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WS sells a form HERE for HO but they don't have one for O that I can find.  I am about to start my tunnels on my layout and I am thinking of making my own version of this form to crank out my liners in plaster or hydrocal. Any thoughts on if I am doing this the hard way? I have seen the Foam and Window Screen method from Ericstrains but if I an cast the rock walls and the support structure as one why the extra steps? Your thoughts? Suggestions? Insults?

 

I am using FASTRACK with 036 turns. I will have 2 tunnels about 4 feet long each.

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Originally Posted by lehighline:

While aluminum foil is a good idea, do be aware that is does mess with TMCC signals in the tunnel. That is why I do not use it.

 

Chris

LVHR

Well, I'm 100% postwar, so it's all the same to me. But, in my experience, it is rare that there is any need for more than 10 or 12 inches of tunnel lining. I am guessing that that wouldn't matter much.  Could be wrong, though.

I'll share this idea given to me by my late friend and forum member, Owen Sturm (Paulinskill).   Get a piece of foam - any thickness - and take it to a pile of gravel (or buy your own gravel).  Put the foam on top of the gravel and press the foam into the gravel.  Jump up and down if you have to.  You're just trying to get the gravel indentations on the foam.   Once done - paint.   You now have tunnel liners.

 

--Greg

Last edited by Greg Houser

another simple solution is to shape your tunnel from aluminum foil which is properly crumpled nd shped. using the no stick type with the nonstick side facing outward away form the foil, will allow you to shape plaster over the foil an remove the foil when the plaster sets and you have a simple non RF-interfering tunnel..

 add some tempra paint of an appropriate color and the most you will have to do to finish iot is add seom highlights with dry brush and some smoke residue

Thanks for all the ideas! After looking at them and what I had on hand and the cost of what I would have to buy I went with the build it my self option.

 

Here is the wooden form I built between commercials during the Superbowl yesterday. I hope to add foil for texture on the inside and to pour plaster today.

O gauge tunnel form

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  • O gauge tunnel form

@ Jester red... nice form, use the non-stick aluminum foil, I remember doing the aluminum foil think when I was like 16 and oisking stray bits of aluminum foil out fo the plaster for weeks!

 

also; is there enough interest in an O scale rubber tunnel liner mold? 
I am thinking rough cut and lined curved wall molds  in flexible latex rubber maybe $15? I could do them up this week as I am in a sculpting sequence in the shop

Last edited by the mountain man

The plaster has dried and the casting came out in three large pieces. Not bad in my book for a first try. My next discovery is that hot glue does not stick to plaster. Which resulted in four large pieces when it came back apart. Next I will try drywall putty to stick it back together so I can make a latex mold. If anyone else knows a good way to make plaster stick together I would love to hear it!

used crazy glue on wet plaster, it takes days for the water content to reduce enough for hot melt  to fill gaps use baking soda and crazy glue (ACC)

 

use plain old spackle for smoothing the joints you filled and hit the whole thing with a little pam or such before you star making your latex mold. imbed cheese cloth wet with ammonia for strength and dimensional stability

 also try using foam sheet for the mold support

Last edited by the mountain man

I understand that many of you like the foil lined tunnels. That solution has ben posted here many times. That just isn't the solution I am looking for. I want this layout to be around for a long time and I don't think that painted foil will stand up to the test of time as well as the plaster. And I already bought the plaster so if I don't use it my wife will make me sleep on the couch with it instead of in bed with her.  So no offense is intended to the foil tunnelers out there it just isn't the way I want to go.

a couple of "tricks of the trade" ( mind you I do "face off" stuff for a living)

 when applying the latex thin the first coat, with 1 part ammonia five parts water to a heavy cream consistency, wet you brush with a fifty fifty water ammonia mix and keep it wet. Ammonia is the preservative for latex

 do not use tap water with chlorine!  the chlorine will jell the latex and it will go on globby.  

Don't rush coats let each dry until the "white" goes away.  after the second or third layer embed cheese cloth wet with the same ammonia / water mix you are using for your brush wring it damp dry and layer several coats of latex over it. 

 let the whole gizmo dry for a few days,  you can accelerate the cure with moderate heat but don't go over 140 degrees best to stay near 120 for a top temp. I usually will put curing latex on top of one of those iol filled heaters. 9 that's me all high tech)

this will sound weird, but if you want a less flimsy mold you can add a little flat house paint to the latex, mix thoroughly . the resultant mix will be a little harder when cured. but be ware that what you don't use will gel in a few weeks or months  with the wall paint added. it does make for a more stable and rapid built up of the mold however

 your plaster master ( the casting you got from the mold form and aluminum foil) wil absorb some water right off hence the reason for thinning the first couple of coats plus this will eliminate air bubbles. you can rub a little spackle into any voids in you master before you start, ( they will show up in the latex)

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OGR Publishing, Inc., 1310 Eastside Centre Ct, Ste 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

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