pushing versus pulling

[stevek]

Hi,

I am wrapping up my dust collector, pictures will follow soon.

I had a question wrt to pushing versus pulling.

The reason why I built my Thien dust collector is to clear the leaves off my roof.
I rigged 2 1/5 ' vacuum hoses to my leafblower/vacuum/shredder and added lots of extensions to reach the top of my roof.
The fine dust and finely shredded leaves were clogging up my leaf collection bag.

I have the possibility of 2 configurations:
as a vacuum: leaves -> inlet hose - dust collector - vacuum -> open air
as a blower: leaves -> inlet hose - vacuum/shredder - dust collector -> open air
(I am not too worried about the superfine dust that would get out)

I see pictures online of both configurations:
Shop vacuum setups are usually the first configuration, where the dust is collected before the vacuum.
I see dust goes through the blower, typically in converted harbor freight dust collectors.

Any experience with what is most efficient? I will probably test both and post results here.

The advantage of the 2nd configuration is that it allows me to line the trash can with a bag, which would a bit more challenging in the first configuration to prevent the bag from being sucked into the vacuum.
But in the second configuration I will need to clamp down the separator lid or it will be blown off.

Does anybody have any thoughts?

[stevek]

I did a quick test tonight in the pull configuration (my neighbors probably not happy me running my blower at 10pm), because of the length of the hoses and probably leaks everywhere, I loose a lot of suction.

Parts I used:
90degree elbow (street elbow) 2'
connector that came with the hose for inlet
another connector that came with the hoses goes into the elbow wide flange
2 sheets of plywood
4' water pipes for spacers (3x)
3 carriage bolts
6 washers
3 nuts
3 wing nuts
some plumbers putty (epoxy) and some JB weld I had laying around
32 gallon bucket
weather strip at the top of the bucket

The flange on leave blower is a 5' to 4 'duct inside is a rubber 3' to 2', then a 2' 1/2 vacuum hose connector fits snugly into that.
(I could add a hose clamp there but it does not seem to be necessary)
I need to make the seal between the 5' and leave blower more effective with some weather strips (I had an old sock in there before).

I am wondering if the trash can top diameter of about 21 inches is too big for the 2' 1/2 pipes I am using?

To be continued...

[stevek]

I tested the push setup tonight, I made some minor modifications here an there, this seems to be a flexible setup.

Some preliminary testing shows good suction, the leaves are being shredded very finely and deposited in the trash can.
Because of the size of the leaves they have the tendency to clog the hoses, but if I take it slowly this is a working setup.

Some of the fine dust blows out of the filter, but since I am outside and where I live is mostly desert, I could care less.
Hopefully over the weekend I will have pictures of my roof before, during and after and contents of the filter.

What I added was a 3'' street elbow, it fits nicely over the outlet of the blower/shredder, then I have a reducer that reduces the 3'' to 2'', the connector that I had epoxied on the lid fits snugly into that. Don't even have to glue anything.

I made a minor change to the intake baffle, I pushed a metal 4'' to 3'' reducer inside the intake duct then had a rubber 3'' to 2'' attached to that with a hose clamp, then the 2''1/2 vacuum attaches to that.

i am still thinking the 2''1/2 pipes are to small for the size of the lid for this unit to work effectively.

[WayTooLate]

Steve -
I am afraid that the leaf blower is just not big enough to move enough air to make the system work is good as it could... 

I placed a lid on a 30 gal 'Brute' trash can to use it with my table saw.  It is nice having the 30 gallon capacity, but it doesn't separate is nicely as a smaller diameter 5 gallon bucket.  My ideal solution is to cut the bottom from the bucket and place it over the 30 gallon container.  I get the better separation plus the higher capacity.  My only drawback is the increased height gets in the way... 

Collecting your leaves creates a lot of volume, so you want the large container.  But you need a smaller cyclone that will work well at lower cfm...  Perhaps the next time you need to clear your roof you could try putting the smaller can on top.  For a leaf blower, I would try a 2-3 gall container. 

Question:  Are the leaves dry or wet?  From your desert clime, I assume that the leaves are dry - so they should pick up easy and crumble into smaller particles.  If they are wet, you will probably have a problem with them sticking to everything...  Unless they clog the hoses, the cyclone won't care.  I have vacuumed lots of wet debris through the cyclone.  It makes a mess, but if it will dry without turning to paste, it seems to clean/clear itself with more use. 

I will look forward to the pictures!

[stevek]

I built another dust collector over the weekend, using 3" pipes using an inverted bucket. Air outlet through the bottom, baffle held in place with a couple screws through the side, hole in the side of the bucket for the intake.
Everything fitted nicely together, this was the perfect simple setup (pictures to follow), but then the whole bucket fell over while it was running, :(.
Then my leafblower died, not sure what is wrong with it, it does not seem to be getting any fuel. :(

In any case, I bought a new electric leafblower, most powerful I could get at the local hardware store, I tried it in the pull setup (leafblower on the outlet) on my first lid, but the vacuum it created would collapse the bucket. The problem with this leafblower was that the outlet was square, not very useable for a push setup.

Then I found the gas powered leafblower that was the perfect fit at another hardware store, it is little bit more powerful than my old one.
The outlet (blowing) fit the 2"1/2 vacuum fittings nicely so I can connect a vacuum hose directly from the leafblower to the inlet of the dust collector bucket.

A couple of quick tests today and some small improvements look like a reliable working setup.
The only problem is that the leaf stems tend to clog up the pipes if I suck up too many at the same time.