Hollowing 2D - 3D

Basic options available for all users - Advanced features for Pro and Premium users

Hollowing and it's functions are located under

1. Prepare > 2. Hollow > 3. Hollow 3D or 2D

Hollowing a model will reduce the weight, cross-section and the resin consumption of your prints. There is not a single function that will save you more money and help you get better results than hollowing, especially 3D hollowing.

The four primary hollowing tools

Hollowing 3D

3D Hollowing is a simulation. It will give you a preview of what adding additional geometry to your 3D model could look like. This is done by creating a new, low polygon surface as an internal cavity inside your 3D model.

3D hollow can be exported, converting the simulation into new geometry in your model, solidifying it.

Interior view or blockers will no longer function with "solidified" geometry.
3D Hollowing works by creating a lower quality internal projection of the objects outer shell.
Only available to Pro and Premium users.

3D hollow has two customizable operations

Thickness

Thickness will allow you to set the wall thickness. This is the wall between the outer shell and the newly created cavity in your object.

Smaller objects will be limited on how thick the wall can be.
Can be set between 0.5mm and 10.0mm at 0.1mm increments.

Quality

3D Hollowing Quality allows you to determine the resolution or quality of the hollowed cavity.

More polygons will give you a more accurate 3D hollow.
Can be set between 1, low polygon to 4.0 high poly count.
More system resources will be required to process the higher quality settings.

How to 3D hollow an object

Select the object you wish to hollow from the Lychee Scene.
Under Prepare, Hollow, Hollowing 3D.
Using the slicer or typing in, choose the desired Thickness and Quality.
- If you have a preset, click the Gear icon to Save or Load your Hollowing 3D preset.
Click on Add/Update, all selected objects will be be given the chosen properties.
Use the Layer Preview Slider to review the 3D hollowing effect.
Don't forget to add drain holes and check for suction cups, continue article for instructions.
Slicing or Exporting the file will finalize the 3D hollowing effects.

Hollowing 2D

Your 3D model is not altered in any way. Instead Lychee slicer will back out the inner pixels of each slice. By doing this, the printer wont cure any resin in the areas displayed in black in the slicer.

All the other features like the hollowing blockers or the holes are compatible with the hollowing 3D.

Enable/Disable

When enabling 2D hollowing , all objects in the scene will be effected. To disable 2D hollowing per object this can be done by clicking on the Enable/disable hollowing 2D icon in the Objects Menu.

Thickness

Allows you to set the thickness of the wall between the outer shell and blocked out area represented in black.

Can be set between 0.5mm and 10.0mm at 0.1mm increments.

Dimming

Fade every adjacent pixel in a checkerboard pattern from off -> grey -> on

Can be Enabled or Disabled according to your preference.

Infill

Density

- Sets the Percent of the infill that will be converted to an autogenerated support suture.
- Can be set to 0% no infill, to 100% full infill.

Dimming

Apply a Gray value to the infill.
Allows you to cure the resin to a softer hardness than the shell of the print. The lower the %, the softer the cure will be. Going to a low value will cause the infill structure to not fully form.

Pattern

Set the diameter of each lattice structure that makes up the infill.
Can be set between 0.8mm and 3mm in 0.1mm increments.

Type

Pick the pattern of infill structure.

Lattice
Double Lattice

How to 2D hollow an object

Under Prepare, Hollow, Hollowing 2D.
Under Preview toggle the feature ON. This will apply 2D hollowing to all objects in the Lychee Slicer Scene. Unless 3D hollowing has been applied overriding 2D hollowing per object.
Use the sliders or type in your desired settings for Dimming and Infill.
- If you have a preset, click the Gear icon to Save or Load your Hollowing 2D preset.
Use the layer slider to review the 2D hollowing effect.
Don't forget to add drain holes and check for suction cups, continue article for instructions.
The black areas will not be printed when using Lychee Slicer, 2D hollowing cannot be exported.

Holes

Not to be confused with a Boolean, holes are a function of 3D hollowing.

Holes have two distinct ways they can function.

Slicing your Lychee Scene:
- Holes will function like Hollowing 2D. Holes both BLACK and RED will block the printer from curing resin in any area they occupy.
Export or "solidify" your object using the 3D drain holes conversion tools.
- Holes that are BLACK will drill though the object till they locate surface polygons. This is to drill into any voids and prevent resin pockets. If the object has no voids, the hole will drill all the way though the mode and out the other side.
- Holes that are RED will be ignored as Lychee has calculated that the geometry intersecting the hole is overly complex.

Geometry Type

Sets the shape of the hole

Cylinder
Cube

Diameter

Set the diameter of the hole between 0.5mm and 100mm in 0.1mm increments.

Penetration

Set the length of the hole.
Holes that are converted to geometry via exporting or conversion will extend infinitely till they reach the a shell of your model. If there is no void, it will punch though the entire model to the opposite side.

Editing Mode

Classic - Holes can only be adjusted though the sliders or dragging the hole after placement.
Advanced - Gives advanced scaling, rotation and movement controls. Available for Pro and Premium.

3D Drain Holes Verification

Real-Time Verification

Checks in real time that placed holes pass a series of operating checks for export.
Holes that fail this check will show in RED.
- Red holes will still function when slicing the scene. However they will be ignored during exporting or conversation.
- Try adjusting the holes position and scale to get it to turn black. The more complex geometry the hole interacts with, the higher the chance of failing the verification check.
Click "Show" to center the camera on a verification failed hole.
Can be Enabled or Disabled according to your preference.
Pro Premium only

3D Drain Holes Conversion

Convert holes into Caps to be used to more easily repair the model in post processing.

Hole Only

Convert any selected hollowing hole into a geometrical hole.
- Will also convert hollowing 3D into geometry as well. Afterwards the target object will no longer have an outside or inside. Disabling the use of the Interior/Exterior View button.
Only the selected hollowing hole into new geometry.
Only the area occupied by both the the hollowing hole and the object will be converted.

Pro or Premium only

Cap Only

The Hollowing hole will be converted into a new object in the scene.
Only the area occupied by both the the hollowing hole and the object will be used to create the cap.
The Cap will have a diameter smaller than the hollowing hole, set by the value specified under Cap Gap.

Cap Gap

Sets the tolerance between the cap and the model
Can be set between 0.1mm and 10mm in 0.1mm increments.

Pro or Premium only

Cap + Hole

Convert ALL hollowing holes into geometrical hole(s).
- Will also convert hollowing 3D into geometry as well. Afterwards the target object will no longer have an outside or inside. Disabling the use of the Interior/Exterior View button.
Only the area occupied by both the the hollowing hole and the object will be converted.

Cap Gap

Sets the tolerance between the cap and the model
Can be set between 0.1mm and 10mm in 0.1mm increments.

Keep Cap in Place

ON - Any cap created will remain where it was generated.
OFF - The Cap will be moved to location 0x 0y 0x on the build plate upon generation.

Pro or Premium only

Object is a hole

Used to convert any object into a hole.

Any area that the converted object occupies, will be blocked from printing.
This is much like 2D hollowing where it will only be applied when slicing.

With little imagination this can be very powerful tool when used to prevent sections of your model from being printed.

Will convert any selected object into a hole.

OFF

If an object has been converted to a hole, selecting it and then selecting OFF will convert it back to a normal object.

Pro or Premium only

Blockers

Blockers are a function of the 3D hollowing simulation. Not to be confused with a solidified 3D hollowing.

They will prevent Lychee Slicer from generating a 3D cavity in any area they occupy.

They cannot be used to fill in an existing hollowed area or suction cups created by the objects geometry.

Blockers have two distinct ways they can function.

Directly Slice your Object:
- Opposite of holes or 2D hollowing, any areas occupied by a blocker will be activated. Curing resin to fill that area.
Export a 3D hollowed object with blockers occupying a void.
- The exported geometry will not extend beyond the space occupied by the blocker.

Show Wireframe

The outlines of the placed blockers will remain visible

OFF

The outlines of the placed blockers will be hidden unless you're in the Add/Edit Blocker interface

Add/Edit Hollowing Blocker

Pick between three basic shapes to place into the scene.
- Cylinder, Cube or Sphere
Once a shape has been placed use the axis modifiers to scale, move or rotate the blocker to the desired location.
Duplicate will make a copy of any selected blocker.
Exit to return to the Prepare menu.

Suction Cups are a very common problem in resin 3D printing that causes frequent failure.

Not to be confused with peel force or cross sections. Suction Cups are created when you have a void in your model with no way for resin and air to escape during the print.

Because of these suction cups, large forces can be applied to your 3D prints that can cause parts of the model to break off, cause degenerate holes, tear the model off the supports, and more.

To make matters worse, you can also have areas where liquid resin gets trapped, which can also cause prints to burst over time and spill resin everywhere.

Suction Cup Detector

Detects Suctions cups highlighting their surface area with a yellow pattern.

Search Selected

Search all selected objects for suction cups.
This search will include suction cups created by hollowing or the geometry of the model.

Show

Center the camera on a detected suction cup.
- Selected suction cups will be highlighted in blue.
Use the arrows to move between detected issues.

Delete

Hitting the Trash icon will delete the yellow pattern generated by the suction cup detector, not resolve suction cups.

Pro or Premium only

How to resolve a Suction Cup

Use Blockers to fill Emulated 3D hollowing voids.

Cannot be used to fill suction cups caused by the Objects Geometry.

Use Holes to open a suction cup to air and resin flow.

Be careful. This hole must have a minimum size to make the resin circulate as efficiently as possible, especially for resin with low viscosity. The bigger the holes and the more of them, the better.
3-5mm is a good starting point for small to medium prints.

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