Week 10:

Molding and casting:

New week with new thing to learn and try , this time I have to make some thing I like using molding and casting process , and because I like medals , I decided to make one ,

I started to design my medal on fusion , I got my inspiration from world skills 2015 Sao Paulo,

so I designed my medal to be close to it, by using Fusion 360 , that i started using it in week 3 , I used a simple tools , to design my medal , of coarse in the skitch I a started with a circle and a lines , when i want to turn it in a 3D model I used extrude.

Draft angle :

I have been read a bout the draft angle and try to get more information about it to decided wither I use it or not , after reading this Page, I decided to not use the draft angle , because I will not use the injection method , I will pour the resin and the material that I will use it will not be too hard to eject .

so after designing I have to make my mold on wax using srm-20 CNC machine from Roland that I explained how to use it in week4 , however I used Roland SRP Player , to create my tool path, and by operating V Panel and setup the machine and putting the wax I started to cut

1-First I choose the orientation of my design so the part that I want to cut will on the top, then I set up some options that SRP player offer , like type of milling , how I would like my surface finishing look like , is my model have a lot of curves or not , and the last option is to choose geometry , do you want to cut only the upper part or up and down , for my side , you can see in the pictures below the options that I chose.

Modeling wax is the material that I used to make my medal , so after choosing the material , I should specify the dimensions of it , after choosing the sizes of the raw material , it will show the whole material that you got, it shown in the picture below , now after setting the material and the size of it, pressing the toolpath to create the path of the cutting tool but,

before selecting the create tool path button , we should go to the edit to edit our parameters , and now we have two operations or process we are doing the ROUGHING and FINISHING , so on the editing , we are able to choose the tools that we will use on our ROUGHING or FINISHING process, from my side I choose 1/8 ball mill bit in both operations , the reason that I used it , I have a little small details on my medal , and I want it to be catted on the right way with right dimensions , and as shown in the pictures below , for ROUGHING cutting parameters I did not change the feed rate or the spindle speed , for the cutting amount is 0.6 mm per cycle , because we don’t want to go to deep that may cause a damage of the tool or the material , so for the cutting amount it depend on the tools that we use and the material , however we leave a 0.2 mm margins that we can cut during FINISHING process , to get nice and smooth surface , so for the FINISHING process, I kept it the same spindle speed and feed rate , but the cutting amount is 0.2 , as I mentioned before I left a margins in the ROUGHING process of 0.2 , so in this process will be only on cycle of cutting , and for sure in the FINISHING process I don’t need any margins left in my part so I leave the finish margins as 0 mm .

After choosing the tool and setting all the parameters that I need , I will create the tool path , after generating the tool path you can check the time estimated to finish cutting , preview and check on your tool path , so if you are confident and happy from the preview you can start cutting , from my side I chose to save it as output file so I can initiated on Vpanel easily by using other laptop, however before I got the file there is one step I have to do , I should choose my zero point or my reference point . then it will save as prn file extension.

however , I did my all measurements to make sure that the drill bit will not hit the wall and the depth of cut will be enough , and everything run smoothly , and I believe that the finishing was brilliant.

and now is the time to make my mold from the silicone , and I choose Dragon skin 20 , after reading the datasheet , I am able to use it.

there are part A and part B and the mixing ratio is 1:1 I used almost 50 grams in total which mean 25 grams for each part ,however after mixing it , it is time to pour it steady and nicely , as shown on the data sheet the curing time is 4 hours , so I pour it and I came back after the 4 hours

so far so good , I am on the right way and my mold is ready , to cast on it , and I have to choose my casting substance , so I chose the smooth-cast 327 , with mix ratio 1:1 and the curing time is 4 hours as well

after mixing the part A and part B to gather and adding a brown color which was the available one , I started to pour the resin , but I was fast

Because I was fast the bubbles form on the top

after 4 hours my medal is ready now ,

Fusion File , STL File