Built on a coffee maker. And on a budget. No precision rails or bearings. True Delta Kinematics. Great prints.
Here are two useful links for understanding delta kinematics:
Online calculator based on above equations:
I seem to recall that the labels for the dimensions in the calculator are a little misleading, so be sure to double check the drawings in the first link.
Here's where you can enter those parameters into my modified marlin code on github (originally modified from an early version of the firepick-delta firmware). Starting around line 198 in Configurations.h:
#define DELTA_E 50.8//172.0//131.636 // End effector length #define DELTA_F 158.3//152.4//81.4//190.526 // Base length #define DELTA_RE 163.5//114.5//270.000 // Carbon rod length #define DELTA_RF 50.8//77.0//86.000 // Servo horn length
The un-commented values above are the dimensions used on this printer (in mm).
The coffee maker hotplate has a significant delay which causes control problems....
By the time the sensor sees a temperature change, enough energy has been put into the plate that it shoots up to a very high temperature. The process does not seem to stabilize with just PID control.
To correct this, we edited the PID algorithm. Now the hotplate is pulsed on between 0 and 1 seconds every 10 seconds according to the PID algorithm.
More details coming....
To correct for distorted prints. Print a 1 in cube, measure dimensions, calculate transformation matrix to correct and update firmware.
Pretty straight forward here: Arduino Mega + Ramps 1.4.
SSR for hot plate control.