to form a helix spiral

Dear all

I am unable to for a helix spiral using attached code.

First i want to mirror the generated curve in opposite direction and then i want a helix spiral to be formed with certain height and with certain gap. The gap can be taken as 0.5 and height as 60 mm.

The code is attached below.

Thank you

clc
R=30; %% radius of curvature
W=0.0125; %% width of grating
r=10;  %% radius of workpiece
th_1=(asin(W/R)); %% angle at which blazed grating existd
th_2=2*(asin(r/R));  %% angle at which primary profile exists
n=round(degr_2/degr); %% number of grating 


for i=1:n
    th (i)= (((i*th_1)-((th_2)/2)));
    x(i)= -(R*cos(th (i)));
    z(i)= (R*sin(th (i)));
end

X1=x;
Z1=z;
figure (1)
plot(X1,Z1); hold on

Answer 1

[Voss]

clc
R=30; %% radius of curvature
W=0.0125; %% width of grating
r=10;  %% radius of workpiece
th_1=(asin(W/R)); %% angle at which blazed grating existd
th_2=2*(asin(r/R));  %% angle at which primary profile exists
% n=round(degr_2/degr); %% number of grating 
n = 1e5;

for i=1:n
    th (i)= (((i*th_1)-((th_2)/2)));
    x(i)= -(R*cos(th (i)));
    z(i)= (R*sin(th (i)));
end

X1=x;
Z1=z;
Y1=th;
figure (1)
% plot(X1,Z1); hold on
plot3(X1,Y1,Z1);

xlabel('x');
ylabel('th');
zlabel('z');
view([30 60])

[Kundan Prasad]

i want to maintain of gap of 0.5 within every revolution till the height of 60 how it can be done??

[Voss]

clc
R=30; %% radius of curvature
W=0.0125; %% width of grating
r=10;  %% radius of workpiece
th_1=(asin(W/R)); %% angle at which blazed grating existd
th_2=2*(asin(r/R));  %% angle at which primary profile exists
% n=round(degr_2/degr); %% number of grating 
n = (2*pi/th_1)*120;

for i=1:n
    th(i) = i*th_1 - th_2/2;
    x(i)= -R*cos(th(i));
    z(i)= R*sin(th(i));
end

X1=x;
Z1=z;
Y1=th./(240*pi-th_2/2)*60;
figure (1)
% plot(X1,Z1); hold on
plot3(X1,Y1,Z1);

xlabel('x');
ylabel('th');
zlabel('z');
view([30 60])