06-29-2010, 05:25 PM
Josh, Justin is right. I am using corrugated styrene for my roll-up doors. You should have a close look at the corrugated styrene sheets. The both sides of the sheets I am using are different and the"backside" looks more like a rolling door than the "front".
To build some of my structures from Hydrocal was an interesting experience and the results are really convincing. They do look better than styrene structures, but Hyrocal structures take a lot more time to build.
Yep, that is exactly how I did it and I also used this method to do the doors. As far as I can remember I used .040" and .060" sheets to make the molds. Better make some small castings and put them together than making one big casting. The wall sections in the pic from my thread are about 6" long and they were easy to work with. For my second Hydrocal structure I made a 1' long casting and that caused some trouble. The casting will bend upwards in the middle when it is drying. I had to break the long casting into three pieces and put them together again to get a straight wall section. You can put some heavy weights on your molds to prevent that, but I think it is easier to make smaller castings. 5 minute epoxy works perfectly to put castings together or to glue castings to a cardboard sub-structure. White glue works as well, but it takes much longer. The nice thing about working with Hydrocal is that you can always use plaster to hide joints, make windows fit perfectly or just to hide flaws.
That is what I used. On the box it says that you should mix 2 1/2 parts Hydrocal with 1 part water – well, that did not work for me. The castings I did with this mixture were all very hard at the front (the bottom of the mold), almost like ceramics, and so soft at the back that it was impossible to glue them to cardboard. Air bubbles were another big problem. When I changed the mixture to 3 parts Hydrocal and 1 part water, these problems did not occur, but you have to work this thicker mixture into the mold using a stiff paintbrush.
I am not sure if building Hydrocal structures is the way for you to go. They do look fantastic, that is for sure, but they are definitely not the best and absolutely not the easiest way to go. If you want to get some good result quick and easy, use styrene. It is cheap, it is very easy to work with and you get good results in no time.
Another thing you should bear in mind is that you are building modules and not a permanent layout. Styrene structures weigh much less than Hydrocal structures and they are much easier to handle, as Hydrocal breakes easily.
To build some of my structures from Hydrocal was an interesting experience and the results are really convincing. They do look better than styrene structures, but Hyrocal structures take a lot more time to build.
Quote:Now when you did your plastic mold, did you start with one sheet and then just stack sheets on top of each other to get the raised features?
Yep, that is exactly how I did it and I also used this method to do the doors. As far as I can remember I used .040" and .060" sheets to make the molds. Better make some small castings and put them together than making one big casting. The wall sections in the pic from my thread are about 6" long and they were easy to work with. For my second Hydrocal structure I made a 1' long casting and that caused some trouble. The casting will bend upwards in the middle when it is drying. I had to break the long casting into three pieces and put them together again to get a straight wall section. You can put some heavy weights on your molds to prevent that, but I think it is easier to make smaller castings. 5 minute epoxy works perfectly to put castings together or to glue castings to a cardboard sub-structure. White glue works as well, but it takes much longer. The nice thing about working with Hydrocal is that you can always use plaster to hide joints, make windows fit perfectly or just to hide flaws.
Quote:Would Woodland Scenics Lightweight Hydrocal work for casting?
That is what I used. On the box it says that you should mix 2 1/2 parts Hydrocal with 1 part water – well, that did not work for me. The castings I did with this mixture were all very hard at the front (the bottom of the mold), almost like ceramics, and so soft at the back that it was impossible to glue them to cardboard. Air bubbles were another big problem. When I changed the mixture to 3 parts Hydrocal and 1 part water, these problems did not occur, but you have to work this thicker mixture into the mold using a stiff paintbrush.
I am not sure if building Hydrocal structures is the way for you to go. They do look fantastic, that is for sure, but they are definitely not the best and absolutely not the easiest way to go. If you want to get some good result quick and easy, use styrene. It is cheap, it is very easy to work with and you get good results in no time.
Another thing you should bear in mind is that you are building modules and not a permanent layout. Styrene structures weigh much less than Hydrocal structures and they are much easier to handle, as Hydrocal breakes easily.
Kurt