Thank you, Craigslist! (And a question about cutting very fine angles in foam)

ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Whether you're a master model railroader or just getting started, you'll find something of interest here.


DairyStateDad

Mumbling in the corner
Got really lucky last night (no, it's not what you think, not even with the CL reference ;) !)

I found a big supply of 4x8 x 2-inch thick DOW XPS Styrofoam (blue board) for my subroadbed -- brought home 4 slabs of it. Should be all I need for a long time -- about half of it will go toward the layout now, and the rest for the future as scenery support, elevation risers, etc. Cost about half what it would in the store. I already have a few large scraps of 1-inch that a buddy had stored in his garage and didn't need, so at most I might need another 2x8 or 4x8 1-inch or 1/2-inch board.

The lovely DairyStateMom agreed to help haul it home in her Vibe, and when we couldn't fit the full sheets in (duh!), the seller kindly sliced it up with his circular saw in accordance with my instructions. In return, I suggested to him that he post signs to sell more of his stock in local train stores. (He had it leftover from a siding project on his home.)

I'm still refining my final track plan, which I hope to post sometime. I know that building benchwork first and then doing the plan is B@$$-@ckwards, but it's a long story: I built the benchwork originally with another plan in mind, then decided that plan wouldn't work for me for a number of reasons. So I came up with new ways to configure the existing benchwork that work much better, both for the space I am in and for my ultimate desires for the layout. That tends to be my style, for better or worse: trial and error.

Thinking ahead, I have so much blue board now that I will be able to use it to make risers for grades and elevated track. The trickiest part there will be getting the angles right for the percentage of grades. Based on my rough calculations, I should be able to hold grades to no more than 2.5 or 2.75% -- and less if possible. The angles of inclination for even those are very, very slight, less than 2 degrees. So how to cut those angles into the risers I make with appropriate precision might be a bit of a challenge. As far as I can tell, even pretty pricey chop saws don't get much more precise than about 1 or 2 degrees of angle, whereas I'm looking to cut something to, say, a 1.4-degree angle... Any thoughts about how to get that fine a cut would be welcome!
 

logandsawman

Well-Known Member
I am not the railroad pro, but I am a math whiz.

2.5 % means 2.5 inches of rise per 100" of run, or like 1.25 per 50", and so forth. In a/b = c/d; a x d = c x b. Put any values in this equation and solve for the unknown.

You can tell me the length of your run, your desired percent slope, and I will give you the total rise at the end.

If not totally confused, ask Bruette. Or Stoker. Or if I am on, I will try to be simpler.


Later, logandsawman
 

DairyStateDad

Mumbling in the corner
Thank you, logandsawman, but that's not really the issue. I know how to figure percents and grades.

My intent is to cut risers from 2-inch thick segments of extruded foam. The risers would be placed on edge (ie, on the 2-inch edge). So I'd have a series of risers at various heights made from foam.

Since the risers themselves would be 2-inches thick, and assuming the bottom of each one is square, I'm assuming the tops should be sloped at a slight angle to correspond with the desired grade.

I have a list of the angle of inclinations for various percentage grades (I got that by using an online calculator and then plugging in various percentages. For grades 5 percent and below, the angles are all *really* small -- a 5% grade (steeper than I am planning on) is less than a 3-degree angle, for example.

So... if my grade is 2%, the slope at the top of the riser should be at a 1.15-degree angle. Ideally, I'd cut that angle into the foam using a chop saw, but I think the saw is likely not to be able to measure the angle so exactly.

Or to put it another way, if the riser is 2 inches thick, the back of the riser should be 4/100ths of an inch lower than the front. (2 percent of 2 inches = 0.04 inches).

Or about 1 millimeter...

hmmmm... I figured with a 2-inch-thick riser, putting the proper slope on the riser would be better. But maybe it's not so critical? :eek:

*shuffles feet, feeling foolish*
 

logandsawman

Well-Known Member
Sounds like thinking out loud got you the answer.

Happens to me all the time, I start asking a question and by the time I finish, the answer comes out of my own mouth.

Later, logandsawman
 

logandsawman

Well-Known Member
Heat up a big kitchen knife over the stove flame until it is very hot and you will cut the foam like butter.
 

DairyStateDad

Mumbling in the corner
Cool design for the cutter. I've heard about this in concept, so thanks for the link... I will look into that...

Perhaps I could wire that kitchen knife straight to a 110 volt plug? (OK, that is totally a joke...)
 

Rico

BN Modeller
A short answer would be to attach the risers to the Styrofoam roadbase on the flat tops, then set it on a table at the grade you want.
Cut from the edge touching or closest to the table the distance the other edge is off the table and you will have the bottoms at the angle you need.
Um... clear as mud? I don't know how to explain it without a diagram which I could whip up when I get home.
 

DairyStateDad

Mumbling in the corner
OK, I think I get your suggestion, but feel free to diagram it.

And I've got plenty of time to work this out . . . my mind has just been on this now that I've got all these supplies on hand!
 
I use a lot of foam for my model airplanes. I built this foam cutter from a $15.00 door bell transformer, $5.00 dimmer switch, some scrap wood, I use braided stainless steel lead material for fishing.

To make tapered cuts, use a long rip fence, hot glue a piece of foam to one end of the piece of foam you are cutting to angle it. Glue the block on again for the next cut.

Buzz.

foam scroll saw rip fence.jpg

foam scroll saw botom1.jpg

foam scroll saw side view.jpg
 

jdetray

Well-Known Member
I used a miter saw to cut my risers from pink foam.

grades700.jpg


After a little trial and error, it was not too difficult to cut the angles fairly accurately. But I found that extreme accuracy wasn't too important. The thick adhesive that I used -- Liquid Nails for Projects -- more than compensated for small errors in the angles.

- Jeff
 

Rico

BN Modeller
I think Jeff is correct in that the space could easily be filled in with adhesive.
It would be a pretty small angle for that amount of grade.
 

Cjcrescent

Master Mechanic
I agree with this as well. Imagine that you're using wooden risers. The angle left over is just so small that the thickness of the adhesive will be enough to compensate for a true angle surface to matter. In over 50 years of model railroading, I've never worried about having the surface of a riser cut to match a grade. I've also never had a problem with it at all.
 

logandsawman

Well-Known Member
DairylandDad,

Let us know what you come up with, and throw on a photo if possible.

Tons of good advice here.

Thanks, logandsawman
 

DairyStateDad

Mumbling in the corner
Let us know what you come up with, and throw on a photo if possible.
Tons of good advice here.
Thanks, logandsawman

Will do, LASM. The point that the slope is small enough that the adhesive is probably enough to account for it really hit home! Pictures coming as soon as benchwork finished...
 

Steve S

Member
If you do build a hot-wire cutter, be sure to use it outdoors or you'll be sleeping on the couch for a week. Melting foam stinks to high heaven.

Steve S
 




Affiliate Disclosure: We may receive a commision from some of the links and ads shown on this website (Learn More Here)


ModelRailroadForums.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com

RailroadBookstore.com - An online railroad bookstore featuring a curated selection of new and used railroad books. Railroad pictorials, railroad history, steam locomotives, passenger trains, modern railroading. Hundreds of titles available, most at discount prices! We also have a video and children's book section.

ModelRailroadBookstore.com - An online model railroad bookstore featuring a curated selection of new and used books. Layout design, track plans, scenery and structure building, wiring, DCC, Tinplate, Toy Trains, Price Guides and more.

Top