I can't get square cuts either, so this is what I do:
If you are talking about on the edges that would be toward the isle way, I cover mine with paneling to make a facia. Where the foam and facia don't quite meet, I fill. If it is a large area, I use expanding insulation foam in a can and spray it in, let it cure, then cut it as required. You need to watch out that the expandable foam insulation doesn't push the facia out. I clamp a board on the outside of the facia temporarily to prevent bulging of the facia. If it is a small area, I fill it with latex caulking.
If you are talking about the gap between sections, you could do the same thing but put a sheet of wax paper on the end of one half, then spray the foam in. The foam will stick to the unprotected foam surface and the wax paper will not let it stick to the other module.
On a different note, I am using one inch blue foam on top of 1/4 inch Luan plywood which is fastened to a grid-work frame. It is quite sturdy. I am not sure why you are using 3/4 inch plywood over the Sievers grid, then foam on that. I know it will be very sturdy, but it will also be very heavy. My grid frame is glued together, and the Luan glued to that, and the foam sheet glued to the Luan. It makes quite a ridged box like structure.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
The most accurate cuts in 2" foam are going to come from a table saw...I used mine frequently to cut my 2" foam and had no regrets in doing so. If you don't own a table saw, you might need to call in a favor of a friend.
Don Z.
Research; it's not just for geeks.
You can use the "score and snap" technique. It's not for small cuts, but if you have to make a long, clean break it may be the best.
Measure both sides of the sheet, and draw a line where you want to cut. I usually start with a thin-blade utility knife, and slice down on both sides. That will get me in about a half inch. Next, I take a heftier knife and cut further down, again on both sides. By this point, you should have sufficiently weakend the foam along that line that it will snap cleanly.
It takes an iron man to play with a toy iron horse.
Don, what tooth blade did you use? Any brand that you've found that works better? And what about shavings? Vaccume hook up? Heck I've GOT saws, all sorts. Maybe even a small skillsaw would work too if a table saw does. If that's the case Locogirl, you can pick one up for a very reasonable price and then just mark with straight edge or even clamp a straight edge to the foam for a nice guide.
- Harry
Loco wrote: Don, what tooth blade did you use? Any brand that you've found that works better? And what about shavings? Vaccume hook up? Heck I've GOT saws, all sorts. Maybe even a small skillsaw would work too if a table saw does. If that's the case Locogirl, you can pick one up for a very reasonable price and then just mark with straight edge or even clamp a straight edge to the foam for a nice guide.
Loco,
My tablesaw has a 12" 60 tooth blade on it right now. I do have a dust collection system hooked up to the saw, but there isn't much in the way of shavings from the foam to speak of. I've used my jig saw with a plywood blade to cut curves in the 2" foam and then used a sanding block to clean up the cut edge. I could have left it as it was after cutting, but the obsessive compulsive perfectionist in me wouldn't hear of such a thing...
I have cut foam on a tablesaw to get straight cuts. I was making coal loads, so I was using 1 inch thick material. The normal tablesaw blade has a kerf of 1/8 inch. I think a blade for cutting plywood may be thinner.
Regardless, while there may not be any shavings, you will naturally get whatever the blade cuts dropping on the floor and to some extent blowing around the place because the material is not as dense as wood. It also wants to try to cling to other things due to static electricity. With the dust collection system, which I wish I had, I think that the mess is minimized. Without it, there may be a lot more loose stuff to pick up.
The good thing about the table saw is that the blade is stationary (rotating in place) and you are moving the work through it. There is also the stationary fence which acts to guide the piece being cut. You could get a similar smooth cut using a circular saw with a proper blade, assuming that you can clamp some sort of guide to the foam. I believe that this is where one would run into a problem, since the foam would collapse if "C" clamps (for example) were used to clamp the guide to the foam. If you are very good with the circular saw and have a steady hand, you could mark your line on the foam and cut free hand. If I tried that, the cut would be wandering all over the place. Norm Abrams I'm not.
I've been using both table saws and circular saws with a plywood blade (fine) for years. There is some sawdust, but it's easily vacumed up. At Dunham Studios we also use band saws.
To make inclines, (ramps, as we called them in the shop), we would figure the dimensions and lay it out on the 2" foam, then cut the "wedge" or ramp out with the table or circular saw. To make it bendable you just cut vertical saw kerfs every couple or 3 inches half way through, then turn it around and repeat for the other side, (it looks sorta like the WS stuff).
I have also used a jig or sabre saw in a pinch, but you can't rely on them for a true level suface as the blades tend to wander, a band saw is better.
For scenic work that doesn't require accuracy, I use the score and snap method and fill in with spray foam. I often use spray foam to glue layers together (it'll never come apart at that seam!) and use 3" screws as clamps, (the screws are left in place if they're not got to interfere with further construction). In general, we use a latex contact cement to glue layers together and to glue the cork or foam roadbed and track down, although if in a hurry, we have also used 3M Spray77 contact cement for the roadbed and track.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
I take two straight edges, such as yard sticks, and clamp them on either side of the foam then use a hot wire cutter that I just run along the two straight edges with the foam in between them.
It's fast and easy.
Dave
Lackawanna Route of the Phoebe Snow
I used 2-inch blue foam on top of Seivers Benchwork. What I did was lined up the foam on the benchwork to reduce the amount/number of cuts that I had to make. I then used a weighted down yardstick on top of the foam and the edge of the benchwork underneath to keep an old but sharp serrated steak knife in line and gently made sawing cuts through the foam.
There are pics of the results on my site.
Kevin
http://chatanuga.org/RailPage.html
http://chatanuga.org/WLMR.html
MisterBeasley - that is what the building supply guys did in Bishop so I could get the pieces in my truck, but I cannot say that the "score & snap" was any better - maybe their skill level? Anyway, my question would still be what would one suggest to use to fill the small gaps when I put the pieces together on the tabletop?
Loco wrote:Don, what tooth blade did you use? Any brand that you've found that works better? And what about shavings? Vaccume hook up? Heck I've GOT saws, all sorts. Maybe even a small skillsaw would work too if a table saw does. If that's the case Locogirl, you can pick one up for a very reasonable price and then just mark with straight edge or even clamp a straight edge to the foam for a nice guide.
I get nice smooth cuts with an ordinary 60 tooth carbide blade in my radial arm saw. The band saw also goes thru the foamboard with ease. There isn't much blue dust, and a shop vac hooked up to the dusk collection ports sucks up most of it.
David Starr www.newsnorthwoods.blogspot.com