This device was originally designed with a spiral spring as an actuator (attached stl file).
However, given the visco-elastic characteristics of PLA, this spring loses its effectiveness very quickly.
It took looking for another type of actuator and opted for the use of bicycle inner tubes.
A piece of inner tube (700x20 to 23mm for road or racing bike) of about 900mm in length allows the spring to be made.
This inner tube is installed in double thickness in the system. The two ends are fixed in the hub and the central fold on the training cleat. The winding is done in a spiral on the rollers (see photos). To prevent residual air build-up, a hole must be drilled in the central part of the air chamber.
Fixing is done by creating a loop which is inserted into the housing and then a stopper is placed in this loop.
The tension can be adjusted by varying the length of the inner tube and the offset of the arms. The travel takes place at an angle of about 120 °.
The design of the spring box was made for a door whose axis of rotation is to the left when pushing. For the other direction it is necessary to carry out the parts marked "sym" in their file name.
All parts are printed with 1.2mm wall thickness and 20% infill except:
the tray which has an infill of 40%
the spring (for those who want to try ,,,, for info, the direction of the spring must be such that its diameter increases with the torque exerted) the thickness of the outer walls must be greater than 2.4mm.
If possible, axes and bores should be printed vertically for best quality.
The axles and bores must be lightly sanded and lubricated (Teflon grease, ,,,,,).
Do not exert a large torque without having placed the cover of the spring box.
You will need screws type TTPC20.
| AXERESSORT_x1.STL | 393.4KB | |
| Axe_palier_x1.STL | 82.6KB | |
| BielleBRAS_x1.STL | 696.5KB | |
| BielleMOYEU_x1.STL | 495.9KB | |
| BielleRESSBRAS_x1.STL | 630.4KB | |
| BielleRESSMOYEU_x1.STL | 465.3KB | |
| Charnièrefixerepriseh60_x1.STL | 1.1MB | |
| Cleat_Taquetsym_x1.STL | 49.7KB | |
| Cleat_Taquet_x1.STL | 50.1KB | |
| Cover_Couverclesym_x1.STL | 546.0KB | |
| Cover_Couvercle_x1.STL | 546.7KB | |
| Device_implementation.pdf | 93.1KB | |
| Palierdouble_x1.STL | 2.2MB | |
| pion_x4.STL | 47.0KB | |
| RESSORT_SPIRAL_x1.STL | 213.2KB | |
| roller_rouleau_x15.STL | 227.4KB | |
| rondellereprise_x1.STL | 156.9KB | |
| Rondelle_charnfixereprise_x1.STL | 156.5KB | |
| Stopper_Arretoir_x3.STL | 44.9KB | |
| Tray_Plateausym_x1.STL | 668.6KB | |
| Tray_Plateau_x1.STL | 670.1KB |
