Large Prints

Slicing a model into parts can reduce print time, reduce support material and allow you to print models which are larger than the print bed.

0.0 Print and Printer Sizes

This is the maximum build dimension for the main printers at NExT Lab 3D printers.

Printer

Build Size

Replicator +

295 (x) mm X 195 (y) mm X 165 mm (z)

For models that are larger than the Replicator + build volume, you can consider either:

  1. Slicing up the model

  2. Using the Replicator Z18, this may increase time for your model to be completed due to limited availability.

Printer

Build Size

Replicator Z18

300 (x) mm X 305 (y) mm x 457 mm (z)

1.0 Using the Replicator Z18

This section will supplement our 3D Printing Guidelines and general considerations that should be given to models that are to be printed on the Z18. Given the nature of the printer and their limited number, we take extra precaution for the usage of this machine.

1.1 Reasons to Use

If the following reasons are not too high priority, it is highly recommended that you slice up your prints.

1.1.1 Structural Integrity

If there are many critical areas that don't allow a model to be split up, use the Z18.

1.1.2 Aesthetics

If seam lines will ruin the finish of the model, use the Z18.

1.2 Setup

1.2.1 Makerbot Print: Adding the Z18 Printer

Add an unconnected printer using the button at the bottom right of the screen. Add the Replicator Z18 Printer.

1.2.2 Makerbot Print: Exporting

When your file is ready to be sent of to the printers, export your file using the [EXPORT] button on the bottom right of the window. The output file will be a .makerbot file. This file is a code package which cannot be edited or fixed.

Be sure to use the following naming convention that explicitly identifies the project as a Z18 project.

Be sure to use the following naming convention that explicitly identifies the project as a Z18 project.

123456_18hr_Z18_NewFile

2.0 Slicing up Large Prints

2.1 Reasons to Use

Slicing a model into parts can reduce print time, reduce support material and allow you to print models which are larger than the print bed.

Models should be cut into smaller components in two main cases.

  1. The model is too large for the print bed

  2. The model will require a large amount of support material

Figure 0.0 - Large models need to be split up or re-designed for printing

If we were to attempt to print the above model, there would be no perfect way to orient the object on a print bed (support material would be extensive, and the model would be unstable during printing), nor would it fit on the print bed (shown here in correct scale).

By splitting up the model into smaller pieces with final print orientation in mind, it can be printed at the desired scale and without supports.

2.2 Splitting up a Model in Rhino

Meshes can easily be split up or trimmed in Rhino using the "MeshSplit" and "MeshTrim" functions. While "MeshSplit" will maintain both parts, "MeshTrim" will remove one of the parts.

2.2.1 Mesh Split

Any curve or surface can be used to split a mesh. The main advantage of using Rhino to perform mesh splits is that models can be split along curves rather than straight lines.

To split a mesh in Rhino:

  1. Import your model into Rhino

  2. Draw a curve where you intend to split your model.

  3. Type the command [MeshSplit]

  4. Select you model, and hit enter

  5. Select the curve as your Cutting Object and click [enter]

  6. The resultant meshes should be split

  7. Meshes can now be exported as .stl files for optimal orientation for 3D printing

Figure 1.1 - Models can be split using curves and the MeshSplit command

2.2.2 Limitations

Rhino3D is by no means the most appropriate software package for working with meshes. Sometimes Apparent Intersections are not recognised, and it is not uncommon that the split will fail.

2.3 Splitting a Model in Meshmixer

If only simple "Plane" cuts are required, Meshmixer is a more appropriate software for the task. Meshmixer can be extremely quick and easy to use.

2.3.1 Plane Cut

Figure 2.1.1 - Plane Cuts in Autodesk MeshMixer

In order to perform a plane cut:

  1. Import the model into Meshmixer

  2. Select the model.

  3. Go to Edit > [Make Solid], use settings that leave acceptable resolution when previewed.

  4. Accept preview.

  5. Orient your view as to allow for easy selection of split area.

  6. Go to Select, choose [Lasso], draw selection over approximate area to be split.

  7. Go to Edit > [Plane Cut]

  8. Draw a straight line over previously "lassoed" area, control finer location of plane position using gumball controls.

  9. Go to Cut Type > [Slice (Keep Both)]

  10. Go to Edit > [Separate Shells]

Figure 2.1.2 - Plane cuts are the most simple method to split up large parts

2.3.2 Use of Aligning Pins

Aligning Pins are dowel joints which allow split parts to be aligned together once printed. These can either be friction fit or glued.

Figure 2.2 Aligning pins are helpful in assembling a series of printed parts

In order to create an aligning pin between two parts:

  1. Go to View > [Show Objects Browser]

  2. Click the [Show (eye)] icon to hide one of the pieces to be aligned .

  3. Go to Meshmixer > Drag a Primitive (Cylinder of Rectangle work best) and drag the object to the joint.

  4. Scale and orient pin using gumball tool

  5. Go to [Objects Browser > Duplicate] to duplicate the pin object twice

  6. [Hide] the two extra copies of pin via the eye symbol.

  7. Go to [Objects Browser] and click on object from which to subtract pin, then click on Pin itself

  8. Select [Boolean Difference].

  9. [Unhide] the other object and one copy of the pin

  10. Repeat Steps 7 and 8 as necessary.

  11. [Unhide] the last remaining pin and go to Edit > [Transform]

  12. Decrease size by 0.5 mm in the correct axis to allow for tolerances for a good fit.

Make sure that when creating your aligning pins, they are toleranced and slightly undersized (under-size by 0.5 mm or more as a rule of thumb).

2.4 Other Resources