How to caculate the a b c towers for delta printer

gorf25

I have a program I setup to calculate the corners for a delta printer, to move to the A B C tower centers.

but I don't think I am getting the correct results.

this is how I am doing the math

void modify(mStruct *v,double build_radius)
 {
  double x_theta = 210,y_theta = 330,z_theta = 90;
  v->A_towerx = build_radius * cos(x_theta);
  v->A_towery = build_radius * sin(x_theta);
  v->B_towerx = build_radius * cos(y_theta);
  v->B_towery = build_radius * sin(y_theta);
  v->C_towerx = build_radius * cos(z_theta);
  v->C_towery = build_radius * sin(z_theta);
 }

it seems to be off by a few mm's I suck at math so I assume I am going abut it wrong...

any suggestions?

Thanks gary

Repetier

Not sure what you think tower centers are, but I think your build_radius i snot correct. Have you added effector radius from effector center to effector joints for diagonals? horizontal_radius does not account that value.

gorf25

what I am trying to do is get the correct travel to the a b c towers to do the paper test in each corner.

as far as I know I only needed the to know  that they are at 210 330 and 90 and than the, print radius or a little less than

the actual print radius which should give me the x y distance for each tower to start the calibration..

thanks gary  

Repetier

Yes,if you use effective horitontal radius that would leave the diagonal vertical to tower if that position is possible on your delta.

gorf25

an example is I think if I use 100 for the radius the z corner c tower should be x 0 y 100

but with the math I entered in the c program the x 0 is coming out way off and so is the y.

so I assume my math calculation is not correct just looking to see if anyone knows the correct way to

do the math...

thanks gary

Repetier

Yes, you have x and y switched in your formula. 0° is pure x axis and cos(0)=1 so that must be x.

gorf25

  double x_theta = 210,y_theta = 330,z_theta = 90;
  v->A_towerx = build_radius * cos(x_theta);
  v->A_towery = build_radius * sin(x_theta);
  v->B_towerx = build_radius * cos(y_theta);
  v->B_towery = build_radius * sin(y_theta);
  v->C_towerx = build_radius * cos(z_theta);
  v->C_towery = build_radius * sin(z_theta);

when I cout<< the values with a radius of 100  I get

A corner x= -88.3877
A corner y= 46.7719
B corner x= -99.1199
B corner y= -13.2382
C corner x= -44.8074
C corner y= 89.3997

there defiantly not right but I'm not  sure what your formula is ?

thanks gary

Repetier

I know what your error is:-)

Programming languages take angles as radians and not degrees so multiply by pi/180 to convert to radians.

gorf25

A corner x= -86.6025
A corner y= -50
B corner x= 86.6025
B corner y= -50
C corner x= 4.66906e-012
C corner y= 100

That worked fine I used a radius of 100 the only incorrect value was the C corner x should  = 0

Thanks for you help

gary

Repetier

The error is just rounding error. 0.00000000000466 is nearly 0.

gorf25

thanks got it working ended up using

std::cout.precision(4); 
 cout <<"C corner x= "<<std::fixed<<towers.C_towerx<<endl;

now I get 0 correct awnser

Thanks gary