# Tunnel building for beginners?



## jonyb

I'm gonna start forming a tunnel pretty soon that will be on a curve. Both sides will be exposed. I've got 5 tunnel portals to start with, 2 for each end, and 1 for the back where the track will split off to a future expansion. I know that you're not supposed to put switches in a tunnel, but I did. I'm gonna try to make a small section close to there removable for access. That will be close to a wall, so if it's not perfect, that's okay. 

The issue I'm looking at is making the forms. I'll cut out facings for the portals from 3/4" MDF, what I'm wondering about is what to make the forms out of. Once they're formed, I'll use plaster cloth. 

Any suggestions? I've looked a little for youtube video's, but didn't find anything that really covered what I'm doing. Most mountains or tunnels are close to a wall and are only 1 sided.


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## bradimous1

this thread has an image of Massey's tunnel... 

http://www.modeltrainforum.com/showthread.php?t=8588&highlight=tunnel

you can use screen over the foam to better form the mountain and use drywall mud over the screen


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## sstlaure

You could also do a cardboard weave for the structure then cover with plaster cloth.


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## tjcruiser

Several options to build a tunnel:

1. Carve out of wedding-cake layers of "pink stuff" foam sheets.

2. Build a "basket weave" form out of strips of heavy corrugated cardboard, then cover with plaster cloth.

3. Build forms out of aluminum window screen.

Sean (NIMT) offered an excellent tutorial on the latter method ... easy, with great results ...

http://www.modeltrainforum.com/showthread.php?t=6374

TJ


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## Massey

That tunnel in the post above was just some pink foam formed around the tracks to hide them. I did another couple of tunnels on other layouts here is what I did.














































Those were from my first 2 layouts. I dont have any pics of the tunnel from the 3rd layout but it was all done in a similar fashion. If you notice I the first layout there is even a place where the tracks go over the top of the tunnel.

Massey


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## NIMT

I use plywood or MDF to make my form boards then attach screen to that.


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## gunrunnerjohn

Sean, point him to your thread on making mountains, that seems appropriate for tunnels as well.


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## waltr

Her's another way to make a tunnel (the tunnel is the second page).
http://www.railwayeng.com/Newloop/index.htm


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## bradimous1

waltr said:


> Her's another way to make a tunnel (the tunnel is the second page).
> http://www.railwayeng.com/Newloop/index.htm


wow... that is awesome!!!


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## bradimous1

> Now we are going to sprinkle dirt and rocks all over this
> Formation. Then pour diluted white glue on all the rocks and dirt.


1. why would you do this in this order
2. how much would you dilute the glue


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## sstlaure

You sprinkle the rocks/etc dry to get a nice even spread, then you apply the diluted glue/water/alcohol mixture to fix it in place.

1 part glue, 4 parts water, 1 part isopropyl alcohol would work just fine.


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## bradimous1

sstlaure said:


> You sprinkle the rocks/etc dry to get a nice even spread, then you apply the diluted glue/water/alcohol mixture to fix it in place.
> 
> 1 part glue, 4 parts water, 1 part isopropyl alcohol would work just fine.


:thumbsup: thx


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## tjcruiser

gunrunnerjohn said:


> Sean, point him to your thread on making mountains, that seems appropriate for tunnels as well.


I think that's the thread I linked to in Post 4, above ...



tjcruiser said:


> ... Build forms out of aluminum window screen.
> 
> Sean (NIMT) offered an excellent tutorial on the latter method ... easy, with great results ...
> 
> http://www.modeltrainforum.com/showthread.php?t=6374
> 
> TJ


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## jonyb

Excellent info here fellas! 

I've been watching Massey's thread, the one I had seen on his was situated in a corner, mine will be out in the open. 

I've also seen Sean's thread with the screen. That's a great idea, and I'll probably try that, but where his is also in a corner, that brings the question of how to make a mountain, or the best way to make the peak of the mountain? 

I'll take a picture later of the area I'm working with, maybe you guys would have a better suggestion.....


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## tjcruiser

You could "frame" the mountain with woven, arched strips of 1.5" (or so) wide corregated cardboard. When you weave it together (like a loose-woven basket), and staple the overlapping joints, it yields a reasonably strong mountain frame.


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## bradimous1

that link from waltr has got to be the easiest way to do it


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## sstlaure

The reason I didn't go with the stacked foam method was that I wanted the insides of the mountains to be hollow, making it easier to access my trains and wiring that ran through there.

The cardboard strip method is very easy as well.

I think for my new layout I'm going to do cardboard strip for the structure, then use NIMT's screen/drywall mud method to cover. That plaster cloth got expensive.


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## bradimous1

I just ordered a new dremel today... which will hopefully help me shape my mountain


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## sstlaure

A serrated steak knife works well also. 

Have your vacuum cleaner ready - It will work, but you'll make a serious mess with a dremel.

The best way is to get a hot knife or heated wire cutter. Cuts quick and little to no mess.

Keep in mind that you will be putting a thin layer of drywall mud (or similar) over the top of the foam so you don't have to be exact with the shaping of the foam....just kind of close.


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## tjcruiser

bradimous1 said:


> I just ordered a new dremel today... which will hopefully help me shape my mountain


On foam???

A dremel would be a bit small, I think. I'd suggest serrated cutting knives (per above), along with a 60-grit 1.5" diameter sanding drum mounted in a drill chuck, and perhaps a belt sander, too.


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## bradimous1

tjcruiser said:


> On foam???
> 
> A dremel would be a bit small, I think. I'd suggest serrated cutting knives (per above), along with a 60-grit 1.5" diameter sanding drum mounted in a drill chuck, and perhaps a belt sander, too.


I didn't get it necessarily for that... I just wanted it, so I ordered it. Had my choice of a few things through work and that was the winner.


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## Massey

when building models, having a dremmel around is almost a must have like model glue. I have 2 of them one for normal use and a 75th anaversary model.

Massey


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## tjcruiser

Thumbs up from me on the Dremel, too. I use mine ALL the time on my Lionel tinplate trains. You'll really get great use from yours.

TJ


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## gunrunnerjohn

I have three Dremel tools. Well, actually two Dremel brand and one off-brand I got for $20. I dig one out almost every day, what a handy little tool.


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## jonyb

X10 on the Dremels..... 

After looking at the layout today, I think it won't be double-sided like I had originally thought. I'll put up a pic tomorrow and see what you guys think the best way to do it would be. I'm thinking the mesh screen idea would be perfect.

Anyone know the inside opening dimension of the dual track tunnels?


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## Massey

I doubt there is a standard dimension for tunnel bores. I think it is going to depend more on the structure of the rock and how much support is needed for the tunnel liner or reinforcement. Some tunnels are not tall enough to permit the transit of double stacks or extra height cars, others can handle it just fine. Some that could not clear double stacks but were in areas that had high traffic levels had the floor lowered to clear the double stacks and other overheight cars.

Massey


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## NIMT

jonyb,
Here is a chart for all the clearances.







So height in HO is 23' X 12 = 276" / 87 = 3.17" off top of rail so 3 1/2" off of the layout surface is a good height
And width in HO is 9' x 12 = 108" / 87 = 1.24" off of center line to side and 2" center to center on straits and 2 1/4" on curves
So 1 1/4" + 1 1/4" = 2 1/2" for a Single tunnel and 1 1/4" + 2" + 1 1/4" = 4 1/2" for a Double tunnel.
This chart is in real dimensions so just multiply dimension in feet x 12 then divide by your scale dimension HO = 1/87.
Hope this helps!


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## jonyb

Thanks Sean and Massey! I was actually asking the inside width of the Woodland Scenics tunnels, I didn't word that question right. Ive got the single track portals, but the track is too close together to use singles, and (after searching) a little too far apart to use a double track portal. I'm gonna try to move the tracks closer together to see if I can use the double. The opening on it is 4.5, just like Sean said.


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## jonyb

Here's the area I have to work with. I moved the track on the left hand side of the pic closer together, and it's 4" wide, so I believe a double tunnel portal will work. On the right hand side, it's far enough away to use 2 separate portals. If they were built, they'd be facing where I took the picture from. I think I'll build a wall in teh background to start with.


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## jonyb

I wonder how well Sean's screen idea will work with Plaster Cloth? I've changed all the track to flex and have a plan for the mountain/tunnel portals. Hope to start on them next week some time. I already have the screen and other materials to start this, just need to buy some time.


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## NIMT

Yes sir it will work, it's a little more expensive, but I take it you already have the cloth?


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## jonyb

Yes, I've got the cloth. Wasn't sure if the cloth would be too heavy once it was wet.


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## Evan

I would suggest using the cardboard "basket weaving" strips and weave them like a basket. Works pretty well I think, for a cheap price!


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## seabilliau

I am in the middle of making my tunnels but am trying to figure out how to mold around the opening without getting drywall on the plastic. I can put painters tape on it, but am unsure of the technique. The two pics should explain what I am trying to do.


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## NIMT

Either use a chunck of foam to make the entrances or a piece of plywood.


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