Good link that, and congrats on building your cyclone. I followed
the same route a few months ago and I still get a glow of
satisfaction every time I use it.

This is an opportune moment to post an update on the pressure
relief valve (mentioned in a previous thread a couple of weeks
ago) to prevent the bin collapsing and eventually splitting under
blockage conditions.

I made it. In fact I made two versions and tried various springs
from the Screwfix compression spring kit which I ended up buying.

I was delighted with the ingenuity of them and the way I had
re-purposed throwaway stuff like offcuts of copper pipe and a
used decorator's filler cartridge, until I found they didn't
work.

However, I now have a clear understanding of the problem and
other potential pitfalls.

I have a new and completely different design that takes these
into account and should work raps own head touch wood.

More details on the problem, the new design, and a load of
alternative design ideas that could be made to work as soon as
I've made my prototype and seen how it does. I'll probably knock
up some web pages because it's quite interesting (if you're the
sort of person who can get all juiced up over adventures with a
home-brew pressure relief valve).

Yes, it would have been easier to fibreglass my bin or buy a
steel one, but I wouldn't be having all the geeky fun and
learning wot I am learning with all this.

The end product will, if it works as expected, be fairly easy to
make, should work with minimal tweaking on a variety of bin
desgins and vacuum strengths, and look pretty gnarly into the
bargain.

W.







"PoP" wrote
in message ...
We've had some threads on this forum recently relating to
building
cyclones for dust collection in a workshop. I've just built a
cyclone
based upon the excellent articles posted previously, but the
one item
I had difficulty obtaining was a suitably long vacuum hose for
connecting to various workshop devices.

I thought I would pass on the following URL for anyone who
might be
looking to acquire a vacuum cleaner hose for use in their
workshop.
I've now got a 15 metre x 38 mm hose which allows me to put the
cyclone and vacuum cleaner into the roof area of my garage,
freeing
floor area downstairs and keeping the vacuum equipment out of
the way:

http://www.ezee-fix.co.uk/

Very helpful people, they do spares for all the major vacuum
cleaners.
The 15 metre hoses are available in both 32 mm and 38 mm,
product
codes VH1 and VH99 respectively.

If you do order a hose don't forget you will also need hose
ends
(called 'Tool End' and 'Machine End'). I had to phone up to get
these
added to the order because they aren't on the web site.

PoP

On Mon, 15 Sep 2003 19:18:49 +0100, PoP
wrote:

http://www.ezee-fix.co.uk/

Very helpful people, they do spares for all the major vacuum cleaners.

Don't they just, and for the total diy-er I spotted they do fans, even
for the infamous kirby, and I reckon that could prove interesting,
given it's reputed suck power. (I make model hovercraft too for fun,
so that may well be worth a tinker with!) Thanks very much for a
multiple useful link!

Take Care,
Gnube
{too thick for linux}

On Mon, 15 Sep 2003 20:41:33 +0000 (UTC), "Woodspoiler"
wrote:

This is an opportune moment to post an update on the pressure
relief valve (mentioned in a previous thread a couple of weeks
ago) to prevent the bin collapsing and eventually splitting under
blockage conditions.

I've had a couple of thoughts about this collapsing bin syndrome,
which go like this.....

The bin I purchased (from Homebase) was a sturdy ribbed plastic design
which I thought was strong enough to withstand the pressure. My 1200w
vacuum cleaner thought different, and the moment I blocked the input
to the cyclone the dustbin did an instant impression of pulling its
belly in to fit in a tight pair of trousers. Quite comical really, but
still a problem. I haven't implemented either of the following, but
I'm musing that I might try them.

The first idea I came up with was to visit a local bike shop to see if
I could buy a wheel rim of the appropriate dimension which would fit
snugly in the middle (vertically) of the bin. No spokes or anything,
just the rim. These rims are designed to be sturdy and I don't think
would crumple under the pressure.

The second idea (which I literally had last night) has the same
general principle, but uses a piece of thin plastic tube (say 15mm or
less) wrapped into a circle, joined together at the ends, and hot
melted to the vertical centre of the bin. Sounds doable to me, the
only potential issue I can think of is that the tube might not bend
into that tight a circle.

With the latter it might be possible to use some 8mm or 10mm CH pipe
rather than 15mm plastic to do the job.

With either of the above ideas it ought to be possible to insert
multiple rings into the bin to provide strength if required.

PoP

On Mon, 15 Sep 2003 19:18:49 +0100, PoP
wrote:

We've had some threads on this forum recently relating to building
cyclones for dust collection in a workshop. I've just built a cyclone
based upon the excellent articles posted previously, but the one item
I had difficulty obtaining was a suitably long vacuum hose for
connecting to various workshop devices.

Further musings on this idea.....thoughts welcome on my general ideas
in case I've overlooked something obvious.

Now that I have my very long hose I can move my cyclone into the roof
space of my garage/workshop, thus freeing up floor area down below. I
have a spare vacuum cleaner which can be placed on permanent duty
upstairs, and I can switch on/off by running its cable down.

This only leaves the issue of emptying the dustbin of sawdust. Perhaps
not such a difficult task to shimmy up the ladder every so often to do
that, but knowing my aptitude for laziness I'll probably overlook the
emptying until the cyclone starts filling the vacuum cleaner and I
hear the vacuum whining that it maybe needs emptying, exacerbating the
problem with a vacuum dustbag which now also needs emptying. So I've
thought of the following to solve this problem.....

I cut a large hole in the base of the dustbin - leaving a rim of
perhaps an inch or so all round the base that I can use to screw the
dustbin down to the loft floor (bear with me....this must sound like
Heath Robinson on overtime!).

I then get a ginormous funnel, the sort you can get from Boots the
Chemist for brewing beer etc. Basically the bigger this funnel is the
better - and if it is transparent so much better still, because I can
then see when the sawdust needs emptying without having to open
anything up.

I cut a hole in the loft floor into which the funnel sits, its pointy
end extending down into the workshop area. The dustbin sits over the
top of the funnel, so that any dust that falls to the bottom of the
dustbin automatically falls into the funnel, and thus into the
workshop below. This dustbin to funnel arrangement would need to be
airtight.

I close off the pointy end of the funnel with a plug, then use the
cyclone. It does its thing, and any dust collected falls down into the
funnel which is poking thru my workshop ceiling. Every so often when
the funnel is obviously full I put a black rubbish sack around the
pointy end of the funnel, release the plug and download the dust.

This approach seems to offer a possible advantage of making my cyclone
dustbin that much deeper in depth. No idea what this might do to the
airflow within the cyclone, but I imagine the deeper the cyclone is
the better it might work.

Haven't built this yet, and I might be able to improve the design
further by connecting a length of vacuum hose to the pointy end of the
funnel so that I can empty the arrangement from floor level, rather
than having to climb a stepladder to reach the funnel.

Anyone see an obvious problem with this design?

PoP

Interesting ideas PoP. I hadn't considered those. However, I see
a flaw (in the case of my own bin anyway).

Any sort of strengthening rib would have to go half way down the
bin as that's where I get most deflection. I don't have a problem
in the upper part near the lid.

Whether the rib is horizontal (i.e. a hoop) or there are multiple
vertical ribs, if they are inside the bin then they are going to
interrupt the airflow in a place that is important for the
functioning of the cyclone effect.

You may find that the bin still works but less efficiently.
That's OK if your modification is easily reversible.

If you mount them outside the bin, any residual delfection may
eventually work the bin loose of the glue holding it to the rib.
Strnghtning it it in some way (self tapping screws though from
the inside?) may work or you may get material fatigue after a
while. Still, if the bin is only a fiver you can afford to
experiment.

Interrupted air flow is why I rejected one obvious valve design:
a rod attached to the outside of the inner blucket and sticking
out radially so that it enters a short rigid tube (say 20mm +
diameter) attached to the outer wall of the bin. If the rod ends
just inside the outer mouth of the tube, then when the bin begins
to collapse it will quickly emerge from it. If the mouth is
covered with some sort of weakly spring-loaded cap, under normal
conditions no air will be admitted, but as soon as a collpase
starts the cap will be forced open by the emerging rod.

This is a visually neat and easily implementable idea that may
work, but even if it does, the rod will introduce turbulence into
the cyclone air flow and therefore isn't too desirable from that
point of view.

My current idea is to use the initial bin deflection as a
trigger, but the mechanism will be external. I have refined it
down to a fiarly minimal form. All I have to do is find time to
make it! Hopefully within the next week.

The advantage of a valve is that it maintains air flow through
the vacuum. The motor may overheat if a blockage is allowed to
persist.

W.

PoP wrote in message . ..

The second idea (which I literally had last night) has the same
general principle, but uses a piece of thin plastic tube (say 15mm or
less) wrapped into a circle, joined together at the ends, and hot
melted to the vertical centre of the bin. Sounds doable to me, the
only potential issue I can think of is that the tube might not bend
into that tight a circle.

Hi

How about a few metres of 15mm Hep2O type tube wrapped in a helix with
maybe 4 'wraps' from top to bottom and hot melted into place. You
could put it on the outside to help with emptying the bin, ie keep the
insides smooth.

IanC

On 16 Sep 2003 05:42:08 -0700, (Ian Clowes)
wrote:

How about a few metres of 15mm Hep2O type tube wrapped in a helix with
maybe 4 'wraps' from top to bottom and hot melted into place. You
could put it on the outside to help with emptying the bin, ie keep the
insides smooth.

That's a good idea.

PoP

"PoP" wrote
| This only leaves the issue of emptying the dustbin of sawdust.
| Perhaps not such a difficult task to shimmy up the ladder every
| so often to do that, but knowing my aptitude for laziness I'll
| probably overlook the emptying until the cyclone starts filling
| the vacuum cleaner and I hear the vacuum whining that it maybe
| needs emptying, exacerbating the problem with a vacuum dustbag
| which now also needs emptying. So I've thought of the following
| to solve this problem.....

Put an infra-red led on on side of the bin and an infra-red photocell on the
other side an appoprriate distance from the bottom. It doesn't matter if
they're in-line or if the photocell picks up light scattering inside the
bin, because you are relying on the settled sawdust blocking the led
completely. However the surface should be smooth so that 'ambient' sawdust
doesn't settle on the components causing a false 'full' indication

Owain