Workshop dust extraction (again)

[nothanks]

I still haven't found the right round tuit to get the extraction system sorted, but it's getting closer. I recently bought a "Dust Commander" cyclone and (very much to my surprise) it's a brilliant gizzmo, so that's motivated me to sort out a proper system. I have a standard high_volume_low_pressure (HVLP) chip collector for the planer, thicknesser and spindle and will be using the cyclone+dyson for things like table saw, router, bandsaw and sander. I plan to put both vacuum systems in a closed cubicle, exhausting to the outside world, and to run smooth pipework across the ceiling (with a static wire!) to several drops, with appropriate reducers, bungs and/or blast gates. I can't decide whether I need to run separate 100mm and 50mm pipes, or whether I can have one 100mm "distribution" pipe and connect either the cyclone+dyson (via 50mm) or the chip collector (via 100mm), depending on the tool that's connected. What does the team think? I can't think of a better way to phrase it - I hope it makes sense.

[John Rumm]

Yup cyclones are good, although they will still miss the very fine stuff, so either additional hepa filtration or exhausting the air is better from a health point of view.

People tend to make lots of fuss about static discharge wires etc, but in reality the only real fire risk with wood dust is when the collection system ingests sparks from grinding etc, static is not going to be a problem...

One thing to keep in mind if venting the collection air, is you will need a way for outside air to get back in, since you are not trying to de-pressurise the building! Also a high rate of extraction will also significantly up the heating costs in the winter.

Best option is usually large ducting from the extractor and only reduce near the tool. However you need enough power at the suction end to cope with the pressure drop in the small hoses.

If you need low volume high pressure for small tools and you have not got the power at the head end, then you are usually better off with a M class dust collector close to the tool for the small stuff and save the ducted system for the tools that can produce large volumes of chips rather than smaller quantities of fine dust.

110mm soil pipe is a very cheap way to do the larger ducting for a small to medium power system (1 to 2hp collector). More powerful systems hay want 5" or 6" ducting for the initial runs.

To get complete collection at the tool, you need adequate speed of airflow to overcome the speed of particle ejection from the tool - and that can be quite a challenge when you think of the blade/cutter tip speed on some of the tools. Although generally collection at source is better than trying to filter it out of the air later. If you can't always ensure full collection at the source, then budget for one or more air cleaners as well.

[Tim Lamb]

In message , [e-mail] writes

It is some years since I did my extract system so actual cost recollection may be dim:-) I don't recall 100mm steel pipe being hugely expensive. One lesson has been to avoid small bore (50mm) convoluted plastic pipe if at all possible.

[Brian Gaff]

I have many qualms about sawdust. I once visited the aftermath of a sawdust fire caused by a faulty vacuum device. Not pretty at all, in fact highly dangerous. Brian

[Andrew]

Adams GF should have bought one of those :-)