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Dust Collection: If squished 4" wire hose to 1" oval, venturi effect?

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Forum topic by Holbs posted 12-20-2018 04:27 AM 427 views 0 times favorited 4 replies Add to Favorites Watch
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Holbs

2213 posts in 2448 days


12-20-2018 04:27 AM

I am working on my bandsaw dust collection. Will have a 6” duct feed to it branched off to 4” wye so will have 2×4” ports. One will be installed to the lower wheel area. What to do with the other 4”. After some vids and topic discussions, I wanted to try something. I currently have a damaged 4” spiral wrapped plastic dust collection hose that was walked on or something. It’s now oval. I placed this damage piece (about…eh…12” long) under the bandsaw table with the 1” gap clearance down there. I have yet to fully connect to my 3HP dust collector.
I was thinking of the ‘ol carburetors and the venturi affect of pulling air through a smaller opening increasing the speed. Will this apply to this dust collection setup for the bandsaw blade?
A 4” hole will have a 12.5” square inch area. With this damaged hose, the opening hole is more like 5-6” square inch area.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"


4 replies so far

View SuperCubber's profile

SuperCubber

1078 posts in 2703 days


#1 posted 12-20-2018 12:04 PM

That seems like a logical line of thinking, but as the air exits the Venturi, it will slow back down. I don’t see a big benefit.

-- Joe | Spartanburg, SC | "To give anything less than your best is to sacrafice the gift." - Steve Prefontaine

View EarlS's profile

EarlS

2879 posts in 2767 days


#2 posted 12-20-2018 12:58 PM

Yes, the velocity will increase through the venturi, but it will result in a lower airflow at the mouth of the pipe where you want the highest air flow to pull the dust and chips into the hose. You would be better off to leave the 4” line the same size and not reduce it and make wide mouth inlet for the bottom of the bandsaw.

BTW – there was some discussion on the Spring Swap forum between Dave Polaschek and a couple other LJ’s about making DC adapters to use under the bandsaw table. I’ll post a note there to have him chime in here.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View MikeDilday's profile

MikeDilday

258 posts in 878 days


#3 posted 12-20-2018 01:02 PM

If using a 6 to 4” wye gives you an extra 4” why didn’t you just use a 6-4 reducer and only have one 4” pipe?

-- Michael Dilday, Suffolk, Va.

View Holbs's profile

Holbs

2213 posts in 2448 days


#4 posted 12-21-2018 02:25 AM

The measurements underneath the bandsaw table (clone bandsaw) is roughly 1 ” of space. That is my limiting factor. The venturi center point would actually be where the bandsaw blade is. But Earl says slow air flow from the get go due to the venturi anyways. Hmm…
Well…I’ll try it out anyways :) I just bought that router dust collector vinyl boot thingy (Milescraft Dust Router). Wonder if a 2nd one would work on a bandsaw.
Will be a busy weekend for installing and testing!
If all else fails, new DIY bandsaw table with dust collection chambers here I come! Even if it means losing 2-3” of resaw height (as if there is much to begin with on this 14”).

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"

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