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.

--
Cheers,

John.

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