This is my first blog post of many of findings whilst I researched into the design of my 3d Delta printer. This post will cover FSR’s used in the case of Spatial One (my 3D delta printer) for bed levelling. I have tried many methods of bed leveling and using FSR’s to this date is very reliable and accurate although in the future i will look at more cost effective and accurate solutions.
Basics on bed leveling:
A FSR bed leveling system works by having three FSR’s on the circumference of the bed, when the probe (usually the hot end) makes contact with bed the FSR’s change in resistance and the electronics controlling the printer detects this.
Force Sensing Resistor optimized for use in human touch control of electronic devices such as automotive electronics, medical systems, and in industrial and robotics applications. FSRs are two-wire devices. They are robust polymer thick film (PTF) sensors that exhibit a decrease in resistance with increase in force applied to the surface of the sensor.
The set up of the bed leveling for the smoothie board on Spatial One:
I use 3 FSR’s (force sensitive resistors) under the bed and FSR controller by John Socha-Leialoha’s. The FSR are placed under the circumference of the bed at 3 equidistant points and connected to the FSR controller and the controller connects to the z max on the smoothie board. Then i run the G32 command and the smoothie board runs the full calibration sequence automatically, where the hotend acts as the z probe and the FSR detects the probe contacting the bed.
FSR controller available from our website
I looked at two types of FSR’s; FSR 400 and FSR 402 from our website FSR 402 .
The FSR 400 has the following specification: