design

My little sister likes to cook and makes things a lot so we have a lot of molds at home. She makes chocolate in them and stuff like that in a lot of shapes

i decided to make a mold for my sister. i dont think she can use it for chooclate because that wont be safe but it can be used for other stuff. i used the design software tinkercad. It is a very simple software to use and i was trying it for the first time. it is so simple and just drag and drop parts.

I made a small teddybear panda and a star becuase i though my sister will like it. I made it from drag and drop things to the page and resize.

After i made the design since it will be in mold it needs a flat bottm so i removed bottom part of the design to make it flat.

i am milling on machinable wax on very small block (32 mm * 80 mm). I had to resize to make it fit in the block

download stl

Link to design file tinker

machining

I milled the design on modella srm 20 machine. Same machine i used to make pcbs. There was a lot of options for tools to use with the machine in the lab.

Software i used is called SRP player and i can put stl file in it and it makes path and sends to the machine. Its a good software and simple but i found out i can use only one tool for roughing and finishing so i had to use the smallest one possible for good finishing. Smallest one in the lab is ¹⁄₆₄ inch but thats too small so i used ¹⁄₃₂ inch tool.

The software is weird i have to zero the origin point in the middle of the piece but i did that and started milling. it took 2.5 hours to mill the whole thing.

problem

Problem i found in the milling is that the software doesnt make a slope for cutting (its not advanced software) and thats better for the milling becuase to mill the bottom the top of the bit touches the sides and makes the wax move.

mold - silicone

Mold material i am using is Silicone Plastique which is a mold putty that has the consistency of cookie dough and is very easy to mix and apply. And is food safe and dries very fast. i know the mold i make isnt going to be food safe because the wax it will be on is not food safe plus it is kind of old.

link

safety

This mold material is very safe. It is food safe. It can be mixed with hands without using gloves or glasses.

mixing

I used 14 grmas of part A and part B of the mold by weighting them on sensitive scale

I mixed both with hand until i had one color. Then put it in the wax and left it to dry. This kind of mold material has to be applied in layers for best results. I made two molds to experemtnt on them. It took 1.5 hours to dry

cast 1 - wax

I found sticks of wax and wanted to see if i can use them for the cast. They are solid and i melted them in an electric oven in an oven safe container. The material is not meant for casting but i decided to try it.

safety

Handeling the oven requires oven safe container and oven safe gloves and keeping an eye on it to make sure it is melting okay with not problems. I wore oven safe gloves the whole time.

casting

It took longer than i expected to melt. I dont have data sheet to check exact material but it took 20 minutes to melt in 200 degree C in the oven.

It took 1 hour to solidify and to get the cast. It isnt a very clean pour but the material is soft so i cleaned with cutter

cast 2 - epoxy

For cast 2 i used Alumilite’s Amazing Clear Cast material. It is a clear casting and coating epoxy that cures to a rigid, durable, clear plastic. Has part A and part B and need to be mixed in equal ratios.

page
tech data sheet
safety data sheet

safety

I checked safety data sheet before using (linked above) and it said that this material causes skin irritation, may cause an allergic skin reaction, causes serious eye irritation and to avoid inhaling.

I used safety gloves, goggles and breathing mask to avoid it getting on my skin, eyes or to inhale it and did the casting in well ventilated area

casting it

I measured equal amounts of a and B part in seperate cups.

Then mixed together and poured in the mould

design 2

I made a second design for a mold for my final project . It is what i wanted to do at first but then i didnt have enough machinable wax or enough time to do it. I designed it using solidworks. It is a 3 part mold. The other design was 1 part, normally molds have 1 or two parts only but for the complex shape i want i need 3.

This is the design download solidworks
download STEP