Lattice Benchy

Print a lattice Benchy — the little tugboat that 3D printers are traditionally tested on, rebuilt as an open mesh. It’s a deliberately awkward part: overhangs everywhere, a hollow hull, and hundreds of thin struts that the printer has no chance of producing unless you support and orient it properly. Getting it out in one piece means you’ve understood supports, rafts, and the Print Validation panel, which is the whole point.

Read this first: the Resin 3D Printer (Formlabs Form 3) manual, especially Preparing your file in PreForm. You’ll also need Form Wash and Form Cure afterwards. This activity assumes both.

The activity

Download Lattice_Benchy_FCC.stl from [model download link — ask a staff member] and open it in PreForm.

What you’re aiming for:

• Scaled to 50%. Open the Size tool and set the scale to 0.5. At full size this is a long print for a practice part, and the lattice reads just as well at half scale.

  

• Supports and a full raft, auto-generated. Open the Support tool. Under Touchpoint Placement, leave everything ticked on Auto Placement. Under Support Structure, set Raft to Full Raft and Pillars to Classic, and turn Allow Internal Supports on Model off — internal supports inside a lattice are close to impossible to remove without snapping struts. Then click Auto-Generate All.

• Print Validation read and understood. Open every flag PreForm raises and work out why it’s complaining — that’s the exercise. Then treat them differently, because they are not equally serious. Minima are the ones to clear: an unsupported minimum starts a blob of resin in mid-air, and what falls off ends up in the tank, which is the one failure that can cost the tank rather than just your part. Flags on individual struts of a lattice this dense are another matter — the example pictured above was printed from exactly these settings with flags still showing. If you can’t tell which kind you’re looking at, ask a staff member before you print rather than after.

Then print it, and take it through wash and cure.

Hints

• Orientation is doing most of the work here. Lay the boat flat and the hull becomes one enormous unsupported overhang; stand it dead vertical and the first layers have almost nothing to grip. Tilted off both axes, as in the picture above, is what you want — every layer then has some of the layer below it to build on.
• Don’t fight the warning count. Chasing Print Validation to zero on a lattice means burying the model in supports you then can’t get out. Aim to understand them, not eliminate them.
• Leave the supports on until after curing. Washed-but-uncured resin is soft, and those struts will tear. Flush cutters, after the curer.
• Look at the hull before you print. It’s a mesh, so it drains on its own and doesn’t need a drain hole — which is exactly the contrast worth noticing against a solid hollowed model, where a sealed cavity would ruin the part.

Questions worth thinking about

1. How would you print this with less mess and less cleanup?
2. Could you get this part off the platform without a raft? What would you change?
3. Which faces came out cleanest, and what did that have to do with where the supports landed?
4. What is this machine genuinely better at than the FDM printers — and where would you have been better off using one of those instead?

When you’re done, follow Finishing up in the manual and take your boat with you.