Initial Delta Value Setup

mattr254

I'm having issue's setting up a home brew delta, The information that I have input into the config doesn't seem adequate for what a delta printer needs. The setup seems surprisingly vague. Yes there are pictures like a value for printer radius (which doesn't have an input). There is no Delta Smooth Rod, Carriage Offset, Effector Offset. I have put my values into the printer and they do not seem level during transition moves. The printer is "square" and have had limited success with Marlin (just cant dry print) with the moves being level and consistent. This is the information that I input
Z length 200.0 mm << Should be Usable height
Diagonal rod length 210.0mm << No brainier picture makes that easy to figure out
Horizontal radius when centered 125.0mm << If I'm reading this correctly should be the Delta Radius not to include Effector or Carriage
Floor Safety margin << No clue what that is
Max Horizontal Radius 90mm << should be half of your horizontal print area
Angle of column A/B/C << didn't touch, should be 120 off for a circle but a triangle has 180 degrees ?
Radius Error Column A/B/C << didn't touch
Diagonal rod Error Column A/B/C << didn't touch (I think should be used to compensate for slightly longer or shorter rods)
If you open the config.h file there is the ability to input effector and carriage off sets but no support to show what the intention of the values are. I figure if it was important it would be part of the web input. I'm not trying to fine tune yet to within a miniscule.000mm. I'm trying to keep the print head from drooping 9mm to the corners. I would blame it on the machine except I've been able to get it to not vary more than 1mm with Marlin.

Lars

Hello, 

The following is my (limited) experiences from aligning:

Z length   <-- First roughly measure the distance from table to your endstops. Then subtract 20 from that. Set that as your Z length. Later you will use G32 S2 and that will measure the exact length for you. It is important that you set Z length to less than your actual length if you plan on autoleveling with probe. The probe will only register contact when below what you set as z=0.  Thus before using G32 S2 you go to  Z=0  which will then be some 20mm above bed.  And then it aligns it self nicely.

Horizontal radius when centered (called something like Horizontal Rod in EEPROM in Repetier Host and called ROD_RADIUS in configuration.h) - I found this to be the most critical length of them all. 

 Angle of column A/B/C -  A circle has 360 deg and  you are seeing this from the center of your print area (this 120deg x 3). On mine I found that 55mm from the center I get a deviation of some ½ mm between the two towers when changing one tower by ½ a degree - My printer has 210 mm rod lengths. 

As you said, in configuration.h you also find:

END_EFFECTOR_HORIZONTAL_OFFSET 

CARRIAGE_HORIZONTAL_OFFSET 

 

In my experience they also have to be set but that could be false as I was changing many parameters at the same time. They don't hurt anyways. 

Finally remember that in configuration.h you also find:

#define Z_PROBE_X1 20

#define Z_PROBE_Y1 20

#define Z_PROBE_X2 160

#define Z_PROBE_Y2 20

#define Z_PROBE_X3 100

#define Z_PROBE_Y3 160

These values are used for auto-leveling - They have to be changed for small printers like ours. 

Don't do like me and spend hours trying to figure out why auto-leveling keeps going outside print area....

Finally, finally  - One thing I found, If you have an angle

You can put the long side on your bed and the other one to your towers to see that the bed is level to the towers. That way you can convince your self that whatever off-sets you get when leveling is related to wrong lengths set in the config.

You can then setup a script that goes close to one tower and then the adjacent point (which will be between two towers). If you think about the cosine / sinus relation of angles on the rods that should tell you a lot when you then get different Z values.  I found that more efficient then measuring at the 3 towers as suggested else-where. 

Lars

Oh and...

M502  - Reset all settings to the ones in your config. It gives me peace to do this every time I upload new firmware - Then you are sure the EEPROM is not messing with you.

And:

M322 S3 ; Reset auto level matrix permanently

I know I wrote a lot more then what you asked for and maybe you know all this. Just had to get it off my chest because I spend so much time fiddling around with these things  

Cheddy

I'm having a lot of trouble getting the slider movement to work properly on my reprap delta printer (RAMPS 1.4 w/Repetier-firmware.) I used the configuration tool to set the initial values, but using manual commands through Rep-Host doesn't work correctly. The different tower motors seem to be uncoordinated. Hitting the home button causes the Z slider to move up, but no movement on the other two towers.

Can somebody please post a sample configuration.h file for a generic reprap delta printer, so I have a clean starting point.