re: Danger of sawdust combustion?

For anyone thinking that explosion risk from a dust collection system is not fact, or that grounding is not required I advise you to read the NFPA material on this issue. The NFPA only writes rules based on deaths. If you want to learn more go to http://www.nordfab.com/wp-content/uploads/2013/03/GaryJohnsonArticle.pdf
The article is written for businesses, however the principals that relate to explosion apply to any size machine.