Week 9 - Molding and Casting

Assignment  -  design a 3D mold, machine it, and cast parts from it

  1. create design
  2. mill wax on modella - select bit - set up wax on mill - use fab modules - set xyz - rough cut then finish cut
  3. make a mold from the milled wax
  4. cast final object from mold
Steps I followed and problems I had to overcome

I designed a tile in Inkscape using the robot face from my final project as a starting point and followed the tutorial Molding & Casting using Machinable Wax. I designed the tile using shades of grey (grayscale) to define the different heights. Black being bottom of the part and white the top, then exported as a .png image.  Save as STL file for 3D models and 2D save as PNG files.

 

My designs below showing the grey scales, the first one I changed as not enough grey scale. Second shows more grey scale to create depth and third shows inverted gray scale to make it easier for the 1/8th bit to access the detailed shapes. This did help and I managed to cut a successful mold.


                      facedesignfortile              facedesign2                face3



settings for make.path on larger scale design

settings


final settings below


settings_modella   settings


Mill the wax on the modella


Having set up the wax for milling I choose the bit. Selecting the appropriate bit I originally thought of changing to a smaller 1/32 as my pattern is detailed but having thought it through was unable to do this as the drill bit could not of managed the depth. Having chosen my drill bit an 1/8th inch endmill for the modella I used the Fab Modules and set x y z zero settings and checked my design would fit on the wax with a little extra space. I had to get the settings exact because my wax block was small in dimensions. At this stage I set my pattern to fit the wax block several times which became time consuming. Having scaled my design to fit the wax block and set xyz, I choose wax rough cut and went to make path.


At this stage I hit problems


At first I thought there was something wrong with my design but after lengthy problem solving and advice we realised the design was too small for the 1/8th inch bit and was why  some of the cutting paths were not showing. At this stage I inverted the gray scale ( see image above) to make it easier for the drill bit to access the more detailed shapes. This worked well for the rough cut.


At this stage hit another problem


When pressing view to to see the wax block the drill cut through the wax block unexpectedly and I had to hit the stop button. This was annoying as I lost all settings and had to kill the setting in terminal to reset. Having lost all the settings I did try to reset them but it didn't work. I have now used the first rough cut quite successfully to create a mold and caste. ( try not to turn the machine off between cuts as you loose the settings)


wax roughcut below

waxface    face

plaster




Things Learnt
I enjoyed this process and would like to experiment with it further. I was impressed by the quality of the wax mold made on the Modella but not by the time it took to cut!   I went on to make a mold and take a cast from the above. Knowing more about the process I would have chosen a different design for the tile and made it  double the size suitable for a 1/8th bit. Fit the design to the process.



I made another simple 3D model using the modella

RWwax



Files

face

face_inverted gray scale