Simulating RepRap play/backlash in Phun
Ton Zijlstra
http://blog.erikdebruijn.nl/archives/107-Phun-simulations-with-RepRap.html
by Erik de Bruijn.
Phun is a physics simulation tool. The model used is downloadable at the URL.
From that URL:
This is a simplified simulation of the mechanical "Cartesian bot" of
The RepRap. It allows you to play with things like play (a.k.a.
backlash), tension of the belt that drives the axis, etc. You can
explore what happens if you change the weight of the extruder (low or
higher), if you change friction of the surface of the Rods, etc.
The backlash of the extruder is a bit exaggerated, but this allows you
to clearly see what the sources are, and whether it is constant,
linear or non-linear while varying various properties. For instance,
further away from the driving pulley, the backlash increases. The
backlash is asymmetrical, just like in reality. In my previous post I
talk about a means to mitigate most of the backlash. This makes it
possible to have a 'cheap' or low-cost mechanical frame, and still get
a lot of repeated accuracy and precision out of it. I've implemented
this in my GCode script.
You can see the backlash the best if you change directions once the
system has settled.
If you want to run the simulation yourself:
- download Phun here (free, as in free beer)
- install "Phun"
- download this model
best,
Ton