J. Phil Thien's Projects

Well, I finally had several good days to begin the construction of my Thien separator.  Here is a photo of the nearly finished product.  I need to secure the plexiglass and seal some joints, then I will be ready to test the bellmouth outlet.  However, before I do another thing, I need to do some serious cleaning of my shop - remind me not to use MDF again!  Also, before I can test, I need to do some work on my DC piping.

If you have interest in seeing some of the sequential construction photos, let me know and I will post more.  I've included just one so you can see the bellmouth attachment.

Very tidy. I'm looking forward to reading the results.

Dave

I would like to see how you installed your plexiglass. The lexan I used ( 1/8 th inch) had a tendency to snap. I did not place it in a dado, I predrilled and countersunk some holes then tried drilling through that into the wood. It worked well on half the holes, then I hit the edge  of a hole in the lexan with the drill bit while holding the lexan in the curve. It snapped as soon as the bit hit the edge.

Looking at the tophat built by galerdude, it looks like that is how he installed his. Not sure.

Thanks, looks very good,

Raymond

Quote from: RCOX on August 26, 2011, 05:11:08 AM
I would like to see how you installed your plexiglass. The lexan I used ( 1/8 th inch) had a tendency to snap. I did not place it in a dado, I predrilled and countersunk some holes then tried drilling through that into the wood. It worked well on half the holes, then I hit the edge  of a hole in the lexan with the drill bit while holding the lexan in the curve. It snapped as soon as the bit hit the edge.

Looking at the tophat built by galerdude, it looks like that is how he installed his. Not sure.

Thanks, looks very good,

Raymond

Raymond,

The plexiglass is the primary reason my separator is not 100% complete.  I haven't figured out how I'm going to do it.  There are two issues, retaining it and sealing it.  It is possible that both needs can be met with a single fastening device, but I'm thinking they are going to require separate solutions.  If you Google "attaching plexiglass to wood" you will find a lot of information, most of it pretty discouraging.  Maybe we should start another thread to solicit ideas and experience on this subject.  I know there are several people who have built separators using plexiglass or polycarbonate, but none of them have discussed this constuction problem.

Below is the design sketch I created for my separator.  As you can see, the 1/8" plexiglass is held in place by a top and bottom retaining ring.  The dado at the top doesn't serve any real purpose other than the plexiglass I had was about an 1/8" too tall and I didn't want to risk trimming that small amount off. 

I have not done enough testing yet, but my current plan is to drill oversized holes in the plexiglass and then drive truss head screws radially into the retaining rings.  I might put a nylon or rubber washer under the screws, but the whole reason for using truss head screws is to keep the retainer profile very low.  I would have countersunk the screws as you did,  but several online sources strongly recommended against that because it causes stress points where fractures will occur when flexed.

For sealing I may use silicone caulk, but I would like to avoid that mess.  The only other idea I've come up with is to cut a shallow dado all the way around the middle of the retaining rings and then put a piece of rope caulk in the dado.

OUTSTANDING! MORE PICTURES~! :o

Quote from: RCOX on August 26, 2011, 05:11:08 AM
I would like to see how you installed your plexiglass. The lexan I used ( 1/8 th inch) had a tendency to snap. I did not place it in a dado, I predrilled and countersunk some holes then tried drilling through that into the wood. It worked well on half the holes, then I hit the edge  of a hole in the lexan with the drill bit while holding the lexan in the curve. It snapped as soon as the bit hit the edge.

Looking at the tophat built by galerdude, it looks like that is how he installed his. Not sure.

Thanks, looks very good,

Raymond

Raymond,
  The lexan I used was a little less than 3/16's and I did use screws on the bottom plate of the sandwich to pull it up tight to the edge and to help seal. I pre-drilled and countersunk the holes after pulling it out of the assembly and with it laying flat. On the top, the circular dado is all that holds the lexan in place and the vertical bolts around the perimeter seems sufficiant to seal the top. In my limited experience with using lexan in the sign industry it has been extremely difficult to snap lexan. Many times, 3 to 5" waste strips (3/16") were folded in two to fit in the dumpster, with out breaking. You can try using a heat gun to make it a little more plyable but it does get soft quickly. Acrylic or plexiglass on the other hand is very shatterable, I've seen panels break just from wiping with alcohol (?), don't know why. I do know that plexiglass is fragile and that is why the sign industry uses lexan for large lit panels because it stands up to the abuse. I've shattered lexan in a panel saw and with a skill saw, both with inadequate support. Ideally to saw or drill lexan, it should be supported on both sides and lay flat. That's just my experience and I'm no expert on the subject, just sharing what has worked for me.
   Retired2, your new separator really looks good. nice job.

Thanks,
Gale

O.K. Don, you asked for it!!

Here are some cutting and assembly photos of my Thien separator.  I have stolen as many ideas and techniques as I could find on this forum.  So, if you see something that looks like yours, thank you for your help!  I hope I've added a few tricks that might be of use to others.


The following photo shows the baffle sandwiched between the top and bottom plate.  The three pieces are pinned together by 1/8" dry dowels.  These pins proved very useful several times throughout the cutting and the assembly process.  In this photo the sandwich has been bandsawed to reduce the amount of material that had to be routed away.  All three pieces were routed at the same time with a 2" long cutter.



After the sandwich was edge routed, it was opened up so the drop slot could be routed in the baffle.  I didn't worry about cutting into the bottom plate when I routed the slot because in my design the center of the bottom plate is removed.



Then I removed the baffle, flipped the bottom plate over and routed the trash can groove.



To finish the bottom plate, I routed out the center, leaving just a ring and a corner to support the inlet pipe.



Next, I created another sandwich for the two plexiglass retaining rings.  Again, the dry dowel pins were used which keeps things aligned for several machining operations.



These are the completed retaining rings.  Dados were cut for the vertical ribs, the center was removed, and the corner was cut out to mate with the inlet port framing.



Next, I completed the top plate.  On the bottom side I cut a circular dado to receive the top edge of the plexiglass.  Then I cut a hole large enough to insert the bellmouth outlet pipe.  For testing purposes I wanted to be able to remove the outlet pipe without having to remove the entire top plate.



This photo shows the outlet pipe in place.  It has two collars.  One forms the plug for the hole in the top plate, and the second forms the flange for attaching the assembly to the top plate.



Now the assembly begins.  I had a circular piece of MDF waste, so I decided to make a stiffener plate for the baffle.   It is set well back from the drop slot in order to maintain the 1/4" thick edge.  At this point all three pieces are glued together using the dowel pins for alignment.
 


Next the two plexiglass retaining rings were glued up.  You can see screws where the dowel pins once were.  That was a blunder and they were removed after this photo was taken.  There will be screws inserted in these locations, but they are longer and attach the top plate.  Same is true for the bottom plate.



Next the inlet pipe mount was created by face gluing several pieces of maple.  The maple has been machined to provide stops for the plexiglass and to maintain the curvature of the separator's inside diameter.



Next the plexiglass cage is attached to the bottom plate and baffle assembly.  Then the plexiglass is cut and checked for fit.



The inlet port is attached with hex head screws.



And finally, the top plate is attached.



That is the status of my separator as of today.  I'm sure everyone is eager to hear how this bellmouth idea is going to work out.  I am anxious to try it as well, but there is still work to be done, and I am on the east coast so I may be testing it as a water pump!!

I am very impressed with this. I laughed my butt off at the water pump testing, I am in Northern Virginia, so I might be joining in on that test. Anyway, I regretfully have to report that my scroll inlet top hat design did not perform as well as I thought. It works, the problem is that velocity drops dramatically just inside of the inlet opening at the curve before entering the baffle. You learn from your mistakes right? But this little number you came up with, yes, I will be making myself one of these the minute I get up from this chair. I am very anxious to see some video of yours running. Great work!

Quote from: Don_Z on August 26, 2011, 01:41:41 PM
Anyway, I regretfully have to report that my scroll inlet top hat design did not perform as well as I thought. It works, the problem is that velocity drops dramatically just inside of the inlet opening at the curve before entering the baffle.  I am very anxious to see some video of yours running. Great work!

Sorry to hear the scroll inlet did not work out.  The whole time I was working on my separator, I kept wondering if I should have incorporated a scroll.  It seemed like a good idea, but a couple things kept me from trying it.  First there is the task of fitting an egg shaped separator onto a circular waste drum.  Then I kept thinking that the air that has made a full revolution will hit the entrance wall at a pretty blunt angle.  That may be an oversimplification of what truly happens, but it seems the once-circulated air should intersect the new air as tangentially as possible.  Not sure if that makes sense or not, but that is part of the reason I felt a rectangular inlet slot would be better.  It is narrower than a round slot so the two air streams should join up with less turbulance.

Quote from: galerdude on August 26, 2011, 12:46:13 PM
......Acrylic or plexiglass on the other hand is very shatterable, I've seen panels break just from wiping with alcohol (?), don't know why. I do know that plexiglass is fragile and that is why the sign industry uses lexan for large lit panels because it stands up to the abuse. I've shattered lexan in a panel saw and with a skill saw, both with inadequate support. Ideally to saw or drill lexan, it should be supported on both sides and lay flat. That's just my experience and I'm no expert on the subject, just sharing what has worked for me.
   Retired2, your new separator really looks good. nice job.

Thanks,
Gale

I'll be keeping my fingers crossed when I finally attach the plexiglass.  It wasn't too difficult to bend to the diameter of my separator, but to seat it perfectly, I warmed it with my wife's hair dryer.  That softened it up quickly and it snugged right up to the retaining rings.

I've drilled a few test holes and found that brad point drill bits with the spur or lip work much better than a conventional drill bit.

Galerdude: Thank you for the info. I am not sure the polycarbonate I used was actully Lexan or not. My tophat is working for now so I am going to concentrate on my ductwork. I will look for actual Lexan when I do rebuild. Thanks for the information. Curious as to how a dado in the top and bottom panels would work? Just cut the top and bottom, cut the dado all the way to the edge on the entrance side, assemble that part and then just slide the Lexan into the dado so it is a captured fit. I am thinking that should seal it well enough that I wouldn't need to attach or caulk it. Thoughts?

Retired2: Top shelf work. I, like everyone else, am awaiting the results of the belled outlet. Thanks for the pictures, they are very informational.

Everyone on the east side be careful doing this upcoming storm. Hope everyone gets through with dry wood.

Raymond

My experience with polycarbonate is that it does not snap, but I only have 2mm sheet. I suspect that it was not poly.

Also, poly is very temperamental about what you use to clean it with, paint thinners, acetone etc, will cloud the surface. WD40 is good for removing stains. Keep a few offcuts in a draw for testing cleaning products.

Dave

I used OPTIX by Plaskolite Acrylic Sheet.. 0.080" thick.. which is sold at Home Depot in 30x60" clear sheets. Only downside is I only needed @7" width but al most the full 60" length for my top hat and it cost @ $55 for the sheet. There will be other projects.. in fact a few friends will likely do a group build of these soon. Ripped the strip off on a table saw with no problems, wrapped into a 20" dia circle no problem and easily would go much tighter than that with no signs of stress on the material at all. It could be drilled and countersunk lightly, but I didn't need to do that.... just cut the acrylic to length, laid a bead of chalking in the dados, inserted the acrylic and clamped it in place and waited for it to dry. I wasn't satisfied with the adhesion of the chalking, or even PL construction adhesive to the acrylic so I sealed it with "Goop Automotive Adhesive and Sealant". This stuff was developed to attach auto weather striping but I am convinced it will stick anything to anything else. It is about the consistency of silicon sealant, comes in clear form in a tube and forms a flexible air-tight, water-tight bond and can be spread.. costs maybe $8 and can be bought at any auto supply and many other places too. That will seal it for sure. Rather than scratch out my botched bed of chalking, I just ran a bead of Goop around the perimeter of the acrylic window.. top and bottom, and that formed an air tight bond that isn't coming apart in this lifetime. It may not be pretty but it works great.
The 0.080 thickness of the acrylic is plenty strong and robust for this application.

wrt selecting material, I too considered MDF and chose 1/2" construction grade plywood and put the premium side to the center because it's smoother and a few minutes with a ROS finishes it well. Lighter, stronger, easier to work and little dust.. 4' x 4' should do the job in most cases.

I am curious if by adding the stiffener like you did wouldn't that cause added stress or flex on the 1/4 Hardboard?  ???