J. Phil Thien's Projects

Phil,  Amazingly, my original question was going to be a two part question, but I decided not to complicate things till you answered the first part.  Well, you answered both parts. 

The second question was of course, what effect a turn ahead of the entry point might have?  But your response showed some deeper insight that I had.  I wasn't aware of the helical behavior of the air stream, but I was thinking that a turn results in the heavier particals being thrown to the outside wall.  Maybe that is an over-simplification and it really doesn't work like that.

Whatever the behavior of the dirt laden air in a turning pipe, if it is known and predictable, then surely some turns are beneficial and some are counter productive.  I would guess that most of us have some kind of change in direction just prior to entering our dust collectors or separators. 

Chuck,  I think an implementation like you sketched might produce too much turbulance and therefore be counter productive.  I was thinking of an external transition piece that bolts to the mouth of the separator.  I would not make any changese to the typical top hat design other than the inlet port would be rectangular in shape rather than round.  The transition would be smooth like the one on top my thickness planer and it's length would be determined by the fabricator. 

Phil,  I'm getting close to building my first top-hat separator, and was wondering if any of your testing included variations of the inlet shape?  Most everyone goes to great pains to insert a round inlet pipe tangentially and then shape the end to match the inside diameter of the separator.  This makes perfect sense since the separation process is dependent upon spinning the dust laden air stream around the inside perimeter of the separator.

Since the objective is to get the waste against the outside wall, would it make more sense to use a retangular inlet that is taller than wide.  Also, key to this concept would be an "eccentric" transition piece that would go from round to rectangular, keeping the area roughly constant.  For example, my piping is 5" diameter so I was thinking of transitioning from 5" round to 5"x4" rectangular, or even 5.5"x 3.5".  My thinking is the transition piece to rectangular moves the air stream closer to the outside wall before it enters the separator body. 

An eccentric transition piece might be more difficult to fabricate, but it seems if a rectangular inlet is better, then the transition is optimal if it is eccentric rather than concentric.

Comments?   

Nice separator!  That thing looks like it could be really heavy when it is full.  How do you empty it to bags without putting half the dirt back into the air?

I'm thinking about implementations that would put a bag inside the drum, so I wouldn't have to transfer it when it is time to empty it.  I'd also like an implementation where the drum can be removed without disconnecting hose.  The only idea I can come up with is to put the drum inside an airtight box with a sealed door, but that has some challenges too.  How do you seal the door so it isn't more complex to open than removing a hose from a standard configuration.  Secondly, how do you get the separator waste to drop into the drum and not all over the inside of the sealed box. 

I'll probably build something pretty basic initially, just to get into operation.  Then I'll "over-engineer" my second one!

Quote from: Chuck Lenz on July 21, 2011, 09:32:22 AM
Retired, brag away, I think that it turned out very nice, and with the really close paint match, anybody that didn't know any better would think that it is a Powermatic accessory. I wouldn't have known if you hadn't said anything. A new thread may not be a bad idea to attract people looking for that type of stuff. The reason I ask about some of this stuff and the price is in the last couple of years I've been designing and building dust hoods also. I bought some equipment to do this type of work, but no where close to what a full blown sheet metal shop has but it gets the job done. So far all my stuff is rivited and everyone is happy with what I have built for them. It's interesting that the hood has baffles in it. I built a hood for my Ryobi AP 12 Thickness Planer, the factory accessory hood was only meant to be used with a vacuum, the port on it was only about 2". The new hood works extremely well with a 4" port, and I noticed that since I put the hood on, whenever I turn the DC and the planer on the air going through the planer makes a fluttering sound. I also know that I don't want to forget to turn the DC on before planeing.           

Chuck,  I've seen several of your posts with hoods you've built.  You do nice work and I'm sure your riveted implementations work just as good as any welded model. 

I probably need to clarify my comment on internal baffles.  The baffles in my planer hood are really just an internal plenum.  They do not get into the air stream, they just surround it and direct it upward.  From your last photo, it looks like your baffle restricts the airstream.  I'm guessing that you did this to keep the rectangular area close to the area of the circular outlet.  You may find the baffle could be opened up more and the fluttering noise will disappear with no loss in performance.  If you hear a fluttering noise, that is turbulance, and turbulance degrades performance. 

Like others have reported, when I added a hood and DC to my planer and jointer, the noise level increased.  I have a sound meter and confirmed it was not just my imagination.  I believe most of this noise comes from very high velocity air passing the cutterhead, in fact, more air than is needed.  I over-engineered my hoods so that all the air had to pass around the cutterhead thinking this was the best way to suck up every morsel of dust and chips.

By designing my hoods "too tight", I merely suffocated my DC, and increased the noise at the cutterhead to a really uncomfortable level.  Once I gave the hoods more air to breath, the noise level improved and there was no loss in pick-up, in fact it was probably better.  The key is to be sure the air you give the DC is still coming from a direction that aids in dust collection.

Some people reported the sensed a drop in noise level when they added a Thien separator.  That is not surprising to me since the separator adds some static pressure losses that will reduce the amount of air passing over the cutterheads.  That doesn't mean it isn't working just as well, it just means there is less air, but still sufficient to pick up the dust and chips.

Quote from: phil (admin) on July 21, 2011, 08:57:40 AM

Quote from: retired2 on July 21, 2011, 08:44:09 AM
Chuck, since I'm a new member, I'm not sure of protocol.  Do you think before I post more photos of dust hoods I should start a new thread and put the photos there since they might be of interest to others?  I'm not sure how Phil feels about a lot of threads that are off-topic from the Thein Separator, although that is ultimately where my journey into dust collecton will take me.

Phil thinks you should post whatever you want, wherever you want, as long as it is tangentially related to DC or even woodworking.   This is all about learning from others.   ;D

Thanks Phil.  I'm on a multi-year part-time project to build a dust collection system that doesn't require me to spend 3 hours cleaning up for each hour of work I do.  Based on your response, I will share some of the things I've done in the hopes that it might help or be of interest to someone else.

Regards,
Dennis (Retired2)

Quote from: Chuck Lenz on July 21, 2011, 07:33:34 AM
Thats quite a hood, all welded construction. Who did it ?

It was fabricated by Wm. Brady in Elkton, Md.  Their primary business seems to be commercial HVAC supplies and installation.  They build and stock all kinds of spiral wound pipe.

They fabricated my hood, but I provided the detail design with all dimensions, a prototype mock-up, and I did the painting on the final product.  It is nearly impossible to find an original dust hood for the Powermatic 100 planer since it has been out of production for so long.  I bought the planer new more than 30 years ago.  At that time the optional dust hood was $85.  If you could find one today, it would probably cost three or four times that amount.

It may sound like bragging, but my hood is a better design then Powermatic's.  They just had a rectangular to round transition piece bolted on top the casting, with some baffles extending down into the cutter head area.  Mine also has internal baffles that attempt to closely match the angle of the chip discharge.  Those baffles extend up through the mounting plate.  The rear baffle has a sweeping corner that you can see externally.  The top transitions from rectangular to 5" round to match my dust collection system.

Chuck, since I'm a new member, I'm not sure of protocol.  Do you think before I post more photos of dust hoods I should start a new thread and put the photos there since they might be of interest to others?  I'm not sure how Phil feels about a lot of threads that are off-topic from the Thein Separator, although that is ultimately where my journey into dust collecton will take me.

Quote from: Chuck Lenz on July 20, 2011, 05:05:19 PM

Quote from: retired2 on July 20, 2011, 03:22:13 PM

The local spiral wound pipe shop does custom sheet metal work also, so I designed and had them build dust hoods for my 12" Powermatic planer and 6" jointer.  Both work great.  The bandsaw was a little more of a challenge.

Regards

Retired, I would be very interested in seeing the hoods, and knowing what they charged you for each hood.

Chuck,  here's some photos of the planer hood.  I'll post the jointer and band saw images tomorrow.

Quote from: Chuck Lenz on July 20, 2011, 06:01:42 PM
Retired, if you have a Photobucket account or similar you retrieve the pictures from there to post here. If you don't have a website to retrieve pictures from, Photobucket is free and fairly easy to use.

O.K.  It's getting a little more complicated than I hoped.  I think I have some options that avoid opening another account.  I'll investigate and get back.

Quote from: RCOX on July 20, 2011, 03:38:16 PM
Retired2: I appreciate your input. I knew there was a difference in suction loss with different ells but had never calculated it out. I used some 45 degree ells with a short section of pipe between trying to reduce loss. When you actually put numbers to it, it really changes the whole picture. I think Chuck is on to something with his idea of trying 2 separators. I already have nearly everything I need to change over, I would only need to build the baffle setup for the cans I already have. Will wait on the answer back from Chuck and give it a try. Thanks for the eye opener. 160 ft of pipe equivilent, just from above the accumulator to the dc. Never would have guessed. Thanks

I don't know of anyone who has done accurate measurements for the losses associated with Phil's separator, but I think Bill Pentz claims that "trash can" style separators can use 4+ inches of static pressure.  I don't know if that number is in the ball park for a Thien separator or not, but if so, for a 6" pipe at 4000fpm, that's another equivalent 100 ft of straight pipe.

Quote from: Chuck Lenz on July 20, 2011, 05:05:19 PM

Quote from: retired2 on July 20, 2011, 03:22:13 PM

The local spiral wound pipe shop does custom sheet metal work also, so I designed and had them build dust hoods for my 12" Powermatic planer and 6" jointer.  Both work great.  The bandsaw was a little more of a challenge.

Regards

Retired, I would be very interested in seeing the hoods, and knowing what they charged you for each hood.

I'm a new member, although I've been a lurker for quite a while.   So, I'm not exactly sure how to post photos, but I'll find a few good shots and give it a try.

Quote from: Pillguy on June 03, 2011, 09:14:36 PM
I read the article closely and do agree in theory and Bill Ps article that 6" is best. However several of the machines that supported 6" inlets were incapable of meeting min air flow.  That being said given the data provided, I think 5" will work best for my system. I can source it here in Atlanta and can have it custom made in spiral or 26 gauge pipe for a reasonable price compared to plastic.

Thanks for good feedback!

I'm in the process of building a dust collection system using the Delta 50-760.  I think I read everything I could find on the internet before I started.  I have access to spiral pipe, snap lock in various gauges, and the usual plastic stuff from the big box stores.  I reached my own conclusions about the same time I found this article which nicely summarizes my beliefs.

http://americanwoodworker.com/blogs/shop/archive/2010/10/25/central-dust-collection.aspx

I found 26 gauge 5" pipe at my local plumbing supply costs about the same per foot as the spiral wound pipe.  The difference is the cost of fittings - spiral wound is considerably more, nearly double.  I purchase all my ells from Oneida.  They are 1.75xD.  The longer radius has much lower friction losses.  They are five segment and can be adjusted to any angle, the most common of course is 45 degrees.  When adjusted to 45 degrees the bend radius becomes 3.5xD.  However, the improvement in friction losses is minimal beyond 2.0xD radius.

I also buy my 45 degree laterals from my local plumbing supply house.  The only problem is the branch is inserted with lots of little bent tabs, some of which are then tack welded.  These tabs face the air flow and could be a source of jams if you are collecting a lot of stringy material.  I doubt it would be a problem for the work I do, but I decided to wipe a high tech body filler around the tabs and then sand it down.  It isn't pretty, but it is smooth and effective.  Since it is just on the inside, only the dust will see that it isn't pretty.

I silicone caulk the exterior of all the fitting joints, and I tape the long joint of the snap-lock pipe and the assembly joints.  I'm not sure what the correct name is for the tape I use, but it is silver like duct tape, but it is backed with a thin layer of mastic.  Once you put it on a joint, it is air tight.  If you try to remove it, only the foil comes off, the mastic stays.  I have not found anything that works as a solvent, not even acetone touches it.

The local spiral wound pipe shop does custom sheet metal work also, so I designed and had them build dust hoods for my 12" Powermatic planer and 6" jointer.  Both work great.  The bandsaw was a little more of a challenge.

Regards   

Quote from: RCOX on July 20, 2011, 08:34:26 AM
Another thought on your suggestion. Would it be better, where I have the 90 degree ells to replace them with 2-45 degree ells with maybe a short 6"straight run between each 45? I think I will have enough room to do this if you think it will help. That is what I have done on the pvc main runs in my original setup.

It appears you have four 6" short radius (1xD) ells between the accumulator and the DC inlet.  Short radius ells have considerably more friction loss than a 1.5xD ell.  A 6" 1.5xD ell has losses equivalent to12 feet of straight pipe.  For further comparison, a 2.5xD ell is the equivlent of only 6 feet of straight pipe.  No way of knowing what the friction losses are for your accumulator, but I suspect it is the equivalent of at least another 90 degree ell.

Above the accumulator you have two short radius 45 degree ells that appear to be 4" in diameter.  Two 45 degree ells produce the same friction loss as a single 90 degree ell, that is IF they have the same bend radii.  So, if these 45 degree ells are 4" in diameter and 1xD bend radius, they add the equivlent of another 6 feet of straight pipe.

If we use the losses for 1.5xD ells, your current configuration is roughly the equivalent of roughly 66 feet of straight pipe.  I can't confirm the data, but my notes show the loss for a 1xD 6" ell as the equivalent of 24 feet of straight pipe.  If that is correct, your losses from just above the accumulator to the DC are equivalent to more than 130 feet of straight pipe.   

So, one way to reduce your losses is use all long radii bends.  I have a 5" system and I use 1.75xD ells from Oneida Air.