Moai work flow - Print Orientation

When setting up an SLA print, below these are the steps you have to consider.

Here is the workflow:

1 Print Orientation

2 Hollowing

3 Offset from z-axis

4 Support

5 Positioning

 

Print Orientation,

This is one of the most important decision when making a print and the first you should consider. We are going to demonstrate this point with this Moai print.

 

Factors:

  1. One continuous build, no islands
  2. Minimize surface area on layers
  3. No Cavity Facing straight into the vat
  4. Keep the tall side of prints close to left part of the vat

 

While you may not be able to do all 4 for a given print, you should try to cover as many factors as you can.

Hollowing is a frequently used to save resin that creates cavities. Therefore, when considering

 

We are going to use Peopoly Moai print designed by JohnnieWalker as the example.

Let's first Asura (download here) and load the print file:

 

This file can be print it as straight up as it is shown above. But it does not gives the best results and use too many resins.  The reason why the orientation is suboptimal is that the object is print straight off the plate, making the first few layers susceptible to damages from scrapping. By printing it this way, the layer lines are more visible as well.

Let's first find a better angle to print.

Turning -45 degree looks like it is may work. But the nose part is at an negative angle to the build plate and will need a lot more supports to print well. We decided to try another way.

At 45 degree the other direction looks better but may need too much support at the back of the moai head.

 

 Let's try 25-degree turn on X-axis, and this looks like more workable. This would also make the support to be at the bottom of the base and the back of the object where the details and finishes are less important.

Next, let's do hollowing. It is a crucial method to save resin and time.  Because it is a solid object, I already decided I want to hollow it and once rotation is set, I can decide the hollowing and the locations of drain holes.

Asura has an efficient hollow feature that is the best among free software.  

The default setting works well.  2mm is a bit thick for small object but for this size, it is safer to print thicker.

You cannot do hollow without drain holes and Asura is very intuitive to add drain holes. Simply check the make hole on the spot of the object and it will drill drain holes with enough depth to connect to the hollow portion.

You should have at least two drain holes per hollow portion since this object has one big hollow inside, I select two spots.  One on top of the head and one at the bottom of the base. The top of the head is for the resin to drain out while the one on the base to reduce suction force so that resin can flow out while the object doesn't expect too much downward suction when printing. 

 

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Support is another critical step that cannot be considered away from orientation. You need support to print well but too much support ruins the surface of the print and wastes resin. 

Asura has very easy to use Support features.

 

Simple click on support button and then click generate and you will get a nice set of supports

 

If you want to add or delete support, simply click on Add or Delete and select the spot for the desired function. You can also press A for add and D for delete

 

Add support

delete

For advanced support parameters, please review Asura Wiki for more fine tune features.

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Now you can export to Gcode for Moai printing.

Click on the Disk Icon to bring up the save menu

Select the layer height you would like.  100um is the most commonly used profile.

Click ... in the export tab and enter a file name

And then click Export. 

 

 

You can then copy this gcode onto SD card's gcode directory and print.