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Using Flexible Resin

Flexible resin has elastomeric properties which allow you to print bendable and compressible parts on the Form 1+. Parts are pliable when thin and resilient when thick.

Ideal for

  • Impact resistance for functional engineering prototypes
  • Ergonomic prototyping: handles, grips
  • Prototyping soft over molds
  • O-rings and gaskets in compression, seals
  • Stamps
  • Soft-touch coatings

Not suitable for

  • Simulating very high elongation materials (rubber band)
  • Very fine features or thin walls
  Formlabs Flexible Stratasys Tango Series1 Rubber Band2
Elongation 90% 45-220% 750-850%
Tensile Strength 5.9-6.6 MPa 0.8-5.0 MPa 20-30 MPa
Hardness 80-90A 26-77A 20-30A

Note

Flexible resin is not stretchable as it has low elongation. Full material property specs can be found here. Your model may break if it is exposed to stretching forces.

Below are some recommended guidelines for printing your tactile part in flexible resin.

Design Tips

When setting up your part, make sure that your model is in its final shape. For example, if you are printing a watchband, it should print it in its circular form, not as a straight line.

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A flexible watchband printed in its final shape.

Tall, thin features are harder to print as the material will naturally flex during the peel process. If possible, orient your part closer to the build platform, but no flatter than 20 degrees. You can also reduce this effect by manually adding additional supports.

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Optimal orientation for a flexible model.

Tip

While designing your model, keep in mind that its flexibility willl depend on its structure and thickness. A denser piece will be impact resistant but not very bendable.

Print Settings

Use advanced support settings to adjust supports for printing in flexible resin. Issues may occur during peeling if you move from a layer of large surface area to a layer of small surface area or vice versa, for example, if printing thin features like embossed letters or extrusions on a large, flat surface. Try to match the touch point size, and choose an orientation that will minimize this.

The base thickness for printing flexible pieces should be at least 1.25 mm. The default touch point is 1.60 mm, but 1.80 mm is recommended for larger pieces. Increase the support density for flexible parts with a large cross section.

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Touch point size should be at least 1.80 mm for dense, large models such as this heel.

Tip

Pour very slowly when filling your resin tank as the viscosity of this resin is greater than other Formlabs resins. Flexible Resin will take longer to level out. A cautious approach is to fill the tank to ¾ full so that you do not risk overfilling it.

Finishing

Slowly peel your part off with the scraper, as opposed to trying to pop your part off the build platform. Take extra care to ensure the build platform is fully cleaned after removing your part. The same cleaning procedures can be used for Flexible as Standard resins. Clean the tank with a scraper and comb more slowly than with Standard resins as Flexible is a more viscous material.

If your part still feels tacky after washing in IPA, try post-curing it underwater. Find a clear glass container, place your part in the container, and cover it with water. Leave the container out in the sun until it no longer feels tacky to the touch.

You can sand support marks off flexible prints and apply mineral oil as you would with standard resins.

Contact Support

Questions? Get in touch.

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