Grade transitions with foam

[ndbprr]

Not having used foam before how much flex can beoput in a sheet going into or out of a grade and how did you prevent it from popping back to straight? Thank you.

[MisterBeasley]

I'm using 2-inch foam. I assume it will not flex at all. I try to fill with thin slivers of foam at the bottom, and shave a bit off at the top to get rounded grade transitions. It's a bit messy, but I've also built up my transitions with hydrocal. Then I use foam roadbed, which is compressable and give me a bit of a squishy cushion.

[nbrodar]

2" foam isn't very flexable. 1" foam is more flexable. I just don't use grades at all. For transitions between grades, you could try building up the foam a little higher, and carving the transitions, or try building them up with some cardboard or thin wood. You also could try Woodland scenics inclines.

Nick

[dgwinup]

QUOTE: Originally posted by ndbprr

Not having used foam before how much flex can beoput in a sheet going into or out of a grade and how did you prevent it from popping back to straight? Thank you.

As mentioned, 2" foam doesn't flex well. Thinner foam will flex, but you end up with a spring-y subsurface. Your grade transitions will be curved and it will cause derailments. It is best not to flex the foam, but instead, build the grade by shimming up the foam. Here is a picture showing shims used to build a grade with 1" foam:



The grade at this point is smooth. The track looks distorted in the picture but is actually straight.

Here is another picture that demonstrates several techniques:



The grade here was built by shaving the foam into a wedge shape. (look at left edge of picture, just below the track) Several wedge-shaped pieces were stacked to get the final grade. You can see two wedge pieces on the left side of the picture. After scenery was applied, a little dip was found in the middle of the grade, so a slit was made in the subsurface foam and small pieces of cork roadbed were inserted in the slit to raise only the middle portion of the grade. Had the dip been noticed before scenery was applied, it could have been corrected by recarving the wedge or replacing a portion of the grade with a new piece of carved foam.

Foam is great material to work with. You can use a lot of "out of the box" thinking with it. I think the key is just to take advantage of the foam properties and don't try to force the foam to do something it can't do well, like flexing. You wouldn't build a grade by flexing plywood, so you shouldn't ask foam to do the same thing.

Hope these pictures help you get a smooth grade on your layout.

Darrell, rising to the occasion, but quiet...for now

[selector]

I found that using a long-handled wooden wire brush enabled me to make the grades and transitions that my locos needed to work well. I used long strokes along the axis of the grade and lightend up as I passed over each transition point. W.ith some practice, you can make a fair job of this. It allows you to place your track in a cut, a quite typical setting. If need be, slide thin, but 1" wide, wedges of the same foam under the points where the grade is not constant. Kinked grades will leave longer wheel bases hung-up and not able to contribute to the towing effort up that grade.

[orsonroy]

I've made about 3% grades with 2" foam, backed with 1/4" plywood. It IS flexible, but realistically only in thin strips (less than 8" wide or so).

Of course, my last layout was a foam three-level. The grades ran from 3% to flat, and everywhere in between, depending on what I needed where (more grade on countryside, flat in towns). I bent, flexed and curved the heck out of my 2" foam without any problems, and my layout was on average 12" wide.

[2021]

I just did grade transitions from 0" to 2" and further down from 2" to 4" using Woodland Scenics inclines. It makes a perfect rise - I used a 2% incline but other grades are available. The advantage of this is a constant rise and much less work. For my money, it's the best way to go.
Ron K.

[skiloff]

I agree with the WS foam risers. They are quite inexpensive and save hours of carving time, especially if you screw up and have to start over.

[dgwinup]

WS foam risers are good. They are relatively inexpensive and easy to use. But you are limited to the grades they offer. With blue or pink foam, you can make your grades anything you want or need.

You can make your own WS-style risers and inclines from 2" foam. Cut a 2" square piece of foam off of a panel (either 4' or 8' side). Cut alternating slots down the length of the 2x2" piece. Carefully mark the SIDE of this slotted piece from one top corner to the other bottom corner and cut along the line you just marked. Now you have TWO long inclines of just under 2% if you used the 8' length. Want a different incline? Change your cutting dimensions. A 2" x 4" block, slotted and cut corner to corner will give you about 3 1/2% incline. This is a lot of work, especially keeping the corner-to-corner cut straight. I wouldn't use this method if the WS products will do the job for you, but if you need custom gradients, this is a good way to achieve what you want.

You can also use this method for risers. Just cut off a block for the height you want, cut the slots and you've got your riser. For either risers or inclines, the more slots you cut, the more flexibility you will have.

Foam is very easy to work with and is adaptable to nearly every situation you can think of in model railroad benchwork. (Yes, you can even make splined sub-roadbed with it!) You could build a small layout with nothing but foam, including framework, legs, scenery bases and other support pieces. And you could carry the resulting layout with one hand. Try THAT with plywood and 1 x 4's!!

Darrell, foaming for fun,but quiet...for now

[Anonymous]

I use 2" foam for my layout,but 1" for the grades.I cut the actual shape of the roadbed[save the edges,I'll explain in a minute].Cut it out of a cardboard template,and trace it to the foam.I make the ends relatively long.I trace the end of the riser onto the top of the bottom piece of foam,and cut it out to inlet the foam into the beginning of the grade.Once you get it glued down and fastened,you can can bend it up from thr parent foam,and make a perfect grade and transition,with little or no sanding,and do the same thing on the top.You can flex it up a little,and work some glue down the sides,and use some sheetrock screws drilled down into the bottom foam to draw it down into the foam to set the height.[make sure it's a light interferance fit] Where you can,block it with styrofoam blocks.Now you can use the cutoffs butted up right against the grade for the hillside.If it's a high grade,you can trace it onto a piece of 2" to make up the height change,and toenail a few screws into it to really make it stable..

[chateauricher]

To make things clearer...

Woodland Scenics make both risers and inclines.

WS Risers lift your track horizontally at 0% grade (available in 1/2"; 3/4"; 1"; 2" and 4" elevations).

WS Inclines are used to form grades (available in 2%, 3% and 4%).

They are not the same thing. It is important to correctly distinqui***he two since you might end up with the wrong product.

WS Incline kits come with an "incline starter" which forms the transition from 0% to the grade you're using. Incline starters are also available seperately in sets of 4 to 8 (depending on the grade you're using).

For more information, go to http://www.woodlandscenics.com/ and click on "Foam System" at the top of the homepage.

---

Plywood can flex (to some degree), and is often used in cookie-cutter style layouts where the plywood is cut to follow the path of the tracks. Using a support frame (most often an L-girder system) with wood blocks (called "risers"), the plywood is raised to form grades or elevated portions of sub-roadbed. The vertical curves (transitions to grade) are very smooth with this style of construction. Plaster covered screen mesh (or other foundation) is used to form the terrain. The plywood is generally used only to support the tracks; and very little is used to support the terrain.

[bgrossman]

Two inch foam is about the same thickness as the width of HO cork roadbed. I have built inclines by laying them out on a sheet of 2" thick foam and cutting out. You can then make the very beginning transition from foam shavings, plaster, or WS incline starters. I have also installed these on curves (24" radius, so far) by making cuts vertically almost all the way thru. The gaps that open can be filled as needed. I then glue the roadbed to the foam as usual.

Bernie

[ndbprr]

So if I put slits in the back of the foam say every 1/2" about 1 3/4" deep I should achieve the same thing or I could cut a transition from a piece of wood or foam on a bandsaw and save the cost. Correct?

[chateauricher]

QUOTE: Originally posted by ndbprr
So if I put slits in the back of the foam say every 1/2" about 1 3/4" deep I should achieve the same thing or I could cut a transition from a piece of wood or foam on a bandsaw and save the cost. Correct?

Foam is not made to bend and still maintain its structural integrity. Foam is not very strong to begin with; so, by putting curf cuts in the foam (as you suggest), you risk the foam breaking as you try to bend it.

Why go to all that trouble if you can avoid it ?

If you can afford it, use Woodland Scenics Inclines and save yourself a lot of headaches. They are well worth the money.