J. Phil Thien's Projects

Every time I run calcs for a system using the HF impeller, I come up with 5" ? duct being most efficient.

I think the only reason to install 6" ? duct is if you plan on replacing the HF unit with one that has a larger diameter (and more efficient) fan and a more powerful motor. The HF unit just doesn't move enough air to keep the FPMs where you want them.

No problems viewing attached pictures (those with thumbnails visible in the posts). I use Mozilla Firefox.

Doug, when you're done with your circle jig, can I borrow it?  ;D

Phil:

It's secured to the shaft that way, but it's an itty bitty screw. The axle sleeve of the fan assembly is press-fit onto the motor shaft. There is an annular indent about 1/4" back from the outer end of that sleeve that sure looks to me as though it's intended that the fan assembly is to be removed from the motor shaft with a gear puller. At least, I can't tug it off with my bare hands.

But the issue is moot, now: I will probably not do this mod to the unit. I redesigned the support structure to leave the impeller/motor assembly as built. The main reason I wanted to rotate the motor is so that the switch faces front. Then I realized I'll wind up with a remote switch anyway, so pfeh, no big deal.

Thanks for looking, though.
Peter.

Right.

The impeller unit and motor are re-situated from the intended vertical plane to the desired horizontal plane. That part's a no-brainer.

What I'm after is rotating the motor with respect to the impeller housing 90? so that the motor mounting bracket which as supplied looks like A in the attachment, winds up looking like B.

Somewhere, I saw a photo where this was done. I thought it was in this forum, but apparently, I am misled.

Yeah, you know, Ron, I did that.

I didn't find what I thought I'd seen here, assumed I hadn't looked hard enough and did it again.

Someone in another forum must have modified the motor orientation on their HF unit.

Thanks for trying though.

I don't remember if it was in here, or somewhere else, but someone re-oriented the motor in relation to the impeller housing on the ubiquitous HF 2 HP DC unit, in a top hat configuration and I would like to do something similar.

In other words, to relocate the impeller so that it blows directly into the filter ring, one must dismount it from the base plate and remount it on a vertical surface. As the machine comes out of the box, that requires a mounting plate on the left. But the install/remod I saw showed the motor mount on the rear. (Left, right and rear, as I'm using them assumes the regular installation with the motor/impeller on the baseplate, inlet in the front, hose up to the filter bags on the right.)

Now, I've looked at my ugly green thing for awhile and near as I can tell, to re-orient the motor requires pulling the impeller from the shaft to access the motor's mounting bolts. It appears that the motor has a C-face mount with something like a NEMA 145 T-base as well. It's this T-base that I want to relocate 90 degrees clockwise (as viewed from the motor side of the impeller). I am pretty sure the motor C-face bolts are behind the impeller. Which means I gotta haul the thing around to someone with a gear puller to remove the impeller first.

Am I right?

Should I redesign my whole mounting arrangement to avoid this hassle?

Thanks.

Quote from: phil (admin) on January 25, 2012, 06:12:20 PMI usually tell people to put the separator in front of the heavy chip producers, and add a baffle to their DC.  That way they get the best of both worlds (sort of).  But adding a baffle to some of the Delta units is problematic.

Something like this?

Planer (jointer, table saw) ? very short duct ? Separator ? ? ? ? duct as required ? ? ? ? Impeller ? Filter ring with baffle.

As opposed to:

Any machine(s) ? ? ? ? duct as required ? ? ? ? Top Hat Separator / Impeller ? Filter ring with baffle.

Retired,

Wow, have a WONDERFUL trip! Take a pic of Everest for me, will ya? (Or K2, I probably wouldn't know the difference ;) )

Anyway, I do appreciate your help. At the end of The Worst Duct is either: a group of sanders (disk, belt, spindle) or a thickness planer. There's a sketchup drawing of my shop layout in Post #4, where I hijacked this thread (Sorry, Doug!). It shows the planer at the end of Worst Duct, but I could move the sanders to just across the wall from the DC closet and put the drill press at the end of Worst Duct and the planer where I show the sanders.

One thing my calcs do NOT account for is the 3'-4' long sections of hose that connects the machines to the blast gate. If it weren't for the need to slide the machines away from the wall for accommodating longer stock, I could hard pipe them.

I don't mind sweeping up chips, such as might be generated by drilling huge holes in pine with a forstner, or by hand planing at the workbench. And, I am hoping that by investing in an air cleaner, I can trap some of the fines that the DC system misses.

Thanks again, sir.
Be safe in Asia.
Peter

Okay...First run on my Worst Duct calcs. It ain't pretty.

25 feet of straight pipe
3 90 Ls (2.5 R/D) = 15 feet
1 45 L = 2.5 feet
1 Wye = 2.5 feet
Total effective length = 45 feet  :o
Figuring the required CFM at the tool = 440 CFM, 4" duct allows 5000 FPM, 5" duct allows about 3200 FPM. (I'm gonna abandon 6" duct).  Loss per foot for 4" = .070, for 5" = .042. (about)
SP loss in duct, then is 3.15 @ 4", 1.89 @ 5". Allow 1" loss at tool, 1" at duct end, and 2 for the Thien.
Total SP Loss for 4" = 7.15; for 5" = 5.89.
According to the Wood Mag test, the HF unit (<6 " SP at 400 CFM) can't move enough air.

I'll need to relocate my machines. Damn.
I think I'm okay at my table saw, because it's only 29 feet (effective length) from the DC and loses 1" SP less. (6.4@4" and 5.4@5").

Y'know, if I didn't feel the need to walk around in my shop, I could just have the pipe at impeller level and avoid all these verticals and bends.  ;)

Am I assuming correctly, that if the SP losses in the ductwork add up to less than the overall SP at the desired CFM for the blower, the system will work?

Thanks Bob.

The HF motor, made in China, has as its motor plate a rather thick coat of shiny black paint. Apparently, they don't want anyone to perform that horsepower calc.   ;D  Some years ago, I slapped a multi-meter on my electric system with regards to determining its stability for my computers. Then, I got a voltage range between 105 and 115. I doubt that has changed much in a decade. There is, on the HF unit's filter ring, a sticker that along with the 2 HP claim and 1350 CFM (which is no doubt obtained by having nothing connected to either the inlet or outlet of the impeller!), states it runs at 14 amps. So plugging that into your formula, using worst case: 105 x 14 / 746 = 1.97 HP. I do not doubt that you are correct that the real life situation is significantly less.

I did run across some useful information at WoodMagazine.com and the .pdf suggested by RonS that indicates a solution closely matching your set-up, Bob. Although that .pdf is three years old (the Grizzly model they recommend is obsolete), it contains the only fan curve data I've seen for the Central Machinery (HF) unit. Based on that data, and forms found at FreeCalc.com, it appears that a 5" metal duct is optimum (as has been said by many others and thanks to them for being right), and that 4" PVC isn't optimum, but isn't significantly worse. (I still haven't found a way to calc SP losses in a long-radius sweep, where R is 4D+)

I also just found out the cost of 5" metal (26 gauge snap lock) available locally: $2.38 per foot, $5.12 ea for a 5-segment adj. elbow. Local price for 4" ASTM D2729 PVC = $1.06 per foot. A 45?? WYE = $10.20, and a 45? L = $5.43.

Cost for my layout: Metal = $230; PVC = $140.

I reported this to the budget director and she said about the cost for metal duct, "That's not so bad, is it?" to which I replied, "Hell, no." I went on to explain that the metal is optimized for my blower and results in fewer restrictions. (A 90? turn is accomplished in PVC by two 45? Ls whereas in metal, it's two 5-segment adjustable elbows, resulting in R/D of about 4, which apparently has about the same SP loss as the equivalent length of straight pipe.)

I'll keep y'all posted.

BTW, Doug: I'm taking a look at reversing the direction in my top hat, so that rotation matches that of the impeller. I'd still use the improvements suggested by retired2: his "air straightener" and bell mouth inlet. The only problem I face is that a long straight run into the separator winds up robbing me of about 4 square feet of floor space in my DC closet. The FreeCalc.com form suggests avoiding any changes in direction within 5D of the end of the duct (or ~2 feet in 5" duct). I have JUST 2 feet from the end of the sweep to the beginning of the cyclone in the top hat. Whew.

This is hard. Are we having fun yet?
Peter

Quote from: galerdude on January 21, 2012, 07:00:16 PMI could be totally wrong here so please forgive me if I've missed something along the way but I don't remember reading about anyone having that information when they built their system. Most builds that I've read about have built a DC system using the available information and trying to apply it to their situation and do the best they can. And a lot of good folk try to share improvements and enhancements that they feel might help someone else.

Which is why I am here, pestering all you good folks.

QuoteIf you were to copy someone's system as in the same diameter pipe, same lengths and same fittings, would that be the system that would work for you? I know when I built my system I had to make some choices. Were they good choices? I dunno, it works.

Obviously, it's absurd to copy someone else's system. At least, not in all details. And yeah, I appreciate that the choices you made, Gale, are specific to your situation. That the choices you made result in a system that works is super.

Now, not to say anything one way or another about anyone's choices (after all, it's the reasons you guys made those choices, that I want to copy if anything), but it seems to me that the more I inquire and gain information, the more evident it is that there is quite a bit of leeway in system design. The Woodcraft classroom shop, easily twice as large as mine, uses 4" pipe everywhere and the place was spotless. Maybe they use a super sucker fan, I dunno. I never saw it in operation. Some people here, and in other forums, use 6" PVC, 5" metal, 7" metal, and so on, with DC units that range from 1 HP to 5 HP. For the most part, everyone's system works. Rockler and Woodcraft and others, even Penn State, sell 2 1/2" systems. I don't know of anyone who uses such a thing, other than in small scale with shop vacs, but all the data I read says that it won't work.

Aerodynamically, the bumble bee can't fly. Yet there are hundreds of them every spring on the honeysuckle out front...flying.

The choices I have already made are as follows:

HF 2HP unit with Thien pre-separator.
No 90? elbow fittings and as few 45? fittings as possible.
All other "bends" made from segmented pipe sweeps with at least 2 1/2" pipe diameter radius.

The only decision that is missing, it seems, is whether to use 4" throughout, a combination of 4" and 6", or 6" as much as possible.

And, I guess, that whatever choice I make, there will still be those occasions when there will be dust and/or chips flying about the place that will have to be taken care of by the good old bench brush and dustpan.

Steve:

QuoteIn my opinion, the dust produced by woodworking is the most significant hazard in the workshop.

With this I am in total agreement. I am a weekend/evening hobbyist. Besides being generally broke, I am also lazy. I have the bad habit of leaving the mess behind when I make something, then have to deal with that mess when I wish to make something else. I can strive to correct that habit, but that's a tough one: it's been my bane for five decades! Why the budget director stays with me is a mystery.

So I figured installing a reasonable (note I am not saying perfect or best) dust collection system would serve to keep the workspace a lot cleaner than it has been for years. And in reading here, the HF 2HP unit seemed to be well-touted, so I bought one. I am already convinced that the Thien baffle and a good filter are a must. I can build the baffle; I can save up and buy a good filter. I can build the gates and install the piping.

All my questions, then, stem from the above limitations: given the HF unit, Thien baffle, one-gate-open-at-a-time situation, future Wynn and future air cleaner, and given that I have a 10" cabinet saw, drill press, band saw, sander, jointer, planer, I need to devise a system that satisfies this:

Quoteif you have a machine that can only support 4" mains, fine use 4" mains and open one gate at a time.

I haven't found anything that says "the HF 2 HP DC can suck workshop dust through A-diameter pipes of L-length with F-number of fittings".

And the reason I am pestering you guys about this is because I don't have the time, energy or budget to do it once, discover that is insufficient, and then do it over. It is definitely easier on my wallet to install 4" pipe. But if 6" will perform better with the HF unit then I can probably swing that.

Thanks for your patience.
Peter

Quote from: sneezy on January 20, 2012, 08:06:49 PM
Peter, could you give some detail on how you made your sweeps?

Sure.
I use Sketchup as follows (refer to attached drawing.
1. Draw circle of desired sweep radius (at centerline). I use 15 inches radius and the default circle with 24 segments.
2. Draw radius lines at 90? to each other.
3. Erase all but the 90? arc, add 6" extension lines. This is important.
4. Make a box so the circle tool will draw a circle in a vertical plane.
5. Hold down shift key and draw the circle at the end of one of the extension lines.
6. Select the arc and both extension lines. Using the "Follow Me" tool, click on the small circle drawn in step 5.
7. Draw a rectangle enclosing the entire structure. Right click and select intersect faces with model.
8. Erase everything but the lines on the rectangle.
9. Extend the radial lines until they intersect.

At this point, Sketchup fails--they do not have a tool that can dimension angles. YOu can use the rotate tool to see them, but only temporary. So I exported the resulting drawing into AutoCAD, and discovered the angles there. The outermost angles (at the 6" extensions) are 7.5? and the internal angles are 15? from one another.

I set my miter gage on my bandsaw to these angles, and cut segments. It REALLY helps if you draw lines along the length of the pipe that are 90? from one another, so you line them up with something on the miter gage. Otherwise, the sweep can wind up going all over the place.

Cutting PVC on the bandsaw is messy.

Using very coarse sandpaper and a rasp, I eased the cut edges. Then, aligning the linear lines, I taped the segments on the INSIDE, one at a time. I used JB Weld epoxy to join the segments.

JB Weld is messy.

I was bothered by how lousy the joints looked so I sanded them down. Don't do this. Put up with messy-looking joints. They're stronger. Once the outside was cured, I gooped JB Weld on the inside joints. This is pretty easy with 6" pipe. It could be damned near impossible with 4" pipe. I'm gonna paint mine.

The 6" extensions will fit into the bell of a pipe or a fitting.

I tried making these with foil duct tape. It works, but man, it's hard! Glue is better. I suppose if I had a plastic welder, it'd be even easier. But I need like 4 90s and a couple of 45s, so it isn't worth the investment.

Hope this is helpful...and more important: useful.  ;D

Quote from: Dougp28704 on January 19, 2012, 06:59:07 PM
Peter,

The dxf design you send me came in fine into SolidWorks. I could build it directly from your design. All of my questions were answered. Thanks again.

I'm glad it's of some use to you. :)

QuoteI havent started making it yet, and I am already over thinking. If I mount my DC impeller in-line above my seperator, the direction is counter-clockwise when looking down from above. The same as in the jpeg you posted of you shop lay-out. Would you sugest that I mirror the design of the seperator? In order to have seperator rotaion the same as DC rotation?

Yeah, I noticed that, too. I believe, based on comments hereabouts by retired2, that rotation of ANY air moving into the impeller is detrimental. (shrug) I arranged my set-up as you see because of physical constraints of the machine room and it's relationship to the workshop. I think I will try some sort of "air straightener" as implemented and tested by retired2. Thinking maybe a stack of aluminum "egg crate" diffuser in the inlet pipe just might do the trick...we'll see.

More important to me is whether to install 6" pipe or 4" pipe. I will use S&D PVC (ASTM D-2729) for two reasons: I can work PVC with significantly more success than metal, and it costs a lot less. 4" pipe and especially the associated fittings, is considerably cheaper than 6", but dust collection pundits claim it won't "do the job".

I am still confused over this issue, and no one's saying yea or nay to either, at least with enough supporting data for my satisfaction. Supposedly, you don't get enough "fines" removal in 4". The HF impeller unit has a 5" inlet. They don't make 5" PVC. I'm worried that necking up from 4" to 6" then back to 5" will result in a "less than optimum" situation. So although I spent two afternoons making 6" PVC sweeps (yeah, they're neat looking), I am leaning toward a 4" system. I can't see a scenario where I would intentionally use more than one drop at a time, unless I forget and leave one open.

And then I read that RonS is happy with his 2 1/2" system! sheesh. Will anyone weigh in on this issue?