On 17/04/2021 09:58, wrote:
On 17/04/2021 01:11, John Rumm wrote:
On 16/04/2021 11:11, wrote:
On 15/04/2021 14:03, John Rumm wrote:
On 15/04/2021 09:08, wrote:

I think about improving DE from time to time (whenever I'm
cleaning-up after a messy job) but don't seem to find the necessary
tuit. My saw has a small hose from the crown guard (hinged on the
riving knife) that goes inside and joins the under-saw 50mm hose to
come out to a 100mm port that I connect to my 2HP HVLP cyclone
extractor. I frequently operate without the crown guard(!!) so plug
the crown guard hose.

One of the problems you might find with the smaller hose up top is
that its not as well suited to the HVLP extractor because of its
higher back pressure. Some people find running a separate LVHP
collector (e.g a shop vac style collector) just for the top hose
works better.
Yes, a little experimentation makes it seem that LVHP is better for
both top and bottom with the current internal plumbing.

I'd like to devise a pivoting and self-adjusting crown guard that's
suspended from a hollow tube that's attached to the saw in some way
and can be used for DE. The crown extraction would be connected to
the under-saw hose with a throttle'able Y connection and then go to
the LVHP extractor.
Issues: how to make the suspension rigid enough (but allow the saw
to be moved), how to improve collection beneath the saw, ...
Suggestions and comments invited.

There are quite a few examples of this kind of thing about - most
are quite large since they need to reach over the saw from far
enough away as to not curtail the maximum size of sheet you can
process.

https://wayofwood.com/diy-tablesaw-o...d-blade-guard/

or

https://www.axminstertools.com/axmin...e-guard-104504



Thanks for those - thought-provoking and similar to what I had in
mind (but I can't believe Axminster sell many at that price)

Probably not - and there are probably cheaper alternatives about. It
was more just an example. Some of the saw makers do their own ones as
well.



You may find that building a cowl to mount under the table to
enclose as much of the blade as you can (either fixed to the
trunnions so that it an tilt, or just wide enough that it can
accommodate the tilt, and connecting that to the HVLP collector will
increase the air speed under the blade high enough that it can
capture everything flying off the tips of the blade, before it gets
a chance to escape again.

My saw was basically designed to just dump dust into its base for
later manual removal. However I added a 4" port to it. Running that
into the HVLP does reduce the amount that gets out of the case - but
not completely. (not helped by other piercings through the case like
by the blade height adjust wheel that let air be sucked in via
alternate routes).

I found just adding a bit of tube split round the blade where it
exits the underside of the table, was quite effective on this
contraption:

http://wiki.diyfaq.org.uk/index.php/...awbench#In_Use

That might not be too difficult to mount such that it moves in
sympathy with the blade tilt.


I'm moving towards using a good LVHP almost everywhere (with cyclone,
50mm plastic ducting and home-made blast gates) and only using the
HVLP for the planer thicknesser, and maybe the (rarely used) wood
lathe. I suppose, if I ever get around to inventing something, a dust
catcher for the chop saw might be HVLP as well.

IME HVLP shines for really high volume dust or chip creation (so
planners / thicknessers), and anything where its difficult to catch
the dust in something first and need to rely on really high speed
airflow to capture stuff being ejected from a blade tip.

Yes, HV for chips and large areas (chop saw), and HP for dust. I
upgraded my bandsaw to a Sabre-350 a while ago, the saw is great but the
dust collection is just a 100mm port into the lower casing - the top of
that casing only has a hole for the blade so most of the dust falls on
the floor; one day I'll make a cowl to go directly under the table and
switch it to LVHP. Ooo, perhaps this is the justification for a 3D
printer :-)

My EB band-saw is similar - 100mm port on the back of the bottom case.
In reality it works to some extent - it seems to stop any dust getting
recirculated round and dropped out of the top housing, and there is a
grid of holes around the table inset that allows some dust to get sucked
away. However its far from perfect. A cowl around the underside could
work well.


--
Cheers,

John.

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