Introduction: HPD F1 2.X
"To finish first, first you have to finish". One big problem with a 3D printed car is durability so the most important changes made have been with the aim to increase this. This has made that the weight of the car (mine is 1130g) is now above minimum weight (1050g). The added weight is not optimal but also not only bad as it is easier to get suspension to work well on a heavier car and acceleration is depending on good traction.
- More narrow chassis to avoid it touching the ground when cornering.
- Better differential.
- Front wing is now using standard mounting holes (a close approximation to the not so standard standard) so you can use wings from Tamiya, Mon-tech, Serpent or use HPD wings on other F1 cars.
- Front and rear wing are made with attention to aerodynamic rules.
- Body is not needing clips for mounting.
- Body is nicer looking.
- Quick release battery clamp
- Rear damper mount is now on a separate plate which makes it easier to adapt to different length dampers.
- Nose cone is now screwed on place.
Step 1: Printing
Material choice is very important for durability. Best results have been achieved with Esun PLA+ and PrimaSelect.
Nose and wing adapter should be printed in some semi flex material to be able to absorb forces in crashes without destroying the front chassis.
The motor pod is difficult as it also need to withstand high temperatures without softening. PETG is an interesting option that is tested at the moment.
Print settings are usually: 0.2mm layer height. 1.6mm shell thickness. 20-25% infill
Recommended print settings for Nose cone: 0.2-0.3 layer height. 0.8 shell thickness. 0% infill.
Recommended print settings for Wing adapter: 0.2mm layer height. 2.0mm shell thickness. 50+% infill.
Many pieces are possible to print without support with following exceptions:
- Main chassis.
- Steering hub.
- Rear axle.
- Rear wing.
- Front wing.
Step 2: Needed Hardware
- M3 screws in different lengths 6/10/12/14mm
- M3 Nuts
- Tyres and wheels
- 2 * M4x20mm counter sunk screws
- Appropriate spur gear (90T 48pitch) and diff balls.
- Pinion (30T)
- Ball bearing 10x15x4mm 2pcs
- Ball bearing 8x12x3.5mm 2pcs
- Axial bearing 4x9mm
- Diff washers from X-ray or Serpent F1 (Serpent: 41186, X-ray:375080)
- M4 threaded rod 150mm
- M4 nylock nut 3pcs
- G20 (3/4") 2mm thick hose gasket
- 48.5 mm shock absorber (Hobbyking: 9655000144-0)
- 2x front springs Xray/Serpent/etc. (X-ray: 372180)
- 2x side springs Xray (373585)
- M4x30mm screw for front axles brass tube.
- 4mm inside 5mm outside for front axle.
- turnbuckles and ballends for steering
- Ball bearing 5x10x4, 4 pcs
The usual stuff
- Low profile servo
- Servo saver (optional)
- Electronic speed control
- Motor (21.5T is recomended)
- Short LiPo.
Step 3: Rear Axle
This video is showing the principle of assembly of the rear axle. It is with the components of the previous version.
Step 4: Assembly Video
Step 5: Tuning Tips
These are the tips from the "Works Team".
We are using 450cst oil and soft springs, I am usually using the softest spring in the series.
On a high grip circuit it you can go harder and on a low grip circuit softer.
373584 C=0.6 - SILVER 373585 C=0.9 - GOLD
373586 C=1.2 - BLACK
373587 C=1.5 - SILVER
373588 C=1.8 - GOLD
Starting point for springs are the 0.9 (Gold) which works very well on slippery circuits.
372176 C=1.5 - GOLD (SOFT)
372177 C=2.0 - SILVER (SOFT)
372178 C=2.5 - BLACK (SOFT)
372179 C=3.0 - GREY (SOFT)
372180 C=3.5 - GOLD
372181 C=4.0 - SILVER
372182 C=5.0 - BLACK
372183 C=5.5 - GREY
The C=3.5 spring is a good starting point.
You can adjust ackerman by using different holes on the steering hub. The holes furthest out is giving the most ackerman and thus most aggressive steering.
The smoother you set the differential the more forgiving the car will become. Setting the differential so soft that it is starting to slip is a good idea when you have slippery conditions. Just remember; it is plastic on plastic inside and too much heat will cause a meltdown.