Fit Tuning (Form 4 and Form 4L generation)

For applications that require high accuracy, Fit Tuning allows users to further dial in the precise dimensional fit demanded by their use case.

Optimize dimensional fit and refine the accuracy of printed parts on Form 4 and Form 4L generation printers with configurable settings. Increasing or decreasing this value can compensate for horizontal expansion during the printing process to customize the fit of dental restorative dies and other end-use parts.

Every printer requires individual testing. Fit Tuning values for one printer may not work on a different printer.

Estimated time: 15 minutes

• Nitrile gloves
• Fit Tuning test block
• Grade 10, 6 mm ball bearing

1. Update to the latest firmware (1.10.0 or later) on the printer you wish to test.
2. Download the latest PreForm version on your computer.
3. Download the test file to a computer.
4. Open the recently downloaded file in PreForm. For best results, do not reposition the model from its default placement in the center of the build platform.
5. Select the printer, resin, and layer thickness you wish to adjust with Fit Tuning.

6. Insert a resin tank and resin cartridge into the printer that match the resin type you want to tune.
7. If your printer is ready to print, click the orange Print Now button to send the job to the printer. Otherwise, click Upload to Queue and start the print job on the printer’s touchscreen.

1. Remove the part from the build platform.
2. Thoroughly wash the test print.
3. Use compressed air to remove any remaining solvent residue.
4. Allow the part to fully dry before post-curing.
5. Post-cure the parts with the recommended settings for your selected resin.
6. After post-curing, allow the part to cool down to ambient temperature prior to moving to next steps.

The Fit Tuning test consists of the printed part and a grade 10, 6 mm ball bearing. Insert the ball bearing into increasingly tighter holes in the block until you find the desired fit.

Step 1: Understand the model

Depending on the printer, the test can result in a value of +20, +10, 0, -10, or -20. The starting position, labeled +20, has the loosest fit. Each hole gets tighter as you move from +20 towards -20.

Step 2: Test the fit

Insert the 6 mm ball bearing into the slot labeled +20. Attempt to remove the ball bearing from the block. If the fitment is loose and the ball bearing is easily ejected, insert the ball bearing into the next slot.

Step 3: Judge the fit

Test the ball in each slot, moving from the tightest to the least tight, until the ball fits securely into a slot.

• If the ball bearing falls into a slot easily or can be pushed into place with a mild amount of friction, the fit is valid.
• If you need to apply constant pressure to push the ball bearing into the slot or the ball bearing does not fit in the slot, try a different slot.

Step 4: Review the results

Once you have inserted the ball bearing into a slot position that meets fitment criteria, the number displayed on the side of the test block is that printer's Fit Tuning value.

It may be necessary to adjust the Fit Tuning test print if the ball bearing fits too easily or if it will not fit in any slots.

Apply the result from the test to the printer that was used to print the test block. Every printer and material requires individual testing.

1. On the printer’s touchscreen, tap the gear icon. The Settings screen appears.
2. Tap Tools > Calibration > Fit Tuning. The Fit Tuning menu opens.

7. Run a test print. Inspect the finished part to ensure improved dimensional accuracy.

If you experience trouble with the procedure or unexpected test results, contact Formlabs Support or your authorized reseller.

Editing previous Fit Tuning configurations

To edit a previously-applied Fit Tuning measurement: