Appreciate the thoughts guys. I was just looking for best practices. I decided to cut several pieces and layers of thicker cardstock and glue them under the portion I was concerned about. I had a little PL300 left in my last tube so I went ahead and glued the piece down and placed my weights on it. The card stock leveled it up nicely. I will get around to the gaps at some point, and maybe I will just try using tape like some have suggested!
Andy
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Milwaukee native modeling the Milwaukee Road in 1950's Milwaukee.
https://www.flickr.com/photos/196857529@N03/
DoughlessWell, I was poking a little fun at our intelligent and thoughtful, and very analytical, colleagues.
In (partial) defense of wall-o-text firehose threads: I think it's valuable to get the different options 'out there' quickly so the people needing assistance, knowledge, enlightenment or whatever won't miss critical options. If it's something they don't need (or don't like) they can hit the back button.
No different in a sense from healthy eating. Good to have the vitamins, trace elements, and a proper mix of food groups ... but you can always opt to eat less, and you don't have to digest things your metabolism rejects...
DoughlessI was poking a little fun at our intelligent and thoughtful, and very analytical, collegues. Forgot to put the little smily face thingy.
Rich
Alton Junction
richhotrain Doughless I'm not understanding why this is so complicated. Maybe boredom is alleviated by overthinking stuff. SeeYou190 After reading this thread I completely agree. Good analysis Douglas! I'm not sure that I follow your objections, guys, or your rationale in this regard. I don't see where anybody is overthinking anything. Everyone is making suggetions to help the OP, and it seems that both of you are doing the same thing. Perhaps you are both having a bad day? Rich
Doughless I'm not understanding why this is so complicated. Maybe boredom is alleviated by overthinking stuff.
I'm not understanding why this is so complicated. Maybe boredom is alleviated by overthinking stuff.
SeeYou190 After reading this thread I completely agree. Good analysis Douglas!
After reading this thread I completely agree.
Good analysis Douglas!
I'm not sure that I follow your objections, guys, or your rationale in this regard. I don't see where anybody is overthinking anything. Everyone is making suggetions to help the OP, and it seems that both of you are doing the same thing.
Perhaps you are both having a bad day?
Well, I was poking a little fun at our intelligent and thoughtful, and very analytical, collegues. Forgot to put the little smily face thingy.
- Douglas
SeeYou190 richhotrain Perhaps you are both having a bad day? I'm having a bad day. My tooth really aches from the root canal and temporary crown yesterday. Good call.
richhotrain Perhaps you are both having a bad day?
I'm having a bad day.
My tooth really aches from the root canal and temporary crown yesterday.
Good call.
richhotrainPerhaps you are both having a bad day?
-Kevin
Living the dream.
Doughless Maybe boredom is alleviated by overthinking stuff.
After reading this thread I completely agree. Thousands of words about a solution as easy as a few swipes with a coarse rasp or the installation of a couple of carpentry shims.
DoughlessI'm not understanding why this is so complicated.
Me neither. Cut and level or slop on something to raise the terrain. Use spackle or wood or plastic shims or whatever. I have used caulk as a leveller before, I just made a dam out of painters tape or the foam itself does the job. I have flooded entire rooms with floor leveller and don't understand how levelling up a few square inches of foam seems to be such a chore.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
1. Secure subroadbed to the benchwork so that it doesn't move.
1a. Now that you have determined a fixed and exact amount of "offage" at the joints....
2. Build up the top of the lower sheet at the joint only where the tracks are going, ensuring the slope does not create a short but still severe grade.
2a. This can be accomplished any number of ways. Cardstock, various lengths of construction shims, scrap styrene, new styrene, old credit cards, your wife's current credit cards....etc.
3. Affix said build up with appropriate adhesive suitable for foam such as silicone caulk, construction adhesive, etc.
4. Lay roadbed
5. Lay track
6. Scenic the sides
7. Scenic the rest of the sharp joint where the track isn't....to taste.
8. Ballast.
9. Enjoy.
OvermodI think the idea to repeatedly check level when laying the foam, and carefully shimming the underside of a gap if the pieces were level across the top, are sound ideas.
THis seems like the obvious answer. Rather than grind and make a mess, just shim under the piece that is lowest to bring it up to level to the higher piece. Snicker snack!
Rio Grande. The Action Road - Focus 1977-1983
Overmod Has anyone gone to the trouble of taking depth measurements on a 'grid' of different points on the sheet? I have to wonder if the same approach with rolled steel might be used here -- cut off and use 'for other purposes' a certain amount of the edge to assure proper quality.
Has anyone gone to the trouble of taking depth measurements on a 'grid' of different points on the sheet? I have to wonder if the same approach with rolled steel might be used here -- cut off and use 'for other purposes' a certain amount of the edge to assure proper quality.
Overmod What could be a great deal of fun is determining if there is any tool or technique that could practically accomplish what a planer does for lumber or plywood.
What could be a great deal of fun is determining if there is any tool or technique that could practically accomplish what a planer does for lumber or plywood.
Now that y'all mention it, I don't think this foam board is manufactured to be dimensionally precise. I can think of a number of logical ways this could be economically manufactured for 'least material waste for a guaranteeable R-value' that would produce exactly the edge variation being described.
I don't remember a truly dimensional thickness insulating panel ... I confess I'd never carefully thought about checking.
What could be a great deal of fun is determining if there is any tool or technique that could practically accomplish what a planer does for lumber or plywood. Perhaps something with cutters if you chilled the foam down? An additive method, with floats or rollers?
Probably extreme overkill, though. I think the consensus so far, which is to tape, dutch, or butter over the edges and gaps, and be precise only where the subroadbed goes, would be the wisest approach.
The Milwaukee Road Warrior I can of course fill the gap with PL 300
Hi Andy,
I'm not sure that I would recommend using PL300 to fill gaps between the foam sheets. I did that about two weeks ago on my own layout which I am building in my insulated garage, and the larger gaps are still quite soft to the touch. I should mention that I am in southern Ontario, Canada so the garage is normally cool at this time of year. I have had a small electric heater running for close to 10 days and it is keeping the garage at a comfortable temperature (I won't say warm) but apparently isn't helping the PL300 much. If I was doing it again I would use low expansion foam.
By the way, I think the Woodland Scenics foam putty is a bit pricey. Walthers regular price is $9.99 and they have it on sale for $7.98 right now. A 16 oz. tub is about the size of a container of cottage cheese. I haven't tried mine yet but I hope a little goes a long way.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Dunno, maybe it will all work out, but it doesn't sound good to me. Before I start laying track, I want my subroadbed as smooth and level as possible. The more you screw with it, the worse things become. If you have solid benchwork, maybe start over with the foamboard.
The 1/8" to 1/4" gaps are horizontal gaps between sheets. The actual top (layout) surface of the foam has about a 1/16 to 1/8" gap vertically at several joint locations. The plywood benchwork is all 3/4" on 2x4 frame and as mentioned earlier, all within 1/8" in height while travelling around the entire layout: i.e. very flat.
The issue here is not with the benchwork but with the slight differences in the thickness of individual foam sheets. I read that Bill Darnaby plans to use a 1/4" sheet of plywood on top of his foamboard next time he builds a layout due to the slight imperfections (waves) he has found in some foamboard pieces. I have noted this too. Sometimes I find slight depressions or "waves" near the edges of foamboard. I'm guessing this is where the banding is placed to sandwich sheets together for transport. Perhaps the Woodland Scenics foam putty can also function as a sort of transition "ramp" between sheets that are reasonably close in height at the joints (like mine), and can even fill in some of these depressions when needed where cork and track will cross them.
In any case, before I started placing any foamboard I went over every joint in the plywood benchwork and made adjustments for smoothness, in some cases sanding out 6" on each side of the joint with an orbital sander. Whatever is going on here is due to some manufacturing tolerance range allowed by Owens-Corning and the way they ship their product to stores.
richhotrain Doughless Even two sheets of plywood can have a slightly different thicknesses when butted together. Took the words right out of my mouth, Douglas. I was just about to write the same thing. Owens Corning recommends DAP 230 or HVAC Foil tape to fill gaps on 2" foamboard, but I can't help but wonder if simple masking tape wouldn't do the job. That said, 1/8" to 1/4" differences in height at the joints seem like something more than slight differences. Vertical differences of 1/16", on the other hand don't seem so bad. But, honestly, any differences in height or any gaps easily become problematic. As careful as I was in building my layout with 1/2" plywood surfaces, all gaps needed to be filled and smoothed with caulk before landscaping or ballasting. Any height differences at joints are unacceptable. You don't want any humps or valleys in the track work. I run into problems with my yards with height differences no matter how slight. I call them "hump yards" as I watch freight cars and passenger cars roll down the unintended inclines. Rich
Doughless Even two sheets of plywood can have a slightly different thicknesses when butted together.
Even two sheets of plywood can have a slightly different thicknesses when butted together.
Took the words right out of my mouth, Douglas. I was just about to write the same thing.
Owens Corning recommends DAP 230 or HVAC Foil tape to fill gaps on 2" foamboard, but I can't help but wonder if simple masking tape wouldn't do the job.
That said, 1/8" to 1/4" differences in height at the joints seem like something more than slight differences. Vertical differences of 1/16", on the other hand don't seem so bad. But, honestly, any differences in height or any gaps easily become problematic.
As careful as I was in building my layout with 1/2" plywood surfaces, all gaps needed to be filled and smoothed with caulk before landscaping or ballasting.
Any height differences at joints are unacceptable. You don't want any humps or valleys in the track work. I run into problems with my yards with height differences no matter how slight. I call them "hump yards" as I watch freight cars and passenger cars roll down the unintended inclines.
I would think that if you had a vertical difference of 1/8 to 1/4 inch you'd almost have to have butted two different dimensions of sheet product by mistake.
The Milwaukee Road Warrior Thanks for the info everyone. There must be a small discrepancy in both the plywood and the foam thicknesses. The benchwork itself was all built with a level and varies within a range of only 1/8" vertically when traveling around the entire layout ~ 50'. I suppose I could have bought a laser to get it even closer. The vertical differences are small and I might be able to slip something between the foam and the plywood like card stock or styrene. The horizontal gaps are larger. I hadn't considered just putting tape over them... do you think that will hold up long term? I would be afraid I would somehow cut thru the tape while doing something else and end up with a gap again. I do not intend to ever tear down this layout. It is being built-in permanently (although, if I can bribe my wife in future years to get more of the basement I plan to extend it). No one mentioned any kind of sanding down of the actual foam surface on top to eliminate the vertical difference - so I will take that as a sign that won't work. I do have Dynaflex 230 on hand so I might try that for filling the horizontal gaps. I will feel more comfortable knowing the gap is gone and I can't accidentally expose it again down the road.
Thanks for the info everyone.
There must be a small discrepancy in both the plywood and the foam thicknesses. The benchwork itself was all built with a level and varies within a range of only 1/8" vertically when traveling around the entire layout ~ 50'. I suppose I could have bought a laser to get it even closer.
The vertical differences are small and I might be able to slip something between the foam and the plywood like card stock or styrene.
The horizontal gaps are larger. I hadn't considered just putting tape over them... do you think that will hold up long term? I would be afraid I would somehow cut thru the tape while doing something else and end up with a gap again. I do not intend to ever tear down this layout. It is being built-in permanently (although, if I can bribe my wife in future years to get more of the basement I plan to extend it).
No one mentioned any kind of sanding down of the actual foam surface on top to eliminate the vertical difference - so I will take that as a sign that won't work.
I do have Dynaflex 230 on hand so I might try that for filling the horizontal gaps. I will feel more comfortable knowing the gap is gone and I can't accidentally expose it again down the road.
You want the vertical joints to be as smooth as possible for the trains. The roadbed will tend to sink into the lower section over time, unless you're unlike most people and ballast right away and harden it up with glue. Some sort of support under the roadbed void would be wise.
I would think it would be difficult to sand the foam down to where it would get a gradual decent without the dip in the track and trains being obvious. Seems like it would take a lot of sanding to get the gradual grade, but maybe not.
The horizontal gaps are from imprecise long cuts I suppose? I would think that simple caulk would work, then covered with normal landscape material or ground cover.
I think the idea to repeatedly check level when laying the foam, and carefully shimming the underside of a gap if the pieces were level across the top, are sound ideas. If the idea is to get the foam down fairly 'rough' first, and then 'cut' the subgrade into the foam to correct level and transition, you might want to consider some variant of a hot-wire tool, which will eliminate the many crumbs from using a Surform (or its baby sister for fine work the Dermabrade).
My understanding was that sanding was the wrong approach in foam entirely, the grains tearing rather than shearing the material, and little removed pieces of foam rapidly 'clogging the grit' and just sliding. A metal milling cutter might work but the pain to align it using usual tools might not be worth the 'fun'.
I'd also mention that nothing keeps you from using sealing material and tape from making a trough in the foam and using self-leveling cement or similar material in places to get finish subgrade. (You can reinforce such a cast internally, and then tilt the result slightly after it sets if you want 'plane' subroadbed surface with a grade, and work out how to make the correct vertical curve to level sub...)
I just use a rasp to smooth out uneven foam surfaces where the track goes. If the track doesn't go there I leave it uneven just like the real world.
I like duct tape for the cracks, just to keep the ground cover from falling through to the underworld. I used painters tape in the photo below and it is amazing how it just disappears once covered.
The Milwaukee Road Warrior richhotrain Duct Tape? That stuff will never peel. Rich Yeah that's tempting! I kinda get the feeling I would be a guinea pig for some of these techniques lol. I'm told there are TV ads for Flex Seal tape where a guy tapes shut a hole in a boat hull and makes it seaworthy again. Maybe I should look into that
richhotrain Duct Tape? That stuff will never peel. Rich
Duct Tape? That stuff will never peel.
Yeah that's tempting! I kinda get the feeling I would be a guinea pig for some of these techniques lol. I'm told there are TV ads for Flex Seal tape where a guy tapes shut a hole in a boat hull and makes it seaworthy again. Maybe I should look into that
Yes the painters tape I would not have thought of. Again, only concern there is will it hold up year after year? I suppose painting it into place would increase its strength and lifespan.
On Great Stuff foam, there are blue cans for window and door, green cans called Pestblock, red cans for the typical gap sealant up to 1", orange cans labeled "Fireblock", and black cans labeled "big gap" for gaps up to several inches. I've used all of them before. Great material, but definitely messy!
The Milwaukee Road Warrior I should add: I'm well-versed in using Great Stuff. Love it for many uses. Not sure how well it would work in this application, unless I use the formula that expands the least, for window and door installations. It does tend to leave a "pitted" structure when you cut into it tho: its like sectioning a bee-hive and exposing all the "cells" inside. Not sure how well this would look when painted, but I suppose at that point I could fill in the small "cells" with foam putty or some other sandable material that would paint the same as the surrounding board.
I should add: I'm well-versed in using Great Stuff. Love it for many uses. Not sure how well it would work in this application, unless I use the formula that expands the least, for window and door installations.
It does tend to leave a "pitted" structure when you cut into it tho: its like sectioning a bee-hive and exposing all the "cells" inside. Not sure how well this would look when painted, but I suppose at that point I could fill in the small "cells" with foam putty or some other sandable material that would paint the same as the surrounding board.
I didn't know there were different kinds. I used the little red plastic tube to fill in gaps between sections of foam. I did not get cells that could not be covered by ground foam. I was very stingy in the application of the GF.
I have also used it for big gaps, say between the foam and a curved fascia. You do get cells the size of gaps in home made bread.
I like the idea of blue painters tape. That is cheaper, less messy.
Henry
COB Potomac & Northern
Shenandoah Valley
I have not yet addressed the gaps but for the height difference I used the wooden shims that you buy by the bundle to match up track height.
Use a good level and pay some attention to keeping things flat. Very slight grades will seem to work fine, but after a while you'll run longer trains and perhaps see some stalling on those minor grades.
Don't be satisfied with "good enough for now." When you're a couple of years down the line, fixing problems like this will be more of a problem.
I cover horizontal gaps with thin strips of plaster cloth, which will eventually get Gypsolite or other scenery on top of it. I like Woodland Scenics foam roadbed. It will compress enough to smoothly go over a small vertical rise once track is down, and once ballested you won't notice it.
It takes an iron man to play with a toy iron horse.