Steps to Casting Models

So this post will look at the process I take from designing my pieces in Solidworks to preparing the model for cutting and then assembling the model ready to be casted. The process is very lengthy but I enjoy being able to alter my designs bit by bit instead of hand building in clay and having no real control or exact structure.

I begin my designs with a recognisable vessel form. I draw out the profile of the form in corel draw and import it into Solidworks, this is then revolved into a vase form to see whether the size is correct. I then go back into Corel Draw and break up the vase profile into 5mm wide layers ready to be revolved in Solidworks again. Creating this piece gives me a form to work around with the bubbles in an assembly.

I use 6 different sized layered bubbles in my assemblies in Solidworks and I match up the layers to create full, flat slices. Once I've adjusted my designs after hours of test pieces I save my assembly as a part and combine all the bubbles together so that they can't be moved, from here I cut extrude the model layer by layer and take a sketch of the layer, save it as a DXF file and import it to Corel Draw where its numbered and ready to cut. 1 file is shown below the vase takes up 3 x 500mm by 500mm pieces of perspex at 5mm thick. I use the company SHEET PLASTICS to order my perspex, If you buy through EBAY with them you can usually get free postage, especially with the clear perspex, at £11.40 a sheet it can be costly to design the models but once the mould is done it can cast up to 100 vases.

Once the files are done they can be laser cut, each piece takes around 20 minutes to complete, I use my universities machine at the moment but I have been quoted around £15 for a sheet if I were to cut outside of university. Below is a video of my vase being cut on the laser cutter, it isn't the fastest machine but it gets the job done much faster than I could do on a band saw.

 

Once cut I have to use my stanley knife with a sharp blade and scrape away the melted edge the laser cutter leaves on the layer before I glue it together as I dicovered while making a mould that the edge causes the model to get stuck. Scraping away the edge also stops the plaster seeping in between the slices which also causes the model to get stuck and nip away the sharp edges. This process takes around 3-4 hours per model but once it's done I can start gluing. I use technicqll glue which is specifically for perspex, it bonds the perspex strong and dries clear. 

Once the model is assembled I begin to turn a spare for the base and a pouring hole on the lathe, and line up my model to work out where the parts will be on the mould, ensuring that they are even as possible. I took a lot of time on the moulds making sure that they were as neat and tight as possible, that way you can make the most of your mould and it is easier to clean up once you slip cast.