Dust collection - spark bong

[Technohedge]

Hi guys, been looking at a lot of info on dust collection, (I have been reading that recent thread on airborne dust collection too) and have recently built a funnel type extractor under the grinding belt that goes to a shop vac. seems to be quite effective, but i havent used it in anger yet as i want to be sure about metal/wood collection.

If i was to use a spark bong type arrangement to surpress metal sparks, is it safe to use both wood and metal in the same vac unit? I assume the main fire risk is the sparks, how well does a well built unit prevent them from getting to the terminal collection bin?

My plan would be to just use the bong arrangement and suck both wood and metal dust through if at all possible.

Does anyone have any guidelines for the bong arrangement? Would like to get max spark reduction with minimum vacuum reduction

 

[Stacy E. Apelt - Bladesmith]

Yes, if the bong is working right, no sparks go to the vac.

 

[Maineiac1]

Ive actually mounted a 3 gallon trash can on my grinder stand under the platen, I dangle the shop vac hose into it a few inches, all the sparks seem to go to the bottom of the can and the "dust" gets sucked up pretty well. Works good with wood but there is still a lot that gets slung around with the belt and straight back at the wall.. I still keep my messy equipment cordoned off from the benches and whatnot.