That's good thinking, Bill.
That's good thinking, Bill.
Moderator
Good idea. I sized a bunch of rings to make flanges and such by slicing out a thin section. When heating, I use a propane torch with a wide flame adapter or a heat gun if I care if it looks pretty.Originally Posted by Bill Dufour
Also, on his web site Pentz has some ideas about building/adapting various custom PVC fittings.
JKJ
Folks, I stayed up all night working on this, and the better part of this day.
I have calculated the actual surface area of the intake of the HF 2hp dust collector by measuring everything on the input side without the plastic "Y", subtracting the surface area of the grill and came up with the surface area of a pipe with an id of 4.85".
Last edited by Bill Jobe; 06-11-2017 at 11:27 AM.
Contributor
I have a feeling that you put more thought and calculations into the dc flow rates then the designer did. I am sure they just chose a standard pipe size used in Asia. Probably came between two sizes and choose the smaller size since it is cheaper. Like between 5 or 6" use 5" it costs less so that makes a better machine.
Probably the same design consideration on the impeller size. like if we use 12" we get 10 per sheet but 13" only gives 9 blanks.
Bill D
Member
Log into the Australian wood working forum and all your flow questions will be answered and a lot more besides that as well. I think it is the only place any real questions are being asked and answered.
Chris
Everything I like is either illegal, immoral or fattening
Member
The mods don't allow links to other fora, I have had the conversation before concerning links. Do a Google search, it comes up straight away. The bloke doing it is a world leader in clean room design so he has a few credentials to back his work.That's interesting! I've studied turbulence and laminar flow and all I can say is it's too complicated for my feeble mind.
The big question: What are the numbers for the flow? (is the difference significant or "just barely"?)
Please provide a reference for that research. ("Proof" without reference is just rumor!) I did a google search and have not yet found the study you mentioned. I did find some interesting discussions and a telling picture, here for a sharp bend on a tee:
Attachment 361731
https://www.physicsforums.com/thread...e-bend.185436/
(Those physics guys are entertaining!)
Was the OZ research done with S&D ducts and standard fittings? What was the duct size? Did they test with multiple sizes? (The ratio of cross-sectional area to circumference goes up significantly as the radius increases which may make a huge practical difference depending on the air speed.)
One cure for inefficiencies might be a more powerful cyclone. So far the 5hp ClearVue exceeds my expectations. Perhaps a 2 or 3 hp machine would be unsatisfactory for my duct work. If it works...
JKJ
Chris
Everything I like is either illegal, immoral or fattening
Moderator
Is there not a published paper on the research? I hope the proof you mentioned is more than a discussion on some forum, regardless of the stated or presumed credentials of the participants.
The details of the methodology and data from a well-designed experiment or even the theoretical results from a computerized flow model could be useful to woodworkers everywhere. Casual claims may be entertaining to read but are hardly the basis for useful design criteria. I would like to run this by a couple of physicists I worked with before I retired.
I did try a google search and didn't find this research. Although you can't post a link to the forum you could post the exact google search string that points to this discussion and perhaps the name of the forum.
JKJ
Member
Chris,
I did several Google searches, including one for "Australian wood working forum" and then searched withing that forum for anything relating to ducting and or elbows and maybe buried within the hundreds of pages of babel there is some useful information. I thought this 'new' information would be useful but maybe this unnamed scientist in this unknown forum post is just finding out what is already known: a long sweep 90 is less restrictive than 2 45s (so a 90 is less restrictive than 2 45s). However, 2 regular 45s are less restrictive than 1 regular 90 as stated in the Engineering Toolbox website (search for: Equivalent length of fittings like bends, returns, tees and valves in hot water heating systems) the tables show the various equivalents.
I think if you can't direct someone to a specific post in a forum the material is probably not any good.
BTW: If you are in Australia doing a general search your results are going to be different than someone in another part of the world doing the same general search.
Hope this helps,
Carl
Member
Bill - wow analysis paralysis is a common affliction. I wouldn't begin to try an read the whole thread.
Just to say forget the research and remember two things:
1)Undersized ducts = most common mistake.
2)Keep your curves smooth and Bob's your uncle.
In the end, its amazing how well a poorly designed system can actually work.
(How do I know that?) LOL
Moderator
Links to other websites are allowed in posts. In fact, they are encouraged. However, links for the sole purpose of marketing, generating traffic to a site, or any other commercial advertisement deemed to solicit commercial benefit are not allowed. Links to other public or private forums are not allowed. Links should be submitted as references, for the sole purpose of generating or supporting discussions on SawMill Creek.
The TOS have more information regarding links.
Last edited by Lee Schierer; 06-12-2017 at 12:24 PM.
Lee Schierer
USNA '71
Go Navy!
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Lowes has the 35 and fittings.
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