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DIY Harbor Freight Air Filter

Yeah. Scary how long it took you to come up with the independent air flows clause. After the recommendations for this modification were already made? I chose to error on the side of caution, and I don't recommend changing systems/processes until after I have done my due diligence.
 
I don't really know what you are talking about "independent air flows clause". Are you talking about the motor cooling being separate from the blower? Because they are all that way, I was just informing you of that fact, I didn't "come up with it". The burden of proof is on you my friend, not me, because you inferred what I was doing was unsafe, but with no evidence to prove it. So I did my research to show it was safe, and you still insist I did something wrong. If I discovered I was wrong, I'd admit to it and chalk it up as a learning experience, it appears that you are unwilling to do so and instead chose to attack me instead.

Do you know if there is a way to delete this thread? More for your sake than mine, because you are not coming across very well here.
 
I’m not the one recommending modifications to equipment with out understanding the dynamics of its basic operation.
I don’t/won’t feel bad about bringing up a plausible concern about motor over amperage. Obviously the design engineers that made this product were on that same school of thought that I was when they included the over load trip feature on their device. Sure, I was wrong about the airflow across the motor. That’s fine, the fact still remains that you could not address that concern of mine in post #2. Here we are at post #8 and now you are all researched up and talking intelligently. You did not do your due diligence prior to making this recommendation. Fact is, you didn’t research any of this until I brought it up. So for that, you are welcome.
 
I didn't bring it up because you seemed to be knowledgeable in blower motors, said you were a mechanical engineer, and it was obvious to me because one side of the blower contains the motor and the other side contains the fan. That's how blower motors work, the motor cooling is outside the device usually so they get fresh, cool air, and the other end contains the motor shaft that the working fan is attached to. I shouldn't have to explain this to a mechanical engineer.

And one other thing, you seem to be suggesting that I am recommending that people do this, when in fact, it's a "here's what I did today" in my grow room. The same thing people do on this site all the time when they make their own DIY lighting, automated watering systems, etc.

I appreciate your concern, but when I proved it was invalid and the reasons behind why, that should be enough. There is no reason to switch to a personal attack on my tactics of sharing it to the site. We learned a lot about centrifugal blowers from this thread, but the main thing I learned is to steer clear of Toker1.
 
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You are defining this application, but no not all applications are in fact this way. Most motors I come across in the field are attached to a gearbox then the drive shaft for the application.
I never said I was a subject matter expert on blowers. Lol not my industry. I do know what motors do when under load, hence my original concern.
My concerns were all legit. You even needed to consult an expert to answer my questions properly.
Yes, posting “what you did “ publicly is in fact recommending it publicly. What would you call it?
Steer clear of whom you wish.I will steer clear of people modifying equipment who have not thought about the process they are modifying. People who do that are dangerous to be/work around. If that butt hurts your ego, I’m over it. Safety is my concern, not a bruised ego.
 
"But you are increasing the resistance causing the motor on the blower to work harder and draw in more amperage. Just be caureful with these types of modifications." That was your first reply. Which is patently false because a restriction in flow actually draws less amperage.

" If it was not designed to bear additional load (like from the resistance of the filter and ducting) you will be shortening the useful lifespan." Second falsehood because restricting the flow does not create fan resistance, it reduces it.

"Back to amps going down, if amps decrease there is less electric potential to push the motor and speed Will therefore
decrease." Third falsehood. Amps go down because of decreasing load and speed goes up. No load=less amps.

You have been a bully on my thread, totally junked it up and now are being a bully insinuating that I'm "butthurt" I'd delete the thread if I could, but I'll let the readers sift through this crap to find the truth.
 
Yes... that’s what I was saying. I admittedly said I’m not the subject matter expert on blowers. Just referencing my knowledge about motors themselves. If you had done your research prior to my asking... you should have said the resistance on the intake is independent from how hard the motor works. That would have made sense.
Second point... that’s why I said “if it was not designed” all you had to say was, it was designed for that type of resistance.
Third point, load on the motor which you are saying is independent.
Why are we just discussing this all now? Why didn’t you answer these statements like this before. It’s because you didn’t know. You made the design, but didn’t think about any potential implications. If you had done the proper research you could have easily answered each one of these statements very easily. So if you want to blame someone for making a mess here, check yourself. These questions would be easy to answer for someone who has actually put a little thought into their designs.
 
I can't take credit for the design, it's already a well proven system within the DIY laser cutter crowd as well as the 3D printing crowd and I'm probably not the first one to use it for a grow room either. You did force me to do the research on this already proven safe system. And that was mentioned early on. I'm putting up a bunch of disclaimers on the first post and that's the last you'll hear from me. Hopefully someone gets some use out of this thread.
 
Right on man. I didn’t mean to open such a can of worms, this seems like a very well designed blower. Seems like they made it to be able to work with the resistance of the filter and ducting in the way you are using it. So no harm or bad words from me. Thanks for addressing these concerns about motor changes and the response to those changes. As you can see from the report below most motor applications are much different from how this was designed. Obviously these principles were incorporated into the final design and are optimized to deal with such changes in operation. I only know what I know and I’m a bit more educated on blower design today than I was yesterday.
 
Yes...that means when designing a motor for a specific application more load requires higher voltage/amperage (perhaps different larger motor). It’s not a reaction to increasing load on a single motor. Yes I agree, more loads require more horsepower. So in short, don’t undersize the motor for the application it is being used for. More load requires a bigger motor in general.
This quote below is directly related to the reaction of increasing load on a single motor.

The formulas indicate that an increase in power due to an increase in the service load requires a proportionate rise in the torque so it can match the load. This increased torque draws a bigger electrical current into the motor.
 
It seems very smooth and quiet and I'm only running it on the lowest setting and my house has no smell for the first time in several grows. I don't know why I didn't think of using it in my grow room sooner, I already had it for several years just waiting for me to finish building my laser cutter. I've got an RPM/strobe meter and I can see if the RPM's go up as the filter gets more restrictive. Not sure how much life I can expect out of the charcoal, but I've got refill charcoal for it and a shaker table so I should be able to settle it in just as well as factory.

I DIY almost everything. I built a CNC machine from scratch a few years ago, and within two years I was machining rocket parts in my basement for the Navy ramjet missile program out at China Lake. I try to learn something new every day, and now I know the science behind blowers and it's totally counterintuitive to what I believed before this thread.
 
CNC is so bad ass! I have had the pleasure of working with a cnc horizontal lathe. Before that we were using the old school dial in lathes. That’s a skill set in itself. Not enough machinists left in the country though. It’s a talent that is fading way to quickly!!
 
The thing to consider is that the centrifugal blower is going to be at its highest load when it is totally unrestricted. Adding filters or long runs of ductwork with actually reduce the load because it will get less air. Just consider the air is the load. So it's actually safer when you add ductwork and filter because it is drawing less amps because it becomes more and more unloaded as the filter gets plugged. It's similar to an airplane propeller will be under more load on the ground than it will at altitude. At the same power setting, the RPM will rise as it gains altitude because the air gets thinner. The load on the motor eases at higher altitudes, so they have less fuel consumption at cruising altitude.
 
I have several lathes, all manual though. The mill is the only CNC I have unless you count my 3D printers, which are technically CNC machines. I have an old WWII era screw machine too. Google that if you want to see how nuts and bolts were made pre-CNC. They are actually faster than CNC if you set them up right.
 
The load on a motor is what a motor must physically push past in order for that equipment to function properly. Typically a motor’s actual duty is about half of its capabilities. (Safety factor) In this application, the desired reaction is the air flow rate. When we restrict the desired end effect, a typical motor will increase the torque/speed in an attempt to obtain that desired rate (load is increased because motor is pushing harder to obtain same results). We can add control devices, such as a VFD, to regulate this phenomenon. But just a motor alone will respond by fighting harder to push past the restrictions. This can lead to motor burn. The load on the motor increases because of the air flow restrictions that it must now move past in order to reach the original desired air flow rate. That motor responds by drawing in more amps to increase the torque and maintain that airflow rate that is the desired flow rate to maintain standard operation. Obviously, Chicago Electric has added some control devices to allow the amperage to decrease upon flow restrictions. Which means it can operate at a varied load. Most motors are not designed that way. They will push and push harder until they burn up components or the desired end result is reached.
 
Increasing the RPM is increasing the load on the motor, it has to work harder to get the desired results. A flying plane uses less fuel than take off because of Newton’s law of motion. An object at rest vs an object already in motion. Getting the plane up to the desired speed required for flight (from 0mph) requires much more torque than maintaining that speed through the air. So load is decreased because the motor doesn’t need to work as hard just to overcome the drag/ friction of flight.
 
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Decreasing the air load on the motor is not "loading" the motor, it is unloading it. I can't spend the time teaching you physics if you insist on being right about your absolutely wrong theory. And you are now explaining Newton's third law and aerodynamics to a rocket scientist. The air is the load. When you remove the load (restriction), the motor works less hard and RPM's rise, amperage goes down, not up. It's as simple as that. I really don't have the time to go around in circles with this trying to teach you. Feel free to do your own research but please refrain from trashing up my thread with this theory of yours based on incomplete understanding of how fans work. I've done the research, now please do yours.
 
You must not have watched that video link I already provided. Skip to 2:13 please. https://www.youtube.com/watch?v=qX-G...grayfurnaceman

Here are a few more links if you really want to learn. Any more of your similar comments after you visit these links, I will have to consider that you are trolling me because this should make it very cut and dried for you. These are from an engineering site for mechanical and electrical engineers aka experts.

https://cr4.globalspec.com/thread/108775/Squirrel-Cage-Blower-Speeds-Up-When-Airflow-is-Blocked
https://cr4.globalspec.com/thread/28775/Blocking-off-inlet-on-squirrel-cage-blower
https://cr4.globalspec.com/thread/31800/Squirrel-cage-amperage-related-question
 
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