I need a hefty vacuum cleaner to build a vac forming table. In the USA
theyre referred to as shopvacs, which I assume just means heavy duty.
About 4Kw should do the trick. Im hardly expecting to find one for
sale in this group but does anyone know who makes these things so I
know what to look for? A Vax is nowhere near big enough.

Evacuated

On Thu, 25 Nov 2004 12:36:16 +0000, strung together
this:

but does anyone know who makes these things so I
know what to look for?

http://www.elektrabeckum.co.uk/eb/uk/en/produkte/dustcollectors/dustcollectorspa2000d_0130020011.html

Or;

Numatic NTT2003 on http://www.numatic.co.uk, look out, it's another
one of those crappy frame affairs.

Or are we looking proper industrial sized, not for home use.
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A.C.S. Ltd
Please reply to group or use 'usenet' in email subject

wrote:
I need a hefty vacuum cleaner to build a vac forming table. In the USA
theyre referred to as shopvacs, which I assume just means heavy duty.

Generally, it's just an industrial vac.

About 4Kw should do the trick. Im hardly expecting to find one for
sale in this group but does anyone know who makes these things so I
know what to look for? A Vax is nowhere near big enough.

'4Kw' may be misleading.
All electrical appliances in the US tend to be wildly optimistically
rated.
A typical practice is to measure the instantaneous startup current,
and then multiply by the line voltage.
This means that you get ridiculous numbers like '5Hp' compressors that
run from a plug that won't handle more than 1.5Kw.

Why do you think that a Vax is nowhere near big enough?

Why do you think that a Vax is nowhere near big enough?

I beleived a Vax only rate at about 1.5Kw? All the sources I've tried
so far recommend about 4Kw. If I become convinced a Vax wlll be enough
could hire before I buy,

Evacuated

wrote:

I need a hefty vacuum cleaner to build a vac forming table.

Do you think that a vacuum cleaner will take the pressure low enough.
IME, vacuum formers tend to use vacuum pumps, and go down to a few cm of
pressure. How big a table do you want? How are you heating the plastic,
which types of plastic are you planning to use, etc?

Regards
Capitol

"Capitol" wrote in message
...


wrote:

I need a hefty vacuum cleaner to build a vac forming table.

Do you think that a vacuum cleaner will take the pressure low enough.
IME, vacuum formers tend to use vacuum pumps, and go down to a few cm of
pressure. How big a table do you want? How are you heating the plastic,
which types of plastic are you planning to use, etc?

Regards
Capitol


I'd have thought any vacuum would suck things to shape if the material was
soft enough and the end of the hose was properly sealed. But something like
these:

http://www.bocedwards.com/vacuum/dry..._overview.html

would do a great job of making anything pop into shape in the correct
former/mould.


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Capitol wrote:


wrote:

I need a hefty vacuum cleaner to build a vac forming table.

Do you think that a vacuum cleaner will take the pressure low enough.
IME, vacuum formers tend to use vacuum pumps, and go down to a few cm of
pressure. How big a table do you want? How are you heating the plastic,
which types of plastic are you planning to use, etc?

I wonder how your common-or-garden vacuum cleaner motor would regard
being connected in series with a few others with intercoolers in line,
to increase pressure difference.

Do you think that a vacuum cleaner will take the pressure low enough.
IME, vacuum formers tend to use vacuum pumps, and go down to a few cm of
pressure. How big a table do you want? How are you heating the plastic,
which types of plastic are you planning to use, etc?

There are many sites and advice on the web from people forming with
industrial vacs. My platen is about 2 feet sqr and qtr inch deep air
space, i.e. about 2.5 litres volume. I've built a grill to heat the
plastic and it's 0.75mm HIPS. That side of the setup is fine, it's
getting the air out according to my vacuum guage readings
Evacuated

wrote:
Do you think that a vacuum cleaner will take the pressure low enough.
IME, vacuum formers tend to use vacuum pumps, and go down to a few cm of
pressure. How big a table do you want? How are you heating the plastic,
which types of plastic are you planning to use, etc?

There are many sites and advice on the web from people forming with
industrial vacs. My platen is about 2 feet sqr and qtr inch deep air
space, i.e. about 2.5 litres volume. I've built a grill to heat the
plastic and it's 0.75mm HIPS. That side of the setup is fine, it's
getting the air out according to my vacuum guage readings

If it's getting the air out, what's the problem?

Frequently, the mould is on a plate which is moved up to push the mould
through the plastic on small vacuum formers. The mould plate is mounted
above a tank of the same area, but about 3x the depth of the plate
movement, which has previously been evacuated to low pressure, .05bar.
The action of moving up the plate, allows the evacuated tank to equalise
with the base of the mould which has vent holes inserted to aid airflow
into the vacuum. This action provides about a +0.25 bar vacuum. I think
this is rather more than the average shop vac. Many shop vacs use two
bypass motors(no cooling problems) to give better "suck", but as these
are a fan action, the suck will disappear if the airflow is blocked.
(AIUI All fans only operate by sucking, so if you block the airflow
you've had it!) If you wish to find out how well units suck, you need to
do a search using " wet & dry vacuum water lift" The norm is in the
region AFAICS of 7' which is roughly +0.8bar. If you are simply heating
the plastic and then sucking down at the same time, the temperature
control is very, very critical, too low and the material splits/doesn't
form properly, too high and you get holes everywhere! The process is
also dependent on the prior history of the plastic, who made it etc and
a lot of suck it and see is required.

Good luck

Capitol

Thanks everyone. The problem is the vacuum gauge is only showing about
6 inches mercury, so the table may be leaking. My delay in replying is
because I've decided to use a tank between the pump and table, i.e.
empty the tank, release a valve and woosh (hopefully) as air leaves
the table. My tank (OK my pressure cooker) now shows 16 inches
mercury which is the best I've got so far. Cannot get a release valve
til Monday but does half an atmosphere seem sufficient?
Has anyone a better idea for a home made vacuum tank?
Evacuated

In article ,
" says...
Thanks everyone. The problem is the vacuum gauge is only showing about
6 inches mercury, so the table may be leaking. My delay in replying is
because I've decided to use a tank between the pump and table, i.e.
empty the tank, release a valve and woosh (hopefully) as air leaves
the table. My tank (OK my pressure cooker) now shows 16 inches
mercury which is the best I've got so far. Cannot get a release valve
til Monday but does half an atmosphere seem sufficient?
Has anyone a better idea for a home made vacuum tank?
Evacuated

A propane bottle would give you more capacity, and a valve already
fitted.

On Thu, 25 Nov 2004 12:36:16 +0000, wrote:

I need a hefty vacuum cleaner to build a vac forming table. In the USA
theyre referred to as shopvacs, which I assume just means heavy duty.
About 4Kw should do the trick. Im hardly expecting to find one for
sale in this group but does anyone know who makes these things so I
know what to look for? A Vax is nowhere near big enough.

Evacuated


If it's like the one the guy used to make his STormtrooper suit then
I'd have thought a Henry would be just the job or his older brother
perhaps? ;-)

"Shop" to me means something that's built to use rather than built to
look pretty in the living room.

Mark S.

"Mark S." wrote in message
...
On Thu, 25 Nov 2004 12:36:16 +0000, wrote:

I need a hefty vacuum cleaner to build a vac forming table. In the USA
theyre referred to as shopvacs, which I assume just means heavy duty.
About 4Kw should do the trick. Im hardly expecting to find one for
sale in this group but does anyone know who makes these things so I
know what to look for? A Vax is nowhere near big enough.

Evacuated


If it's like the one the guy used to make his STormtrooper suit then
I'd have thought a Henry would be just the job or his older brother
perhaps? ;-)

"Shop" to me means something that's built to use rather than built to
look pretty in the living room.

Mark S.

Isn't there a problem is the air flow is "stalled"? I believe that the
current drawn can rise and the cooling air is diminished. The universal
motor has its speed limited by the air resistance I believe. Change this by
restricting a flow and the speed might rise.

--


Regards

John
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wrote:

I need a hefty vacuum cleaner to build a vac forming table. In the USA
theyre referred to as shopvacs, which I assume just means heavy duty.
About 4Kw should do the trick. Im hardly expecting to find one for
sale in this group but does anyone know who makes these things so I
know what to look for? A Vax is nowhere near big enough.

Axminster do one with a couple of 1kW motors in sequence... might be
enough, failing that a pair of them.

--
Cheers,

John.

/================================================== ===============\
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Hi All

On the subject of vacuum cleaners, you have to be a little careful.
I'd forget anything domestic for a start, they won't take the strain
for long. Look at Numatic or Nilfisk.

There are two types of motor used in commercial vacuums. Vacs designed
for dry use have Direct Cooled motors - that is, the air they suck
passes over the armature etc to cool it down. Stop the airflow for any
length of time and the motor will overheat - no good for vacuum tables.

Vacs designed for wet or wet/dry use have By Pass motors. The air they
suck is diverted sideways away from the amrature (wet air on electrics
not being a good idea) and they have a separate fan on the back for
cooling purposes. They will continue to operate without any airflow,
so won't burn out on a vacuum table.

By pass motors come in two types - peripheral discharge and tangencial
discharge. By discharge I mean how the air leaves the motor.
Peripheral discharge have slots around the casing, tangential have a
tube.

Two tangential by pass motors can be connected in series (inlet of one
connected to out let of the other) to increase vacuum. Most twin vac
carpet extraction machines work like this.

Connecting in parrallel, as in most twin motor vacs only increases
airflow, suction remains the same.

Hope that helps

Dave