nygma
Registered
I wanted a project with is rather simple in terms of skill set and tools required. I knew that buildings are something I would rather not spend money on, so I decided to build one. To be close to prototypical I decided to build from concrete. Also I wanted the process that is repeatable in case I would like to build more of the same type. After all how hard can this be?
I decided to do the following: build a box as the outer contour of the building. Build a smaller box which will go inside. Space between the two will form the base of the building and the walls. I decided to place the two 3 cm apart. I also got some 3 cm wide timber which was cut to short pieces and placed between the boxes. These create a void in the cast for window and door openings. These window and door placeholders and fixed to the outer box with screws from the outside. By unscrewing them I can disassemble the mold leaving the placeholders in the concrete to be push out from the opening.
All this is reusable as I can assemble the mold again and cast another building. Also if I fix the placeholders into different position (and different sizes) I will get a building with the same overall dimensions, but still a different design.
First stop was to the DIY store to get some ready mix concrete, offcuts of wood, some timber and screws. The first model is going to be HEV class 3 station building which was used in many branch lines around Hungary and the neighboring countries. Plans for this building is available online from vasutallomasok.hu. Scaling down the drawings to 1:32 took just an hour. Each elevation fits on an A3 size paper.
It took a few hours to cut down the sides with a jigsaw, chop up the timber for door and window openings, make everything up and screw the whole together. I drilled the holes for the screws to make sure I don't break the timber. I was not very precise with drilling them and some of the window openings are off from vertical, but concrete isn't a precise material either, so I am hoping that I can hide these imperfections later.
This is the outer box with the placeholders in place. The one on the bottom will create a hole in the base for electrical wiring.
And the inner box in the shape of the roof.
Finally the first batch on concrete mixed, ready for pouring into the mold. The inner box is not inserted yet, I wanted to see how the concrete spreads on the base. Before casting I painted the entire mold with cooking oil as release agent. That was my best guess, and there was nothing else around.
And finally, all concrete in. I had a 25kg bag and only a few kilos left. So this is going to be a heavy building. Maybe in the future I should think about going down to 2.5 cm thickness. My son did not help with the project, but was there to take credit. While the walls were cast I used a watery mix making sure that the concrete flows into the cavities easily. I tried shaking the entire mold as much as I could also to help this. Finally, when it was up to the sides I used a piece steel rod to vibrate the concrete. That's all I could do. Since the walls are already 3 cm thick I thought it gives it enough structural strength and I do not need steel in the structure. Will see.
To complete the triangular shape of the end walls, I prepared a final and drier mix. It was hand form against the mold and stayed like this without any further support. I though this is going to be the most difficult part of the build, but it was easy.
When it was all done I left home only returned a couple of hours later. When I checked the mold I saw that screws let go and the mold opened on two sides to about 0.5 cm. The screws I used were just too short and broke free. The concrete was still wet. I poured more water on it, push the sides back and fastened with a longer screw. I used an electric screwdriver which has enough torque to bring the sides together again. Fingers crossed the concrete is going to heal and forge completely after all. I am going to wait for a day before I break the mold.
I decided to do the following: build a box as the outer contour of the building. Build a smaller box which will go inside. Space between the two will form the base of the building and the walls. I decided to place the two 3 cm apart. I also got some 3 cm wide timber which was cut to short pieces and placed between the boxes. These create a void in the cast for window and door openings. These window and door placeholders and fixed to the outer box with screws from the outside. By unscrewing them I can disassemble the mold leaving the placeholders in the concrete to be push out from the opening.
All this is reusable as I can assemble the mold again and cast another building. Also if I fix the placeholders into different position (and different sizes) I will get a building with the same overall dimensions, but still a different design.
First stop was to the DIY store to get some ready mix concrete, offcuts of wood, some timber and screws. The first model is going to be HEV class 3 station building which was used in many branch lines around Hungary and the neighboring countries. Plans for this building is available online from vasutallomasok.hu. Scaling down the drawings to 1:32 took just an hour. Each elevation fits on an A3 size paper.
It took a few hours to cut down the sides with a jigsaw, chop up the timber for door and window openings, make everything up and screw the whole together. I drilled the holes for the screws to make sure I don't break the timber. I was not very precise with drilling them and some of the window openings are off from vertical, but concrete isn't a precise material either, so I am hoping that I can hide these imperfections later.
This is the outer box with the placeholders in place. The one on the bottom will create a hole in the base for electrical wiring.
And the inner box in the shape of the roof.
Finally the first batch on concrete mixed, ready for pouring into the mold. The inner box is not inserted yet, I wanted to see how the concrete spreads on the base. Before casting I painted the entire mold with cooking oil as release agent. That was my best guess, and there was nothing else around.
And finally, all concrete in. I had a 25kg bag and only a few kilos left. So this is going to be a heavy building. Maybe in the future I should think about going down to 2.5 cm thickness. My son did not help with the project, but was there to take credit. While the walls were cast I used a watery mix making sure that the concrete flows into the cavities easily. I tried shaking the entire mold as much as I could also to help this. Finally, when it was up to the sides I used a piece steel rod to vibrate the concrete. That's all I could do. Since the walls are already 3 cm thick I thought it gives it enough structural strength and I do not need steel in the structure. Will see.
To complete the triangular shape of the end walls, I prepared a final and drier mix. It was hand form against the mold and stayed like this without any further support. I though this is going to be the most difficult part of the build, but it was easy.
When it was all done I left home only returned a couple of hours later. When I checked the mold I saw that screws let go and the mold opened on two sides to about 0.5 cm. The screws I used were just too short and broke free. The concrete was still wet. I poured more water on it, push the sides back and fastened with a longer screw. I used an electric screwdriver which has enough torque to bring the sides together again. Fingers crossed the concrete is going to heal and forge completely after all. I am going to wait for a day before I break the mold.
