XY Plotter v2 understanding X_STEPS_PER_MM and $6 command

fourchette · 2015-08-12 17:22:34 UTC

Hello,

i’m struggling understanding the meaning of $6 commands and the relationship with speed of drawing

While using GRemote.bat i noticed the following command
$6 X174.9781 Y174.9781 Z174.9781
the firmware source seems to say that it changes this parameter X_STEPS_PER_MM and Y_STEPS_PER_MM

github.com

Makeblock-official/XY-Plotter-2.0/blob/master/software/GCodeParser/process_string.ino#L409


case 5:
 //ENABLE SERVO MOTOR FOR Z
 if(has_command('Z',instruction,size)){
   Z_ENABLE_SERVO = search_string('Z', instruction, size);
   
 }
 break;
 case 6:
 //set XYZ STEPS PER MM
 if (has_command('X', instruction, size)){
		X_STEPS_PER_MM = search_string('X', instruction, size);
    x_units = X_STEPS_PER_MM;
    Serial.println(x_units);
}
if (has_command('Y', instruction, size)){
		Y_STEPS_PER_MM = search_string('Y', instruction, size);
    y_units = Y_STEPS_PER_MM;
}
if (has_command('Z', instruction, size)){
		Z_STEPS_PER_MM = search_string('Z', instruction, size);
    z_units = Z_STEPS_PER_MM;

Assuming X_STEPS_PER_MM stands for the number of steps to travel 1 millimeter on X
Assuming the micro is set to 8, then each round of stepper will require 200*8 = 1600 steps
Since there is a 18T pulley mounted on the stepper
since the pulley 18T internal diameter is 9.29mm according to its documentation
=> then one round of this pulley will boil down to traveling 9.29 * 3.14 = 29.18 mm
29.18 mm <=> 1600 steps
1 mm <=> 1600/29.18 = 54.83 steps to make 1 millimeter

=> 54.83 is way different from 174.9781

???

And yet, when i use the following gcodes
$6 X174.9781 Y174.9781 Z174.9781
G0 X0 Y0
G0 X10 Y0
=> with my ruler i can measure that it does travel 10 millimeters on X

So I must be mistaken somewhere. What does X_STEPS_PER_MM = 174.9781 mean ? Where does this value come from ?

i’m confused

Thanks for the help

fourchette

fourchette · 2015-10-01 04:18:21 UTC

doesnt anyone have a clue here ?
what’s wrong makeblock ?

fourchette · 2015-11-10 22:56:20 UTC

maybe comment from Adrian The User Guide and Troubleshooting of Stepper Motor and Stepper Motor Driver:

for starters i have the distance of 1 revolution wrong.

i have the feeling i need to read again adrian comment after a good night sleep

@Adrian_S => if you see this post, can you please comment ?

Adrian_S · 2015-11-20 19:12:54 UTC

Soon after I posted that the mDraw package arrived and I switched to it, so I am afraid I won’t be able to help you with GRemote. The header switches are changed to work with mDraw to the highest setting, and so I no longer use Gremote or BenBox. Since nobody ever replied to my query regarding the dip switch settings my guess about them could be incorrect (I was assuming switches 1-3 on the stepper boards equated to switches 5-7 on the datasheet in the absence of an actual datasheet for the board)

Reading back to your earlier post, I wouldn’t use the pulley diameter in the calculations, the most accurate figure to use for the distance moved in one full revolution of the pulley is the length of belt equivalent to the number of teeth on the pulley, so for an 18-tooth pulley, measure 18 teeth on the belt.

fourchette · 2015-12-01 17:25:31 UTC

thanks for the advice adian

i solved it by myself by using your tips

LLH 1/8 th (default) $6 X174.9781 Y174.9781 Z174.9781
LHL 1/4 quarter $6 X87.48905 Y87.48905 Z87.48905
HLL 1/2 (half) $6 X43.744525 Y43.744525 Z43.744525

now we’re getting pretty decent speed

system · 2018-06-10 14:34:19 UTC