J. Phil Thien's Projects

Alan provided the most likely answer.  I have only plugged my top hat twice.  Once when I overfilled the waste drum, and another time when I was planing wet cypress.  The wet cypress resulted in very long shavings which looped around the end of the separator drop slot.  The end of my drop slot has well rounded corners, but it is unlikely that any modification would have allowed these wet stringy shavings to drop without hanging up.

Since I have a clear sided separator it was easy to watch the plug occur.  It only took a minute and it shaped the same way every time.  The shavings would snag at the end of the drop slot and then a wave would form and back up immediately filling the slot as it went.  That is when I started suggesting folks end their drop slot with a slight tear drop shape.  It would not help wet cypress, but it might help with what is likely the second most problematic wood, cheap sappy pine.

Your drop slot is plenty big, so that is not the issue, pay attention to any corners or edges at the end of the slot.  Round everything over, including the top and bottom edge.  Sand it as smooth as possible.  And if you want to spend well over a grand, buy a helical segmented cutter head for your thickness planer and jointer - you will never have the problem again!  😀

Quote from: SpaceGrey on December 26, 2019, 02:03:36 PM
DustySanders, I took that into account, didn't include any measurements over the bellmouth opening, they were quite off and I couldn't calculate properly what those CFMs would be.

retired2, I think the difference you and I see is because I did all the measurements without any hose attached into the input (which I admit is not a real life scenario). Getting blower measurement with say 10 ft of hose attached directly to the blower will lower flow significantly. Then if I'd do the same with 10 ft hose attached to separator, it'll be lower as well (vs. no hose), but the different wouldn't be as significant since we already got some flow loss over separator. As a result the flow difference (Blower+hose) vs. (blower+separator+hose) would be less comparing to scenario (blower) vs. (blower+separator).

I don?t disagree with your comments.  I just thought it it?s worth mentioning that in your final configuration use as little hose as possible since hose has about 3x the line losses of a smooth pipe of the same size.

Quote from: alan m on November 27, 2019, 11:22:06 AM
the idea is to have the chamber  moving as fast as posible to seperate the dust but have below the baffle moving very slowly. the slower the air below the baffle the better . air moving below the baffle will reagitate the seperated dust.

i dont know if something like this would be a good thing or not . my gut instinct tells me that stopping the air spinning  below the baffle can only help. the problem is how to do that without creating other problems. you could create a blockage very fast or stop the drum filling evenly and building up in one side more that others

Come on Alan, you?ve been talking about this for 18 months and haven?t made any effort to test it.  I gave you a crude way to test the idea in a matter of minutes, and it was a non-destructive test.  If the results look promising, then you can build a gold plated one.

DustySanders brings up the question of how you are measuring performance, which is a good point.  You could be seeing differences greater than mine due to your methodology.  I followed Phil?s procedure, and that is to take readings at the end of a straight pipe.  Take several measurements along the edge of the pipe and several in the middle, then average the results.  Because of the way air flows in a round pipe, the readings will be different along the edge than in the middle.

If you are measuring air speeds that are near or exceed the stated range of your anemometer, you should increase the pipe diameter with a reducer,(increaser), and then add a short section of the larger diameter pipe and then take new readings.  The FPM will be lower, but the volume is greater so the calculated CFM should be similar, and most likely more accurate if you are pushing the limits of your cheap anemometer.

Posted and discussed back in 2014. 

http://www.jpthien.com/smf/index.php?topic=1048.0

Quote from: SpaceGrey on October 07, 2019, 09:44:56 PM

Quote from: retired2 on October 07, 2019, 07:20:30 PM
SpaceGrey,

I want to compliment you.  You are one of the few people who have built different configurations and then captured data to show what each one is going.  That is one helluva lot of work, but the data is so valuable.  The has been a lot said about the performance of 2X separators, but unless my memory is failing me, it has all been subjective.  Yours is the first I have seen with actual data.

I agree, it is interesting that the 2X doesn?t seem to care about the outlet pipe ending.

Thanks again for a great piece of work.  Unfortunately, you still don?t have a conclusive answer to why your performance losses are so much higher than mine.

Appreciate your compliment.
I think I'll try to get to the bottom of it once I get my mental capacity recharged :)

Few question about your setup:
- What size inlet pipe goes into your impeller? Mine is 5".
- Have you measured your impeller flow in bare configuration? Nothing attached to it at all, no filter, no nothing?

BTW, adding that additional lip to create additional flow curve before it hits air from intake (per your link above) didn't provide any improvement in my case.

My inlet is 5".  I have not measured the air flow with nothing attached.  However, one of my tables lists airflow with and without a separator.  All my measurements were taken at the end of a drop about 20 feet of 5" pipe away from the blower.  I believe one of my data points is without the exit filter.  That was done to determine a best case scenario in replacing the bag filter with a pleated Wynn filter.  I can't remember, but I may have posted flow data after I installed the Wynn.

SpaceGrey,

I want to compliment you.  You are one of the few people who have built different configurations and then captured data to show what each one is doing.  That is one helluva lot of work, but the data is so valuable.  There has been a lot said about the performance of 2X separators, but unless my memory is failing me, it has all been subjective.  Yours is the first I have seen with actual data.

I agree, it is interesting that the 2X doesn?t seem to care about the outlet pipe ending.

Thanks again for a great piece of work.  Unfortunately, you still don?t have a conclusive answer to why your performance losses are so much higher than mine.

Quote from: SpaceGrey on October 07, 2019, 07:30:13 AM
Retired2, what do you use for impeller?
I think impeller is a culprit here, mine is "so called 2HP" Harbor Freight.

I use the Delta 50-760 dust collector without any modifications, except for a Wynn filter.

You could be right about the HF being the source of your problems.  So many people think the HP rating is a good way to compare blower performance.  It is not!  You need to have the fan curve which shows the relationship of CFM?s and static pressure for a particular blower.  Fan curves are almost never provided for dust collectors and shop vacs.  The reason is simple, manufacturers don?t want you to know how their blower performs under various loads compared to others.

Quote from: SpaceGrey on October 04, 2019, 07:12:27 AM

Quote from: retired2 on October 02, 2019, 01:05:41 PM
The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

I took that picture before making everything round, it's not straight in reality.
I'm also going to attempt making your tweak from the post mentioned later tonight.

Don?t expect my minor tweak to make much difference in your performance.  I believe it?s benefit is small at best, maybe not even measurable.

With regard to the comment on the depth of your bellmouth.  I tested mine at several different positions and there was very little difference, but ironically the air flow was best when it was positioned closest to the baffle.  Admittedly, my separator is a single height and it is uncertain what differences that might make.

I have no personal experience with double high builds, but the advice I usually give for the depth of the outlet is to place the flange of the bellmouth level with the bottom of the inlet, or even lower if the height is sufficient.  Since I don?t have a unit it to test, I don?t know if that is good advice or not, but I have not heard anyone report back that it doesn?t work well following that advice.

Quote from: bbain on October 03, 2019, 02:57:15 PM
I really don't think masking tape and plastic wrap are sufficient to get good enough sealing.  You will have lots of losses without proper sealing.

It also looks like the inlet is too far down in the tophat try rising it a bit and see what effect that has.

The inlet looks to be as high as it can be placed without changing its shape.  Considering single height separators work fine with the inlet flush with the floor, I don?t think the inlet position is the OP?s problem.

The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

Sorry, I don?t have an answer.  It looks like your air straightener has a lot of vanes, but I?m not sure how that could be any worse than my plastic tubes.

What?s the ID of your separator chamber?

38% for mine.

I appreciate your compliments, but Phil is the real genius here.  He is not as active on the forum as he once was, but he knows more about what works and what doesn't than I ever will. 

I'm pretty sure your separator size will work, it is just a matter of how much more frequently you might have to clean your filter due to bypass.

It's a lot of work to build a separator so I would suggest build it as optimal as you can.  Go buy a large Brute garbage can at HD or some other retailer.  They are light, but sturdy, and they don't cost an arm and a leg.

The closer the swirling waste stream is to the edge of the outlet pipe, the more likely bypass will become a problem.  There is no magic formula or rule of thumb to determine where bypass becomes unacceptable.  You have three variables to tweak, the separator diameter, the width of the inlet port, and the diameter of the outlet pipe.  And keep in mind that adding a bell mouth will improve air flow, but it makes the effective diameter of the outlet pipe much larger.

I don't believe a deeper chamber will significantly reduce the amount of bypass from a small diameter separator.