Doorstep climber - New Tracks part 2
Learning from our previous mistakes is a big part of rapid prototyping, so once again we went to improve the tracks for our track system.
We didn't change much about the model, although we took extra care on feeding it to the shop-bot computer.
What we did change was the material in which we would carve the model for the mould. This time we used machinable wax.
To get the whole mould in one go we needed to melt down some wax bars, and pour it into a container with the size of the bar that we needed.
These bars where put on the shop-bot and then we let the machine do the talking.
We also decided to switch materials for the mould. This time we made them out of silicone based rubber, which should prove to be less adhesive to the pu rubber which we still where going to use for the tracks.
These moulds turned out pretty nice, so we decided to get casting as soon as possible. Since needed to cast several pieces of the tracks before we could make one complete tire-track, we wanted to make a device that could be reused several times, and that wouldn't have to be taped together. So we came up with the idea of two planks with 6 screws and bolts. The Mould would fit between these planks, and with the use of the screws and bolts it was possible to apply pressure where necessary.
At our first try we scooped the mixture of rubber into the mould. But the same problem we had at our previous try occurred again.The casting time was too short to fully fill the mould.
This try also produced a small part of the track, so we thought of a solution to get the mould filled up completely. Feeding the rubber to the mould in a steady stream and in small quantities proved to be the solution.
After a curing period of 48 hours we could finally open up the mould to witness the first complete part of the track.
