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Old 23-02-2015, 02:09   #1
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Balancing a fan blade

Anyone with ideas how to balance the blade on a Caframo Sirocco? My new fan vibrates causing the bulkhead to act as a drum!
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Old 23-02-2015, 04:27   #2
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Re: Balancing a fan blade

Return to place of purchase for full refund or exchange? They shouldn't do that! If unable, do what they do with ceiling fans and glue weights onto the blade(s) to balance, or maybe even trim the overweight blade until balanced. I'd be first checking that the shaft isn't bent or the blades don't have uneven pitch first, however.
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Old 23-02-2015, 05:45   #3
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Re: Balancing a fan blade

get s spare blade set, what are they, 15 dollars a set?
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Old 23-02-2015, 06:51   #4
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Re: Balancing a fan blade

Pure hit and miss, take a weight that you think appropriate and tape it on a blade, if the vibe is worse, try another blade until you get a reduction in vibe, then move the weight in or out until the vibe is least. You can of course decrease or increase weight, but moving it in or out along the blade does the same thing.
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Old 23-02-2015, 07:50   #5
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Re: Balancing a fan blade

Quote:
Originally Posted by Reefmagnet View Post
Return to place of purchase for full refund or exchange? They shouldn't do that! .............
Yep. You're not supposed to have to fix a new product.

That's the advantage of paying full price at West Marine. They will take that fan back, no questions asked. If you are nice enough, they will let you test the replacement before you leave the store.
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Old 23-02-2015, 08:18   #6
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Re: Balancing a fan blade

Place a piece of tape on each blade in sequence. See which one resolves the vibration.
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Old 23-02-2015, 09:57   #7
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Re: Balancing a fan blade

Had the same problem with a couple of those nice little fans. I just cut a disc of spare rubber sheet and slipped it between the bulkhead and the mount - noise gone.
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Old 23-02-2015, 10:27   #8
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Re: Balancing a fan blade

On a fan, the radial weight is not as near as important as the pitch. It works by cutting slices of air out of the mainstream and moving them in a different direction. If the blade is warped a little, the amount of air moved with that blade will weigh more or less than the blades next to it. so it tries to move ahead of the other blades, but cannot because of them all anchored at the hub. so It can be balanced statically and be unbalanced while rotating. This makes it a little hard to balance a fan.
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Old 23-02-2015, 10:54   #9
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Re: Balancing a fan blade

Remove the fan blade and install on a shaft with a ball bearing in the hub so it rotates very freely.

Fix the shaft horizontally to spin the blades. Fix a marker on a stable stand that you can move up to the spinning blades. Spin the blades and move the marker until it just touches the blades. Do this for the front and back.

This will show you if any blades are not lined up in the same rotating plane. If not too far out then trim the leading and/or trailing edge of the blades until they are in line.

Then spin the blades until they stop naturally. Mark the blade on top. Repeat a couple of times until you find the same blades is consistently at the top. That will be the lightest blade. Add a small bit of weight to that blade and repeat. Keep doing this until the blades no longer stop with the same one on top every time.


OR, take the fan back and get one that works.
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