Dust collection

[Radar]

I'm setting up my new knife shop in my existing wood shop. I've got a couple of primary concerns, first being fire safety, second being contamination of my lumber with abrasive dust that will dull my woodworking machine tools.

I have a 2 hp, 1200'ish CFM, quasi-2-stage dust collector. It's basically a single stage machine that places a cyclone in a 32 gallon garbage can in series. How crazy would I be to get a second garbage can to be dedicated to metal grinding and partially fill it with water as a spark arrestor? As a secondary protection measure, I could put a fibrous filter over the outlet port of the cyclone to keep the big steel particulates out of the primary collector.

I certainly don't want hot sparks getting to combustible dust, how long do the sparks remain hot enough to be dangerous? If I put enough distance between spark source and combustibles, can I minimize the risk enough for comfort?

Thanks for any suggestions (or warnings).

Radar

[Ray Rogers]

I have the same dust collector you have (2hp w/cyclone). When I first set it up I had it collecting dust from several machines but now I have it dedicated to my primary grinder. Even dedicated as it is it doesn't catch all the abrasive dust so if you are worried about contaminating your lumber I would say you probably should continue to worry. I don't know how much contamination there will actually be but I do believe that the only way to avoid cross contamination between the wood and metal functions is to separate the shops.

Putting water in the cyclone should solve any fire hazard as far as the wood dust in the collector is concerned but it won't stop the hot metal from melting your collection hoses. After burning a hole in mine I decided to simply shut off the collector when I'm grinding metal with coarse belts, turn it on when shaping handles or doing finish work with finer belts that don't remove large amounts of metal (no sparks). Yup, get some metal dust around but it is the compromise I made....

[Radar]

Thanks for the response Ray. I suspected as much for the cross contamination and will probably have to take some steps to minimize it. One thing I can possibly do is build a "tent" around the grinder and pull fresh air in through the front opening with an old furnace fan, sort of like a laminar flow bench often found in chem-labs. I think that, coupled with active dust collection should help considerably. I had considered that sparks might attack the flexible hoses. My thought was to make (at least) the first run from the grinder out of steel dust collection pipe. That should allow the grinding debris enough time to cool before finding its way to plastic.

I'm glad to hear that my thoughts on fire safety aren't way out of line too.

Thanks again for the prompt response. How do you find time to make knives?

-Radar