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Discussion Starter · #1 ·
Never came across this problem before..


I have some styrene warpage.. /DesktopModules/NTForums/themes/mls/emoticons/sad.gif


 I suspect its because of the thin strips glued over the thicker base,


and a lot of glue contact area..and the small size..this doesnt seem to be a problem with Large Scale! ;)


Its two On30 cab  walls...quite a bit smaller than anything I have built before.


they are approx 1.5x1.5" square.


1mm thick stryrene for the base, with 0.5mm styrene strips glued on top.


here are some pics:





 


The cab walls are now about a week old, and there is definate curvature to the sides..


all 4 sides are cupped/arched/curved slightly..no longer flat.


Im using Ambroid Pro-Weld for the glue..


any ideas for preventing this?


thanks,


Scot
 

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Scot, I am not surprised. After I built my styrene station--out of 0.100 sheet overlaid with 0.020 boards and battens--I found that the walls wanted to bow, even though I reinforced them longitudinally with thick styrene strips. I mean, it's not a huge bow, but it's a bow nonetheless. The only way I could prevent against further bending was to glue the four walls to a base--ABS, I think--forming a box, which is further reinforced by the ceiling and the roof. Kinda like a racing car monocoque body.


My feeling is that once you attach the cab walls to the floor and roof, there will be less of a tendency to bow. I think...


But then, I know jack about the properties of plastic./DesktopModules/NTForums/themes/mls/emoticons/tongue.gif


 


 
 

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Scot...there is an article in either the current Garden Railways or the current Model Railroader regarding the use of adhesive film to glue sheets of plastic together. The film comes in rolls....is very thin...and has adhesive on both sides. You lay it onto one part....then cut around the part with an Exacto blade to trim off the excess. Next you remove the protective layer...and stick it to the other piece of plastic.

This product is used extensively in the automobile and airplane construction industry. Look for the article. I couldn't find it online as the issue is too new.
 

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Hmm.

No. I thought I had an explanation, but if I was right, they'd be curving the other way. What did you use for adhesive?
 

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Discussion Starter · #6 ·
Posted By Torby on 01/05/2008 1:13 PM
Hmm.

No. I thought I had an explanation, but if I was right, they'd be curving the other way. What did you use for adhesive?


 


Torby, im using Ambroid Pro Weld. the container says: Professional Plastic Welder For Styrene, Butyrate, ABS & Acrylic It doesnt really have a complete list of ingredients, except to say "Contains methylene chloride" The curve is toward the "front".


in this picture:


 





 


Imagine the center of the cabs nailed to the wood, and the 4 corners bending upward.. thats the direction of the curve. thanks, Scot
 

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Posted By altterrain on 1/5/2008 12:35:13 PM
Subject: RE: Styrene warping.
Message: Was that Jack Verducci's article in the Feb GR using double stick tape?

-Brian

I don't recall if Jack wrote it.  But it had a photo of a wide roll of tape...say 8" wide...and two smaller roles of which one was red.  This stuff is really thin and is designed for laminating.  I just recall it's the current issue of either GR or MR.
 

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The article Mike mentions is indeed in Garden Railways, February 2008. And it is by Jack Verducci (see Mike, yer two-for-two so far!).:) It's in Jack' s column, "Garden Railway Design & Construction, " page 93. He calls the stuff "Killer Red" and its made by Bron Tape. Jack writes that another supplier is Johnson Plastics, which refers to it as "pressure sensitive adhesive."


Couldn't you guys just buy the dang magazine and save me all this typing?/DesktopModules/NTForums/themes/mls/emoticons/plain.gif
 

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This happens with wood if you don't follow the golden veneering rule; "do the same to the front that you do to the back". I'm surprised that it happens to styrene though. I built a cab of styrene, but the difference was I did it in 3 layers so that the front and back looked pretty much the same. It wasn't to prevent warpage because I thought plastic was too stable, but I imagine that it might be the glue that is contracting, so if you use 3 layers they should cancel out.
At least, thats my theory
 

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If you read the article in GR Jack credits a guy for referring him to the Bron Killer Red tape.  I am that guy. (though they misspelled my last name )  /DesktopModules/NTForums/themes/mls/emoticons/crazy.gif  This tape is an incredible material.  It is SUPER STRONG.  It is an industrial product generally not sold to the public.  I have used this material professionally for years as a museum model fabricator.  They will sell to anyone but I believe there is a minimum order.

Killer Red is actually a copy of a 3M product called VHB which stands for "very high bond".  The tape is very thin-- unlike traditional foam mounting tapes.  It is water clear.  The red color is actually the separator film that protects the adhesive.  The adhesive is water resistant.  It works best on smooth, non-porous materials like plastic, but I have used it on wood as well.  I use this stuff all the time.  It works well for laminating layers, making jigs, "clamping" parts temporarily while you drill for fasteners, etc.  I use it on nearly every project I make.  It has changed the way I fabricate things because applying adhesive can be fast, clean and the bond is instantaneous.  I highly recommend this product.  It isn't cheap though--  a 3/4" wide roll will set you back about 35 bucks.  The rolls last a long time.  Narrower widths are available all the way down to 1/4" and they are cheaper.

If there are any other questions feel free to ask.  Russ Miller is also familiar with this material.

Regards,

Eric Maschwitz
 

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Does styrene have a grain? (I know Mylar does).

I wonder if your top and bottom layers are 90 degrees apart.

I think we need Fletch or some top modeling expert to chime in here.


I love your "Ministry of Silly Walks" avatar. That guy is a master/DesktopModules/NTForums/themes/mls/emoticons/laugh.gif
 

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I've also seen this warping happen with plastic weld glues, but not really sure what causes it.


Don't forget these plastic "weld" type glues will disolve the outside layers of plastic that it touches, so when you put the parts together, the slurry (for lack of a better term) mixes together, and then dries together bonding everything.  Maybe this slurry is expanded and when finally dries, shrinks up a little causing the warping.  Not sure, just a thought.. 


-Ray
 

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I would speculate that the styrene is not warping, rather the glue is shrinking between the two pieces and causing them to bow as a result.
 

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Discussion Starter · #15 ·
Thanks for the ideas everyone..

I belive the warping is the result of using too much glue..I really slather it on to get those nice welds!
Posted By rkapuaala on 01/06/2008 3:46 PM

I would speculate that the styrene is not warping, rather the glue is shrinking between the two pieces and causing them to bow as a result.


 


 




yeah..thats probably part of it too..
I read somewhere (probably one of fletch;s masterclass articles) that if you try to weld wide pirces of styrene together, watch out about getting liquid glue trapped in the middle of flat pieces..because its not exposed to the air, and it cant properly dry out..my warping problem is most likey a result of:

1. overall piece is small
2. very thin pieces of styrene..1mm and 0.5mm,
3. gluing wide flat section to other wide flat sections.
4. gluing flat panels to only one side, and not the other.
5 glue not able to dry inbetween the wide flat panels.

or just one, or two, or three, in any combination.

I dont think im going to repeat this particular piece right now..so I wont be able to report the same cab walls if using less glue.
but im sure I will build something sililar at some point..I think the main "take away" as they say is "too much glue"..dont more than in needed for the job.

Scot
 

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Scot,
I've had some success with weighting a piece like this that I thought was going to warp. Even where I used to work where we used VHB tape to glue laminate tops to sheet metal cabinets or safes we'd weight it down to improve the adhesion.

The warning with using a weight would be that the parts tend to "slide" then. Sort of like dropping the boogie board on the last little bit of a wave on the beach and stepping on it. If you don't step directly down you'll slide a bit on the water. I've got a few scrap pieces from that reaction. Clamping gives the same type of "sliding results" if you aren't careful.

Chas
 

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I entered "Killer red" in Google and got a list of wine dealers./DesktopModules/NTForums/themes/mls/emoticons/sad.gif


However, "Killer red tape" identified some distributors. The tape comes in widths from 1/8" to 1" -- I did not check VHB to see if 3M makes it in other widths.


Mark
 

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This has been a BIG problem for me too! I've bought styrene in many places, from 4' X 8' sheets down to Evergreens small packages. Yes it warps, well sometimes!
My findings;
I never layer more than 2 layers at a time. I sand the surface in one direction right after gluing it together so it can breath till dry and ensure there isn't any air pockets. I line the plastic with a pencil and always make sure the lines go across each other when laminating. I now make my walls thick, 1/4", sometimes more! I have a habit of floating two sheets together, maybe too much glue.
I wish I knew the answer. Some stuff warps, some don't. I thought it was sunlight. I thought it was change in temps. I wish I knew how to and the tools to work with BRASS.........
Little Paulie
 

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I have had various problems, including warping, when using solvent type glue. When laminating surfaces I use CA glue rather than solvent type glue. I use a surface plate or piece of plate glass to set up the parts on and then wick in the CA and follow with zip kicker. Works for me in making styrene patterns in the past.

Jack
 

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Hi Jack, maybe I should say Jack, hi ? CA glue, Zap-a-Gap ?
question; can this be spread out, on say 2 sheets 4 X 8 inches ? What do you use to spread it ? Should the styreen be sanded first ?

Little Paulie, with lot's of questions!
 
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