I built a delta earlier this year and found that the most important point is to make sure the angle of the push rods from the ball joint centres is exactly 60 degrees to the vertical slides.
Using Marlin as control sw :- got the angle wrong on my first attempt (58.62 degrees), I modified the angle value in config.h expecting the calculations to then be corrected.
This approach did NOT work so after very careful measurements, recalculated and extended my rod lengths to correct the angle to 60 degrees.
these are my Marlin config.h settings :-
#define DELTA_SEGMENTS_PER_SECOND 200
// Center-to-center distance of the holes in the diagonal push rods.
#define DELTA_DIAGONAL_ROD 311.8 // mm
// Horizontal offset from middle of printer to smooth rod center.
#define DELTA_SMOOTH_ROD_OFFSET 248.82 // mm
// Horizontal offset of the universal joints on the end effector.
#define DELTA_EFFECTOR_OFFSET 43.3 // mm
// Horizontal offset of the universal joints on the carriages.
#define DELTA_CARRIAGE_OFFSET 49.5 // mm
// Effective horizontal distance bridged by diagonal push rods.
#define DELTA_RADIUS (DELTA_SMOOTH_ROD_OFFSET-DELTA_EFFECTOR_OFFSET-DELTA_CARRIAGE_OFFSET)
// Effective X/Y positions of the three vertical towers.
#define SIN_60 0.8660254037844386 // 0.8660254037844386
#define COS_60 0.5 // 0.5
These are for my machine it will not be correct for you, notice the number of decimal places for SIN 60 !!! rounding errors will cause problems.
I have errors in the Z plane when the head moves, the bed appears to be dished but with in 0.15 mm, a sort of doughnut shape ,but after the first layer is layed down the errors are compensated for.
My m/c has a working bed of approx 200mm square, most accurate being the 200mm dia. Like everyone I wanted to make the largest working volume possible, experience has shown me it's not worth the struggle. I don't use the area I have as it takes so long to first draw such a large item and than hours to print it out only to find it was not quite correct. My Z plane is 440 mm which I now realise is well ott, I built from the materials I had and not wanting to cut them down, maximised the size. Configuring Marlin is by a long way the most difficult part of the project.
a very rewarding project and I hope this may help.
Using Marlin as control sw :- got the angle wrong on my first attempt (58.62 degrees), I modified the angle value in config.h expecting the calculations to then be corrected.
This approach did NOT work so after very careful measurements, recalculated and extended my rod lengths to correct the angle to 60 degrees.
these are my Marlin config.h settings :-
#define DELTA_SEGMENTS_PER_SECOND 200
// Center-to-center distance of the holes in the diagonal push rods.
#define DELTA_DIAGONAL_ROD 311.8 // mm
// Horizontal offset from middle of printer to smooth rod center.
#define DELTA_SMOOTH_ROD_OFFSET 248.82 // mm
// Horizontal offset of the universal joints on the end effector.
#define DELTA_EFFECTOR_OFFSET 43.3 // mm
// Horizontal offset of the universal joints on the carriages.
#define DELTA_CARRIAGE_OFFSET 49.5 // mm
// Effective horizontal distance bridged by diagonal push rods.
#define DELTA_RADIUS (DELTA_SMOOTH_ROD_OFFSET-DELTA_EFFECTOR_OFFSET-DELTA_CARRIAGE_OFFSET)
// Effective X/Y positions of the three vertical towers.
#define SIN_60 0.8660254037844386 // 0.8660254037844386
#define COS_60 0.5 // 0.5
These are for my machine it will not be correct for you, notice the number of decimal places for SIN 60 !!! rounding errors will cause problems.
I have errors in the Z plane when the head moves, the bed appears to be dished but with in 0.15 mm, a sort of doughnut shape ,but after the first layer is layed down the errors are compensated for.
My m/c has a working bed of approx 200mm square, most accurate being the 200mm dia. Like everyone I wanted to make the largest working volume possible, experience has shown me it's not worth the struggle. I don't use the area I have as it takes so long to first draw such a large item and than hours to print it out only to find it was not quite correct. My Z plane is 440 mm which I now realise is well ott, I built from the materials I had and not wanting to cut them down, maximised the size. Configuring Marlin is by a long way the most difficult part of the project.
a very rewarding project and I hope this may help.