Hi propmaster - is the full file with the knurling of particularly large size? If so then probably it exceeds some kind of upload limit in the forum software.

In cases like that for particularly large files you would need to use a file sharing service to host the file and then post the link to it, rather than using the forum's built in attachment mechanism.

There are various free file sharing services out there, 2 common ones are dropbox and Windows Live SkyDrive:

https://www.dropbox.com/
http://skydrive.live.com/

- Michael