On 19/10/2020 11:24, John Rumm wrote:
On 17/10/2020 00:45, TimW wrote:
In my shed I have a basic, noisy 1500w Screwfix table saw. When I use
it I connect a 1000w wet and dry vacuum cleaner to the underneath
extractor outlet and an old 1000W henry type hoover to the overhead
guard. This takes care of the sawdust probably as well as can be
expected BUT THE NOISE IS DEAFENING, the lights flicker and it's
probably going to annoy my neighbours soon.
Is there some better way of extracting dust from power tools? Some
kind of cyclone thing? or a quieter single dust extractor. Trouble is
these days you just have to buy the stuff off of a catalogue.
There are two basic options for dust collection, low volume high
pressure (LVHP) small hose, and high volume low pressure (HVLP) large
hose. Vacuum cleaners and dedicated small dust collectors are usually
LVHP. Big bag style chip collectors are HVLP.
Then dust filtration is whole other subject.
Both have LVHP and HLVP a place - but much depends on the type of dust
you are collecting, and the source.
For *effective* collection from a saw, the air speed needs to be faster
than the blade tip speed, and the volume high enough to capture the dust
at the point of creation - so air moving at 150mph+ is ideal since you
need to capture the dust coming off the blade tips at that speed. (a
LVHP system will capture the the dust that hits a baffle of some sort
and falls into the saw body, but won't catch the stuff thrown in your
direction by the top of the blade. Blade guard collection helps in that
it physically intercepts some of the blade tip dust.
Things like planers and thicknessers especially need HVLP just to cope
with the rate and volume of chip creation. Table saws can go either way,
but HVLP is usually better for cabinet saws (although contractor
portable saws are often only ported for small hoses).
So hand held tools like sanders etc producing fine dust, are normally
optimised for LVHP, and usually benefit from good fine dust filtration
since the dust is not being ejected at speed, and the air paths
convoluted, and for ease of use, small diameter hoses work ok, and the
high pressure overcomes the flow resistance.
Bagged chip collectors [1] are typically large dirty fan type designs
powered by quiet induction motors. In use the air flow noise is probably
comparable to the motor noise, and they are typically quieter than the
tool itself. Filtration performance on them depends on the construction
of the bags. The basic cloth ones given good airflow but only large
particle filtration, felted top bags, and plastic dust bags give finer
collection (at some expense of airflow), and pleated cartridge filter
style top bags can do HEPA style filtration but need lots of power to
maintain air flow.
Of the "bin" style vacuum collectors - some are very much noisier than
others (some of the early generations of wet'n'dry vacs were
astonishingly loud!). As you go up market they get quieter. Note there
is a big jump in price the moment you move to M class [2] filtration
(which is usually the legal minimum for on site use in businesses).
So in short, a chip collector will be a much quieter option, and
probably work better on a table saw if it has a decent port size
(ideally 4").
[1]
https://www.axminstertools.com/axmin...tractor-105184
[2]
L Class = 1.0% Dusts with maximum allowable concentrations 1 mg/cubic
meter
M Class 0.1% Dusts with maximum allowable concentrationsÂ* = 0.1 mg/
cubic meter
H Class 0.005% Dusts with maximum allowable concentrations 0.1
mg/cubic meter
L class will normally do for table saws and softwoods, M class for table
saws and hardwoods and MDF etc, plus also sanding.
(H is only for specialist applications like machining asbestos, or
collecting soot).
I use a Jet JCDC-1.5 HVLP cyclone extractor for the table saw and
planer/thicknesser, and an Earlex LVHP+Dust Commander for routers,
sanders, etcetera. Until recently I used LVHP for the bandsaw but
upgraded the saw and the new one came with a 4" port, which seems odd.
The problem is the Bosch chopsaw, which comes with a 2"'ish port that is
totally inadequate. I keep meaning to add some sort of scoop behind it
but too many other jobs keep cropping-up. What do others do about
controlling chopsaw dust?