A small insert doesn't collect dust as well as a large insert because
the small opening restricts the cfm. But a large insert doesn't
support the work as well.
Is this correct?

I was thinking that the insert behind the bit doesn't support anything,
so opening up the insert there would increase the cfm and improve dust
collection; make the opening an oval rather than a circle.
Does this make sense?

Assuming you are with me so far, would it be reasonable to make this
oval by screwing the aluminum insert to a block of wood, and going at
it with a hole saw? The material left could be cleaned up with file.
Or possibly a router? If I don't mind maybe dulling the bit, is a
carbide router bit safe on aluminum? I know I once erred with my
omnijig, and the router cut into the aluminum pretty effortlessly. I
just don't know how safe it might be, again holding the insert screwed
to a piece of wood.

If none of this makes sense, I broke a rib last week and the muscle
relaxant doesn't agree with me...

toller wrote:
A small insert doesn't collect dust as well as a large insert because
the small opening restricts the cfm. But a large insert doesn't
support the work as well.
Is this correct?

I was thinking that the insert behind the bit doesn't support anything,
so opening up the insert there would increase the cfm and improve dust
collection; make the opening an oval rather than a circle.
Does this make sense?

it does, but my guess is that a series of smaller holes around the main
(zero clearance) hole will be more effective and safer.


Assuming you are with me so far, would it be reasonable to make this
oval by screwing the aluminum insert to a block of wood, and going at
it with a hole saw?

with all clamped to the drill press table, yes.



The material left could be cleaned up with file.

a little sandpaper may help too, for getting rid of sharp burrs.



Or possibly a router? If I don't mind maybe dulling the bit, is a
carbide router bit safe on aluminum?

it's pretty grabby, and the results of that grab are not pretty, for
your fingers or the tools/materials.


I know I once erred with my
omnijig, and the router cut into the aluminum pretty effortlessly. I
just don't know how safe it might be, again holding the insert screwed
to a piece of wood.

it makes me nervous to do it. when I can I use a more appropriate
cutter- one with a larger number of smaller teeth. there are some
really good solid carbide die grinder bits with 1/4" shanks with tooth
configurations made for aluminum out there, and they aren't really
expensive.




If none of this makes sense, I broke a rib last week and the muscle
relaxant doesn't agree with me...


excuses, excuses....

Sounds to me like all your dust collection is from below the plate. It also
sounds like all your cuts are on the edge. I have never tried dust
collection from under the plate but, it seems to me that it would be the
least effective way to do it as the router fan is pushing air up past the
bit, thus working against your dust collector. The table I have right now
has no dust collection, something I plan to change here shortly. The one I
used to have had dust collection through the fence. That was very effective.
Virtually nothing escaped it on edge cuts.

"toller" wrote in message
oups.com...
A small insert doesn't collect dust as well as a large insert because
the small opening restricts the cfm. But a large insert doesn't
support the work as well.
Is this correct?

I was thinking that the insert behind the bit doesn't support anything,
so opening up the insert there would increase the cfm and improve dust
collection; make the opening an oval rather than a circle.
Does this make sense?

Assuming you are with me so far, would it be reasonable to make this
oval by screwing the aluminum insert to a block of wood, and going at
it with a hole saw? The material left could be cleaned up with file.
Or possibly a router? If I don't mind maybe dulling the bit, is a
carbide router bit safe on aluminum? I know I once erred with my
omnijig, and the router cut into the aluminum pretty effortlessly. I
just don't know how safe it might be, again holding the insert screwed
to a piece of wood.

If none of this makes sense, I broke a rib last week and the muscle
relaxant doesn't agree with me...

"CW" wrote in message
nk.net...
Sounds to me like all your dust collection is from below the plate. It
also
sounds like all your cuts are on the edge. I have never tried dust
collection from under the plate but, it seems to me that it would be the
least effective way to do it as the router fan is pushing air up past the
bit, thus working against your dust collector. The table I have right now
has no dust collection, something I plan to change here shortly. The one I
used to have had dust collection through the fence. That was very
effective.
Virtually nothing escaped it on edge cuts.

You are correct, all from below. I am using a TS wing, and it is difficult
to get it above, though I might have to work on that.

My first table, a Crapsman which really earned the name, was all above.
Still, half the debris went down.

wrote in message
ups.com...

toller wrote:
A small insert doesn't collect dust as well as a large insert because
the small opening restricts the cfm. But a large insert doesn't
support the work as well.
Is this correct?

I was thinking that the insert behind the bit doesn't support anything,
so opening up the insert there would increase the cfm and improve dust
collection; make the opening an oval rather than a circle.
Does this make sense?

it does, but my guess is that a series of smaller holes around the main
(zero clearance) hole will be more effective and safer.

That is a good idea, thanks.

Assuming you are with me so far, would it be reasonable to make this
oval by screwing the aluminum insert to a block of wood, and going at
it with a hole saw?

with all clamped to the drill press table, yes.



The material left could be cleaned up with file.

a little sandpaper may help too, for getting rid of sharp burrs.



Or possibly a router? If I don't mind maybe dulling the bit, is a
carbide router bit safe on aluminum?

it's pretty grabby, and the results of that grab are not pretty, for
your fingers or the tools/materials.


I know I once erred with my
omnijig, and the router cut into the aluminum pretty effortlessly. I
just don't know how safe it might be, again holding the insert screwed
to a piece of wood.

it makes me nervous to do it. when I can I use a more appropriate
cutter- one with a larger number of smaller teeth. there are some
really good solid carbide die grinder bits with 1/4" shanks with tooth
configurations made for aluminum out there, and they aren't really
expensive.




If none of this makes sense, I broke a rib last week and the muscle
relaxant doesn't agree with me...


excuses, excuses....

toller wrote:
A small insert doesn't collect dust as well as a large insert because
the small opening restricts the cfm.

Are you using a shop vac or a dust collector. If the latter, you might
try the shop vac. The higher suction it produces gives much better
results with small openings.

Also, I'd second the ported fence idea. It sounds like you're currently
using the table saw fence, but you could build an auxiliary fence that
attaches to it or rides on it. Port the aux fence for dust collection,
and you'll be happier.

I collect dust via a shop vac and ported fence, and for edge cuts almost
nothing escapes, even with MDF.

Chris

Chris Friesen wrote:

Are you using a shop vac or a dust collector. If the latter, you might
try the shop vac. The higher suction it produces gives much better
results with small openings.

I have had the same experience.

Shop Vacs work much better with hand sanders, biscuit joiners, routers,
etc... than a choked-down DC.