tardy in offering my comment here, but I have used cork caulked directly to 5/8" plywood, and it is quite decently quiet. We should remember that a dual density interface is what helps to cancel out sonic waves, whether the kind we can actually feel under our feet or the kind we can hear. So, rubber over concrete offers some vibration absorption, but medium density foam over rubber over concrete does much better.
1/2" plywood ribbon subroadbed worked great for me; I supported it on 18" centers for the most part. I did learn extra risers and cleats were needed where there were grade transitions or grades on curves to bend and hold the plywood the way I wanted it. Grades on curves - especially steep grades on sharp curves; I had 4% on 18" radius - require a fair amount of "twist" in the plywood to keep it level across the rails throughout the curve/grade. Without enough risers and cleats to put in this twist, I had negative super-elevation on half the curves, and positive on the other half. Looked ugly. I don't know if the cleats and risers would hold well enough inducing this twist into 3/4" plywood. Perhaps with more gentle grades and curves this is not a problem.
A report I read from one MR who tried laminating 2 layers of 1/4" plywood to get enough strength after flexing the first layer into shape said "don't do this!" Too much work for the return, and required LOTS of clamps.
Choice of roadbed material is really up to you. All the common choices will work fine for flex track on roadbed on the 1/2" ply subroadbed. Homasote, although sometimes difficult to find, is the top choice for spiking track and/or the best noise reduction. But if the white-glued ballast extends from the track to the plywood or foam subroadbed, the noise absorbtion qualities of your roadbed material are lost anyway.
my thoughts and experiences, your choices
Fred W
Skip the homosote. Foam roadbed on 1/2 or 3/4 inch ply supported by risers is plenty and is easy to work with. If you screw the risers to the joists, you can adjust them as needed by as little 1/16 inch to level out things. No matter how well you plan, small adjustmensts are nice.
Atacking sxtruded foam for scenery is REALLY nice. I had not done it before this layout and I am addicted. You can carve all your terrain directly in the foam. It takes time, but little talent. I paint the foam with acrylics for rock and use ground goop for soil. It makes nice scenery quickly.
Okay, I think I will be in good shape. 1/2" plywood ribbon with cork roadbed and then track, all on top of risers and cleats above the joists. The scenery base will probably be 2" extruded foam stacked up to the level of the track or above (like mountains). Then the only thing I don't know about yet will be to cut out the ribbon where a bridge goes and just use the bridge. I guess this is starting to get off-topic so I will probably start a new thread when I get to that point.
Thanks to everyone for their help.
FT
I don't think you need foam over plywood for a ribbon roadbed supported by L gerders. Foam is great for forming terrain, the plywood with cork gives you a nice flat, solid roadbed. Homasote it especially good for cases when you are going to spike or nail the rail down, with the plywood and cork you can use caulk and avoid all those issues. In my opinion. I think noise is not going to be a big deal.
Jeff But it's a dry heat!
RFinch wrote: You could always use extruded foam insulation glued with non-silicone latex caulk to the plywood base. This has been described by a number of people in this forum who apparently have had great success with it. It might make your trains run a little quieter....
You could always use extruded foam insulation glued with non-silicone latex caulk to the plywood base. This has been described by a number of people in this forum who apparently have had great success with it. It might make your trains run a little quieter....
I don't know if I can find Homasote or not, I am not too worried about that. Let's assume for this discussion that I cannot find it. Are you saying that over my plywood subroadbed I should put 1/2" or 1" or 2" of foam? And this is for noise? Is cork on top of plywood still pretty noisy? I would think in N scale the noise would be pretty minimal because of weight.
Personally, I made my own 1x3s by buying 1x6s and ripping them in half on a tablesaw. You save money on lumber and the resulting dimensions are the same.
Ron
Owner and superintendant of the N scale Texas Colorado & Western Railway, a protolanced representaion of the BNSF from Fort Worth, TX through Wichita Falls TX and into Colorado.
Check out the TC&WRy on at https://www.facebook.com/TCWRy
Check out my MRR How-To YouTube channel at https://www.youtube.com/c/RonsTrainsNThings
Have you tried the Homasote website to see if there is a location near you for the Homasote sheets? I live in the Martinsburg, WV area and know of two Home Depots within 30 minutes of my house that carry 4'x8' sheets of Homasote. Don't count on the floor personnel in Home Depot to know they have it in the store. I found it in one of the stores by looking around in the sheet goods area in spite of the fact that the Home Depot people in the store swore they never heard of it. It's used for sound proofing in construction so it shouldn't be a big problem finding it even if you live in a warmer area of the country, e.g., Florida. You could always use extruded foam insulation glued with non-silicone latex caulk to the plywood base. This has been described by a number of people in this forum who apparently have had great success with it. It might make your trains run a little quieter. Be sure to do a splice plate between the pieces of plywood when you are assembling your sub-roadbed. When I did my layout, I used a scrape piece of the 1/2" plywood to form a splice plate that extended 4"-6" on either side of the joint in the plywood. I then glued it to the underside of the plywood sub-roadbed. Clamp it while the glue sets. If the splice plate is too wide to get clamps to the middle of it, use short wood screws, e.g., 3/4" long to hold the splice plate to the bottom of the sub-roadbed until the glue sets, then you can remove the screws so you don't hit them later in the construction.
Hope this helps,
Thanks for the info Bob. I can't find Homasote anywhere around where I live, I will use a plywood subroadbed and cork on top of that, then the track. I would rather use 1/2" plywood but didn't know if I'd have problems with sagging. One place near me has "handy panels", basically 4x4 sheets of plywood but with a good finish on both sides, in either 3/4" or 1/2". This would make the weight much easier to handle. I also had thought about 2 layers of 3/8" or 7/16" inch with staggered joints. I agree that L-girder is more flexible: I like that you can move the joists somewhat to clear room for turnouts, etc.
Thanks,
To ft-fan:
I think that 3/4" plywood might be overkill for your sub-roadbed, especially for an N scale layout. It depends on the cost differential between 1/2" and 3/4" plywood. I think you might find 4'x8' sheets of 3/4" plywood rather difficult to handle by yourself because of their weight. I model in N scale and in my last layout I used 1/2" plywood with 5 plys as my sub-roadbed with Homasote glued on top. I used "L" girder construction and supported the plywood-Homasote combination on risers on 12" to 16" centers with no problem with sag. One of the advantages of "L" girder construction is that you can easily vary the distance beween joists to provide the support a given situation requires. I am about to start construction on my next N scale layout in which I plan to use B-C 1/2" plywood with either Homasote or extruded foam insulation glued on top.
I've read it twice, but there is so much info in it, sometimes I forget where to look. I'll check it out again. Thanks.
I'm thinking I'll use ribbon roadbed on risers attached to the joists, rather than a flat table-top. The scenery base will be foam on top of the joists and stacked up to the right height. Will that change anything? Thanks for your help.
Yep, I figured I'd do that, they won't have to be very big, but it will probably keep the wood intact. What do you recommend for spacing on the joists?
I think I am going to use 1x3 for the rail and 1x2 for the flange on my l-girders, too. I think that will be plenty strong for my little proposed layout. I plan to use birch, they are real straight and finished nice and square at our local home center. They also have firring strips, but they have rounded corners and are much too warped for my liking. I will probably use 1x3 for the joists, too. My question is how far apart to put the joists. In our floor and walls, they are 16" centers, but I think that is a bit much. What has anybody else used for their centers for joists? My sub-roadbed will probably be 3/4" plywood, and I'm going to be building in N-Scale....
Thanks for your input.
RFinch wrote: I'm not a structural engineer, but I'd not skip using a splice plate on the 1x3 web of your 14-foot-long L girder unless the girder is supported by legs on either side of the splice. In other words don't put the splice point, as you built it, in the middle of a span. Without the splice plate at the splice in the web component, the only thing that's keeping the splice joint from separating is the 1x2 flange. If a force is applied to the top of the flange above the splice in the 1x3 web in a downward direction, the girder will potentially break at that point if it is in the middle of a span. Again, refer to the Westcott book for specifics. Bob
I'm not a structural engineer, but I'd not skip using a splice plate on the 1x3 web of your 14-foot-long L girder unless the girder is supported by legs on either side of the splice. In other words don't put the splice point, as you built it, in the middle of a span. Without the splice plate at the splice in the web component, the only thing that's keeping the splice joint from separating is the 1x2 flange. If a force is applied to the top of the flange above the splice in the 1x3 web in a downward direction, the girder will potentially break at that point if it is in the middle of a span. Again, refer to the Westcott book for specifics.
I wasn't clear. I hate when that happens. Staggering the joint was in addition to the splice plate, not instead of. I'd never think of leaving that out. We glued them on and used plenty of screws as well. Thanks for making that point so that someone else doesn't make that mistake.
Well, I am an expert, now , having spent a fair part of yesterday building benchwork with my son. Let me say again that Linn Westcott's book is an very useful resource.
We built a 14 foot by 30 inch bench, with a 16 inch upper deck over the back. We used 1x3 and 1x2 pine, cheapest they had at Lowes, and 2x2 pine (we had trouble finding these that were not so bent as to be useless, there weren't many left). The wood comes into Lowes in 6 stick bundles with plastic staps, and we found many of these bundles to be suprisingly straight, compared to what I usually see when it has been laying loose. I'm sure it wants to bend, but I think that it will be discourages from doing so once it is in position. We made 14 foot long L girders using 1x3 web and 1x2 flange, we staggered the joint, although the book showed just using a splice plate. It wasn't that hard to do it our way, and it makes me feel better, anyway. I was pleased by the feel of the girder, especially for its weight. The 2x2 legs braced as shown in the book made the structure very solid, and the four legs are plenty. I'm not going to climb on top of this thing, but I am not convinced I couldn't.
The things that pleased me most: The construction of the girders went well. Small bends in wood get straighted just by building the girder. The girders just don't flex vertically. They are pretty rubbery horizontally, but that will decrease as joists are added. It was pretty quick, straightforward, and didn't require any unusual tools. We did use two drill, one to predrill and one to set screws. Predrilling might not be 100% necessary, but with the inclination of the 1x2s to split, and going into the side of wood that is a short 3/4 wide, it seemed prudent.
Not we just have to make the rest, two wall mounted sections and another table to link with the first.....
2x2 spruce/pine/fir lumber is perfectly adequate for the legs of most layouts if properly braced as mentioned above. The problem these days is finding good quality, straight 2x2's in any of the home improvement stores, eg., Home Depot or Lowes. It might be easier to find straight 2x3's even if these are overkill for your application. Alternatively you could get some good, straight 2x4's, eg. select grade, let them acclimate in your train room for a while to see if they warp and then rip them down the middle to form two 2x2's which hopefully will remain straight. This of course assumes you have or have access to a table saw to do the rip cuts. This is how I produced the 2x2 legs I used on my last layout and they stayed perfectly straight. This also might turnout to be cheaper than buying 2-2x2's. The key in using any dimensional lumber is to give it time to dry and acclimate in the location where it'll be used to assure it will not warp after it's been installed.
jbinkley60 wrote: You might end up thinking that 2x3s for legs are too big. I originally looked at them but went with 2x2s.
You might end up thinking that 2x3s for legs are too big. I originally looked at them but went with 2x2s.
As long as it is braced right 2x2s are plenty. I was amazed at how useful Westcott's book is. The examples will lead you right through most normal situations. It isn't all intuitive, but it is good stuff.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
Thanks for the great advice everyone. I barrowed the "How to Build Model Railroad Benchwork" book from a friend and read the whole thing. It was a great book but a little advanced for me. I'm just following the benchwork from a project railroad and using common sense. I just got back from Lowe’s with building materials. I have decided to use 1x4s for the outer frame, 1x3s for the stringers, and 2x3s for legs. Tomorrow I'll start construction! (finally).
I would strongly recommend that you refer to the Kalmbach book, "How to Build Model Railroad Benchwork", 2nd. Edition by Linn Westcott. This book has a lot of useful info on building benchwork that will stand the test of time. I would specifically refer you to the table and info. on page 35 where the sizes and lengths of girders and joists are discussed with regard to their installed strength.
You should also consider making the 1x3 or 1x4 from 3/4" quality plywood sheets cut to the appropriate width. You have nice clean straight edges to work with. The 8 ft lengths with no warp or twist. Also, the plywood should give a slight increase in strength over a solid piece of pine. Plywood L-girders need to considered becuase of the difficulty in finding good, straight lumber nowadays. Figure the cost of a sheet of plywood and then figure that 1 sheets will yield 12 nominal 4" wide by 8 foot long strips. Depending on the plywood used, it might be cheaper too.