On Thu, 30 Aug 2012 09:28:44 +0100, The Medway Handyman wrote:
Well having actually owned a Henry and a DC04 the DC04 has more suction
than the Henry even with a brand new bag in the Henry. Even the Earlex
wet 'n dry has more suction than the Henry(*), has a capacity at least
double the Henry and costs half as much and will do wet if required.
(*) When the filter is clean, plaster or wood sanding dust will clog it
but will also clog the bag in the Henry. Henry bags aren't reuseable with
a fair bit of faffing about. ie no clip holding an end closed so they can
I never use my Earlex wet. The filter rots a week afterwards.
Otherwise it's a decent workshop vac.
The vacuum I have most of is the Aldi fireplace emptier (three of
those). Tin bucket and decent build quality, it's excellent for
building into a router table or bandsaw as per-machine dust
collection, especially if you give it a cyclone up front. Maybe a bit
noisy for bandsaws.
A Henry with a plaster chaser lasts less than 10 seconds before
it's clogged so the airflow has dropped too low to consume the
Dyson is the only thing I've found that can consume the dust from
a plaster chaser without failing, and subject to pauses for
emptying, just keeps right on going. And not a scrap of dust in
the post-motor filter, but as it filters down to 50 microns
whilst maintaining full flow (something which no other domestic
cleaner comes close to, and is completely impossible with a bag
which would fit in a domestic cleaner, and impossible with a
bag of any size for any length of time), that's what I'd expect.
[email address is not usable -- followup in the newsgroup]
I've just bought my fourth Henry(ish). Apart from one lost in a
burglary, they're all still working. Two have lasted over ten years so
far. The only repairs have been new filters and one new hose where
someone drove over it. One caught fire(!) and apart from a burned
filter, it survived.
Parents went through two Dysons within a year.
Talking of Dysons, the latest adverts talk about them being
"digital". How the H??? can a vacuum cleaner be digital? It's
an electric motor, that's conversion of electical energy into
motion energy, ie /electrical/,*NOT* electronic, and very
definitely not digital electronic.
probably has a sensor on the armature - you energise the pole that will
'kick' the armature in the right direction and then once spinning the
two pole motor will keep going in the right way.
Its the same as model aircraft 'brushless' motors. Although those are
three phase normally.
I liked this
"They are incredibly efficient too – due in part to high tolerances. For
example, the impeller spins at over 600mph with only 0.3mm clearance
between the blade tip and the impeller housing"
1/. the "for example" gives absolutely no description of efficiency at
all. In fact...
2/. Things don't spin at 600mph. That's linear velocity and if that
refers to the tip speed of the impeller...
3/. Mach 0.9 for an impeller is not only extraordinarily inefficient its
inefficiency manifests as MASSIVE noise, too. You WILL get transonic
airflow over parts of the blade.
( http://www.youtube.com/watch?v=Y6vWavvB9nI&feature=related )
Actually the efficiency will be down to having that neodymium magnet and
plenty of copper so the winding resistance is low. Even hand wound
motors can get up to the high 70s or more, and careful choice of
laminations magnets and bearings can net you over 90%. Its not hard.
Just expensive. I doubt Dyson have that sort of efficiency though - its
marginal gains for a lot of expense.
The model aircraft boys are chasing the ultimate power to weight, and
heat is a problem so they do go to extremes. Essentially 90% efficiency
to 95% means double the power for the same heat rise. However that in
itself becomes a useless exercise as battery weight totally dominates
past a certain point.
All of which confirms the suspicion that Dyson are long on bullshit and
short on engineering.
Their technology is not selected to last, be tough, or be efficient: Its
selected for the maximum ability to brand-differentiate from their
rivals and construct an appealing narrative about the product.
Or as we used to say about Microsoft
"Designed to sell, working is a secondary issue"
(in-ep-toc’-ra-cy) – a system of government where the least capable to
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