Thread: Dust extraction presentation

Originally Posted by Tonyz

hope you charge for your time and knowledge

Nope, it's a no charge service.
I call it Taxpayer payback.
Taxpayer paid for all my expensive training so it's time they got something back
I do charge for travel expenses if I go to the country.

embarrassed ...I wrote that then watched your vid....opps i thought stupid comment.

wow your vid is very entertaining, I learnt from it. thanks again for your commitment to this forum

The problem with dust extraction is that if you don't do it properly is about as good as not doing it at all, and doing it properly is basically prohibitive for most people. It takes a good chunk of your time, space and money, and most people are short in at least 2 of the 3.

Not to mention most of them don't have a clue either. Because nobody tells you when you're planning your little arts and crafts corner that you have to be the absolute master of every molecule of air, that you need to control it, accelerate it to specific speeds and direct it exactly where you want, and you have to do it with a giant expensive and noisy installation that you will probably have to finetune for the rest of your life. I think if they knew, most of them would reconsider the merits of collecting stamps instead lol

I disagree that giant expensive machinery are essential. If you are only setting up an arts and crafts corner that you plan to use a couple of 1/2 days a week then perhaps a bathroom fan will do Many weekend warriors in a single car garage can get away with a 2HP DC with some 4" ducting to collect the chips and a couple of decent ventilation fans.

Unless you're main activity is really dusty, like turning or using arbor tech type carvers,then I reckon spending 10% of you total shed+tool+machine cost on dust extraction is not unreasonable. I agree most people don't have the time or background to work it all out from scratch which is where nerds like me can assist.

Thanks for the presentation Bob. At about the 20min mark you talk about a drum to collect hot sparks before they get to the dust collector. Can you please give some more details on the design of that drum? I was thinking this may be a good idea when collecting dust from the bench grinder.
Thanks

Originally Posted by mannetje

Thanks for the presentation Bob. At about the 20min mark you talk about a drum to collect hot sparks before they get to the dust collector. Can you please give some more details on the design of that drum? I was thinking this may be a good idea when collecting dust from the bench grinder.
Thanks

It sure is a good idea. Unless you use CBN or diamond, grinding dust is not just metal but contains a substantial amount of the grit and other material used in abrasives. The material ranges from stone to Alox and some have silica, fibreglass and resins. I did a study of the dust coming from a thin metal cutting kerf and found it consisted of two major fractions, one that fell out of air suspension about 8X faster than wood (that was probably the metal) and the second largest component that fell out of air suspension about 2.5X faster than wood (that was probably the abrasive). This is good in the it settles out of the air much faster than wood but it is still not a healthy proposition if you spend a lot of time grinding. As most woodworkers don't spend a lot of time grinding I post the WIP of the metal dust catcher in the metal work forum.

Metal dust catcher

This is my fave photo taken using the metal dust catcher on my home made thin kerf cutting saw.
The saw is attached to a variable speed grinder geared up to run at up to 12,000 rpm.
When cutting most of the sparks are shot by the blade down under the table into an open baked bean can.
In this photo I'm demonstrating what happens when the workpiece touches the back of the blue and throw up a shower of sparks which the metal dust catcher seems to do a good job of catching.
bestofthebest.jpg

Ok, thanks for the reference to the post on the metal work forum. So it seems that there isn't anything fancy inside the drum - just an inlet and an outlet. I take it no sparks get sucked into the outlet flex but they are all caught in the drum? I do have 2 CBN wheels on my bench grinder which currently has no dust collection, however I do notice a significant increase on my particle meter (Dylos) after sharpening on the bench grinder. It does drop off back to ambient levels though within about 5 mins.

Originally Posted by mannetje

Ok, thanks for the reference to the post on the metal work forum. So it seems that there isn't anything fancy inside the drum - just an inlet and an outlet. I take it no sparks get sucked into the outlet flex but they are all caught in the drum? I do have 2 CBN wheels on my bench grinder which currently has no dust collection, however I do notice a significant increase on my particle meter (Dylos) after sharpening on the bench grinder. It does drop off back to ambient levels though within about 5 mins.

Yeah I wouldn't worry about that level of exposure. It'll be all metal dust anda s you say it drops off pretty quickly.

I'm not worried about sparks mixing with the dust. Many years ago I set up a metal linisher connected direct up to my wood dust extractor via a 3m long 10mm diameter transparent flexy laying under the bench. At night I could see how far along the flexy the sparks were going ie <1m. After a year or so I could see the build up of metal dust in the flex which also started to slightly block the flex. The sparks are after all just hot metal dust.

What I'm more worried about is a piece of hot metal being sucked into the dust collector bags - metal is also not so good for the impeller either. This is the job for the drum. It also does a fair job on the sparks as I can see no sparks making it into the drum outlet through the (once transparent) flex.

Ok, great.

And do you put any water in the bottom of your drum? It seems that some people do this but if no sparks are reaching the outlet then perhaps this isn't necessary.

Originally Posted by mannetje

Ok, great.

And do you put any water in the bottom of your drum? It seems that some people do this but if no sparks are reaching the outlet then perhaps this isn't necessary.

No water - It just makes a mess.