# its a Cyn

## Molding and Casting

Assignment: Design a 3D mold, machine and cast design.

 Final cast with Smooth-on 325 click image to enlarge

### 3D image

#### Character design

Used Rhino3d to draw character within mold box.

1. Character should have strong corners perhaps deeper then looks good in a render. This character's antlers weren't thick enough making them very weak with some of the casting materials.
2. Draw a complete character, place in box, add long cylinders for mold matching pegs, then finally add plane through center and do a number of Boolean2d to make the front and back of mold.

### ShopBot

Material used for mold was Machinable wax

#### PartWorks 3D

Preparing design

1. Save drawing as a STL
2. Open PartWorks 3D on ShopBot
4. Enter units and tool size because STL file does not contain units
5. Enter scale, for example, 70%
6. Enter material size
7. Set zero on surface that isnt moving
8. Rough cut
Tooling: 4 (four) fluted .125 inch endmill
Cutting Parameters: Passdepth: 4.0, Stepover: .635, SpSpeed: 12000, Feed: 60, Plunge: 10
Toolpath: Rapid: 2.0 mm, M-Allow .5, ZLevel: Raster X 4.0
Finished cut
4 (four) fluted .125 inch ball endmill
Cutting Parameters: Passdepth: x.x, Stepover: .xxx, SpSpeed: 12000, Feed: 60, Plunge: xx

### Molding

#### Example calculation:

1. Using PMC® -121-30 Dry - Easy To Use Urethane Rubber
2. h * w * d = VOLUME (rubber needed to make the mold). Then divide the VOLUME by the specific volume yield of the mold rubber (constant 963 cm3)
3. (h * w * d)/ 963 cm3 = Weight in kg of PartA and PartB need to make mold
4. (8.8 height x 9.0 width x 2.0 depth) / 963 cm3 = Approximate Weight of Product Needed 0.16 Kg of Part A and 0.16 Kg of Part B

#### Other calculation options:

Smooth-on has a free iPhone applicationto calculate how much PartA and PartB you need.

Smooth-on has the same calculatoron their site

Smooth-on has an explanation of this calculation on their FAQ

### Casting

Experimented with different casting materials

Hydro-Stone
Plus: dried quickly
Minus: too thick to pour in molds small holes
Smooth-Cast- worst results.
Plus: Quick curing time, minutes!
Minus: Ruined my mold.
Crystal Clear - best results.
Plus: Easy to pour. Colors can be added.
Minus: Long time to cure 16+ hours. Shrinks.
Final cast with Smooth-on 325
Plus: Easy to pour. Colors can be added.
Plus: Cure in 20 to 30 minutes.

### Lessons Learned

Mold design: While designing mold think how the cast material will flow into the finished mold. Place pouring holes to allow the best flow of casting material.

Wax is brittle a small piece of the design broke off, for example the characters nose. However the finish pass had enough to cut a small nose.

Know what end-mills are available before creating file in PartWorks. The 1/16 inch ball nose end-mills had a 1/4 inch shank that would have skimmed the interior of mold therefore making it unusable for my design.

End-mill stick out was to short rough end-mill kissed the top of the material when doing the peg holes.

Amount of mold release should be light spritze which is then brushed with soft brush, a few minutes later a second light spritze.