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Forum topic by ShemATC posted 05-20-2017 12:47 PM 424 views 0 times favorited 7 replies Add to Favorites Watch
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ShemATC

10 posts in 648 days


05-20-2017 12:47 PM

So I’m constantly looking for various modifications for dust collectors, since an out of the box layout simply won’t fit space wise in my garage shop.

I came across this version completely randomly and I’d never seen any other versions like this.

http://www.ibuildit.ca/Workshop%20Projects/dust-collector-rebuild-2.html

For those that don’t want to go to the link, this person completely boxed in their filter bag, then added the blower to the top of the box. (Note he also added a Thien baffle between the bottom bag and the filter). Essentially he created the same layout order a shop vac uses. Intake-filter-blower-exhaust.

Except for having to deal with the stream of exhaust air at full speed (I’m sure it could be easily routed and dispersed as needed), does anyone see a problem with this? Obvious that a better filter would allow better airflow, but does putting the blower after the filter drastically change performance? If it doesn’t then this seems like a great idea. You’ll never get any chips sneaking past a separator to the impeller, it’s extremely compact (essentially the space of the typical Filter/Bag layout), and can easily be upgraded simply by changing out the blower on the top.

I guess the only question is how the airflow is affected by pulling air through the large filter space. It’s also not encouraging that there are no commercial units designed this way.


7 replies so far

View AZWoody's profile

AZWoody

1138 posts in 1064 days


#1 posted 05-20-2017 01:43 PM

First impression to me is that would kill airflow, especially with that blower. Putting the filter in front would quickly build up static pressure which that blower being shown is really not capable of handling. By looks I’m assuming it’s the HF dust collector. It has an undersized impeller so anything in front of it that adds resistance such as ducting, elbows, cyclones and even filters drops the cfm greatly.

Other dust collectors might fare better, but still, putting the filter before the impeller adds a blockage to the system which would get worse as the filter clogs with dust.

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ShemATC

10 posts in 648 days


#2 posted 05-20-2017 02:19 PM

I would say ignore the specific blower used, my question is more about the setup in general.

I tend to agree about adding a blockage to the system, but (playing devils advocate) isn’t that the same issue you’d have with a clogged filter placed after the blower also?

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AZWoody

1138 posts in 1064 days


#3 posted 05-20-2017 02:32 PM



I would say ignore the specific blower used, my question is more about the setup in general.

I tend to agree about adding a blockage to the system, but (playing devils advocate) isn t that the same issue you d have with a clogged filter placed after the blower also?

- ShemATC

No, because a blower works on moving air at a high volume, not suction. If it was based on suction, like a shop vac, then the filter before the blower would be ideal.
Putting the filter before the blower starves the impeller of air, killing all air flow in the system.

View JBrow's profile

JBrow

1275 posts in 760 days


#4 posted 05-20-2017 03:44 PM

ShemATC,

The biggest problem I would expect from the design executed in the link is boxing in the filter bag setting atop the blower housing. The air sucked into the dust collector is blocked from re-entering the shop. If boxing in the filter is desired, whether a bag or a cartridge, it would seem prudent to me to install the four sides and the top panels so that a gap of 2” – 3” all around the perimeter is incorporated. The gap between the upper box frame and the panels would allow air escaping the filter to return to the shop. But even with this gap, I would think that some static pressure (that reduces air flow at the machines) would result. But the gap would add far less static pressure to the system than a fully enclosed filter box.

The design executed in the posted link does not seem to provide for a fine dust collection bin into which fine dust that falls when the filter is cleaned or the machine is turned off. In the executed design, that fine dust seems to fall into the impeller where it is sent back up into the filter bag when the machine is turned on. A just cleaned bag or cartridge would get dirty in a hurry. I would think it better to provide for a place for the fine dust from the filter bags or cartridge to fall and which can be accessed so the fine dust can be removed.

I am a little confused by “…does putting the blower after the filter drastically change performance?”. But if this means the separator (for example the Thein baffle), then air from the machines should enter the Thein baffle. Air from the Thein baffle would exit into the impeller and exit the impeller and enter the filter. This seems to be the standard method for incorporating a separator into a dust collector. The air flow of the system will probably be reduced by some amount when a separator (Thein baffle or cyclone) is introduced. These separators add to the static pressure of the system. The amount of the added static pressure would depend on the materials and design of the separator.

One aspect of the design executed in the posted link that I like is the chip collection contained in an enclosed space that features a door to empty the chips (dust collection chamber). This is similar to a design I implemented. However, in my system, a fiber drum sets in the lower space that seals to the top of the dust collection chamber with a bicycle inner tube. The fiber drum is easily and quickly removed for disposing of the chips. The seal at the top of the fiber drum keeps the dust collection chamber relatively free of debris. I also included a viewing window through the top of the dust collection chamber and some lighting so an eye can be kept of the level of collected debris.

One issue to consider if you move forward with enclosing your dust collector is ease of maintenance and service. The filter requires cleaning, course debris must be removed and disposed, and a repair could be required. Designing the enclosure to make these go faster and easier would complicate the design and construction, but could be appreciated later on.

The second issue is sizing the enclosure to allow any upgrade fit to within the enclosure. The upgraded blower and/or filter could be larger and obviously if the enclosure is too small, the enclosure could not continue in use with the upgrade.

View Carloz's profile

Carloz

989 posts in 431 days


#5 posted 05-20-2017 04:28 PM

I think that is a crazy idea. I do not see how it saves any significant space but essentially makes the dust collector useless.

View JuniorJoiner's profile

JuniorJoiner

480 posts in 3280 days


#6 posted 05-20-2017 04:45 PM

i find that design confusing, don’t see how enclosing the dust bag would be anything but counterproductive.
there are many ways to save space with wall mounting a mobile dust collector, putting it up higher to give some floor space back.
I will add pics of my frankencollector, i did this because i had a dust collector that worked, and just wanted it off the floor. Plus, i never have the cash to just buy a new collector, so i got pieces to make it over time.

-- Junior -Quality is never an accident-it is the reward for the effort involved.

View Rick_M's profile

Rick_M

10642 posts in 2220 days


#7 posted 05-20-2017 08:14 PM

If you read the article, he didn’t leave it that way very long. He has a forum, ask him.

-- http://thewoodknack.blogspot.com/

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