Instructables
Picture of Magnetic propeller balancer

So you have spent a lot of money on your diy quadcopter(or any multirotor) and refuse to give any more, but you still need a propeller balancer. Balanced propeller is very if not the most important thing for multirotors.

Guess what, you can make your own, from old computer components.

If you happend to work in ICT company, there is always a lot of that stuff around. Besides broken hardware, some tools may also come handy. Let's begin with stuff you are going to need.

 
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Step 1: First things first

If you are lazy and don't care about 20 bucks, go and buy propeler balancer. Go for a booze right away.

Step 2: Stuff and tools

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1. Piece of wood,

2. Set of screw thingies,

3. Drilling machine,

4. Handsaw,

5. Angle grinder,

6. Broken DVD writter,

7. 4x Hard disc drive,

8. Rack server,

9. Hammer,

10. Ruler and

11. Sandpaper.

12. 2-8x Pen

Step 3: Disassembling hard disk drive - harvest magnets

Disassamble hard disk drive with appropriate screwdriver. Make sure you have made backup before. If you are stuck with some plastic hooks, take hammer and brake them. Repeat as many times necessary. Don't worry about hammer and you can't overdoit smashing hard drive. Now if magnet is free to take out, take another hard disk and repeat this step 3 more times.

Now you should have 4 magnets. If you have less, you don't know how to count or you dissasambled some SSD or whatever.

Step 4: Disassembling hard disk drive - harvest metal axle

Use screwdriver to unscrew all screws. Now, it won't allow you to open it just like that. Help yourself with hammer, convince him. Eventualy all vital electronic parts will move away in several dozen pieces. Take out shorter axle and throw away smashed DVD writer into garbage(recycle!). Or you can intall into colleagues PC. Either way is ok.

Step 5: Rack server - harvest hdd case

Download manual for your rack server and find a way which one of 2 possible plastic handles enables taking out hdd case. After that, unscrew 4 screws or 5 or 6, depends on the case. All you need from this are two metal side thingies. Rest of the case you can put back into rack server. Then you can practice hammering on server.

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graydog1114 months ago

Good Instructable. I am now hunting for two big magnets to balance my lawn mower blades. http://www.instructables.com/id/Lawn-Mower-Blade-S... I have one 12V electromagnet I made that will lift about 250 lbs, but too much work to make another. Any suggestions?

Harbor Freight Tools has magnets at a reasonable rates. Hope this helps

motions5 months ago

Oops. Friction.

Step 4: Disassembling hard disk drive - harvest metal axle

That should be not hard disk drive

Should be cd or dvd drive

3 1/2" Floppy Drives as well...

What is a floppy drive?

c13378 morsed24 months ago

its a flying car!

lol....yeah, I know....I'm showing my age now. hahah

I am older than you I bet!

Nice instructable, I don't have a large quad copter, but my roommate does, and I am going to show it to him, maybe even have a go at making it.

When I started work in the US, I was using 8 inch floppies, beat that if you can. And my very first hard drive drive as a 20 MB, ST225. 20MB, YOU CANNOT BUY THUMB DRIVES THAT SMALL TODAY.

(Glad you took the last comment as a joke)(and I lived in a paper bag in the middle of the street)

Later everyone

altomic morsed24 months ago

(and I lived in a paper bag in the middle of the street)

Luxury!!!

mayra63854 months ago

Sad ću te tužiti tvrtci NoviNet da si im ukrao kemijsku!!! :D

JayGeeBSE4 months ago

To the person who commented that this only produces static balance, and not dynamic: Please note that the thickness of a propellor (IE the along-axis measurement) is tiny compared with the diameter, so there is very little scope for the dynamic balance to be significantly out. Not worth worrying about. In contrast the long thin arnatures of slot cars really need dynamic balancing. As far as I know until recently you could only do dynamic balancing with electronic vibration sensors and electronic flash. Recently I saw a way to do it (was it on Instructables?) using the vibration sensors in a smart phone. But limited to items you could balance with stick-on tape, and that does not include armatures.

fabelizer5 months ago

Very entertaining read! Thanks. Nice project.

Could be a fun motor too! Electronic commutation anyone?

enriqueconde5 months ago

Very nice but be aware that this is only static balancing!

clazman5 months ago

Again I was enticed by the headline to view a nice piece of work with high precision components only to discover the use of a scrap of low tech low precision wood. Don't get me
wrong, I enjoy items made from wood. This is NOT such a place.

Why not use the power supply housing or maybe the drive housing?

vincent75205 months ago

Why do you have to steal a pencil ?

Stealing is wrong, even on the internet. ;))

rimar20005 months ago

You don't explain how to use the device. I think that it does not work.

Bill WW rimar20005 months ago

At first I thought I would not understand because of all the computer hardware terminology like HDD, Rack Server, SDD, still do not know what is an ICT company.

****

Al principio pensé que no lo entendería porque de toda la terminología de hardware como HDD Rack Server, SDD, todavía no sé lo que es una empresa TIC. Pero, entiendo "sierra", "lapiz"...

Bill WW rimar20005 months ago

It took me a while to understand, but yes, a static balancer held by magnetic field. A very interesting concept.

My concern (posted above previously) is that the axle or other components may not be on center. Best would be to use the same axle as in the actual engine, or identical.

***************

Me tomó un tiempo para comprender, pero sí, un balanceador estático realizado por el campo magnético. Un concepto muy interesante.

Mi preocupación (publicado anteriormente anteriormente) es que los componentes del eje u otros pueden no estar en el centro. Mejor sería utilizar el mismo eje como en el motor real, o idéntico.

Buen dia, amigo.

Danijel0frk (author)  rimar20005 months ago

Propeler balancing is more or less known only in rc circles.
In a nutshell, the goal is to identify heavier side of propeler, and then
sandpapering heavier or putting tape on lighter side. Also there is a
process of hub balancing.
I might record a video how this diy balancer works with explanation how magnets
provide almost frictionless axle turning :)

on the contrary sir , even in the real world propellers need to be balanced, I have been working in the aircraft manufacturing industry for over 25 years and an aircraft cannot be certified to be airworthy unless the propeller has been inspected and balanced by a certified aircraft tech, after wich they will affix a certification stamp of airworthiness ,, this certification law has been in effect since 1945

criggie larz0015 months ago

Does the certification stamp unbalance the formerly-balanced prop ?

larz001 criggie5 months ago

lol no it doesn't, once the alcohol in the ink evaporates then the remaining pigment wouldn't weigh enough to make a difference

larz001 larz0015 months ago

also I loved the ible,, I have owned the topflight mag balancer for over 20 years now and love it, wish I hadda thought of this 20 years ago lol

I would love to see a video!

Thanks, I know what is static balancing and dynamic balancing too, both are used in all devices that have high speed rotating parts, not only in RC. But I have not any idea how you could use your device. Maybe it is the best of all, maybe it does not work.

Being Instructable an "all purpose" site, your instructable is read by many persons like me, that have no knowledge about RC but are interested in good ideas.

Danijel0frk (author)  rimar20005 months ago

I appreciate your comments, you are absolutely right. After all this was my first "instructubles" . For example, axle must be perfectly horizontal and perpendicular to both sides(magnets). Also cones must provide perfect vertical spin of propeller. Any imperfection of the hub must be somehow eliminated. Any little variation will give false results. Soon i will make an update with some pitfalls and explanations about workings.

Now I am understanding your proposal. Your device is a static balancer. Good idea to use magnets, but your axis should be turned by a good lathe, not by hand.

A common error (not yours) in this method is to think that the propeller MUST BE horizontal to be balanced. If it is the case, the propeller is unbalanced laterally. You must do a large series of measures, ensuring that the propeller stops in DIFFERENT positions each try.

Static balancing is problematic and difficult.

As a newcomer in Instructables, you should know that later additions to your post will be seen by few or none persons. You must wait to finish the instructable BEFORE publish it.

Danijel0frk (author)  rimar20005 months ago

This diy project is based upon several videos and articles about balancing propeller. Your explanations go way beyond those instructions and understanding. If you have good web resources, please post it, so everyone who reads this instructable will know to which level is this balancer precise and what are the drawbacks and errors.

I'm working on a solution which will provide better precision with common tools, but won't go to the scientific level of precision, because balancers for RC in this price range don't provide that. Also there must be a way for calibration of balancer.

No, I have not web resources. I only tried to do propeller balancing a few times. Your idea is good, but if the axis have 0,01 mm eccentricity, it will work against you. Its mass also matter, lightweight is better.

Poppy Ann5 months ago

This sounds easy but the problem is unless the pen thingy's are a very very good fit then they will be out of center, I bought one (or) two genuine magnetic prop balance's and even on them they are not that good unless you get one that the holders are tight on the shaft i noticed if i balance the same prop that it alters every time i do it due to the holder having a loose screw thread.

a quick tip on grinding the center axle to have a point is hold the axle in a electric drill and grind it whilst it is turning.

also you can pick one up from hobby king for $6.72 product id: 171000401-0

another thing to watch out for is hitting a magnet hard will de magnetise it so don't hit it to much with a hammer.

but all in all a good instructable.

Bill WW Poppy Ann5 months ago

You said: "unless the pen thingy's are a very very good fit then they will be out of center." Exactly my thought also. This Instructable will do an excellent job balancing the entire assembly of propeller, pen thingy's, and axle. But the pen thingy's and axle could be suspect, because yes something may be off center. The test assembly may not be identical center or alignment compared with the actual propeller shaft and bearings.

Bill WW5 months ago

In the intro photo, is the left hand side of the axle levitating? Wow!

onemoroni15 months ago

Ahh yes, manly man activity with tools! Nice build.

maxom5 months ago

After looking at this, I believe if I need a prop balancer, I would definitely go shopping.

cepterbi5 months ago

had fun reading. don't have a helicopter so i'm good anyways.

Too funny! The excellent sense of humor is only exceeded by your imaginative and useful creation of this very useful device. Hats off to a great instructable!

perfo5 months ago

nice instructable with a good bit of humor, thanks.

LancasterPA5 months ago

Ha, Ha, I thought this was for a real airplane propeller. What was this guy going to do with all these little things. My propeller is 60 inches. Maybe back in the day when they were getting rid of Univac's the parts and magnets would have been big enough.

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