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southpier
New Hire
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 Posted - 06/10/2012 : 1:46:46 PM
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i need to build several concrete walls in 1/32 -35 scale. not important if i build up with materials, or build a mold and cast them.
what is important is that the seam lines protrude from the concrete face just as an original board form would encourage.
i don't want to scribe the joints, since that would leave the negative of what i'm trying to achieve.
did a search but it appears to be an exercise unto itself. any help appreciated.
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Sean_OBrien
Engine Wiper
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Posted - 06/10/2012 : 2:35:06 PM
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I've actually had OK luck with building the molds like you build concrete forms using strip wood/plywood as small as 1:48 scale (haven't tried smaller...though it should work too).
Work it just like the big ones are put together, and then remember to reinforce your joints with packing tape (outside of the mold...that way you don't get leaks). I always have oiled the insides of the wood. You then mix up your preferred scale concrete mix (I like a mortar mix for that scale with some screened gravel/pool filter sand added into the mix for the aggregate). Put it in and vibrate the heck out of it till you start to see a bit of moisture show up on the tape. Let cure for 24-48 hours and then strip the forms.
You will end up with the lines just like the real thing - though depending on how well you cut the wood...it might be a bit too subtle for your needs. To add a bit of extra texture, use a wire brush in a Dremel and just zip down the edges of the boards before you cast. It gives a little extra texture to the final seam line.
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eTraxx
Fireman
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Posted - 06/10/2012 : 2:37:27 PM
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I did a little bit of that for my Caddo Creek Dam. On this page .. http://www.railroad-line.com/forum/topic.asp?TOPIC_ID=34260&whichpage=4 .. I glued a couple strips of paper on the surface to replicate the lagging movement ..
Painted it blends in .. with just a hint of movement .
.. and finished ..
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Country: USA
| Posts: 1992 |
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mark_dalrymple
Crew Chief
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Posted - 06/10/2012 : 3:06:03 PM
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Hi.
I made up a mold with strip styrene. I cut up lots of little bits and glued them randomly to a piece of sheet styrene, then glued on the strips leaving random gaps between them. I also cut the strips to appropriate prototypical timber lengths. The small bits in behind gave it that 'in and out' look when glued back. Quite happy with the results and have used it a fair bit so far (Ho scale).
Cheers, Mark.
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Country: New Zealand
| Posts: 526 |
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southpier
New Hire
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Posted - 06/10/2012 : 3:39:46 PM
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jeeze; they all look good. most likely will mix 'n' match these ideas for variety.
guess i came to the right place!
thanks
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| Posts: 35 |
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Neil M
Fireman
Premium Member
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Posted - 06/10/2012 : 8:00:41 PM
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Lots of ideas here!
Mark, I really like the finished look of your retaining wall! I think the formwork builder would get told off by the foreman for building formwork that moved that much during the concrete pour, but the finished effect is lovely.
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| Built a waterfront HO layout in Ireland http://www.railroad-line.com/forum/topic.asp?TOPIC_ID=22161 but now making a start in On30 in Australia |
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Country: Australia
| Posts: 2173 |
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kruisyk
Crew Chief
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Posted - 06/11/2012 : 05:38:16 AM
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Try the technique typically used to fill corner joints on hydrocal structures, just don't sand it down when done. Use two pieces of blue painter's tape, apply spackle to the space, let dry, remove tape. Might give you what you're looking for.
Dave K.
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| "Promote what you love instead of bashing what you hate." |
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Country: USA
| Posts: 590 |
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southpier
New Hire
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Posted - 06/11/2012 : 08:25:08 AM
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oh man; you guys have got this down!
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R.BOUDREAUX
Fireman
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Posted - 06/13/2012 : 3:44:54 PM
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Southpier,
I just had a crazy idea to make a conc. formed wall. I have not tried this, but it sounds crazy enuf to work.
Take some 'peel off and stick -on' labels. Score then from the back side with a fine point scoring tool.
Peel off and stick to your "wall". The reverse scored lines should show up as 'smushed out' conc. joints.
Good luck.
Rich
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Country: USA
| Posts: 1342 |
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eTraxx
Fireman
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Posted - 06/13/2012 : 4:14:32 PM
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I think in order to get that effect .. really .. you need to construct the form out of stripwood .. leaving narrow caps where you want the concrete to show as having pushed through. From the back side, press spackling so that it oozes through like you want. When that is dry .. use it for a master and cast as many as yo wish.
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Country: USA
| Posts: 1992 |
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R.BOUDREAUX
Fireman
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southpier
New Hire
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Posted - 06/14/2012 : 5:24:48 PM
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i dare say that might be the way to go with a minimum of pain.
for mold release, does the residue affect stain/ painting of the concrete?
i've used spray products (cooking oil) on rock molds filled with water putty and not noticed any effect.
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| Posts: 35 |
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eTraxx
Fireman
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Posted - 01/07/2013 : 2:32:47 PM
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Experimenting with textures. My plan is to make it look as if an abutment had been poured in a timber mold. Ok. I KNOW someone will point out that generally .. the board in forms didn't bulge and 'generally' .. cement didn't bulge between them.
My reasoning for that is .. the boards used for a form were tongue and groove. That was because as the cement pressed against the form the pressure would actually lock the boards together.
Still. I have never allowed logic to stop me in the past. Tongues WOULD break and split allowing individual boards to bulge out .. and ridges of cement to ooze between the boards. For me .. that adds interest.
So. Some experiments ...
In the photo the bottom part there are two strips of index card glued to the board. In the top portion you see two outlined areas. The top one has a strip of index card as in the bottom and the lower one just the board. They have both been an experiment with oozing concrete. I placed some blue painter's tape leaving a small open strip. I then used some Acrylic Gel .. smeared sideways on the top strip .. and dabbed with my finger on the bottom. Pretty happy with the results (the strips are 1/4" wide by the way)
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Country: USA
| Posts: 1992 |
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southpier
New Hire
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Posted - 01/07/2013 : 4:16:55 PM
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that upper section looks great.
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| Posts: 35 |
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