SLS scaling calibration is how you get parts to come out at their nominal size. A Fuse 1+ user on the Formlabs forum reported that every component came out 0.3 to 0.5 mm short in Z. X/Y scaling kept flat dimensions in check, but they wanted the same kind of fix for Z.
What does SLS scaling calibration fix?
Formlabs’ built-in tool corrects X and Y, not Z. Formlabs says X/Y scaling improves dimensional accuracy and repeatability within a ±150 μm tolerance window.
How does the X/Y tool work?
You print Formlabs’ test part without moving, rescaling or reorienting it. Wait at least 5 hours 30 minutes before post-processing, then media blast it and take 12 caliper measurements. The printer rejects any value more than 1.5 mm from nominal (30, 60 or 90 mm). Run the calibration for each printer and powder combination, because units vary. A Formlabs rep confirmed on the forum that new values apply to every job with that powder, including jobs uploaded before the change.
What about Z?
Operators disagreed. One said you can scale X, Y and Z individually in PreForm. The original poster said that in their PreForm version (3.33.2), reducing Z also scaled X and Y. They suggested a Z offset based on a measured test piece instead. Two other users reported the same problem. One said dimensions still didn’t fit after running X/Y calibration. Until there’s a dedicated tool, measure Z on a known part and document any correction you apply in PreForm.
When should you recalibrate?
- After firmware updates: in another forum thread, a production operator reported that an update changed their dimensional accuracy. They had to run the new X/Y calibration to get back to their old results.
- After changing bed temperature: one shop re-ran X/Y calibration after setting a new bed temperature offset.
- When switching powders: calibration is stored per material.
What should you tell customers?
Quote SLS tolerances you’ve measured on your own printers, not brochure numbers. Ask which dimensions are critical, so you can check them on the first article.
Related on the Solvi blog: MJF Tolerances: Clearance for Holes and Nut Pockets; MJF Threads: Print Them, Tap Them, or Use Inserts?.
Sources: Formlabs forum “Fuse 1+ Z axis scaling” thread; Formlabs forum “X/Y Calibration” thread; Formlabs forum Nylon 12 GF thread; Formlabs forum “Nylon 12 Burr on edges” thread; Formlabs: X/Y Scaling (Fuse 1 generation).