Patent Free Protection?

I have an idea that I wish to keep free for all to use. Does publishing on Instructables count as Prior Art to the US Patent Office? Does the Patent Office check Instructables in patent searches? I check Patent Free on all my Instructable ideas, so is this enough?
Thanks, Carl.

Yes, the changes in the US system align it with the rest of the world, any publication before filing is prior art and stops anyone (including you) from patenting it.