Increasing impeller size

[Mike Cruz]

Has anyone tried to increase their impeller size? I don't mean buying a new larger impeller for their existing DC. I mean taken your impeller and welded maybe a 3/4-1" strip of steel to the ends of each blade to increase it from say 12" to 13 1/2-14"?

I know there will be other factors involved, like the opening to get said hypothetical impeller back into the DC housing being big enough. And, how large of an impeller can the housing take. Also, will the motor be able to handle a larger impeller? Just a little background... I have a Grizzly 3 hp DC model G1030 (the four bag model). The inlet is 6". The impeller is 12". They claim (haha) that the impeller draws 1800 cfm. The newer model claims (haha) to draw 2300 with a 12 3/4" impeller. Now, maybe they didn't just increase the size of the impeller, but also the shape/dynamics of it. But the way I see it (could be all wet), the 2 hp and 3 hp versions of this DC are identical other than one having 2 bags and one having 4 bags. If the 2hp 2 bag model can handle the 12" impeller just fine, the 3 hp 4 bag model should be able to handle a larger impeller.

Please, let's not take this into the direction of what filters are on the DC, etc. Thanks.

[Chris Damm]

I have a Jet DC-1900 3 HP four bag DC. It has a 14" impeller. The housing is about 18" in outside diameter with an 8" inlet. If you can balance the impeller you should be able to increase the size if you really have a 3HP motor.

[Matt Meiser]

A guy who went by "Dizzy" on the web did it several years ago. http://web.archive.org/web/20031207135813/http://home.pacbell.net/jdismuk/cyclone.html I think you'd want to make sure whoever is doing the welding is really good. If I did the math right, the tips of those new extensions would be moving at 210 feet per second. Even then I'd think it would pretty much be luck if you have an efficient fan.

If you really want a bigger impeller, I wonder if the 14" impeller from the comparable Jet would fit? IIRC (and I might not be) the 2HP DC1200 had a 12" impeller and the 3HP DC1900 had a 14" impeller while the comparable Grizzly's used smaller impellers. (Edit: Chris posted while I was typing this and confirmed my memory.)

[Mike Cruz]

Matt, I did some research about a year ago and the challenge was to find an impeller that had the same shaft size and configuration (straight and keyed vs tapered). I don't remember if Jet's fit the Grizzly or not. But one thing I do remember is that impellers aren't cheap. So, I was hoping to not have to shell out the $ for a new one. I thought that if I tried to lengthen my blades, it would be a pretty cheap fix. But if for some reason it doesn't work, then I could either try to find an impeller from another manufacturer that would fit and spend the money, or just get another 12" impeller from Grizzly to slap back on there. Lengthening the blades was suggested to me by another Creeker at one point. Just wondering to what extent it has been successful... Thanks for the link. I'll check it out.

Alan, thoughts?

[Mike Cruz]

Matt, I couldn't get the link to work. Looks like it just kept cycling through...as if it were searching but not finding results. Not sure why...

[Matt Meiser]

Try going to http://www.archive.org and pasting "http://home.pacbell.net/jdismuk/cyclone.html" into the search box.

The site is no longer available but has been captured by archive.org.

[Chris Damm]

Dizzy had some real good ideas (I've borrowed more than a few) and he was a first class fabricator. He died a few years ago, way too soon.

[Dan Hintz]

Try going to http://www.archive.org and pasting "http://home.pacbell.net/jdismuk/cyclone.html" into the search box.

The site is no longer available but has been captured by archive.org.
Grrrrr.... company IT has blocked archive.org!

[Chip Lindley]

Most impellers nowdays are cast aluminum. Older impellers were welded steel. With either, welding would need to be impeccable to survive the centrifugal forces of in a blower. Re-balancing would be crucial. One must consider that the impeller clearances inside the blower housing were designed that way for a reason. A larger diameter impeller in the same housing may actually impede air flow rather than increase it. Just sayin'...

[Dan Hintz]

All I can think of right now if those electric turbochargers they sell for cars for $100 :p

[Patrick Maloney]

Just FYI, I recently bought a 14" steel replacement fan for the Jet DC-1900 and it was right around $100 shipped.

[Mike Cruz]

Patrick, do you know the width of the impeller? Also, does it fit onto a tapered or straight shaft? Thanks.

[Mike Cruz]

Chip, while I've thought about that, I've also looked at a lot of "China" stuff and tilted my head wondering "why'd they do THAT?" since it made absolutely NO sense. Not saying that about this scenario, but I don't believe everything is done for an actual reason...well, yes for a reason, but not necessarily for performance. Many times because of cost or because that is what they "had". Or if was easier to put together that way. Those kinds of reasons. Thanks for the heads up, though. Something to keep in mind.

[Patrick Maloney]

Patrick, do you know the width of the impeller? Also, does it fit onto a tapered or straight shaft? Thanks.

I believe the total height is about 4". It mounts on a straight 7/8" shaft. Unfortunately I have to pull my system apart anyway, so I will take some measurements to double check and get back with you.

[Dan Friedrichs]

Don't forget about the housing - the major difference between an air raid siren and a material handling blower is the distance between the impeller and the housing!

[Mike Cruz]

Thanks, Patrick, I'd appreciate it.

Dan, um, just how close to the housing can you get before it becomes an air raid siren? :o

[Chip Lindley]

Most impellers nowdays are cast aluminum. Older impellers were welded steel. With either, welding would need to be impeccable to survive the centrifugal forces of in a blower. Re-balancing would be crucial. One must consider that the impeller clearances inside the blower housing were designed that way for a reason. A larger diameter impeller in the same housing may actually impede air flow rather than increase it. Just sayin'...

Mike, I did not quite have Harbor Freight in mind when I commented. I suppose I have been blessed to have worked with 2hp Cincinnati, Delta, and Dayton blowers, and a larger 3hp Oneida cyclone system. No doubt those are engineered to some sort of "standards."

Regardless of source, remember safety first. Faulty add-ons to an impeller spinning at 3450 RPMs may be hazardous to your health!

[Patrick Maloney]

The DC-1900 fan is 14" in diameter and 4" tall with a 7/8" straight shaft.

[Aaron Rowland]

Most impellers nowdays are cast aluminum. Older impellers were welded steel. With either, welding would need to be impeccable to survive the centrifugal forces of in a blower. Re-balancing would be crucial. One must consider that the impeller clearances inside the blower housing were designed that way for a reason. A larger diameter impeller in the same housing may actually impede air flow rather than increase it. Just sayin'...

================================================== ==========
I don't think so. The only companies using aluminum impellers are Oneida and PSI on their cyclones . The rest are steel including DC baggers and cyclones. Lots of room for impeller increases. Radial Scroll housing clearance are not critical.

The reason al is used is to shorten start up time for the motor. Steel being much heavier takes longer to spool up. Fire safety is used as a marketing tool for al because it won't spark like steel. However al struck by a steel abject can cause a thermite reaction . True? I don't know. Fire is a non issue for hobby Dc's anyway. At least I never heard of one.

[Aaron Rowland]

Has anyone tried to increase their impeller size? I don't mean buying a new larger impeller for their existing DC. I mean taken your impeller and welded maybe a 3/4-1" strip of steel to the ends of each blade to increase it from say 12" to 13 1/2-14"?

I know there will be other factors involved, like the opening to get said hypothetical impeller back into the DC housing being big enough. And, how large of an impeller can the housing take. Also, will the motor be able to handle a larger impeller? Just a little background... I have a Grizzly 3 hp DC model G1030 (the four bag model). The inlet is 6". The impeller is 12". They claim (haha) that the impeller draws 1800 cfm. The newer model claims (haha) to draw 2300 with a 12 3/4" impeller. Now, maybe they didn't just increase the size of the impeller, but also the shape/dynamics of it. But the way I see it (could be all wet), the 2 hp and 3 hp versions of this DC are identical other than one having 2 bags and one having 4 bags. If the 2hp 2 bag model can handle the 12" impeller just fine, the 3 hp 4 bag model should be able to handle a larger impeller.

Please, let's not take this into the direction of what filters are on the DC, etc. Thanks.

================================================== ========

You noticed the impeller and HP sizes. Only recently have buyers wised up to the fact that the impeller diameter controls CFM not the HP. I assume you are trying to bump your CFM up a bit. Adding on a 3/4" strip will tack on about 15% more CFM and that's for real. Most 2HP still run 12" impellers but the trend is bigger. Could be Asian motors are getting better. Other suppliers will follow and bump up to 12.75" to be competitive. If anybody is reading this and in the market for a 2 HP blower make sure it's a 12.75" unit. This is a big deal!.

Have you considered adding an identical blower in series? That will really up your CFM. Up to twice what you have now for only $200. I took some heat on this but It turned out Pentz had a post on this site in 2005 that backed my comments up. I reinvented the wheel it looks like. Find the Pentz article as mentioned in another thread. A very good read even if you don't use it. Pentz referenced Jim Halbert who supposedly was an expert on this. He's the guy who also invented a cheap and simple automatic blast gate according to Todd Crow.

. I think the 2HP blower sells for $260. You can still get it with a 12" impeller. Don't mix the 12" with a 12.75" I think you can mix the 2 and 3 HP motors and they may be the same motor. Check part number under spares. It will cost you a bit to weld or update to a bigger impeller. So $200 or less would be your cost for a killer system. That can also be used on a cyclone and your set for life. This is now a 4 HP rig however and do you have the power to run it? Starting both motors at the same time pulls a big power surge during start up. I use two 5HP motors in series and stagger the starts with a timer to minimize the surge. Your motor does not have a contactor start, I think. So that has to be done on at least one blower for timer delay. If your not remote just turn them on manually , one at a time.. You can also use a power relay with a coil that doesn't cost as much and it work just as well..

Lots of ways to do things.

[Dan Hintz]

Have you considered adding an identical blower in series? That will really up your CFM. Up to twice what you have now for only $200. I took some heat on this but It turned out Pentz had a post on this site in 2005 that backed my comments up. I reinvented the wheel it looks like. Find the Pentz article as mentioned in another thread.
Don't start spreading your series manure in this thread, too... I'll be the one helping Mike clean it up in the end. You didn't just take heat in the other thread, no one agreed with you... more to the point, everyone disagreed with you about running them in series.

[Mike Cruz]

Chip, what I meant by going to HF was that I'm sure I can pick up the measuring devices pretty inexpensively there...since they aren't things I would use on a regular basis. I'm anything but a HF fan. But for something like this, I would imagine they have each device for under $10. I also am going to be very cognizant as to the quality of the welds (if I go this route), and the overall weight distribution. We'll see where this leads. Agreed that I don't want one (or more) of those extensions flying off in mid use. The noise alone would be enough to make me soil myself. Then, the thought of having to buy an new system would get me a bit depressed. So, yes I'll be diligent in not saying "good enough" for this job...

Oh, and thanks Patrick. I'll see if that is what I need.

[Mike Cruz]

Dan, no worries, I was reading that other post. Got my filter on. Aaron, thanks for taking the time to try to answer my question. Unfortunately, I have to agree with Dan, and due to the posting on the other thread, I'll have to take information for its face value.

[Dan Friedrichs]

Dan, um, just how close to the housing can you get before it becomes an air raid siren? :o

You have the opportunity to determine that experimentally :D

(I have no idea)

[Matt Meiser]

And the good thing is if you are too close you have the opportunity to remove some width. But unfortunately that would mean re-balancing.

I suspect when you price the cost of professional welding and recommended balancing, you'll find that you are better off finding a new blower.

[Mike Cruz]

Thanks, Dan... ;)

Matt, I have a buddy (are you listening, buddy, SC?) that is an accomplished welder. I'd have to stock up in some nice beer, though. :) So, cost probably wouldn't be that outrageous. But, I hear you with respects to cost of new vs altering this one...

[Mike Cruz]

No disrespect to Steve regarding the home made SP tester, but does anyone have a good suggestion for a manometer for this application? I looked at Amazon.com but can't tell which ones would work for this. I'm also looking for an inexpensive one since it isn't something I'd be using often. Thanks.

[John Lanciani]

http://ecx.images-amazon.com/images/I/41kmtKRcWQL._SL500_AA300_.jpg

I use the UEI EM151. I initially used it for setup, now I have it on the exhaust side to tell me when it is time to clean the filter. Cheaper than Oneida's filter gauge and a lot more useful.

[Anthony Whitesell]

Thanks, Patrick, I'd appreciate it.

Dan, um, just how close to the housing can you get before it becomes an air raid siren? :o

My off hand guess would be close enough that a large chip chunk of wood may jam the impeller and reek all kinds of havoc when the 3450 RPM blower comes to a dead stop instantly. Ouch!

[Alan Schaffter]

I don't have much to add, but I was around when Jim Halbert and Dizzy were doing their thing. Dizzy used to hang out at The Oak Factory then The Wood Works until his passing. He was a professional and talented welder. His homemade cyclone looked like a production model rivaling those from Jet and Oneida once he painted it with "Jet" white like he did with all his welded shop stuff. I believe he started with a Jet blower with 12" impeller, but don't remember how much he added. I think it was only in the range of 3/4" to 1." I don't remember if the new tips extended past the impeller disk- if they do they won't be as strong as ones attached to the impeller disk.

If you add tips extensions it doesn't need to be pretty but the welds need to be secure and able to handle the forces, including an impact from an occasional chunk of wood. Most importantly it must be well balanced- not only statically but more importantly, dynamically balanced at full or even higher RPM. There are places that can do that for you for a price(?). If it is not properly balanced at the least it will shorten the life of the motor bearings, and the most, the blower will shake itself apart which could be deadly!

I wouldn't be too concerned about housing clearance, just be careful you measure from the center to the closest wall since the housing is somewhat scroll shaped. Also, the blades may fit the housing but be too big to get past the end plate opening. You can usually avoid this to some degree by rotating the impeller during installation.

Another option is to use your existing motor and buying a larger impeller that will fit the shaft (adapters are available). You can even make your own MDF blower housing like a ClearVue- the web is full of homemade blowers of this type.

Once you mount the new impeller, you need to make sure you don't run it without some ducting, and also put an ammeter on the motor to see how close it is running to FLA.

[Patrick Maloney]

Alan, you said not to run the DC without ducting. What happens if you do? How much resistance is enough to safely run it?

[Stephen Cherry]

A couple of dwyer magnehelics are all you need, one for differential pressure, and another to work with a pitot tube.

Let me know, and i can give you part numbers. Of course, they don't really work as well as the piece of aquarium tube with cool aid. Check the picture:

http://en.wikipedia.org/wiki/Pressure_measurement

[Alan Schaffter]

Alan, you said not to run the DC without ducting. What happens if you do? How much resistance is enough to safely run it?

Without SP resistance, there is a good chance you will cause the motor to work too hard, exceed FLA, pop the breaker, or possibly let the smoke out.

[Stephen Cherry]

Sorry, I don't want to rock the boat or anything, but Aaron is absolutely right. And I say this as a former control system engineer with lots of experience with airflow.

It's all how the fan curve relates with the load line. On a high dp system, the load line hits the fan curve at the low flow high dp area. And remember the load is generally a v squared relationship, so it increas slope with increasing flow.

Aiflow is tricky, and if you don't have a lot of experience, it's easy to make assumptions that are incorrect.

Here's something to think about: if you have a system where the duct work is flowing enough air that it has a dp that approaches the static max dp of a fan, you could add a hundred fans in parallel, and you won't measurably increase flow.

[Alan Schaffter]

But if you divide your system, with one blower per branch- you essentially cut the SP resistance in half and double CFM, and don't need to worry about balancing the blowers, etc. That is the easy way to do it. When you talk about the fan curve, what fan curve are you talking about. A fan curve is unique to each blower and determined by a somewhat standard method. I say somewhat, because not all manufacturers do the same. Some take their measurements at the end of a 10' long inlet pipe, some don't. Once you change any parameter- lengthen the impeller blade, etc.- you change the fan curve. Air flow is indeed tricky.

[Mike Cruz]

Alan, thanks. The more I think of it, the more I am leaning toward finding a larger impeller. That said, I do want to find out a couple of things. I want to do my own test on the DC as it is now, to see what its cfm and SP are without piping (basically testing right at the intake), then, after the new impeller is in, doing that again. Do you see a problem with running the DC these two times long enough to get measurements? Or is that even too long?

[Mike Cruz]

Alan, thanks. The more I think of it, the more I am leaning toward finding a larger impeller. That said, I do want to find out a couple of things. I want to do my own test on the DC as it is now, to see what its cfm and SP are without piping (basically testing right at the 6" intake), then, after the new impeller is in, doing that again. Do you see a problem with running the DC these two times long enough to get measurements? Or is that even too long?

[Matt Meiser]

Just attach a length of pipe on the inlet. You'll need to do that anyway if you want to generate a fan curve because you'll need a way to increase the static pressure.

[Stephen Cherry]

I want to do my own test on the DC as it is now, to see what its cfm and SP are without piping (basically testing right at the 6" intake), then, after the new impeller is in, doing that again. Do you see a problem with running the DC these two times long enough to get measurements? Or is that even too long?

If you are using a pitot tube to do the airflow measurement, you need something like 14 duct diameters of length-- 10 upstream and 4 downstream of the pitot tube. Also, some sort of an orifice plate to limit the flow, which should go upstream of the duct.
:mad::eek::confused:

[Mike Cruz]

Maybe I don't need to increase the impeller size. Maybe what I need to do is swap out the motor with this: (:D)

NEW 40 HORSEPOWER BALDOR ELECTRIC MOTOR - $400 (Hershey / Grantville)

Date: 2011-06-22, 8:52AM EDT
Reply to: sale-edarn-2455332033@craigslist.org (sale-edarn-2455332033@craigslist.org?subject=NEW%2040%20HORSE POWER%20BALDOR%20ELECTRIC%20MOTOR%20-%20%24400%20(Hershey%20%2F%20Grantville)&body=%0A%0Ahttp%3A%2F%2Fharrisburg.craigslist.org% 2Ftls%2F2455332033.html%0A) [Errors when replying to ads? (http://www.craigslist.org/about/help/replying_to_posts)]


NEW 40 HORSEPOWER BALDOR ELECTRIC MOTOR - 3Phase 230/460 volt - 1775 RPM - 324T


Location: Hershey / Grantville
it's NOT ok to contact this poster with services or other commercial interests

PostingID: 2455332033

[Alan Schaffter]

1775 RPM

Good price for a BIG new motor but it is 3 phase and you'll not find a cheap way to run it on single phase. RPM is the gotcha. The RPM is a bit too slow for a decent blower. However if you don't use direct drive you could gear it up with belts like many commercial blowers and maybe even drive multiple blowers! I wonder what that sucker weighs? :D:D:D

As to measuring CFM- first without any input resistance you will likely pop the breaker or if the breaker/circuit is rated much higher than the motor's FLA, you will smoke the motor.

As Stephen said, to get a good fan curve you need the right setup. My suggestion is go to Bill Pentz's site- he has detailed instruction for testing. If you are really intent on doing this I have some Dwyer magnehelic gauges (and maybe a pitot tube) that I never used and will let go cheaply- my DC works pretty well. I've followed the best practices throughout, so it does what it does and I'm not going to feel any better (or worse) about it or change anything, knowing precisely what it does. And I'm not concerned about bragging rights :rolleyes: :rolleyes: )

[Mike Cruz]

You know, Alan, I never actually looked at the rpm. Even if it were 3450 rpm, I'm already getting that, so it wouldn't have made a difference...unless I wanted to put a 24" impeller with 12" pipe or something... THEN, a 40 hp motor might be sweeeeeeet.

Anyway, I'll pm you re the mahnehelic gauges.

[Paul Wunder]

Mike,

My second post in your other thread may be helpful:

You can buy a ClearVue cyclone blower housing (15") for $150. It is the same housing used on on the ClearVue model that most of us own. They will also sell you a 15" impeller for an additional fee. I can attest to ClearVue quality and effectiveness.

[Mike Cruz]

My head is spinning so fast right now, not sure where I am! Where I stand right now is that, if Bill is right, and I need 1.5" from the impeller tip to the closest part of the housing, then my 12" impeller is the largest I can fit in that housing...UNLESS, I do a little mod that would raise the housing, leaving the motor where it is, and moving the housing to the left a little. IF I can get by with only 1" to the closest part of the housing, I could get a 14" to fit. This would of course leave me with finding a way to get the impeller INTO the housing...but I have an idea. Then, I have to find the right impeller...

If 1" just will not do, then going the route of getting another housing and impeller might be my best bet. I'll go look at your other post. Thanks for the idea of the ClearVue stuff...I might need that!

[Stephen Cherry]

My head is spinning so fast right now, not sure where I am! Where I stand right now is that, if Bill is right, and I need 1.5" from the impeller tip to the closest part of the housing, then my 12" impeller is the largest I can fit in that housing...UNLESS, I do a little mod that would raise the housing, leaving the motor where it is, and moving the housing to the left a little. IF I can get by with only 1" to the closest part of the housing, I could get a 14" to fit. This would of course leave me with finding a way to get the impeller INTO the housing...but I have an idea. Then, I have to find the right impeller...

If 1" just will not do, then going the route of getting another housing and impeller might be my best bet. I'll go look at your other post. Thanks for the idea of the ClearVue stuff...I might need that!

Why don't you get a plasma cutter, cut off the sides of the housing, weld in some metal where it is needed to get the clearance you need, and leave it at that.

[Mike Cruz]

Hmmmm, a plasma cutter and a welder....where would I find those? :rolleyes: When ya commin' over, buddy-ole-pal? ;)

[Dan Hintz]

Hmmmm, a plasma cutter and a welder....where would I find those? :rolleyes: When ya commin' over, buddy-ole-pal? ;)
Absolutely... because that's one tool we haven't yet used after sucking down several beers ;)

[Mike Cruz]

Speak for yourself! Actually, I think we were pretty sober when we were using those tools...at least I think we were...