UltiCast

Test mold #1 – PVA
17/10/2016
IMG_20161017_125534

  • Layer height: 0.2
  • Temperature: 215/210 °C [first layer/rest print]
  • Print speed: 60/15 mm/s [external/internal perimeters]
  • Travel speed: 130 mm/s
  • Wall thickness: .8
  • Width of nozzle: 0.4
  • Infill: 0% (It was hollow)
  • Buildplate: 60 °C
  • Material flow: 100%
  • Fan speed: 35-100% . disabled for first 3 layers
  • Support: No
  • Brim: No
  • Seam: Nearest
  • Retraction: 2 mm
  • Bottom layers: 2

Comments:
Material printed succesfully, however probably due to a too high fan speed, the outer and inner perimeter layer did not adhere. This resulted in a separation of the 2 layers since the fan cooled down the previously fed material too much, so the new material would not adhere properly. As this was the first test with the self-constructed Python tool which incorporates the slicing of the .stl file, calculate the volume of the parts, and assign the second extruder to feed accordingly. However this time, the offset for the second nozzle was improperly changed in the code. Additionally, the first extruder was not instructed to ‘retract’ the PVA, and therefore kept feeding the perimeter material due to the overpressure in the feeding system.
The bottom was also very thin and fragile.

Test mold #2 – PVA
17/10/2016
IMG_20161017_153453

  • Layer height: 0.2
  • Temperature: 215/210 °C [first layer/rest print]
  • Print speed: 50/15 mm/s [external/internal perimeters]
  • Travel speed: 130 mm/s
  • Wall thickness: .8
  • Width of nozzle: 0.4
  • Infill: 0% (It was hollow)
  • Buildplate: 60 °C
  • Material flow: 100%
  • Fan speed: 35-60% . disabled for first 3 layers
  • Support: No
  • Brim: No
  • Seam: Random
  • Retraction: 3 mm
  • Bottom layers: 2

Comments:
This was again printed with our own Python script, and this time we got the extruder offset value correct (we need to subtract 18 mm in the x-direction). We also used “Seam: Random”, which will distribute the webbing randomly over the perimeter to avoid that the corner will be weaker and not airtight. We lowered the fan speed to 60% which improved the adhesion of the layers, though it still wasn’t perfect and the two walls would still split.
We increased the travel retraction to 3 mm to reduce the webbing (pulling strings when traveling), but this was not succesful yet.
Test mold #3 – PVA
17/10/2016
IMG_20161017_153519

  • Layer height: 0.2
  • Temperature: 215/210 °C [first layer/rest print]
  • Print speed: 50/15 mm/s [external/internal perimeters]
  • Travel speed: 130 mm/s
  • Wall thickness: .8
  • Width of nozzle: 0.4
  • Infill: 0% (It was hollow)
  • Buildplate: 60 °C
  • Material flow: 140%
  • Fan speed: 35-60% . disabled for first 3 layers
  • Support: No
  • Brim: No
  • Seam: Random
  • Retraction: 5 mm
  • Bottom layers: 4

Comments:
We now increased the material flow to 140% to make sure the two walls would stick together, which was very succesful. To get rid of webbing the travel retraction was now set to 5 mm, which was also efficient. There was no webbing but only small lift marks on the mold. This will leave tiny little cavities in the surface of the casted models, but since it will not have any structural effect, we find these settings satisfying for now. The number of bottom layers was increased to 4, which also resulted in a nice, stable, watertight bottom.

Test cast #1two-component silicon
17/10/2016
IMG_20161018_153124

 

Test cast #2 – two-component silicon (casting on top of an already cured cast)
18/10/2016
IMG_20161018_164217

Final test cast – Complete ulticast
27/10/2016

_DSC9685_DxO

IMG_20161028_123542

Comments:
The surface quality is great. The inner air channel is also of high quality and it was easy to remove the inner PVA. This is a successful proof of concept. The time lapse of the thumb being printed is available here.