Welcome to the 405th.
Which version of the Chief are you looking for? All the files are located in The Armoury.
Unfortunately, I don't think any of the files here are in a PDF format. All of them are in a PDO.
Like PaiganBoi mentioned you won't find any PDF files in The Armoury but that's a good thing! With PDO files you can adjust the patterns so that they are scaled to fit you and not some random on the internet before converting to a PDF for printing.
For scaling files I'm a fan of Armorsmith but Pepakura Designer is a good free option too. The easiest way to make a PDF in these programs is adjust the scale of the pieces as necessary and then print to PDF using Adobe or whatever suite you have. I only convert to PDF so that I have a saved copy on record so if I bork something I can go back and print another.
Unfortunetly I'm on a Mac and those files are not available and the emulator sucks!
If someone would be kind to maybe scale them to our sizes and create the PDFS for us that would be ACES!
Let me know guys!