Dustbusters

[Dave]

Don't worry, we all have lives to live :-)

Initially, I was bothered about these details in case I filled the source vac with dust too quick, but when I looked at how it worked, I very quickly found out that what was required was that the speed of air going in had to far exceed the speed that it was drawn out, hence the large diam. of the bucket protecting the suction device.

If the bucket was too deep, there would be less collection capacity.

If too shallow, there would be more dust passed to the suction device. I think this aspect should be considered with the height of the inlet pipe to the chamber. The higher the inlet, the shallower can be the bucket portion.

If too wide, it may hinder the passage of the dust to the more stable lower chamber of the cyclone.

If too narrow, the speed of entry of the dust would be close to the speed of extraction

A simple cloth filter at the bottom of the bucket would sort that out and could be made to be cleanable from a small diam. shaft, connected to the filter, that would enable the dust to be shaken off from above. Pump the handle up and down a few times to shake off the dust collected. With the suction device switched off of course.

All I have to buy now, is the input and output pipe and I will still have change from a tenner :-)))))))) Not that I am tight, you understand ;-)

[John Rumm]

Ultimately the speed in and out must be the same though because the collection hose from the vacuum supply is the same diameter as the dust collection hose.

In theory so long as it protects the incoming airflow from any turbulence generated by the exhaust then it should be fine.

Yup - planer shavings etc.

Can only see that becoming an issue when the bin gets to nearly full - the faster airflow up the smaller bucket may be able to "lift" some finer dust from the top of the pile, whereas, a slower airflow in a larger bucket will be less likely to do this.

Not sure a cloth filter would help much - the only stuff that gets as far as the vacuum bag is as fine or finer than talcum power - and that would either pass through a cloth filter, or possibly form an air tight clog.

If you want top quality filtration with no "filters" as such anywhere in the system, then you would probably be better off with a different design (i.e. one that has a conical cyclone section that sits above the collection bin rather than combining the bin and cyclone, and one that uses a long straight input pipe (i.e couple of meters). That would ensure best quality airflow in, followed by much greater acceleration of the air speed in the cyclone - that way you could spin out stuff as fine as smoke particles)

It's normally the extra hoses / adaptors that cost the money!

[Dave]

Sorry, but a slight correction here :-)

The speed is dependent on the diameter of the pipe in question. I was thinking about the diameter of the bucket. Volume, I think, is what you meant.

Noted.

Thanks, I had not considered this point, I was looking at it from a circular saw and router point of view.

This is what I am going for. Thanks again.

OK then, the filter has been binned, thanks again.

It's only a hobby ;-) All I want to do is stop me from changing the colour of the garden when I DIY (I have to work outside, due to lack of garage/workshop. It's a PITA, but what else can I do but wait for dry and non cold weather :-(

Thankfully, I have most of those, it's just the rigid waste pipe I have to buy now.

I know I have said thanks many times in this post, but you have taken me from not knowing much about how they work, to almost an expert ;-)

I mean this most sincerely folks (who remembers who said that?)

Dave

[John Rumm]

sort of - yes it is volume of air (as in m^3/hr) that must match in and out - but note I did say the hose diameters at the tool and the vacuum supply are about equal - hence the air speed at the hoses will also be about equal. Having said all that, part of the purpose of the bucket in the type of design we are using here is to make this a "non issue" since the exhaust hose never gets near the top of the collected shavings in the bin.

Its probably not an issue to worry about - it would be mechanically difficult to have a gap between the outside of the bucket and the inside of the bin that is less than the diameter of the inlet hose. Hence if it gets all the way down the hose it is less likely to get stuck then (more likely to get stuck in the hose)

Part of the attraction of the cyclone anyway is not having to worry about filters/bags etc any more.

Well the unit I built will certainly handle that requirement. I use my one for all dust collecting and general cleaning up in the workshop. It's fine for hand tools etc and things like the table saw. I expect something with a bigger diameter input might be good if I got something like a thicknesser or a bench planer though.

Aha - perhaps you need to have a bash at one of the other projects that pre-dated the need for the cyclone...

(think this link is still in another thread some place - so you may have seen it already)

had the similar problem to you - either work outside, or work inside and incur the wrath of SWMBO. Neither were ideal for any job that you needed to stop and start over a few days)

Must admit I found having the fixed plumbing from vacuum to cyclone was a bit limiting as the collection hose was not always long enough to get to every place I wanted it. So I scrounged an old set of vacuum tools from my mum's under stairs cupboard! That works quite well as I now can move the cyclone itself a couple of meters when I need to.

Well I would not claim to be any sort of expert myself on cyclone design

- but fortunately they don't seem that sensitive to design in this application! ;-)

Hughey Green would be my guess?

[Dave]

Gone down that sort of path before, usually because of the wife's butterfly mind.

One day I might get a shed that can have the tools set out, but I'm not holding my breath.

Cheers

Dave