This is a fun little 3D print that might be interesting for newcomers to the 3D printing game. The design is based on the mechanical principle of a traditional wooden toy that lets the robot climb up the string if you pull on it.
The STL files are available for download here on github.
Besides the printed parts you will need an elastic band and a string.
I used a elastic band as commonly available for textile work. A normal rubber band might work too but is probably not as long lasting. In any case the band can’t be wider than 5mm (0.19 in) and thicker than 1mm (0.04 in).
Not everything will work for the string as the correct amount of friction in the robots “hand” is crucial for the climbing action to work.
The model is optimised for a ca. 3mm (0.1 in) or a ca. 2mm string. There are two versions of the clamp available for download. From my experience a coreless braided string works best.
The model is optimised for printing with a 0.4mm nozzle. The sloped surfaces look best with a 0.2 layer height but larger layer height wont be a problem. Most of the models parts are optimised for printing without support and all are oriented correctly in the STL files for optimal printing.
The following parts need extended settings.
The video above contains step by step assembly instructions if needed.
If you printer is tuned to produce precise dimensioned part the robot should friction fit together without glue. Otherwise just use glue or tune up the fit with a file or sanding paper if the parts are too large.
Tuning the clamping mechanism
In general the clamp should clamp just hard enough to hold up the robots own weight. Use a round file to smooth the bottom of the groove the rope runs through in clamp-p1.stl’ to remove all the printing striations. Apart from that it’s important that the hole through the “shoe” is large and smooth enough to let the rope slide through without friction. A good way to achieve this is to bore out the hole with a fitting drill. I chose a 3.5mm drill for the 3mm rope I used.
You’re done. Have fun