15.Molding and casting

This week assigment

group assignment:
- review the safety data sheets for each of your molding and casting materials,then make and compare test casts with each of them Group project page

individual assignment:
- design a mold around the stock and tooling that you’ll be using, mill it (rough cut + (at least) three-axis finish cut), and use it to cast parts

Overview

For this week’s assignment, I first made two drawings of the panels in fusion360. I then used the CAM software on fusion360 to create a G-code for cutting.

Since the lab in Kamakura was not available for general use this week, I devoted myself to learning the drawings.

As for casting, I’ll mention it again when the lab is available.

Fusion360 Design

I drew a drawing of the mold for the frame.

Materials to be used

End Mill Tools used

  • ⅛inch (3.18 mm) long 4FL SE

Sketch the outline of the coma.

Rotate the sketch 360 degrees.

I put a fillet on the top of the coma and a chamfer on the torso.

Modify → Aplit Body ,　　and cut the body in half.

Move one body.

I sketched the frame and processing lines for Ferris File-A-Wax Blue.
Size : 147 x 88 x 37mm

Use the Extrude command to create a joint between types.

I realized later that I had made the convex part 5mm and the concave part 6mm, but in this case, it hit there and floated 1mm.
Therefore, the concave part was set back to 4mm.

Make a filler for the casting.

I will be using the SMOOTH-CAST 325.
The holes on the right are air loopholes.

This is another thing to be aware of, but if the inside of the frame is 90 degrees, it won’t shave.
Because the diameter of the bit is 3.17mm.
So I added a 4mm R on each corner.

Similarly, the joint between the body and the axis of the panel has been rounded.

Now, the mold is complete.

Fusion360 CAM

Axis setting

I tried using the CAM function of fusion360.

The first thing we did was set up.

Set the starting point (origin) of the mill for cutting.
The 0 point on the z-axis selects the top surface of the wax.

The x-axis selects the foreground edge.
Then I also changed the orientation of the reference axis.

Select the stock box point as the origin and click on the point in the lower left.
Next, click on Stock (top right).

Stock Side Offset was set to 0 mm and Stock Top Offset was set to 0 mm.
Click OK

There is a new setup2 in the setups folder.　 Right-click to edit or change the settings.

Rough cut pass

Create a toolpath for the rough cut.
I chose 3D → Adaptive Clearing.

Select the tool (mill).

I have filled in the dimensions of the mill I plan to use in Kamakura.

Set Feed & Speed as follows. Next, the path Maximum roughting Stepdown to 3 millimeters and I set the Fine Stepdown to 3mm and clicked OK.

Then, a file called [T1]Adaptive2 was created and the path was displayed. It’s just messy and hard to see.

So I used the simulation function.
There are various patterns of settings, but I chose the following.
Then press the play button. (You can also fast forward.)

The rough cut seems to have a wide pitch, so I changed it.

I simulated it again.

I got a nice rough cut. The time was 56 minutes.

In the rough cut, it seems to cut away from the finishing line automatically.

Note

The only thing that still hasn’t been resolved is that the recessed trench on the right hasn’t been dug.
However, this has been resolved in the final cut phase.

Final cut pass

The next step was to set up a final pass for the finish. I chose a commonly used path tool called Paralel.

The final cut setting seems to require more detailed settings than the rough cut setting.
I found each of these settings difficult to understand, so I made a list.
The following screen seems to be a default automatic setting, but I tried to simulate it once with this.

Then it became a finish like the following. There are some corrections, so I’ve checked them one by one.

For some reason, the front part is not cut?

I was troubled for a while, but the cause was that I had selected only Parallel2 before doing the simulation.
It seems that it was necessary to select Adaptive2 at the same time as shown below.(Press shift to select.)

The problem I mentioned earlier has been solved.

There is still a lot of unevenness in the shaving, so I changed the settings.

I checked the vertical path to try it out. When you do that, it seems to cross 90 degrees and cut.

I changed the pitch to 0.5 mm because I wanted to cut a little finer.

stl data download　　→　coma_side2v3.stl

MODERA Player4

For the first time in a long time, the lab in Kamakura is back in action, so I had to do some cutting.

I tried to export the code to do the cutting with the G-code I created in Fusion360, but I got an error.

Unfortunately, I couldn’t find the cause of the problem, so I used the app I use in Kamakura, MODERA Player 4, this time.

I exported the stl file from Fusion360 and loaded it.

Set the model’s x, y, and z axes to change.

Select roughing and move on.

You have selected the area to be cut.

We’ll move on from here.

Set up as follows and move on

Name it and you’re done.

processing

The processing path is now displayed.

Click on the red box in the bottom right corner to simulate it.

Next, we’ll set up the finish cut.

I may have skipped it in the description of the rough cut, but choose a blade.

The rest of the process is almost the same as setting up the rough cut, so I’ll skip it.

I might have left out one thing, so I’ll add it, but I think I’d like to select X + Y for the scan line, because it will give a finer finish.

Cutting

The material we’re cutting this time is blue wax. It seems to be made from hardened wax.

First of all, let’s get the origin out.

Select two files: Rough Cut and Finish Cut. (Delete any unnecessary files.)

I chose the 1/8 SE 4FL long type for the mill.

Set up the x- and y-axes and the z-axis in the same way as usual and start machining

The machining is progressing nicely. I pressed pause from time to time to clean up the chips and check them.

The rough cut is complete.

Next, we went into the finish cut.
Just down the middle is the finish cut and the first side.

During the process, there was an occurrence that caused the machine to stop. The reason for this was that there was a part that was slightly deeper than the cut depth of the blade, and the wax melted and clung to the mill, preventing it from rotating. By removing the wax and removing the accumulated debris, the cutting was successfully completed.

It was beautiful.

Molding

  • MOLD STAR 16 FAST
  • TB / SDS
  • Color: Blue-Green
  • Pot Life: 6 minutes
  • Cure Time: 30 minutes
  • Mix Ratio By Volume: 1A:1B
  • Mix Ratio By Weight: 1A:1B

Mix the two liquids at a ratio of 1:1.

I used a sander to vibrate and pull out the air bubbles by floating them.

I think it was softer the first time I threw it in, so there were fewer air bubbles. It was not so bad.

casting

When I took it out of the mold I noticed it. When I designed it in Fusion360, I made the depth of the groove 1 mm shorter, but I was shocked to find out that it had the opposite effect. When I think about it, it’s a mold, so we had to think that much into the design. You learn by doing a lot of things!

data download

stl data download　　→　coma_side2v3.stl