[pianotech] Metro Vac 'n Blo

[Overs Pianos]

Hi all,

While the subject of vacuum units is under discussion, a couple of 
years ago after much frustration with vacs which weren't up to the 
task, I built my own. Below is a description of the unit I built with 
image links.

The last vacuum we purchased, a 1300W Shop Vac, had three shortcomings.

1) the outlet blew down to the floor, so that any dust around the 
machine would be blown up all around the workshop and over the user.

2) The OEM dry element filter was only capable of filtering out house 
bricks. Everything else went straight through the filter and out into 
the workshop again.

3) When cleaning out our spray room after a spray session, the 
'filter' element would be blocked within a minute.

My first approach at solving the problem was to buy a Clearvue 
cyclone and mount it upstream from the vacuum unit. This worked quite 
well, but soon after the rebuild I dropped it going down the back 
steps of the workshop, so was forced to do a repair on the cyclone.

For those of you who may have come across Bill Pentz, he has spent 
years working with cyclones and dust collection, and he knows a thing 
or two on the subject. Here's a link to Bill's website.

http://billpentz.com/woodworking/cyclone/index.cfm

After much reading, I decided that the internal helix that Bill 
builds into his cyclones was an excellent idea which might be 
improved by putting in 720 degrees of helix instead of Bill's 360. 
This would force the incoming air stream to remain laminar for a 
complete revolution in the cyclone, allowing more time for the dirt 
to be thrown centrifugally to the outside of the air stream. I built 
a modified cyclone to incorporate this idea, and made up a new 
container to house a much larger and more efficient air cleaner 
element between the cyclone and the vacuum pump. The result is a 
cyclone/vacuum unit which can collect over fifteen litres of dust 
while losing very little suction. Its not particularly portable but 
it does have some grunt. Here are some image links which show the 
detail of the unit I built.

For an overview of the unit.
http://www.overspianos.com.au/cycvac1.jpg

The wand and suction tube are the 50 mm diameter items that came with 
the original 1300W Shop Vac. The floor tool is a ring-in from one of 
my previous vacs. The dust collection drum underneath the cyclone is 
a used 20 litre drum from our lacquer supplier. The vacuum unit and 
dry-element filter is inside the wooden box, which has an exit hole 
in the top so that the outgoing air stream is both quieter and 
directed upwards away from the dirty floor.


http://www.overspianos.com.au/cycvac2.jpg

A closer view of the cyclone body, showing the 720 degrees of helical 
baffle inside the body of the cyclone. Note that the incoming air 
duct is angled to match the helix angle of the internal baffle. This 
is a Bill Pentz idea and a good one. I've used plumbing fittings for 
the cyclone-to-filter duct which is larger than the incoming air duct 
to the cyclone. This reduces air flow losses between the cyclone and 
the filter drum - besides, plumbing fittings are cheap.

http://www.overspianos.com.au/cycvac3.jpg

This image shows the vacuum head on the drum which houses the filter.

http://www.overspianos.com.au/cycvac4.jpg

The image shows the filter. This filter is a Fleetguard element, 
which has a relatively large media area, and a very high efficiency 
with fine dust. This filter doesn't let any of the nasties through 
Gordon. The OEM trashy filter which came with the original Shop Vac 
costs $50 while this Fleetguard monster only costs $70 -  a relative 
bargain.

http://www.overspianos.com.au/cycvac5.jpg

This image shows the shape of the air inlet to the impeller. This was 
made from a piece of PVC plumbing which was turned down in OD to suit 
the inlet size of the filter, with the wooden internal block being 
made from a piece of King Billy Pine, which is very nice wood but its 
no good for piano soundboards.

http://www.overspianos.com.au/cycvac6.jpg

A close-up of the low-flow-loss inlet profile to the impeller.

http://www.overspianos.com.au/cycvac7.jpg

The important thing about cyclones is that to work efficiently they 
require a high rotational velocity of the incoming air. If a floor 
tool is fitted to the end of the wand without some means of allowing 
by-pass it will kill the air-flow volume and therefore velocity. The 
hole in the wand provides sufficient floor-tool by-pass volume to 
allow the maintenance of good airflow velocity into the cyclone. The 
masking tape is a little hi-tech addition to help the incoming 
by-pass air to meet the air coming up from the floor tool without 
causing too much turbulence.

http://www.overspianos.com.au/cycvac8.jpg

After cleaning my workshop and our house after a fortnight's dirt 
build up. The dust drum is well on the way to being full while the 
air cleaner has very little visible dirt on it.

http://www.overspianos.com.au/cycvac9.jpg

A close-up of the dirt collected in the drum

http://www.overspianos.com.au/cycvac10.jpg

A close up of the air filter before blowing it clean with a dusting 
gun. I clean the filter and empty the drum in our spray booth with 
the down draught fan going. My workshop environment has been 
transformed by this piece of gear.

If anyone should be interested in building one of these, there is a 
much higher performance pump available than the one I'm currently 
using. The best pump I've come across is;

Lamb electric
Advantek II - Ultra
Model No. 119998-08

To download a data sheet on this motor, go to;
http://www.rossbrownsales.com.au/page/motors.html

Scroll down the page, looking at the left side of the page, until you 
come to a pdf link called "Vacuum Motors Product Catalogue"
The fifth motor down from the top of the pdf doc is the Advantek II - Ultra.

This unit has a 1700W motor with two stage pump with properly 
designed impeller profiles. It sucks a lot harder than the pump I'm 
currently using (my current pump is capable of picking up 1/2" bolts 
and nuts from the floor). When my 1300W motor dies, I will replace it 
with one of these units.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
_______________________

Web http://overspianos.com.au
mailto:ron at overspianos.com.au
_______________________

A web page with images of recent work and almost-audio-CD quality mp3 
sound files of the Overs piano can be found at;
http://overspianos.com.au/more_info.htm

So put on your headphones, plug them into your freshly restarted 
computer and sit back to over 20 minutes of pure piano.
  _______________________
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