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Dust Extractor inlet diameter resizing

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minilathe22

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Hello everyone,

I have a dust extractor of the centrifugual blower kind, which has a 1HP induction motor and 4" inlet port. Reading about the blower type of extractor, it seems larger diameter piping will give me much better flow as it gives less resistence. So I am considering 6" solid wall tubing to the workspace, perhaps with a reducer to a short section of flexible 4" hose I currently have. I am assuming with 8" or larger piping, the air will be moving so slowly that dust will build up in the pipework and eventually block it.

The inlet of the fan is a simple circular sheet metal piece with an extruded 4" tube, which would be easy to make in a larger/smaller size. I am wondering whether creating a 6" inlet and attaching that as the fan intake will be better than using a 6" to 4" reducer at the existing fan inlet.

The blades of the fan protrude slightly into the 4" circle when viewed straight on, and with a 6" port significantly more of the blade would be protruding, I wonder if this would mess up the suction in the centre.

Any thoughts?
 

Inspector

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Good on you for wanting to improve your dust collection, unfortunately your dusty is too small to draw enough air through 6" ducting to keep it in suspension. You might get away with 5" if your distances are short and you minimize the use of flex hose. To utilize 6" you would need a 2hp DC if you keep the runs short (1 car garage size shop). For longer runs (2 car garage size) a 3 hp is needed as a minimum.

Pete
 

minilathe22

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I guess if my run is fairly short, then it sounds like straight 4" pipe and then a short bit of flexible hose at the end would be the best. I will be using it with a wood lathe to collect chips and dust when sanding. I have not been able to see any 4" bellmouth ends anywhere only really big triangular ones, that I feel would get in the way.
 

Inspector

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Save up for a bigger DC. They don't take up more room than the 1 hp does. Speaker ports come in approximately 4" and are not too expensive.
You can always turn one from wood and you can turn a mandrel to force heated PVC over to make some. If you want to roll your own I can link you to another forum that describes the process. You can probably do better searching your sites than I can.

https://www.ebay.co.uk/itm/383042007072

https://www.hificollective.co.uk/components/flares.html

From this side of the pond.
https://www.parts-express.com/speaker-c ... d--260-403

https://www.madisoundspeakerstore.com/f ... plete-kit/

Pete
 

minilathe22

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I ended up sticking with 4" diameter, metal solid ducting with 2 x 45 degree bends from the loft to a fitting down the wall. Then flexible 4" hose to a "flanged spigot" which was only £2 from here: http://www.ductstore.co.uk/acatalog/Radiused-Flanged-Spigots.html

I then pressed the flange between two circular wood pieces in a vice to give it a bit more angle.

So far it seems to collect dust well when sanding, most chips that go in its general direction get scooped up. It is much quieter than the vacuum style chip collector I had, and I don't mind sweeping up larger chips, the main goal was to prevent dust getting into the air and settling on everything.
 
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