J. Phil Thien's Projects

Well, I have done it.  I changed over to 6 inch pvc and a new two bag 3 hp dust collector.  This thing really sucks.  That is it does well without the thein tophat separator.  The minute I install that into the system, I loose pressure, and quite a bit.  My down draft table, with out the separator, almost would hold the wood down like a magnet.  With the separator the hold down power wasn't even noticeable.  Every tool I tried was the same result, much less suction.  So I guess that unless there is a design flaw in my tophat separator, then I will just stay with the two bagger and not use the separator.  With two bags I can go longer between dumping my sawdust.  Any ideas?
Thanks,
Jon

Quote from: bill70j on April 11, 2011, 07:30:38 AM
Painterman:
To answer your question about the losses through a separation system.  They can be huge, depending on flow.  At max flow they can be as large as 60% of the unit?s capacity.  And that is what you are feeling with your hand testing.  But under normal conditions, they are probably closer to 10 ? 15% of total capacity.  I agree with others that your issues are likely not with your top hat system.

Here is my experience with separator losses.  I built a trash can separator for my Harbor Freight 2HP unit and measured the actual vacuum at two locations with a gage, just like you did with your hands.  You can see from the images below, that at the separator inlet under no load, the vacuum was 1.75" of W.C, but at the blower inlet under the same conditions, it was 6.0" of W.C.  So at maximum flow conditions, the loss through the can was 4.25" or almost 60% of the total capacity of the unit (which is about 7.3? of W.C.).  I did smoke testing on my unit, so know there are no leaks and the losses are real. 

The reasons for my losses are due to the friction loss through two 90deg elbows, the 45deg wye, plus other friction losses from the air moving from the can back into the blower suction pipe.  Wood Magazine just did an article on calculating losses in a DC system under normal conditions (350 CFM).  If I use their spreadsheet, I come up with a predicted loss for my separator system of 1.05? of W.C.  But that is at normal flow conditions.  At max flow conditions for my unit of about 650 CFM, that figure translates to 3.62? of W.C. which is not too far from the 4.25? I measured.

In Wood Magazine?s 3/2008 article, they show your Grizzley1029 as having  something like 900 ? 1100 CFM capacity at max flow conditions and a max static pressure of 9? of W.C. ? far superior to my HF unit.  So you will see even larger differences of loss between max and normal flow conditions.

So are you saying that everything is normal and that my test was really an unreliable test?  You say that I will see an even larger differnce  of loss between max and normal flow conditions.  Is that bad?
Thanks,
John

Hey everyone, I finally had some time to do some "testing" on my new top hat design.  My top hat dimensions are as thus:
overall diameter is 2 feet
inside diameter is about 21 inches
inside height is 6 inches
fall through slot is 1 3/8 inches
thickness of baffle 3/4 inch
intake size 5 inch (with 4 inch attached to it)
exhaust size 5 inch

I took off the inlet hose to the impeller, turned on the DC and felt the force of the suction at the impeller intake.  It is quite strong.  then I put the hose back on between the top hat and impeller intake and felt the suction at the top hat intake.  It seemed like quite a bit less than at the impeller intake.  Like maybe even half.  Obviously this is hard to quantify, but my son and I both thought that is was quite a bit less.  So my question is:  Is my design at fault or is this the normal loss of suction in these designs?  I checked for leaks and did not find any.  I am not sure this is acceptable now.  Is there any changes I can make to the top hat to reduce the loss?  Please refer to the top of the thread for pics.  Thank you in advance.
John

I was wondering what kind of blast gates you were using.  Would love to know.
John

Thanks, Bulldog.  That video was great.  So do you think that most of the noise comes out of the bag area?  And if you built a little enclosure around the bag, would that help with the sound.  With your system, do the fines keep recirculating and never fall down or do you have to empty more often?  I could go for less sound.  Thanks for the explanation and video.  You have my mind a going
Thanks,
Jon

I forgot, one last question.  Is 26 gage metal y's strong enough to have a gate (being pushed and pulled on) and have a 6 inch flex hose hanging off it?  Does it move, bend, or otherwise not be strong enough to survive my shop.
Thanks again everyone
Jon

Chuck, thank you for your help.  I have gone back and forth between metal and pvc.  My thinking was that pvc was smoother on the turns, so maybe was "better".  But when it gets down to it does it make that big of difference?  Does the crimped side of the metal narrow the pipe a bit?  Once again, does it really matter?  I only want to do this once more and would like to do it as right as possible.  I found a good supplier for 26 gage pipe right here in town and they can even supply me with none crimped metal (to give me a choice).  Some one please sell me on using metal or pvc.  The internet is full of both sides, but I tend to favor the opinions of those on this forum.

Thanks,
Jon

Once again thanks to everyone for your help.  Steve, my "clear" bag is difficult to see through but there really is no chips in the bag and very little fines.  I didn't quite understand what you did with your lower bag.  Do you have a bag at all?  Could you describe again?  And how would that lower the sound?  Thanks, Jon

If I do go for a new machine with a 6 inch intake and keep 6 inch trunks as far as I can, wouldn't I be far better off than my machine with 5 inch trunks?  Or is it not worth it?  I noticed at Lowes that the metal is 30 gage and not the recommended 26 gage, but also noticed that the crimping is all going the wrong way for dust collection.  How do people deal with that?  Thanks in advance.

Jon

hi chuck thank you for responding .  my grizzly 1029 is an older version and the intake is  5 inches.
how much does having the separator affect the pressure loss ?   I do plan on upgrading my machine and also all of piping  to 6 inches far as I can. what do people find out after they add the separator as  to the pressure loss ?
thanks jon

Last week I did two things.  The first was to get my 4 inch flex hose off of the ground.  I had two 4 inch flex coming from two trunks of 4 inch pvc.  They just laid on the ground and I was tired of cleaning around them and tripping over them.  So I went to the ceiling and other means.  So I basically added about thirty feet of more pipe/flex with more turns and angles.  I am not sure how much it affected the suction because I was busy making my Thein separator and wasn't paying attention.  So then I built the separator as pictured and then noticed that my suction dropped off quite a bit.  I have a grizzley 1029, 1180 cfm and five inch inlet and outlet.  All my pipe is 4 inch pvc and 4 inch flex. Here is my questions
- how much suction loss is because of the separator
- how much suction loss is because of my basic 4 inch setup with flex connecting the machines, connecting trunks, and the DC.
- if I was to get a bigger machine, say a 1550 cfm or 1700 cfm with running 6 inch  everywhere that I can, would I be back to where I was before last week.  (still using the separator) (by the way the separator works fantastic with sucking over 17 gallons of saw dust during testing and only having about half a cup of fines in the bag).
I know this is all hard to say, but I am willing to buy a newer bigger machine and run bigger pipe if it will make a difference.  It seems that when I put the separator on that I lost a lot of suction.  Is there a way to make the separator more efficient?  My slot is about 1 5/8 inches wide.  Is that to wide? Does it matter?
Sorry about these crazy questions.  Just confused.
I need more suction but want to keep the separator.

Please, any info would help.
Jon