Seperator for fine dust from drum sander

[Jim_Haines]

We built a large Thien separator for our shop planer and it works just great. Now I want to build one for use with our drum sander. This sander is responsible for rapidly clogging the HEPA filter on our new 5 HP Oneida Dust Gorilla cyclone.  Is there an optimum slot width that I should use to collect the very fine sander dust? Chunks and larger pieces of wood are not an issue here.  Also, has anyone built a smaller version of the Thien to fit a 30 gallon plastic barrel?

[tvman44]

I built a Thein separator in a 30 gal. plastic barrel, but I used the standard size slot  I asked the question a good while back about real fine dust and think someone said a narrower slot would be best, but my old memory is not sure.  Maybe someone with more experience will chime in with more helpful info.

[Jim_Haines]

Thanks. Seems that this dust collection issue is somewhat divided into chunks and powder. Our problem is collecting the powder in order to not circulate it back into the shop air while avoiding the inevitable clogging of a filter meant to filter this same fine powder! Somehow, most of the fine powder needs to be removed before reaching the ultra high performance HEPA.

[retired2]

Thanks. Seems that this dust collection issue is somewhat divided into chunks and powder. Our problem is collecting the powder in order to not circulate it back into the shop air while avoiding the inevitable clogging of a filter meant to filter this same fine powder! Somehow, most of the fine powder needs to be removed before reaching the ultra high performance HEPA.

I'm not trying to be flippant Jim, but the reason they make HEPA filters is because most other methods of separation don't work well very well on fine particles.

Centrifugal force and gravity are the primary reasons cyclones and separators work, and they are more effective with particle sizes that have some mass.  Unfortunately, you can't change the laws of physics.

I think the general consensus is that a narrower slot in the Thien baffle works better for finer particles, but you can't just keep turning that knob till the problem is solved.  I can't recall anyone trying a slot size much narrower than 3/4".  I'm sure if a very narrow slot were the answer, it would be common knowledge on this board by now.

One way to solve the problem is vent the offending machine ouside if that is possible.

[Jim_Haines]

Thanks for the response. Its was not at all flippant.  I built a "top hat" variety Thien separator that works fantastically well on a large planer. I thought I'd try it on our problematic drum sander and it collected an amazing amount of very fine dust. Without microscopic analysis, I'd say the dust in the Thein collection bin was basically very short and fine, "fluffy" wood fibers just as you would expect from sanding. The separator that I built has a 1-1/4" slot. Since installing it, our 5 HP Oneida Dust Gorilla has maxed out at about three inches of back pressure on the HEPA filter. If we can maintain that and not cake the filter, we will be happy campers.  In any case,I am building another Thien to be dedicated to the drum sander and I will use a 3/4" slot on that unit.  I will report back on the "fine-fiber" performance for that configuration.  By the way, venting outside is not practical for us. We live in a retirement community, and it would only give the residents another reason to belly ache!

[tvman44]

Jim, please keep us updated on the smaller slot and fines.

[phil (admin)]

Multiple separators seems to help but obviously at quite a cost in airflow.  But it seems the more chances you get at an airstream, the cleaner it gets (even the super-fine stuff).

[hazmail]

Thanks. Seems that this dust collection issue is somewhat divided into chunks and powder. Our problem is collecting the powder in order to not circulate it back into the shop air while avoiding the inevitable clogging of a filter meant to filter this same fine powder! Somehow, most of the fine powder needs to be removed before reaching the ultra high performance HEPA.

I'm not trying to be flippant Jim, but the reason they make HEPA filters is because most other methods of separation don't work well very well on fine particles.

Centrifugal force and gravity are the primary reasons cyclones and separators work, and they are more effective with particle sizes that have some mass.  Unfortunately, you can't change the laws of physics.

I think the general consensus is that a narrower slot in the Thien baffle works better for finer particles, but you can't just keep turning that knob till the problem is solved.  I can't recall anyone trying a slot size much narrower than 3/4".  I'm sure if a very narrow slot were the answer, it would be common knowledge on this board by now.

One way to solve the problem is vent the offending machine ouside if that is possible.

Hi Jim--new to this site and am impressed with some of the ideas here especially Jim Thien's and also "Retired'' Don, so much information here.
I may be able to help you with your sanding dust problem, I make fishing lures (machine) and had the same problem as you (but probably not the volume you have).
If you go to this site, there is an old post, I posted it 20 Feb 2013 about half way down the page (under hazmail  -  ) 
Sorry--Link deleted, see below.
This basic principle should take care of any residual dust- I have used that set up for the past 4 years to catch ALL my dust, BUT have just gone to a "Thien Seperator'' with my same mister idea on the end to catch the residual, this now amounts to probably less than 5% of fine ''talc'' type dust in the water tank -Bliss
The problem with my old fan system was not the misters but the fan was not moving enough dust and had considerable back pressure problems so I went to Jim's separator idea with a few mods.
On making the separator- As has probably been said a 100 times here, if the primary collector drum is not COMPLETELY sealed you get bypass and outside air entering the drum creates a lot a higher pressure and turbulence in there, this just stirs up the already settled dust and out it goes through the exhaust. Thinking mine was sealed enough just with the weight of the fan was a big mistake, sealing the top rim gave me about another 20%- 30% in the drum. Also as Don suggests, I added a PVC ''horn'' (a $3 PVC floor register) and added vanes to the bin inlet and the exit into the turbine.
Hope this helps--If you need them, when I get some pics of the new setup I will post up.
Pete
Sorry can't post the link but here are some pictures:

[hazmail]

Finally worked out the pictures thing, I just had to look   ::)

[hazmail]

Finally got round to getting pics of the new ''Thien'' separator and fine dust ''scrubber''.

Thien 2--shows  the separator with 50 litre collection drum  -
Thien 1- - shows the outside scrubber which captures the finest dust in a water mist spray which falls into a water tray.