I have spent two days this week preparing the slip cast mild for my goblet. Because of the undercuts in the piece I had to make a mold with five sections so that I will be able to remove the piece after casting.
First I marked out on the print where I would build the walls out to make the mold. Or essentials where the seems would be. After marking out two sections it quickly became clear that 3 walls were needed in order to get the piece out of the mould.
I covered two thirds of the piece in clay leaving just the third visible that would be cast first.
I then smoothed out the clay walls.
I clamped wooden walls around the piece, filled any holes with clay and poured in plaster.
Once dry I took apart the mold and cleaned up the plaster a little. The I drilled in a half dome so that the next part of the mold would lock in.
I washed the plaster three times with soft soap. This was wiped off with a sponge and would keep the next plaster pour from sticking.
I then built the second wall and built up the wooden boards.
This was the result of the second pour after removing the walls and clay.
The process was repeated a third time to create the third wall.
This is the three walls completed and the process took about seven hours to get to this stage.
The top of the mold was then planed back.
Lock holes were drilled into the three walls at the top.
I then built walls around the mold and sealed for the pour.
This process was repeated for the bottom.
The five parts were then planed into one nice block.
This is the final reveal as I took out the 3D print.
The mould has now been placed in the drying cupboard and will be ready to use hopefully in three days time.
Over the last weekend I cleaned up and polished my first button for the cushion cover. I cut off the spru from the casting process and then drilled the holes that had closed up. I used my small jewellers archimedes drill to make the holes. I probably should have used an electric drill however this is what I had to hand. As the metal was so thick I ended up getting blisters on my thumb and fingers. This is a good example of using the correct tools for the job that would have less stress on the human body.
I used my jewellers saw to cut out the holes to shape and the filed these down.
I filed and sanded the back of the piece taking it up to a high polish.
Today I 3D printed some handle ideas I made in CAD a few days ago. They are designed around they way honey is found in cliffs in the wild. I was thinking that it would be good to have slightly different handles on each cupboard so as they are all unique and will also emanate the differences in form and shape in the wild.
I decided I wanted to smooth down the 3D prints before casting to see if the final sand casts would also be smoother. I placed the prints into a container with acetone in and a covered lid. I drilled small holes in the prints so I could stand them on a nail in the box elevated above the acetone. When I checked them after an hour there was little change to the prints. I added a little more acetone and left them for another hour. I noticed that some areas had smoothed out and others hadn’t. I tried balancing them on their side in the container and left them for another hour. When I got back some areas had smoothed out too much and other areas still hadn’t.
The smaller of the two prints was very melted and bendy at the end. I think I will reprint them and try using the acetone on a hot plate. I have watched video’s on this and it seems to only take ten minutes at the correct temperature. I think this may have a better effect in smoothing down the entire object.
Today I finished making my CAD model for an idea I had for buttons to finish off my crochet cushion covers. I designed this one around the same ideas as the table I am going to have in my client area. The print took about 30mins to finish building. The first model I made I Boolean differenced the button holes and then twisted the object. I rectified this earlier today to have straight differenced holes so that the casting process might work. This still didn’t cast the way I had planned. I decided that I am going to redesign the model so it is more like a T-bar that I can sew on to the cushions as this way the casting process will have a better chance of working.
I am going to finish off this button although there is a lot of cleaning up do on the underside. I was originally going to cast this in to aluminium; however there was pewter available in the workshop which I have never worked in before so I decide to use that. The pewter melts much easier than aluminium. The crucible was already hot from previous use and the pewter melted like butter without a flame.
One element that I particularly like about this process and the result from this test is the fact that the final button has a texture on it that makes it look like it has been cast using carved cuttlefish. This was the result of the resolution of the 3D printer and the layer size in the build.
Start of the first section of the sand mould. I compacted the sand with the handle end of a mallet.
This is the 3D print I used to cast.
The first half of the mould before carving out a hole for the print.This is the print placed in the mould with the sand compacted around it.
The first half of the mould with talk on to allow the sand to be separated.
The second part of the mould added and the sand compacted on top.
The mould is then taken apart and I removed the print.
I added a hole into the sand to pour though.
This is the mould after the pour.
The mould taken apart.
And the final reveal of the cast which I will now clean up and drill.
I have decided that as a little tongue and cheek I will add a rat handle to my rat brain cell colander. When I thought about it last week I had a giggle to myself about having a rat hanging on my wall and watching me whilst cooking my pasta in my shipping container. The rats tail doubles back to allow it to be hung from the wall. I have spent a few days modelling this and I still need to finish off the bowl and think about how I am going to attach the rat handle to the bowl. I want to try and stay away from using artificial chemical bonding (aka glue), I may add in holes that I can try and plastic weld the two together with my 3D doodle pen. My other idea is to try and make a clip out of the handle that the hands will attach to.
i got my 3D printed resin jig back a few days ago. It has been nearly ten years since I printed my last jig on the SLA resin machine at RCA. This one was printed on a much more modern machine called a form lab which can print in various types of resin. My model had to be scaled down slightly to fit the bed size of the machine. The result of this has been that the tube sizes were too small and closed up making the jig unusable. Although it looks great as an object I will need to rebuild this in CAD.
I got my 3D prints back today of the goblet and tumblers that I will be slip casting into clay.
I am very happy with the scale and weight of the goblet. The tumbler is a little larger than I had expected. It is about the size of a pint glass. I may end up slip casting this and then making a smaller version as a tall glass size.
Today I have managed to finish one side of my cushion cover. Only another 11 to go! While I was making this piece I noticed my hook was occasionally snagging the wool making the piece less tidy. I have decided I am going to reprint the hook in ABS plastic as apposed to the PLA and then smooth it down afterwards using acetone. This will also give me the opportunity to make the handle a little larger. I was constricted by size on my last print because of the size of my home print bed.