Guide – A One Part Mould

Below is a guide which details how I went about making B5100 resin figure.

Here we go:

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B5100 begin as an idea based on some characters I had created for my final major project on my Product Design Degree. ‘ED-IT’ (see photo from 1999 above) was a concept for an interactive musical platform with a handheld recording device, that children would use to experiment with sound.

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I worked up the B5100 design in Illustrator, then looked into ways to create a master model for moulding. I didn’t have access to a fully stocked workshop as I did creating ED-IT at Uni, so after looking into methods to get the crisp and smooth feel I wanted for this figure, I decided the best way to achieve this was to look into getting the parts 3d printed.

3.

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After a couple of hours of researching companies which offered 3d printing services, it seemed that to even get a quote for the work they had to look over a file outputted from a 3d modelling program, and luckily I had some experience with 3dsMax. I hadn’t really used 3dsMax for ten years or so, but due to my design using a lot of simple geometric shapes, I could figure out how to put the pieces together.

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Seeing as all of the parts in B5100 would be resin cast in a one part mould, and a few sections would be duplicated (one overall shape with two identical mirrored parts), I only needed to have certain sections 3d printed, thus saving costs.

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I sent out mainly.stl files to a handful of companies and got a varied range of prices back. I ended up going with a company called 3d Creation Lab who came back with the best pricing. I placed the order after they had confirmed my 3d file was all good to go, and a few days later I received a package in the post with my parts in all their 3d printed glory!.

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When the parts arrived, I could see that they had some lines either from the 3d printing process or from my 3d modelling, where I hadn’t taken the amount of sides high enough to give off a perfectly smooth finish. Whatever the cause, it didn’t take long at all to take some P600 fine grit sandpaper with water and achieve a nice smooth finish.

See some raw 3d printed parts below:

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The front and back ‘head’ sections after a few minutes of sanding.

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Included in the design are two audio devices which (in the fiction) B5100 would use to create music. These two parts I didn’t have 3d printed, instead, I had these cut from 5mm acrylic sheet. The total height of these devices are 10mm, so I had the lines milled 1mm deep into the top 5mm portion, and then I glued that to the bottom 5mm portion to create the overall height.

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Once I had finished all of the master parts, I then needed to plan out the size of the moulds, and work out how much silicone rubber I would need to make them all.

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After working out the size of the moulds I knew I would just under 2kg of Silicone, so I ordered a 2kg set from Tomps.com.

The next thing to do was to create the mould containers. I had some 3mm Foamex left over from other projects so used that.

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I then started to apply a thin bead of clay around the edges of the components, on the side which would go face down in the mould. The clay allows you to position the piece and give it a good seal, which will stop any silicone seeping underneath once poured. When you press the parts down, some clay will press out around the edge, but this is easily removed with a scalpel or a similar tool.

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Once all of the parts were attached with the clay, (make sure to take your time on this part and double check for any gaps) I then built up the walls by using a hot glue gun to stick it all together. The hot glue gives a good seal, which will stop the silicone from seeping out. The glue (when nice and hot) is also easily smeared around and pressed into any offending gaps.

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It’s Silicone time!. I used a RTV Silicone rubber from Tomps.com with the slow catalyst (40 min pot time & 24 hour cure time), as I needed a longer pot time to pour four moulds. They also offer a fast catalyst which has a 10 min pot time and a 4-6 hour cure time.

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I was using all of the 2kg Silicone kit in one go, so I added all of the catalyst and got mixing. You will see that the catalyst has a blue colour to it, so once added to the white silicone you will need to give it a good mix until it is perfectly blended.

15.

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I don’t have a vacuum chamber, so I couldn’t degass the silicone to get rid of all the potential air bubbles. If you are careful with the pouring and go for the ‘thin stream in a corner of the mould’ technique, and let the mould gradually fill up, you will pretty much be ok.

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I left the moulds to set for around 18 hours and they seemed ok for demoulding, so I tore off the walls and took a look…

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All of the pieces moulded pretty well, so it was just a case of removing them all and making sure any clay traces had been cleaned up.

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This is the Fast Cast Polyurethane Resin I used from Easy Composites, it’s a 1:1 ratio of each part.

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I use digital scales to measure out the portions of each, and then give them a really good stir to make sure they are blended together.

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I usually part pour into a mould which has areas where air bubbles could occur, then take a tool with a fine point and mix around in that area to release any which may be trapped.

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I always overfill by a tiny amount to allow for any shrinkage with the resin (which usually occurs).

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After 25 mins, the resin has set and I removed the parts from the mould.

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I find that cast resin parts can have a slight residue on the surface, so I like to give them a quick rinse in soapy water as the next step.

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Once the part has been cleaned, I then carry on using the sink to sand the side of the resin which was ‘open’ in the mould. Due to the shrinkage etc the resin will rarely have a perfectly level finish, so a quick sanding using some wet & dry 400 grit gauge sandpaper will take it down a nice smooth finish.

I then use a finer 600 grit version to give the entire body of the resin a light sanding.

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Here are all of the parts for the B5100 resin.

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A B5100 built out of unpainted resin parts.

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I then give the resin a light coat of white primer, and take a good look around each part for any air bubbles or defects which may need filling. If I do find any I just use a ready mixed filler and leave it for an hour or so to dry, give it a light sanding back and then chuck on some more primer. I mostly use acrylic for painting the parts, they usually take a coat or three to get a good opaque finish, but it all depends on how strong the pigment is.

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Once I’ve finished painting all the parts I then spray on a few coats of Clear Lacquer (from Halfords) to give the parts a slightly matt finish. Once the lacquer is dry, I go ahead and begin to glue parts together using a two part rapid epoxy adhesive (from Wilkinsons). The adhesive takes around two hours to set rock hard.

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Here is the complete B5100. The mixing desk is also made from Foamex, which is painted with acrylic and finished with some clear lacquer. The ED-IT logo is cut white adhesive vinyl.

Do take a look over at my shop for more ED-IT DJ’s – B5100 related goodness.

I hope you find this guide useful! Cheers.