SLA

SLA printing

The Form 3 machines are stereolithographic (SLA) 3D printers. This form of 3D printing in known for its ability to produce highly accurate, watertight, smooth parts and differs from the Fused Deposition Modeling (FDM) technology used by the Makerbot machines in the NextLab.

Stereolithography relies on the ability for photopolymer resins to be selectively cured used a UV light source.

Thickness

1 Minimum Wall Supported Thickness: 1MM Recommended

A supported wall is one that is connected to other walls on two or more sides. A supported wall smaller than 1MM may warp during the peel process.

2 Minimum Unsupported Wall Thickness: 1.5MM Recommended

An unsupported wall is one that is connected to other walls on fewer than two sides. An unsupported wall that is smaller than 1.5MM may warp or detach from the model during printing.

Span

1 Maximum Span: 21 MM Recommended for (5 MM wide x 3MM thick)

A span is the distance between two intermediate supports of a structure. While printing horizontal spans is discouraged, certain geometries print well. For a 5 mm wide and 3 mm thick beam, spans longer than 21 mm are likely to fail. Wider beams must be kept shorter to avoid breaking during the peeling process.

Overhang

1 Maximum Unsupported Overhang: 1MM Recommended

An overhang refers to a part of the model that sticks out horizontally parallel to the build platform. Printing such features without supports is discouraged, as the layers cannot maintain their structure. Horizontal overhangs will be slightly deformed beyond 1 mm and become increasingly deformed as the length of the overhang increases. You can turn on “internal supports” in PreForm to ensure your overhangs are supported.

2 Minimum Unsupported Overhang Angle: 19 degrees Recommended from Level (35 MM long × 10 MM wide × 3 MM thick)

The overhang angle refers to the angle from horizontal that the overhang sticks out. Printing at an angle less than 19° could cause the overhang to break off the model during the peel process. Rotate your part so flat surfaces can be held up by supports if they are not already self-supporting. See the “Print Flat Surfaces at an Angle” section of our Model Orientation article.

Vertical Wire Diameter

Minimum Recommended: 0.3 MM (7 MM tall) to 1.5 MM (30 MM tall)

A wire is a feature whose length is greater than two times its width. The ratio is key to printing wires; at 0.3 mm thickness you can print up to 7 mm tall before you start to see waving. 1.5 mm wires can get up to 30 mm tall without defects.

Surface Detail

Minimum Emboss Recommended: 0.1 MM

Embossed details are shallow raised features on your model, such as text. Details smaller than 0.1 mm in thickness and in height may not be visible on your print.

Minimum Engraved Detail Recommended: 0.4 MM

Engraved details are imprinted or recessed features on your model. Details recessed less than 0.4 mm in thickness and in height may not be visible because they will be fused with the rest of the model during the print process.

Clearance

Minimum Recommended: 0.5 MM

Clearance is the amount of distance needed between two moving parts of a model (e.g., the distance between gears or joints). A clearance of less than 0.5 mm may cause parts to fuse.

Perforations and Holes

Minimum Hole Diameter Recommended: 0.5 MM

0.5 mm Holes with a diameter less than 0.5 mm in the x, y, and z axes may close off during printing.

*Minimum Drain Hole Diameter Recommended: 3.5 MM

Drain holes are recommended for resin to escape in models that are a fully enclosed cavity (like a hollow sphere or hollow cylinder printed directly on the build platform). Without drain holes of at least 3.5 mm in diameter, the part may trap resin and lead to an explosion of the print. Although drain holes are recommended, they are not entirely necessary when using a Form 2 printer.

Positioning the 3D Model:

Suggestion to consider dividing the model into smaller sections to fit into a STANDARD resin printer rather than using a LARGE resin printer. This approach can help reduce costs and significantly reduce printing time.

Post Processing

Support Removal

In many cases, a print will have additional supports generated in the Preform app to ensure it is successfully printed. After the necessary washing and curing processes have been completed, supports can be removed manually - these are generally easy to snap off with small pliers or clippers. Supports may leave behind small bumps which are easily removed with a file or similar tool.

Resin Form3 v.s Resin 3L

We offer two resin printing sizes at FabLab:

-Resin Form3

-Resin 3L

The 3L resin printer is offered ONLY to 3d print geometries which are larger than Form 3 resin printers. Please make sure that you break up your models into small parts and nest them appropriately to fit using the Form 3 print template. Only submit your geometries as a 3L template if the geometry can't be divided into smaller elements. Note that the time estimate for completion of 3L resin jobs is longer than the 3Form, and the use of 3L printer will cost more in compare to the Form 3 prints. Please find different resin printer dimensions here:

Resins at FabLab

All resins used for SLA printing are photopolymer resins, which means they are cured by ultraviolet (UV) light. Photopolymer resins become hard and brittle once cured, and are very difficult to melt and deform with heat. This should be taken into account when considering the requirements and characteristics of your 3d print.

We stock a range of Formlabs resins which are suitable for model making, engineering prototyping and casting. Our standard range for model making includes:

• black

• grey

• white

• clear

• Draft (grey)

We also offer a limited range of specialty resins, which contain additives that give them properties similar to other plastics or materials. Please see fablab staff if your model requires specific characteristics to discuss the use of other specialty Formlabs resins.

Our range of specialty resins include: Rigid 4000, Durable V2, Castable Wax, Flexible. These resins are more expensive than our standard resins. It is only recommended to use these resins if your model needs to withstand mechanical stresses or impact. You can see the cost of our resins in the 'cost' tab.

Cost

Grey / white / black resin = $0.30 x Print Volume (cm3)

Clear resin = $0.60 x Print Volume (cm3)

Castable wax/specialty resin = $0.80 x Print Volume (cm3)

Reducing Cost

Resin printing charges by the amount of material used, and can easily become an expensive product if not planned out properly.

Some methods to cut down the final price of your model may include:

• Hollowing out your model to release unnecessary resin through an opening.

• Considering alternative methods of fabrication for parts of your model. Always consider that planes/bases can be constructed with the laser cutters very easily at a much cheaper cost.

• Prototyping early forms with Makerbot PLA printers. If you’re expecting to do multiple tests and/or complex form iterations, the plastic printers (charging at 30 cents/gram) may be a more economic option before resin printing your final design.

Solid models

Due to the considerable costs associated with resin printing, solid models should be carefully considered before being submitted. Unlike the 3D slicer programs associated with FDM printing (Ultimaker CURA, Slic3r, Makerbot Print), when a solid model is uploaded to Preform it is not filled with internal material space-saving structures and remains solid.

Hollowing

Unless your model explicitly needs to remain solid, there are several methods of hollowing out your item to save on resin while avoiding structural failure. Below we will outline two methods of converting solid geometry to a hollowed-out part.

Drainage Holes

As well as hollowing out your mesh, it is important to include drainage holes so that resin can escape from within the internal cavity during the printing and washing processes. On the Form 3, your model will slowly be lifted out of resin as the build platform gradually moves upward - correctly placed drainage holes will prevent resin from being trapped inside your object as layers are added.

Hollowing a model with Rhino

1. Import your 3D model. Your model should be a watertight mesh - use the 'Mesh' command to convert a Nurbs polysurface to a mesh, and the 'Volume' command to check whether the mesh is closed.

2. Type 'OffsetMesh' command. Enter an offset distance of at least -2mm to ensure the object is thick enough to print. Entering a positive value will cause the outer mesh to grow inside, while a negative value will maintain the outer shape of the model and create an inner offset. Select the 'solid' to ensure the meshes remain watertight.

Supports

Touchpoints

Touchpoints are the points where supports meet the object being printed. These are generally 0.5mm in diameter and make the supports easy to remove. In some cases, the supports will leave a small trace on the object; however, these are generally easy to remove using sandpaper or a file.

Once you are confident your file is ready, please submit job here: