Thread: Question about Dust Extractor setup in double garage/shed?

G'day,

Seeing as this is a Dusty topic, I thought I'd post here.

I wondered what a Big Gulp Chute would be like hooked up beneath my dropsaw - well I tried it today once I hooked it up and even though it has a large mouth it sucks up beauifully!

It's alive!

Should have the rest of the Dusty connected by Friday, I'll get some photos taken of the whole shebang and start a new thread for a gander for all you perves out there.

Wouldnt it be better for Gumb to just enlarge the pipe between the dusty and the bin, 1 run of 150mm flows better than 2 runs of 100mm(does'nt it???). Still be restricted by the single 100mm inlet on the bin tho.

Originally Posted by Harry72

Still be restricted by the single 100mm inlet on the bin tho.

That was my thought too. Maybe worth a try though.

I'm wondering about ripping off the Y at the Dc, and replacing with even a short section of 125mm pipe. In your case Gumby, the piese going into the bin.

I think the point Major makes is that the biggest restriction is right at the fan/impeller/motor inlet. There ain't enough area to let the sucker suck at its full potential. What he has discovered on these units is opening it all up and allowing the wind to flow really makes a difference.

Just quickly working it out in my head, 2 X 100mm inlets have a poofteenth more volume than 1 X 125 mm inlet, but you also have more surface area on the pipe to create more drag there, so maybe no or little gain.

G'day,

Just last night I glued 2 blast gates to 45º joiners at the Y piece, but am interested to see if Major's idea has an increased benefit - but like Gumby, it has me confused.

Always open to better ideas and ways to improve things.

I have run around 600mm of 125mm gal flue pipe from d/c (in outhouse) thru to workshop. This terminates in the Y fitting, bifurcating to 2 x the supplied 100mm flex pipe. One to the supplied plastic 100mm 'gathering' plate(s) fitted to the machine(s) and the other to the machines dust port - anything from 30mm to 60mm via bodgied up hole saw chipboard reducers.

One point of interest is that I will constantly be changing machines and hence dust extractor hose positioning. Couple of magnets glued in a block of wood with a cuphook on opposite side holding a 100mm surclip around the 100mm flex duct allows you to instantly route the hose around the shed roof. The magnet block(s) is just stuck on the roof/wall (steel) anywhere you like, keeping this enormous and intrusive ducting right out of the way.

Haven't finished all the set up yet and will post results next week when all is firing. Early impressions say that fitting the supplied filter bag (2HP Sherwood d/c) instantly cuts the airflow substantially - even when pristine and with no fine dust build-up. Adding the 100mm flex duct (2 @ 3 metres) cuts down even more. First will be solved by cyclone addition and direct outside venting. Second flex issue seems unsolvable, as I do not have space for permanent smooth, large bore duct reticulation.

Also noted, as predicted, the supplied filter bag does not trap all the fine dust, apparent even with the limited testing so far. Once again a cyclone seperator should fix this.

To reinforce another well made point, the grid at the d/c inlet gotta go. Like an idiot I 'permanently' attached the ducting to the d/c, forgetting all the advice. 5 minutes later the things hardly sucking (I'll refrain from simile here) and I'm dismantling my perfect join, finding a few wood shavings have 60% occluded the grid.

Major:

Do the two lines that go to machines end up at a single machine, or do you close one off with a blast gate? If the latter, have you ever tried adding yet one more Y to double up the input to the empeller? You might get even more suction.

G'day Zenwood,

For whatever reason, your attachment shows as a crossed out red square.

Thinking about the Major's discovery, which I think is also endorsed by Bill Pentz, I wonder if the restriction in air volume at the d/c impellor is causing a vaccum and the impellor loses it's efficiency. Somewhat like cavitation around a boat's propellor.

The Major (time for a promotion I think) has delivered more air and hence decreased the vaccum and the impellor works better. True, the vaccum must still exist, in fact due to the increased airflow is increased, but is transferred down the flex duct where it can equalise and where it doesn't cause as much disruption to efficiency. The severe air vaccuum can now disipate in the increased capacity provided by the additional Y duct, before it reaches and stuffs up the impellor.

It seems another blow to efficiency to use the flex duct. The internal ribbing will cause additional turbulence and create vortices, again slowing air throughtput. Smooth, big diameter duct with gentle curves not 90 dgr bends is the go.

It would be great, and helpful, if anyone who knows the first thing about aerodynamics (unlike me) could comment.

Incidentally Major, sorry, Colonel the thing that is confusing about your piccy and post is that the rest of us slobs, being $$ challenged, thought all d/cs came with but a single inlet.

Bodge I think you are right the smoother the air hitting the inlet on the fan the better, the "vortices" you speak of are called "eddie currents" I think(correct me if Im wrong?)
I know with mine earlier I had it hooked up using the supplied tripple inlet thingo'bob using 2 of the 3 offtakes and 2 runs of 102mm pvc, then after hooking it up in the current configuiration having a long lenght of 150mm pvc with only 2x 90° bends the flow with 2 gates open(both 102mm) is heaps more as its collecting all dust from my buzzer now, it didnt before with one or 2 ducts open!

Methinks Bodge & Harry are on the right path here, as although the ductwork is doubled for a short length it's still restricted after the 2nd Wye and it's the restrictions that determine max airflow.

But with the Wye immediately in front of the impeller, if one is blocked off I imagine there'd be both an eddy effect and a slowing down of air due to the venturi effect. This is all right at the intake to the impeller! :eek: Of course, adding the 2nd duct removes both possible problems, but...

I'm wondering: if one removed the Wye from the intake, substituted a srigid piece of PVC and remounted the Wye a foot or two away to ensure a smooth airflow directly into the impeller, would it show the same improvement?

I'm only going by my experiences with carbies, triple-strombies have a similar problem but backwards. It tempts me to try, anyway... by my reasoning it should, and with less mess.

No comment.. just want to keep tabs on this thread,

Himzo.

Skew Im pretty sure it'll make a differance, BP recomends on his site that the inlet duct to a cyclone should be a certain lenght to smooth out the air flow, so probaly getting the wye's far as possible away from the impellor the better. On mine the 1st offtake/dropper would be about 4m of 150mm pipe from the impellor.

Tripple CD stromies eh... must like the ol XU1's, one of my fav cars!(72 LJ the best... was good year!)
That prob was solved with the redline manifold, or match portin the original was a fix, a good 10-20hp gain depending on how bad the castings were!

Thanks for totally confusing me guys! Where's Wayne Davie when we need him?????:confused: ?????