Export a scaled graph to pdf for printing

Hi all! very new to MATLAB here.

I have a code that plots a template for cutting exhaust pipe at user defined angles. I want to print out the curve, to scale, so I can cut it out and draw around pipe with it. For reference, the usual exhaust diameter is 63mm and cut angle 7 degrees.

The code works fine and gives the x and y axis in the correct units. However, from line 33 I am struggling. I have tried a few things, but the pdf will not print in cm, to scale. Any thoughts are greatly appreciated:

% pie cut template v1.2
% exports a printable template to pdf

clear all
close all
clc

d_pipe = input('Enter pipe outer diameter, (mm)   ');
disp(d_pipe);
c_pipe = pi*d_pipe;
disp('pipe circumference (mm) ');
disp(c_pipe);
c_pipe_cm = c_pipe/10;

angle_cut = input('enter cutting angle (deg)  ');
disp(angle_cut);
angle_cut_rad = angle_cut*pi/180;
amp_cm = d_pipe*tan(angle_cut_rad)/20;

x = linspace(-pi, pi, 1000);
x_cm = linspace(0,c_pipe_cm,1000);
y = amp_cm*cos(x)+amp_cm;

figure;
plot(x_cm, y, 'k', 'Linewidth', 3);
xlabel('Pipe circumference (cm)');
ylabel('Cutting template (cm)');
% title('Cutting template');

% graph limits for template
xlim([0, c_pipe_cm]);

% set figure size and position
width_cm = c_pipe_cm;
height_cm = amp_cm;
set(gcf, 'units', 'centimeters', 'position', [0, 0, width_cm, 5]);

% ensure pdf matches figure size
set(gcf, 'paperunits', 'centimeters');
set(gcf, 'papersize', [width_cm, height_cm]);
set(gcf, 'paperposition', [0, 0, width_cm, height_cm])

% export to pdf
print(gcf, 'Pipe template.pdf', '-dpdf', '-r300');

Answer 1

[Anudeep Kumar]

Hey Luke,

I tried out the code you shared and made a few adjustments that should help ensure your PDF exports exactly to scale.

clear all
close all
clc

d_pipe = input('Enter pipe outer diameter, (mm)   ');

disp(d_pipe);

c_pipe = pi*d_pipe;

disp('pipe circumference (mm) ');

disp(c_pipe);

c_pipe_cm = c_pipe/10;

angle_cut = input('enter cutting angle (deg)  ');

disp(angle_cut);

angle_cut_rad = angle_cut*pi/180;

amp_cm = d_pipe*tan(angle_cut_rad)/20;

x = linspace(-pi, pi, 1000);

x_cm = linspace(0,c_pipe_cm,1000);

y = amp_cm*cos(x)+amp_cm;

figure;

plot(x_cm, y, 'k', 'Linewidth', 3);

xlabel('Pipe circumference (cm)');

ylabel('Cutting template (cm)');

% title('Cutting template');

% graph limits for template

xlim([0, c_pipe_cm]);

% set figure size and position

width_cm = c_pipe_cm;

height_cm = 2*amp_cm;% double amplitude for enough vertical space

set(gcf, 'units', 'centimeters', 'position', [0, 0, width_cm, height_cm]);

% Added line

set(gca, 'Position', [0 0 1 1], 'Units', 'normalized');

% ensure pdf matches figure size

set(gcf, 'paperunits', 'centimeters');

set(gcf, 'papersize', [width_cm, height_cm]);

set(gcf, 'paperposition', [0, 0, width_cm, height_cm])

% export to pdf

print(gcf, 'Pipe template.pdf', '-dpdf', '-r300');

Changes I made:

• On line 34, I set “height_cm” to twice the amplitude to give you more vertical space.
• On line 36, I updated the figure position to use the new “height_cm” value.
• I also added a line to set the axes position (set(gca, 'Position', [0 0 1 1], 'Units', 'normalized');). This ensures the exported PDF is to scale, fills the entire page, and doesn't have unwanted margins or whitespace.

When printing, just make sure to select “100%” or “Actual size” in your print settings. This should give you a template that matches your specified dimensions exactly.

Here is the documentation on various properties for Axes, for your reference:

https://www.mathworks.com/help/releases/R2025a/matlab/ref/matlab.graphics.axis.axes-properties.html#budumk7_sep_shared-Position

Hope this helps you get the desired result!

[Luke Cabot]

Hi Anudeep

That's perfect, thankyou!

I tried twice the height before and some other gca settings before, but could not quite get it to work. Your ammendments are exactly to scale. I will try moving the template on the printable area but everything else is fine. Cheers!