alternative to upgrading motor on Pentz cyclone

[David Miller]

Hi all,

This is a post related to my previous 'too much for the motor' post. I have built a Bill Pentz design cyclone and have a 2HP motor driving the Sheldon's engineering 14" impeller. With the cyclone closed off completely my motor is pulling 9.2 amps. The motor is rated for 10 amps. Not good

So now I'm looking for alternatives to buying a $250 5HP motor. If there are none, then I will buy it.

Can I modify the impeller? I'd rather not do this, at least significantly. But if I can shave a little off or something then I might try. How do Oneida, Woodsucker, etc.... get way with only a 1.5 or 2HP motor?

What about modifying the blower housing?

Any other ideas?

Thanks,
Dave

[Jim Becker]

Have you asked Bill this question?

[John P. Smith]

Have you looked at Harbor Freight?

http://www.harborfreight.com/cpi/cta...temnumber=3068

They often put it on sale for just under 100 bucks.

They also have a 3 HP http://www.harborfreight.com/cpi/cta...temnumber=7570

We will probably get some responses on Harbor Freight quality (or lack of), but you asked for alternatives to a $250 motor.
I havent (yet, but am planning to do so) built a blower or cyclone, but when I do I plan to use the HF 5HP motor. I think you need at least the 5HP compressor duty motor. It is really about a 3HP when running, but is rated at 5HP for starting torque. The steel impeller you have takes more torque to get it spinning that to keep it spinning so the compressor type motor is ideal.
Just MHO, am I wrong guys?

[Allan Johanson]

You could always sell the 14" impeller and buy an airfoil instead that's meant for a 2HP motor. Only problem with an airfoil is it won't tolerate any dust so it can only be used on the clean side of a cyclone and you should periodically check the blades for dust buildup. Sheldon sells these too. $175US including shipping.

BTW, have you tried restricting BOTH the intake and exhaust of the cyclone to see just how low you can get the amp draw? Not that it will solve your problem, but I'm curious.

Other companies can get away with smaller motors because their impellers are smaller and they have more restrictive cyclone designs.

With the help of some pulleys you can reduce the speed of that Delta 2HP motor for use on a bandsaw or lathe for a sweet power upgrade. If you buy the proper 3-5HP motor for the 14" impeller on the cyclone I'm positive you won't be disappointed with the performance. I can give you a hand with duct sizing too if you like.

Hey....I just thought of something. Is your motor spinning in the correct direction? The blades on the impeller are curved. They way it is supposed to work is the curved blades do NOT, and I repeat, NOT, "scoop" the air. You want it set up so the curved part of the blade (like the back of a spoon) strikes the air. Backwards from what you might think, but that's how it's supposed to work.

Please double check that.

Good luck!

Allan

[Jim Andrew]

Does the material the impeller is made of make a difference in chance of
causing a fire? I read on some post that the reason some companies make
them from aluminum is because steel can cause a spark. Jim

[Allan Johanson]

Hi Jim,

In a regular single-stage DC, an aluminum impeller might be preferred if you have a floor sweep in your shop and didn't check for small nuts/bolts etc. A piece of steel flying through your ducting and striking a steel impeller could cause a spark and cause a fire. If the impeller was aluminum, a piece of steel hitting it wouldn't cause a spark.

In a 2-stage DC setup like a cyclone, heavy particles go in a bin and never hit the impeller. So if you have a cyclone and a floor sweep and suck up some steel, those pieces will fall in the bin and never have a chance at causing a spark.

Bottom line, be careful with floor sweeps and when fiddling with your machines when the DC is running and you should never have a problem.

If I've overlooked something some of the guys here will chime in.

Cheers,

Allan

[Ken Garlock]

Bill's cyclone has been designed and tested to run using the recommended components. Yes, $242 for a motor is not "chicken feed", but you are getting a brand name Lesson motor with the correct mount to attach it to the blower housing. The fan has been balanced at the factory and I would not attempt to "adjust" it for fear of really getting it out of balance.

I presume you are planning to use the cyclone for a long period of time, thus it is worth doing it correctly the first time. So, get your hot little hands on the keyboard, go to the "Electric Motor Warehouse" and order the motor.

[David Miller]

Thanks for all the replies!

Jim: Bill recommends posting to sites like this for assistance unless you are a customer of his. I respect his reasons for this so I came here.

John: yep, I looked at the HF motor. However, I'd have to make an alternative mount for it (not face mounted) and make an adaptor for the smaller motor shaft. In the end I'd rather go with the Leeson that Bill recommend. Thanks for the suggestion!

Allan: I considered the airfoil but decided against it because of needing to keep it clean and making sure it doesn't stall. I closed off the exhaust and the draw dropped to 9.1 Amps. Not sure if this is enough though. I agree that I probably will not be disappointed with the performance of the system if I go up to a 5HP motor. Heck, it sucks now! Yep, the impeller is spinning the right way. I spent some time at the beginning making sure it was correct. Thanks for the offer to help with duct sizing!

Well, I think it's becomming even more clear that I need to upgrade to a 5HP motor.

**I just ordered the 5HP motor from the motor warehouse!

Thanks again,
Dave

[Allan Johanson]

Congrats on buying the large motor, David. You'll be a happy guy.

Quick note on ducting and we can get into more detail later on, but the part for you to think about first is what are you wanting to achieve with this monster cyclone?

1) Get at least 800cfm at the tools?

or

2) Get as much airflow as you possibly can (within reason) now that you will have this beast in your shop?

If #1 is your plan, then stick with a 6" main duct. Make the initial rectangle to round transition on the cyclone inlet go to a 6" round duct as Bill speaks of in his plans.

If #2 is your plan, then you want a 7" main duct. Don't make the initial rectangle to round transition go down to 6" and then add on an adapter - make it be 7" from the beginning. Mine is 8" and I'm dropping it down to 7" at my first branch. But I made it have an 8" inlet for testing purposes. Going with a 7" main duct should give you the capacity for an extra 200-250cfm at the tool if you choose.

If you are unsure about #1 or #2, then make your cyclone inlet have a 7" round transition and you can always add on a 7"x6" reducer right at the inlet and go with a 6" main duct.

For either option, stick with an 8" exhaust. It almost perfectly matches the rectangular blower outlet size and you will get a little more airflow this way. Here's a pic of my blower outlet. It was easy to make. It's a rectangular ring of plywood screwed to the wooden blower plates and some 8" snaplock pipe from HD was bent to fit on the inside. It wasn't quite big enough at the top and left a little hole, but some metal foil tape fixed that. Piece of cake.

Cheers,

Allan

[Steven Wilson]

Does the material the impeller is made of make a difference in chance of
causing a fire? I read on some post that the reason some companies make
them from aluminum is because steel can cause a spark. Jim

Yes, you should use a non-sparking impeller (cast alluminum). According to Bill Pentz "even cyclones that have the blower on the clean side of the cyclone will still have to be able to take material hits because cyclones send the material right through the impeller if there is a cyclone air leak or the collection bin gets too full." It may also be specified in the Fire Protection Association codes.

[Allan Johanson]

Good point Steve. I suppose there is a chance it could happen. I've simulated a full bin on my system (but not going up the cone) and the cyclone couldn't expell a small piece of poplar that would weigh as much as a small bolt that was at the bottom of the cone. It just clanged around and made a loud noise.

But I plan on building a dust bin level detector one day to avoid the overflowing bin problem once and for all.

I don't think a small leak would be a problem, it would have to be a big leak. I tested that too. The reason is that the heavy particles will be spinning around the cone and a typical leak would allow air in a single small stream. When the spinning chunk hits that incoming airstream, it may lift a bit but as the spinning chunk moves horizontally out of the way then it will fall again. Well, that was my observation when I did my experiment. It may not always be that way.

Cheers,

Allan

[David Miller]

Thanks for the advice, Allan. As it turns out, I'm going with a mobile setup. I'm going to hook a piece of 6" flex to the machine I'm using. Not the best solution but it is only (hopefully) temporary. I will stick with the 8" formed outlet. I have two of the wynn environmental farr style filters stacked. I'm trying to decide how to hook it up to the outlet. Did you use the insulated HVAC duct?

Thanks,
Dave

[Jim Andrew]

Guess that puts Grizzly out of the "which cyclone?" question. As theirs is
a steel impeller. Wouldn't be worth having a fire to save a couple of hundred
bucks. Can someone post a price for 6" S&D pipe? My hardware found a
couple quotes, one was 2.50 and another 3$ per foot. Don't think that is
what Bill meant by saving money. Jim

[Allan Johanson]

Hi David,

I probably won't bother with the insulated HVAC duct. I'm still designing my filter box so I'm not sure how much room I'll have. I have a couple of 10"x8" reducers I was planning on making a muffler out of, but I might just skip it all. I measured my cyclone at 89db about 6 feet away and I expect that to drop when the filter box is completed. We'll see.

My filter box will have two chambers in it, the first being a prefilter chamber where if my dust bin overflows and crap gets sent to my filters, the prefilter will trap it so my good filters don't get contaminated. Apparently once you jam them full of dust it's really hard to get them clean again. I know of a person who did this and the airflow dropped a noticable amount even after cleaning the filters.

I also plan on installing dedicated magnehelic gauges to monitor the pressure in the two chambers of the box to check for partially clogged filters so I will know when to clean them. Should be cool.

Jim, re: steel vs aluminum impeller. Yes, aluminum is the safest way to go. But if you don't have a floor sweep it's almost a non-issue. Well, for me it isn't.

Cheers,

Allan

[Scott Parks]

Can someone post a price for 6" S&D pipe? My hardware found a
couple quotes, one was 2.50 and another 3$ per foot. Don't think that is
what Bill meant by saving money. Jim

Locally where I live, Lowe's charges about $24 for a 10' pipe. Our contractors plumbing supply store charges $13 for a 10' pipe, and about $20 +/- for the non-gasket fittings.