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Posted 15 September 2011 - 11:44 PM
That is not say what I am offering for my solution (or attempts) is for everyone but it is just my 2 cents and might help you with yours.
Comments and suggestions welcome - this is a work in process...
Here is a mockup I am working on for miter saws:
Larger Image: http://www.vitalbodi...1920x1080_0.jpg
I made the dust hood out of card board as card board is easy to work with for a mock up and rapid prototyping.
This uses a 4 / 4 / 2.5 branch as you can see.
The flex hose is from a Hoover and was more flexible than that 2.5" hose I had on hand when the image was taken.
I can use the same hose for my random orbital sander by just popping it off the saw.
Some time later after using this I learned quite a bit and was glad it was made out of cardboard because it needs more work.
First off a hood has to be pretty darn large for a tool like this as it slides and swivels and has a hose out the top - this hood is large enough, barely.
Having the port out the back might have been better but I did not feel I had the shop real estate to commit to that so the top was the best choice.
The ideal shape (might be) a half round cylinder to lower the volume in the hood.
This hood works fairly well with the finer dust if you cut slower.
Much of the larger dust falls to the bottom (which in my case temporarily is a scaffolding) but is at least contained for easy clean up.
A baffle inside to cause more suction to happen down low would have helped but not all suction should be low.
I hope to add a down draft table under the saw - for the better suction down low - peg board scrap is my likely choice.
I think this will take two 4" ports, one for the hood and one for the down draft.
If I put on my dust mask, turn on the DC and cut some boards I can see some dust spraying out the side directly from the blade.
No way to block that with the hood, without the hood being in the path of the lumber - although a brush near the blade would help.
If I cut at the speed the fine dust is sucked into the hood (a bit slower than normal) then I find I can take my mask off perhaps a minute after sawing rather than quite some time later.
When the sunlight shines in the window I can see the dust, and see when there is virtually no dust.
If you build this version yourself you will need a 36 Volt Bosch drill to drill the cardboard so you now have license and a reason to go out and buy one.
Card board needs a heavy duty drill, don't you think ; )
Posted 16 September 2011 - 02:55 AM
Posted 16 September 2011 - 04:31 AM
Posted 16 September 2011 - 04:59 AM
My thoughts were that once the dust settles, I'd still get it the next time I turned on the collector.
I appreciate your lessons learned.
You were wise to mock up with cardboard first.
Posted 16 September 2011 - 11:03 AM
Have a solution in place? Feel free to add an image...
Currently: This hood makes a world of difference compared to no hood - it is quite effective at capturing most of the dust - it could be better though and the main challenge is to add more air (CFM) moving (like having two 4" ports) and better collection of the dust at the behind the saw where the shavings fall within the hood. So far the larger dust/shavings settles to the bottom in a fairly even pattern and I can suck that up with a different 4" hose that I take from tool to tool but it would be nice not to have to.
The other challenge is that SOME dust that misses the hood altogether. What would help for that is some kind of brush on the side of the saw hood/guard. Anyone know what might work for that? When wood is sawn the plastic blade guard goes up and what remains is the blade (cutting wood) and the metal guard - the dust shots from the blade between the wood being cut and the metal guard at perhaps a 45 degree angle - and thus misses the hood. Have you ever seen those large brushes that are used as mud flaps/rock guards on the back of an RV? Something like that but much smaller and finer might help.
One challenge for me is I like to separate my dust. I like to keep the stuff like plastic shavings out of the wood shavings because I use the wood shavings for different things like mulch or compost. This requires an extra effort on my part so it helps to have a solution that enables a fairly fast clean up and the ability to shift from the DC to the HEPA vac. I try to keep the DC "wood only" with no metal or plastic or other odd stuff. Currently I just hook the HEPA vac to the port on the saw and then I have to clean up the mess in the hood when I am done cutting with the same vac. Keeping the dust separate is causing a re-think on the down draft unless the down draft is efficient at self cleaning with the DC or the HEPA vac.
A shoot would need to be a fast clean to work if a shoot is used for example.
Posted 17 September 2011 - 08:59 AM
Interesting setup. I do not get much shavings under the saw. Mostly behind the saw where they fall to the counter within the hood. But then every saw is different.
Have a look here http://woodtalkonlin...4738#entry34738
Southwood seems to have a good idea for the fines below the mitre saw.
Posted 25 September 2011 - 09:42 PM
With a hood this large (made as small as possible in the rectangular format) I would estimate it would take three 4" ports - 2 more than most people have to aim at their hood.
As you know, if you have a duct (let's say 4") and you introduce a much larger area within the duct (like a cyclone or even a large box) the large shaving fall out of suspension.
So, in effect, a hood that is too large does the same thing.
The hood should be as small as possible (half a cylinder rather than rectangular) with even distribution of suction - rather than just at the top, or one side or the bottom.
The ideal hood would be static electricity free, any suggestions on that?
Posted 26 September 2011 - 09:32 PM
But it is made of Masonite and is warped - darn.
What are you all using to create a zero clearance fence on your miter saw?
Also, the ZERO clearance fence does interfere with dust collection to some degree (the dust just hits it) - seems worth but what ideas do you have for this?