Printing Guidelines #

Printer Tuning #

Before anything else, make sure your printer is well-calibrated. I recommend following the steps outlined in the Ellis' Print Tuning Guide . Plus:

• Calibrating flow
• Compensating for hole sizes (Hole Horizontal Expansion in Cura)
• Printing the Robak calibration model to ensure hardware fits correctly

Slicer Settings #

Here are some general rules I stick to:

• Always dry the filament
• Print slowly, under 100mm/s
• Use the highest temperature that’s recommended for your filament
• Minimize cooling as much as possible
• Use an enclosure
• Opt for a .6mm nozzle and adjust line width to around 120%
• Apply 6-8 walls and 15-20% infill for structural integrity

Materials #

A good practice is to use a material you’re familiar with and have readily available. Master the slicer settings for it. I’ve found that different brands, batches, and even colors of the same type of filament can behave differently, making it tough to recommend a one-size-fits-all solution.

Be prepared for a few trial and error attempts to find the right material and settings combination.

My Advice #

The selection of materials, print settings, and the precision of parts play crucial roles in your car’s performance and lifespan. Although experimenting with new methods and tweaks is encouraged, keep these factors in mind while printing Robak parts:

• Calibration is Key: A poorly calibrated printer will result in parts that are not dimensionally accurate, leading to assembly difficulties and drivetrain problems. Play or too much resistance in the bearings and gears will prematurely destroy the drivetrain.

• Lightweight Design: For a faster car, keep it light. Mass hinders acceleration and puts more strain on the power system. Use 3D printing to create hollow structures; as little infill as possible and where possible

• Design vs. Durability: After a crash, you might think adding more material strengthens the design. However, Robak’s parts are already chunky enough for their scale. Making one part stronger may just lead to breaking another, eventually harming the expensive power train.

• Flexible Materials: Although they may appear to be suitable for specific parts and offer a quick solution to layer adhesion issues, flexible materials are generally not recommended. They often require more infill, adding unwanted weight and negating the benefit of hollow structures. Plus, they can make the chassis, suspension and steering less responsive, affecting handling.

  Some parts are designed to break on crashes and if they don’t, the drivetrain will suffer the consequences.

  I believe that to unlock the full potential and push the limits of the Robak design, using higher-grade industrial materials like PA, PC or similar is key. These materials allow parts to be printed with even less infill and fewer walls while still offering good rigidity and impact resistance, and they manage to be lightweight at the same time.

• Bumpers and Wings: These are fine for aesthetics but offer little advantage at high speeds and won’t be part of the main design files.