Greetings from Finland.
I'm currently building a garage that will be partially dedicated to a woodworking workshop. It's close to done and I've been considering dust collection options. I've done a lot of research and asked a lot of questions and what I've come to is I should aim for the following:
-Metal ducting in the size of 150-160mm (I think 5-6.3", metal because it grounds easily, no static issues with dust clinging)
-Ducting in the ceiling rather than walls where possible
-Vent outside (just seems like the best way avoid a lot of potential issues)
-Powerful blower. I have a 3-phase 4kw motor I plan to use in a jointer/planer, somewhat overkill for the small 8" machine I have, but I got it cheaply. I guess it can be refitted later for to a dust collector impeller/fan and be more suited to that task.
I was looking at cyclone separators and I am currently building my own shop vac from leftover parts and a cheap cyclone I bought from china. I was considering building a big one from Bill Pentz designs but since I am venting outside, and also reading Matthias Wandels experiences with his thien baffle system, it seems like this system is entirely adequate in separating most dust and chips and most fine saw dust. I gather there's some contention between cyclone and thien baffle users as well...
Anyway it seems like it works well and well enough for my purposes. I am wondering are there any guidelines for what size I should build given a certain airflow/speed? This will be a large and powerful system, though hopefully it should come out pretty cheap since I am building it myself from spare parts and 2nd hand stuff.
Not a lot of traction, but I guess most of this has been covered on this forum so far. But I have a specific question I'd like an answer to. I plan to use 150-160mm ducting in the ceiling and to the dust collector itself as I mentioned. But many of the ports on my machines are maybe 100mm or less.
Am I right though in making a "backbone" or main stem from thicker ducting while having smaller hoses and pipes to individual machines? Or is it a waste of piping?
Thien separators work very well and are very practical.
I am not quite sure how you are using your 4kw blower? It sounds as though you are sucking from the planer and pushing the shavings and dust out through a pipe system? I do not think that would work. The usual way is to use a pipe system to suck from the machines, pass that loaded airflow through the separator and then into the DC. All suck - not push.
Your blower may not be suitable to make your own DC. It depends on the pressure/flow curves. Unless the blower is specifically designed for this use it will probably not have the right specifications.
If you had a DC with that much power it should be able to handle 150mm (6") pipework with ease. Even so keep all pipework as short as possible, use slow bends, ie with radius twice or thrice the diameter of the pipe or two 45 degree bends instead of one 90 degree. Use "Y" junctions with the incoming branch set at 45 degrees to the main flow instead of "T" junctions. Maintain the 150mm to as close as possible to the machines then neck down to 100mm (4") ot whatever size is on the machine. Keep any hoses to the absolute minimum as they will eat into performance.
Make a top hat separator as here except use polycarbonate sheet and not acrylic for the walls:
http://www.jpthien.com/smf/index.php?topic=563.msg3034;topicseen#msg3034
Close-couple the DC fan to the top hat with an air straightener section.
It is well worth having the DC and separator in a separate walled room or chamber so that the noise of the former and the dust when emptying the latter is kept well away from the shop. You should fit a control system so that your wood working machines cannot be switched on unless the DC is already on. If you are as lazy as me it is all too easy to "forget" to turn on the shaving shifting system.
Consider if it is safe to vent outside! You are collecting shavings for your convenience and dust so that it does not damage your lungs. The most dangerous very fine dust will travel on the wind a surprising distance. Where will it end up and who might unknowingly breath it? If you cannot be certain then fit a fine dust pleated filter. It may even be illegal in your area for you to vent dangerous dust into the atmosphere.
My 4kW motor powers my planer right now, I have no dust collection aside from a small home made shopvac with a small cyclone. What I meant was I could reuse the motor for a DC system. I have no fan for it however.
The idea that the dust outside could travel far and be dangerous to anyone sounds unbelieveable, any data on that? Surely living in a city must be worse given the air pollution and particulate matter in the air from ordinary dust. This sounds even more excessive than bill pentz pages now.
Okay, Dennis, I'll add my $0.02, or the equivalent in Finnish markka. Your most recent post clarifies your plan.
First, as far as duct size. The general rules for maximum performance are to keep duct runs short, wide, and straight as much as possible. That said, assuming you have several dust producing machines you want connected, the typical way is to go with a large diameter trunk line, with smaller branches to individual machines. With a 4 kW blower (16+ amps, I assume), I wouldn't go with less than 6" main duct size, or 4" for tool connections.
I think your major challenge is getting your impeller set up appropriately. As much as I admire Mr. Wandel's skill and creativity, I would be extremely leery of scaling up his wooden homemade impeller to fit a 4 kW motor- it just looks like a disaster about to happen. Design of an efficient impeller (at least to an amateur like me) appears very complex. Maybe you can find a used impeller of appropriate size with a burned out motor, or check out the Cincinnati Fan web site- there's a ton of information there. In the end, it may be more cost effective to get an intact DC blower and find another use for your motor.
I see both BernardNaish's and your points of view regarding dispersal of fine dust to the outside. It really depends on your locale. If your shop is in a more rural, less densely populated setting, fine dust will either settle to the ground or be so diluted that it causes no significant health risk, esp. compared to other airborne hazards. If you live near others, though, it would be more neighborly not to discharge dust in their direction. It begs the question, which I'm not sure anyone can answer, as to how close is too close.
Disclaimer: I am by no means an expert in anything! Good luck with your project.
My motor turns slower than Wandels impeller actually because we use 50hz in Finland, so if I made it to the same size it would be less effective, and probably draw very little power. It could be scaled up a little bit, but it would turn slower and probably be under less stress than his impeller if I made it.
The 4kw motor has a 9.5amp fuse on its control box, more than that it shouldn't use except for short bursts during startup. 400 volts of current does help keep amperage down.
I live somewhat half-way rural, I got neighbors within 10-15 meters of my garage, but if I vented it towards one side, I doubt it would be able to bother anyone, since the DC isn't active all the time and we're probably talking small amounts and it'd be in another direction where there is noone.
DennisCA - venting outside is a great option. I wish I could do the same but my neighbors would complain! When I built my unit I converted a Grizzly 220v 2HP unit and for my shop so far I've not had any issues however as a portable unit it is only connected to one machine when it is used. See the image below.
Running ducts pipe is a great option I will convert mine sometime in the future.
I'd suggest installing micro switches so when you open a gate the unit comes on. Better yet when you turn on a machine, the gate is opened and the DC is turned on.
I'd also suggest installing a sensor to turn off the DC when your can gets full. I don't have this on my unit and at times I do over fill the Brute 20 gal can. When this happens dust goes into the bag otherwise the bag is empty.
If you look closely you can see that the walls of my Thien are Plexiglas. I did this because I wanted to see the action but it also allows me to see when the can is full. However I try to empty the can often and avoid the mess created when the can is full. I don't have a sensor to tell me when the can is full (bummer). If you go the Plexiglas route I suggest building a form to assist in bending the Plexiglas. I did not and it was difficult to correct my mistakes. My Plexiglas is 1/4" thick, I used a MAPP gas torch to heat and bend it. A good heat gun will also work. If you put too much heat it will bubble. Once you goof once or twice you quickly learn how much is too much. :)
Originally I was going to use a 32 gal Brute can but goofed on the spacing and had to use the 20 gal can. But this is good because the full 20 gal can is MUCH lighter than a full 32 gal can.
Somewhere I read that we need not be concerned about the static electricity and the article suggested using plastic pipe rather than metal. I have a central vacuum system in my 3200 square foot house and it has all plastic pipe. I've lived in the house now for 8 years and so far no issues.
Quote from: jgt1942 on December 18, 2014, 02:02:48 AM
DennisCA - venting outside is a great option. I wish I could do the same but my neighbors would complain! When I built my unit I converted a Grizzly 220v 2HP unit and for my shop so far I've not had any issues however as a portable unit it is only connected to one machine when it is used. See the image below.
Running ducts pipe is a great option I will convert mine sometime in the future.
I'd suggest installing micro switches so when you open a gate the unit comes on. Better yet when you turn on a machine, the gate is opened and the DC is turned on.
I'd also suggest installing a sensor to turn off the DC when your can gets full. I don't have this on my unit and at times I do over fill the Brute 20 gal can. When this happens dust goes into the bag otherwise the bag is empty.
If you look closely you can see that the walls of my Thien are Plexiglas. I did this because I wanted to see the action but it also allows me to see when the can is full. However I try to empty the can often and avoid the mess created when the can is full. I don't have a sensor to tell me when the can is full (bummer). If you go the Plexiglas route I suggest building a form to assist in bending the Plexiglas. I did not and it was difficult to correct my mistakes. My Plexiglas is 1/4" thick, I used a MAPP gas torch to heat and bend it. A good heat gun will also work. If you put too much heat it will bubble. Once you goof once or twice you quickly learn how much is too much. :)
Originally I was going to use a 32 gal Brute can but goofed on the spacing and had to use the 20 gal can. But this is good because the full 20 gal can is MUCH lighter than a full 32 gal can.
Somewhere I read that we need not be concerned about the static electricity and the article suggested using plastic pipe rather than metal. I have a central vacuum system in my 3200 square foot house and it has all plastic pipe. I've lived in the house now for 8 years and so far no issues.
Dust explosions in home shop vaccum systems is a wildly exaggerated issue. With a little research on the internet you can find articles dispelling this concern. I can't point you to them, but I think the subject has been covered more than once in this forum.
The reason you had problems bending acrylic is that it is too hard to be used as a flexible material. Think of it as plastic glass. Polycarbonate is ideal for bending and is much more scratch resistant.
So I'm not really progressing here because I don't have a motor I can build from, well I have the 4kw beast but I need it for my jointer/planer. I'm only willing to pay scraps for a used induction motor and so I have to be patient and wait.
But in the meantime I wonder if the separator design that matthias wandel used for his dust collector build has been covered in discussions? Tried searching for his name but did not find much all three mentions of his name are in this thread. I would have thought someone might have been interested in comparing his design vs. the top hat style. The main difference seems to be his is taller.
Quote from: DennisCA on January 01, 2015, 03:43:25 AM
So I'm not really progressing here because I don't have a motor I can build from, well I have the 4kw beast but I need it for my jointer/planer. I'm only willing to pay scraps for a used induction motor and so I have to be patient and wait.
But in the meantime I wonder if the separator design that matthias wandel used for his dust collector build has been covered in discussions? Tried searching for his name but did not find much all three mentions of his name are in this thread. I would have thought someone might have been interested in comparing his design vs. the top hat style. The main difference seems to be his is taller.
There are some double high top hat designs that were covered here, but I can't find them quickly. Do a search on the phrase double high or 2H, I think those descriptions might have been used in the discussions.
Quote from: BernardNaish on December 19, 2014, 03:05:29 AM
The reason you had problems bending acrylic is that it is too hard to be used as a flexible material. Think of it as plastic glass. Polycarbonate is ideal for bending and is much more scratch resistant.
Thanks for the info, now I know!
I read that for cyclones, having a bigger outlet means reducing air resistance and also reducing the speed of the air flow at the outlet, which increases separation. Or so says Bill Pentz, I am wondering if this applies for thien style separators as well? Most people seem to build their separators with identical sized inlets and outlets.
Interesting question! :)
Quote from: DennisCA on January 11, 2015, 03:48:32 PM
I read that for cyclones, having a bigger outlet means reducing air resistance and also reducing the speed of the air flow at the outlet, which increases separation. Or so says Bill Pentz, I am wondering if this applies for thien style separators as well? Most people seem to build their separators with identical sized inlets and outlets.
Don't see any reason why Pentz's statement does not also apply to separators. So, why then do so many have inlets and outlets the same size?
When it comes to stationary systems, I can think of a number of reasons. Most of us don't have the luxury of a 3hp or 5hp behemoth as the heart of our system. So, we start with a 1-1/2 hp that is marginally powered for the task. So, it is advantageous to keep the mains and drops as large as possible, but not so large that the velocity drops below what is required to keep the waste entrained. That usually means mains are the same size as the inlet port on the separator.
Then we come to the separator, which more often than not is sized to match the diameter of the waste drum being used. So, if the separator is far enough from the inlet of the DC, then yes a larger outlet pipe could be installed on the separator and then reduced back down before entering the DC. That sounds good, but there are two problems. First, many people, myself included, have the separator close coupled to the DC and there is not room to make size changes, and keep in mind adding pipe and reducers adds to the system losses. The second problem is that when the outlet pipe diameter gets closer to the inlet pipe diameter the probability of by-pass waste increases. And remember, the diameter of the separator has already been set by the drum.
Hmm, but if one builds ones own DC blower as I might do, then I could perhaps just build it with a big enough port and I could skip using a reducer, 170mm perhaps, with all tubing ahead of the separator being 150-160mm. If I am going to use this 5hp motor of mine anyway.
I was also wondering the same about my little china cyclone, if I should increase the outlet on it or not, but I think with my current vacuum motor for it, that it's too weak to work effectively if I did so, the 50mm piping I have on it now is almost too much for it, built for 38mm originally. I would like to build a wandel style blower for it too so I could get more suction, but need to find a nice priced motor or two... currently on paternity leave with my twin boys so I have somewhat reduced income as well for the time being.
Other things I've picked up from reading the archives here seems to be, bigger diameter = better separation, also more height = better separation, so I am thinking I'll be making a double height separator.
Quote from: DennisCA on January 12, 2015, 12:30:19 AM
Hmm, but if one builds ones own DC blower as I might do, then I could perhaps just build it with a big enough port and I could skip using a reducer, 170mm perhaps, with all tubing ahead of the separator being 150-160mm. If I am going to use this 5hp motor of mine anyway.
I was also wondering the same about my little china cyclone, if I should increase the outlet on it or not, but I think with my current vacuum motor for it, that it's too weak to work effectively if I did so, the 50mm piping I have on it now is almost too much for it, built for 38mm originally. I would like to build a wandel style blower for it too so I could get more suction, but need to find a nice priced motor or two... currently on paternity leave with my twin boys so I have somewhat reduced income as well for the time being.
Other things I've picked up from reading the archives here seems to be, bigger diameter = better separation, also more height = better separation, so I am thinking I'll be making a double height separator.
Well, 5hp sounds adequate for 6" (150mm) mains, and I would not suggest going larger than that because above that size the law of sharply diminishing returns applies. The only reservation I have is 5hp sounds big, but since it is a DIY project, it's real performance specs might be difficult to determine.
Well since I already have the motor and I think a DC is better purpose for it than powering a small jointer it's not like I ought to have anything to lose by making it "too big"?
Quote from: tvman44 on January 11, 2015, 04:23:37 PM
Interesting question! :)
Some time ago I read the results of research completed comparing the Thien and Cyclone. I cannot find the post at this time but the Thien and Cyclone separation results was almost the same. The research was completed by a city gov if I recall correctly.
That would be interesting to read. :)
In order to get moving I've decided to scale down the project a bit so it becomes more affordable, ducting and especially the bends and connections where so expensive I wouldn't be able to acquire the required equipment for a good long while.
So I'm building a more scaled down version based on Matthias Wandels plans and using a smaller 1HP motor. The first challenge is building the impeller.
I am quite excited about this impeller design and the build, from what I can tell it is a lot more effective than the stuff you find in regular DC's (his 2/3rds HP blower outperformed his commercial 1.5HP DC), but you trade off having a material handling collector, this design needs prefiltering, but that seems like a more than fair tradeoff, it was what I was planning anyway, so why sacrifice power?
Looks like I went back on that promise. I am building an impeller for the 4kw motor now anyway, took it off my jointer and I also made the plywood discs and routed grooves into them. I didn't pay that much attention to which way I made the vanes go, but when I realized it I had already done two of them, I figured it would be no problem anyway, this motor is super easy to reverse. A nice thing about 3ph motors that, it's a heavy lunk though, probably 35kg. I took a bit of chance buying that motor since the seller said it was taken out of service prior to 1980, but it works real nice and was only 25 euros:
(https://farm8.staticflickr.com/7764/17665132926_c383de023e_b.jpg)
I set up the bandsaw to cut veneer to make laminations for the vanes, but had to improvise to get thin enough cuts to make laminations from, so I used my router tables subfence. It's a limitation of the fence design of my bandsaw, it's very old, 60 years, likely older, I think.
(https://farm8.staticflickr.com/7659/17665112086_eb4214e53d_b.jpg)
Unfortunately my cameras SD car seem to get some kind of error and the picture of the veneer lying in the clamping form (after I steamed it) didn't make it and I don't feel like going out to the garage again tonight, so I'll get another pic when I glue the laminations. Have a picture of my shop vac instead:
(https://farm8.staticflickr.com/7664/17691668841_e2331aef2b_b.jpg)
I think if this whole impeller things work, I'll make a smaller one and replace the shop vacuum in this one, and likely the cyclone too with a thien baffle. Maybe I'll mount the vacuum motor and cyclone in the router table or something.
Nice, I requested pictures in your other thread re:material for building an impeller but never mind.
Looking good. That's gonna be one heck of a dust collector at 5HP and a 20" impeller. Should work real well.
Bending and laminating isn't as easy as it looks and the results of my first vane where disappointing, it went in the trash. I'm considering buying 1mm thick sheets of balsawood now to laminate with, also building an improved jig. The biggest issue is the width, 10cm wide. The jig I am now looking at is like the one drawn here, I would modify it a bit to use clamping cauls so I get even pressure across the width:
http://www.wood-w.com/lessonsguides/lessonsguides-tapered-laminations-made-easy.html
Another alternative might be to try and bend out that piece of PVC (or whatever plastic it is, you can see a piece of it in the first picture), it was kinda springy and almost the right size, maybe with heat it could bend into a suitable form.
Bending the PVC should work but you'll want to cool it in a mold so it holds its shape and so each vane is uniform.
Check this guy out, you'll get a good idea of how easy shaping the PVC is.
https://www.youtube.com/watch?v=5TbXBlQjRl4
Bending wood is pretty easy though, you need heat and steam and then a mold to hold the shape.
Yeah I had all that, but I can't say it was easy. It was a slow and messy process and the glue up failed and produced inconsistent results for me. The things I made this weekend where just trash worthy. Definitely a learning curve involved here. So hoping this new and improved jig will make glue ups easier. I think with a heat gun I could bend PVC in this as well.
ALso found a pipe of suitable size, 500mm diameter, 1 meter piece I could cut into vanes. 30 euros for a piece. It sounds very interesting.
Quote from: DennisCA on May 18, 2015, 06:31:40 AM
ALso found a pipe of suitable size, 500mm diameter, 1 meter piece I could cut into vanes. 30 euros for a piece. It sounds very interesting.
That sounds promising.
Going to pick it up tonight and a 2.2kw electrical motor (to replace the 4kw one going to my DC, used to be on my jointer/planer, it was too big for that little machine though).
Won't have a lot of time this week to work on the DC though, have to do yard work:
https://farm6.staticflickr.com/5446/17642152710_3475d0db2c_k.jpg
Got the pipe home but I went for a much thicker one instead:
(https://farm6.staticflickr.com/5341/17681393230_98efe2b8df_b.jpg)
It's a bit smaller diameter but I thought it was worth it for that thickness.
And the motor, incredibly heavy for a 2.2kw one:
(https://farm8.staticflickr.com/7762/17869415171_a174a3c64d_b.jpg)
Well that motor sidetracked me a bit but I cut up the vanes today and boy the 12 of them turned out heavy, 3760 grams all of them, which is 8.3lbs, this is gonna be a heavy impeller. I wonder what the larger metal designs weigh...
Just the parts loosely together:
(https://farm8.staticflickr.com/7780/17422055514_3414de989b_b.jpg)
It is actually a little difficult finding weights for blower wheels alone. I went to eBay and found an aluminum 20" blower wheel that is about 20#. But it is wider than yours and has a large hub installed:
http://www.ebay.com/itm/HUNTAIR-71100005-20-BLOWER-WHEEL-105-WIDTH-CW-BORE-1-3-8-175487-/361205375235?pt=LH_DefaultDomain_0&hash=item541984a103
But I think the answer to your weight question is, you're in the right ballpark.
Sounds good then! I had to cut a new disc, the smaller diameter of this pipe I went with was too different, so a new disc has been made and wider grooves, I epoxied them in place with slow setting epoxy, I also screwed them in with two screws per vane, then I trimmed the edges with my bandsaw circle cutting jig to make it proper round. I'm also considering putting construction adhesive around where the vanes meet the plywood and smear it out with a finger, to create a softer surface, fill in any gaps and to add even more strength.
(https://farm9.staticflickr.com/8877/17512203053_9817e29fe4_b.jpg)
There must be some trick of perspective because the inside looks off center, but looking above the individual vanes follow the interior guiding line, I've scaled it to work with an 8" main trunk, though I think I'll go for 6" all the way, maybe 8" after the separator as I understand it's helpful to increase the diameter afterwards for some reson.
I got a pretty serious angle on these vanes too... it sorta looks like an airfoil impeller...
Next step is to make a hole in the middle and try and balance it.
Is there an advantage to larger line after the separator, larger than the line between the blower and separator?
Quote from: DennisCA on May 26, 2015, 01:32:02 PM
I got a pretty serious angle on these vanes too... it sorta looks like an airfoil impeller...
It sure does, it will be interesting to see how this performs.
Quote from: tvman44 on May 26, 2015, 02:51:46 PM
Is there an advantage to larger line after the separator, larger than the line between the blower and separator?
The input side typically has to be constrained to maintain enough fpm to keep debris entrained in the airflow.
No such requirement on the output side, the bigger, the better (provided you aren't taxing the motor).
That is good to know. Might try that on my little 1Hp DC for my down draft sanding table & router. :)
just wondering why u never used stooped dadoes due to the force and getting a good glue bond
I don't understand your question, I had to look up what a stooped dado was (not familiar with the english terminology) and it looks like what I called a groove, which I did make for the dadoes? For a better glue/epoxy bond, and screws in addition.
Dado is the word used in the USA. In England it is a groove if along the grain and a housing if across the grain. Then again a rabbet is a small furry animal that is very good to eat.
Yeah I knew what a dado was, but not a stooped dado? Or rather it was likely a stopped dado, I thought the grooves I made in the disc qualified as such, hence my confusion.
oops i meant stop. im just thinking a pocket to trap the vane would lock it in place better. but it sounds like your gonna run screws up into the vanes. make sure you scuff up the surface to get a good bond
But I've made such pocket already, the vanes sit in them and are also screwed, this has already been done. If you see my latest picture and look you can see how the vanes are recessed & epoxied into place. They are also screwed into place from the other side, but you cannot see that in the picture.
i can see the dado or groove. what i mean is something like a mortice and a tenon on the vane
Not really sure how to make such a thing, some kinda jig on the router table perhaps. Still I am not sure the payoff would be worth it compared to just the groove and screws.
Quote from: BernardNaish on May 27, 2015, 03:31:11 AM
Dado is the word used in the USA. In England it is a groove if along the grain and a housing if across the grain. Then again a rabbet is a small furry animal that is very good to eat.
Sorry Bernard, rabbits are good eating, but rabbets are not! ;)
I balanced the impeller last night and also mounted it on the shaft to test it out. This part is truly finnicky and making your own hub isn't as straight forward as it might seem. Here's where a custom metal part might have done good. There will be shimming, I can feel it.
Did some balancing today, put the impeller on a big ball bearing that's a big bigger than the diameter of the ebore, I added and removed weight until it laid flat
(https://farm8.staticflickr.com/7771/18205487471_34e5314541_b.jpg)
Towards the end I'd put it rocking a little bit and it would take 10 minutes for it to stop so I'd go away and do something else.
Eventually I got it to the point where the water level stopped at these readings, quite centered though perhaps not exactly, good enough?
(https://farm8.staticflickr.com/7797/18016581610_1f54b09916_b.jpg)
(https://farm8.staticflickr.com/7794/18200651862_8087840e5f_b.jpg)
Actually the reason I managed this was I removed the piece of metal I had between the piece of wood and the bearing, that allowed it to dimple the wood and that added friction so it was possible to balance it like this. The stiff and flat piece of metal was important to let the bearing move as freely as possible.
So much for balancing, the impeller blew up on the first test. The jolt of going from 0-2850rpm I think was too much for the design, without the supporting top as well as I figured I'd try without it.
I think this design isn't going to work, too much mass in the vanes. Perhaps only 5-6 vanes and less of a backwards curve, would work better, like this:
http://www.instructables.com/id/Insulation-Vacuum-Homemade-Commercial-Blower/step3/Impeller-part-1/
Sorry to hear about the results of the impeller's maiden voyage- I hope there wasn't any substantial damage or injury involved.
It does remind me of centrifuge calculations I did in my former life working in a hospital lab. I estimate from your pictures that your impeller diameter is about 20 inches (508 mm). The equation for relative centrifugal force is RCF (x g) = 1.12 x radius (mm) x rpm.
At 2850 rpm, your impeller was pulling more than 2300 g's. Just something to consider in deciding how sturdily you want to make your design- or whether you want to continue in that vein (or vane? :) ). Just saying, I think there's a reason most impellers are welded or cast metal. Also, precise balancing is critical.
That is disappointing.
I had high hopes for this. Any pics of the unit where things came apart? It would be interesting to see how parts look after the spin.
No pics but I can see that the epoxy had let go, the bond wasn't very strong after all. So only the screws held it in place and they had been pulled straight through the the plywood bottom when things let go, one vane shot off into the ceiling and broke a fluorescent tube. These vanes are heavy and dangerous, I was lucky I put the circuit breaker on an extension cord and moved to the other side of the shop and stood crouched behind the jointer.
I'm remaking this but using plywood or MDF vanes like Marius hornberger used in his build- I think the lighter weight means there's less momentum to overcome as it starts up so less stress in that initial jolt, at least the vanes shold be light I now feel, the backing disc could probably be made heavier from 18mm plywood for deeper grooves.
Also I think the wood glue bond with wooden components will be a lot stronger than this failed epoxy joint, and safer if it blows up. Next time I'll be testing it with the top on too. I think I will follow Matthias wandels design closer in terms of vane layout for this new design, perhaps make it a little shorter, I had aimed for 10cm but perhaps 8cm will make for a stronger impeller.
Quote from: DennisCA on June 02, 2015, 09:45:51 PM
No pics but I can see that the epoxy had let go, the bond wasn't very strong after all. So only the screws held it in place and they had been pulled straight through the the plywood bottom when things let go, one vane shot off into the ceiling and broke a fluorescent tube. These vanes are heavy and dangerous, I was lucky I put the circuit breaker on an extension cord and moved to the other side of the shop and stood crouched behind the jointer.
I'm remaking this but using plywood or MDF vanes like Marius hornberger used in his build- I think the lighter weight means there's less momentum to overcome as it starts up so less stress in that initial jolt, at least the vanes shold be light I now feel, the backing disc could probably be made heavier from 18mm plywood for deeper grooves.
Also I think the wood glue bond with wooden components will be a lot stronger than this failed epoxy joint, and safer if it blows up. Next time I'll be testing it with the top on too. I think I will follow Matthias wandels design closer in terms of vane layout for this new design, perhaps make it a little shorter, I had aimed for 10cm but perhaps 8cm will make for a stronger impeller.
Even with a successful build, I would always be worrying about when it was going to explode at full speed. Home built blowers, especially large ones, should be isolated from the rest of the shop with a "blast barrier" - a very strong one to keep it from adding to the amount of shrapnel in an explosion.
Quote from: retired2 on June 03, 2015, 06:09:44 AM
Quote from: DennisCA on June 02, 2015, 09:45:51 PM
No pics but I can see that the epoxy had let go, the bond wasn't very strong after all. So only the screws held it in place and they had been pulled straight through the the plywood bottom when things let go, one vane shot off into the ceiling and broke a fluorescent tube. These vanes are heavy and dangerous, I was lucky I put the circuit breaker on an extension cord and moved to the other side of the shop and stood crouched behind the jointer.
I'm remaking this but using plywood or MDF vanes like Marius hornberger used in his build- I think the lighter weight means there's less momentum to overcome as it starts up so less stress in that initial jolt, at least the vanes shold be light I now feel, the backing disc could probably be made heavier from 18mm plywood for deeper grooves.
Also I think the wood glue bond with wooden components will be a lot stronger than this failed epoxy joint, and safer if it blows up. Next time I'll be testing it with the top on too. I think I will follow Matthias wandels design closer in terms of vane layout for this new design, perhaps make it a little shorter, I had aimed for 10cm but perhaps 8cm will make for a stronger impeller.
Even with a successful build, I would always be worrying about when it was going to explode at full speed. Home built blowers, especially large ones, should be isolated from the rest of the shop with a "blast barrier" - a very strong one to keep it from adding to the amount of shrapnel in an explosion.
I imagine a sufficiently strong wood housing would absorb most of the damage, no?
I think one important factor demonstrated here is to never spin-up a partial blower, one that doesn't have both the top and bottom glued on. Having the top in place would have made the entire wheel exponentially stronger.
Quote from: retired2 on June 03, 2015, 06:09:44 AM
Quote from: DennisCA on June 02, 2015, 09:45:51 PM
No pics but I can see that the epoxy had let go, the bond wasn't very strong after all. So only the screws held it in place and they had been pulled straight through the the plywood bottom when things let go, one vane shot off into the ceiling and broke a fluorescent tube. These vanes are heavy and dangerous, I was lucky I put the circuit breaker on an extension cord and moved to the other side of the shop and stood crouched behind the jointer.
I'm remaking this but using plywood or MDF vanes like Marius hornberger used in his build- I think the lighter weight means there's less momentum to overcome as it starts up so less stress in that initial jolt, at least the vanes shold be light I now feel, the backing disc could probably be made heavier from 18mm plywood for deeper grooves.
Also I think the wood glue bond with wooden components will be a lot stronger than this failed epoxy joint, and safer if it blows up. Next time I'll be testing it with the top on too. I think I will follow Matthias wandels design closer in terms of vane layout for this new design, perhaps make it a little shorter, I had aimed for 10cm but perhaps 8cm will make for a stronger impeller.
Even with a successful build, I would always be worrying about when it was going to explode at full speed. Home built blowers, especially large ones, should be isolated from the rest of the shop with a "blast barrier" - a very strong one to keep it from adding to the amount of shrapnel in an explosion.
My solution to this is to put it in a separate storeroom that nobody is in. This will also save space in the shop.
Quote from: phil (admin) on June 03, 2015, 07:14:28 AM
Quote from: retired2 on June 03, 2015, 06:09:44 AM
Quote from: DennisCA on June 02, 2015, 09:45:51 PM
No pics but I can see that the epoxy had let go, the bond wasn't very strong after all. So only the screws held it in place and they had been pulled straight through the the plywood bottom when things let go, one vane shot off into the ceiling and broke a fluorescent tube. These vanes are heavy and dangerous, I was lucky I put the circuit breaker on an extension cord and moved to the other side of the shop and stood crouched behind the jointer.
I'm remaking this but using plywood or MDF vanes like Marius hornberger used in his build- I think the lighter weight means there's less momentum to overcome as it starts up so less stress in that initial jolt, at least the vanes shold be light I now feel, the backing disc could probably be made heavier from 18mm plywood for deeper grooves.
Also I think the wood glue bond with wooden components will be a lot stronger than this failed epoxy joint, and safer if it blows up. Next time I'll be testing it with the top on too. I think I will follow Matthias wandels design closer in terms of vane layout for this new design, perhaps make it a little shorter, I had aimed for 10cm but perhaps 8cm will make for a stronger impeller.
Even with a successful build, I would always be worrying about when it was going to explode at full speed. Home built blowers, especially large ones, should be isolated from the rest of the shop with a "blast barrier" - a very strong one to keep it from adding to the amount of shrapnel in an explosion.
I imagine a sufficiently strong wood housing would absorb most of the damage, no?
I think one important factor demonstrated here is to never spin-up a partial blower, one that doesn't have both the top and bottom glued on. Having the top in place would have made the entire wheel exponentially stronger.
I think it as as well that I tested it without, the epoxy bonding had clear flaws I would not have been privy to knowing about without this test.
I think if I had used screws with large flat heads or washers, those could have held the impeller together, perhaps. And perhaps some other glue, like polyurethane construction adhesive.
Still now I think making the vanes as light as possible is the best way to go, that way the explosion when/if it happens won't be as catastrophic. I think the plastic vanes would work if you used large bolts all the way through, and a steel disc backer instead of wood, that might be strong enough to handle material.
I also remember reading on Bill Pentz site something a bout how a wooden cage stood up to abuse better than a sheet metal one did.
A soft starting unit was cheaper than i had expected, I could get a new one from germany for 140-150 euros shipped. That might be worth it considering the long run.
I cut out a new impeller disc last night at 45cm, I am scaling it down a bit. Partly because I also have plans printed for this impeller to 1:1 so it'll make things easier to visualize. There will be changes though to the vanes I think, slightly curvature and I will make them longer so they go all the way into the hub and cut the vanes at an angle so they don't protrude from the top lid. Much like a commercial impeller.
Well it's going to be a little while now I think. I've had to order new router bits so I can route grooves that will fit my vanes, and bending and laminating those will take a while as well. I've also ordered a 28mm brad point bit because the drill bit I used to make the holes earler was less than optimal.
Going slow, laminating the vanes still, here's a picture:
(https://farm6.staticflickr.com/5580/18883161355_409a92f141_b.jpg)
It actually worked better to just stand the jig up and use clamps.
Also yardworking, prepping & sowing a lawn, casting concrete slabs, stuff like that.
Been on a break, but I've glued and assembled the impeller vanes & hub now, top plate still needed, and then balancing. I will try static balancing this time using bearings on a threaded rod, but I need to wait for the bearings I've ordered. So much waiting.
Spun up the impeller plate only though to test it and thought, damn, this is scary, this is really ****** scary. Definitely don't want to be in the same room.
Picture of the Mark II
(https://farm4.staticflickr.com/3796/20113213816_b05317089e_b.jpg)
Sides will be trimmed yet, should be 18" when done.
Have u balanced it yet?
No point in doing that until I trim it I think, I'll have to rebalance it again then. I've ordered a bunch of ball bearings of the same bore diameter as the motor shaft (28mm) so I can have the impeller turn on those in the circle cutting jig, otherwise I won't get a perfectly centered cut. So gotta wait for those to arrive. Then I can balance it. Building the enclosure instead meanwhile.
Oh yeah good point.
Well I can't wait to hear how this one works.
I have high hopes.
Still waiting for the parts, checking my mailbox every day for the bearings, getting disappointed nearly every day too. Shoulda bought locally.
Well finally got the bearings. So I used my circle jig and made it round:
(https://farm6.staticflickr.com/5816/20498716649_1301b1a307_b.jpg)
Then I balanced it on an M12 rod with bearings:
(https://farm6.staticflickr.com/5780/20498707479_b9e57e3d2d_b.jpg)
And it's back
(https://farm1.staticflickr.com/616/20497453860_c5419b3ef1_b.jpg)
Standing with the switch 10 meters away outside the shop I started it, probably a dozen times. Longest and last time was 5 seconds. Here it's in action, spinning down:
(https://farm6.staticflickr.com/5807/20497449268_23dccc256e_b.jpg)
Seems to be holding up, and while it it's round and turns true in that way, though there is back and forth wobbling, especially on the front face, more so than the back face, which means it's not flat. I am not sure how big a deal it is, if I should set up a tool rest and correct it.
It's a really scary monster, the sound it makes makes me feel like a small bird getting sucked into a jet engine... And all the air it stirs up, jeezus good thing I am putting this in another room. I'd like it in the attic even, far away.
It's alive!!!
Nice work, what a monster!
Thanks! Just got my new router (a bosch GMF 1600 CE, finally something to replace my €40 lidl-special) so I'll be working on a spiral cutting jig to get the walls just right. I figured out I don't wanna glue them together like Matthias Wandel did. I tried that and it quickly got annoying as heck, esp. since I don't have a miter saw or a miter gauge.
Also doing some other projects now so time, always so little time...
Not much has happened, real life interferes a lot. But I've decided to return the air back into the shop after all. So I will put in a filter bank after the separator and before the impeller. I am thinking a manifold that uses 3 or 4 smaller HEPA filters for shop vacs, or however many is needed for the the filters to not restrict air flow too much.
I read it's better to separate before, the impeller dislikes back pressure behind it more than an obstruction in front.
I thought that if the separator was before the blower, that the filters have to be after it.
I have not heard of that, but in the woodgears dust collector, there's a filter manifold before the blower.
Finally got the top and bottom of the scroll housing routed. Now I need to make a hole in the bottom that's the size of the impeller. This so I can disassembled the scroll housing later without much effort. I am copying Marius Hornbergers design in this.
Best way to cut this is with a router compass. I don't have one, but I have a fence and removing the fence part from the shafts is easy and requires no tools, so I made another attachment to work as a router compass:
(https://c2.staticflickr.com/6/5699/21722000798_d25c6c7c11_b.jpg)
Then setting it correctly:
(https://c1.staticflickr.com/1/782/21721763250_8dc42a6afa_b.jpg)
Turn out I didn't set it correctly and made the hole a few millimeters too small, I thought about various solutions to enlarge it a bit but the best one turned out to be using a simple spokeshave and a kind of clamping jig, worked real well. I also routed a rabbet in the hole and I will rout a corresponding one in the insert plate.
(https://c2.staticflickr.com/6/5762/21721997858_bc15b02504_b.jpg)
Next up is to make the insert plate in question and mount it to the motor.
Surprised myself and got even further on this today:
(https://c2.staticflickr.com/6/5719/21729899888_9e62577c41_b.jpg)
(https://c2.staticflickr.com/6/5784/21905748492_fd16a16dc3_b.jpg)
(https://c2.staticflickr.com/6/5688/21905736362_afe34a16b6_b.jpg)
I had to make a kind of complicated mounting method here in order to get the back of the impeller housing far back enough that the impeller wouldn't rub against the housing. The router c ompass jig has been exceptionally useful on its first day. Now I can start working on the walls for the scroll housing, I plan to use 4mm plywood, I have some that is very bendy in one direction.
Assembling the housing today, ran out of screws. Will have to pick it up tomorrow:
(https://c2.staticflickr.com/6/5770/21949187901_e579ecac76_b.jpg)
(https://c2.staticflickr.com/6/5808/21913277196_0030935f7f_b.jpg)
Pre-drilling every hole as not to split the plywood as well.
Looks fantastic, amazing work!
Thanks, I am approaching the stage where I am not sure how I will proceed. Just how the heck am I going to get this motor lifted in position, and how will I make the frame for it, etc.
Quote from: DennisCA on October 05, 2015, 12:00:38 AM
Thanks, I am approaching the stage where I am not sure how I will proceed. Just how the heck am I going to get this motor lifted in position, and how will I make the frame for it, etc.
Designing while you're building goes like that. Not many alternatives, though.
I have video now, first test:
https://www.youtube.com/watch?v=JrW-fWd8g-Y
Started designing the separator. It's always good to have a sketchup model to reference. It's a real powerful tool. I made this 500mm in diameter (20") and I made it 400mm tall. It uses a 160mm inlet and outlet (6.3") so it's a bit more than 2x tall.
I made the baffle from 6.5mm plywood but I am not sure if it will be strong enough, perhaps one can stiffen it up with a cople of wooden boards from the underside.
The plan is it will be screwed onto the ring above it, and you can rotate the baffle to find the best position for it and screw it back in after adjusting.
(http://i.imgur.com/oaYto4D.png)
(http://i.imgur.com/SwPP5dI.png)
(http://i.imgur.com/qmxR7Gm.png)
The opening into the separator wall will be rectangular.
Calculating volume on the container I find a 500x1200mm cylindrical container would make for a volume of 235 liters. Which is a little less than a 240 liter trash bag. 150 and 200 liter trashbags are more common though.
I might make it a rectangular box from a wooden frame and plywood and connect a hose to the separator to prevent the bag from collapsing. Trying to make a round wooden container might be fun too.
I wonder if I should make the whole thing a mobile unit on castors, so I can work on it to completion in the shop and the move it into place when done.
Worked on the setup some more and put some walls in, should give an idea how everything has to be laid out, the walls are 2.5 meters tall for scale. I just used an impeller housing model from Marius own sketchup files as a placeholder, scaled it roughly to size.
(http://i.imgur.com/zAQZK6J.png?1)
(http://i.imgur.com/WhWA3K6.png?1)
I put a filter box below the impeller housing, I scaled it to fit two ULPA level filters I have bought, their combined surface area not including the effects from pleating is more than the diameter of the ducting, so it shouldn't be an impedance. I will also need to place a metal grille infront of the filter to protect them.
An alternative method would be to place the filters after the impeller in the workshop side and have a filter box on the wall, some dust would have to pass through the impeller then, but it'd be simple to attach a grille over the inlet hole. It'd be easier to remove and clean the filters that way and I could make the whole setup shorter.
I wonder if I need to consider a muffler or something after the blower.
I think the filters might be too small despite the pleating, a lot of filters for DC's are much bigger so I think I need to enlarge it, but it'd be too clumsy to keep infront of the blower so I am putting it behind it, I have the two smaller filters (already bought) and one bigger filter that's bigger than both of those there:
(http://i.imgur.com/40mhYrc.png?1)
I hope that's enough...
Moving the filter to the discharge was a good change. I can almost guarantee you that placed in a box between the separator and the blower, that box, regardless of size, it would have created turbulance, loss of airflow, and increased noise. You should review my experience with close-coupling the separator and blower, and the impact of adding an air straightener.
My second comment is that the filter on the discharge looks a little small compared to the cartridge filters I'm usd to seeing. As shown it also looks like at least some of your discharge air is going to have to make an abrupt directional change. That could adversely affect your airflow.
I was always planning on venting outside until I found out the blower needs a few seconds to replace all the air in the shop. So this filter thing is poorly researched and thought out. I am infact quite frustrated at this point to come up with a solution for large enough filtering that doesn't cost an arm and a leg.
Have to say I'm leaning towards bags as it is. Waste a bunch of money on a real expensive filter and ruin it unless you spent more money and put a coarser pre-filter to protect it... Just sounds real clumsy and expensive a setup. Perhaps a two bag setup would be better or something like that.
Well here's an updated design using bags, it would hardly need changing if I went with filters cartridges instead, might just be enough with one filter then. That's the most appealing part, the amount of surface area they have compared to bags. I am not sure how big the difference is in real life. Filter cartridge people seem to think it's all worth it though. I also added a vent hole for venting outside when wanting to. There'd have to be some hatch from the top and side to boot.
There's a lot of sheet goods going into this, I will have to buy some OSB, can't be spending plywood money on all this.
(http://i.imgur.com/YHa6djh.png?1)
You might note the model has expanded, because I put it into a model I have made of my workshops layout, really just a box the right size and with models I pulled from the online library to act as place holders. I suppose the filter box has some sharp turns for the air but it's so large I think it shouldn't matter too much. I think there are some improvements that can be done on the inside by rounding off internal corners where needed.
(http://i.imgur.com/dS3wbJO.png?1)
I haven't yet implemented anything in sketchup regarding air straighteners but I think they are a good idea, not sure if a bell mouth or not wold also be a good idea, seems somewhat uncertain with a 2H design what the better option is.
One thing I am considering is increasing the diameter of the separator outlet pipe to 200mm (8").
Bought the filters instead, got a good price in the end, 22m2 over 3.6m2 for two bags was appealing. And I can slim down the design now.
I have been reading the threads on design and I now think I shouldn't make the rectangular opening into the separator the same size as the box, I should reduce it in size until it is the same area as the ducting. It's bigger now. I think otherwise there will be too much turbulence.
This project stalled out, basically too costly to proceed. I've been recently trying to at least mount the motor in a temporary location to get further but the thing is just too heavy, I don't feel comfortable with the mounting solution after some attempts to get it into place.
So I am thinking about mounting it lower to the floor and having the blower housing standing on it's side, that will make it much easier to get into position. Maybe mount it all on a wheeled contraption like Wandels design, except overkill. It would require a bend after the separator since the motor would not be on top anymore, but perhaps if it's big enough it won't be a problem. Talked to Matthias Wandel about it and he claimed the efficiency loss was minimal due to the size of the ducting.
I was right, I tugged on one of the motor support brackets and it broke off. Not a strong enough mounting solution. But redoing at this point to make it all sit low also seems like too much work just mentally speaking. Already got the stand made and hanger bolts. What I will do is I will make the mounting points in the back plate instead of on the motor itself.
(http://i.imgur.com/qToGpe1.jpg)
(http://i.imgur.com/pCkQxQC.jpg)
(This didn't work out)