Im currently building an Alfa MiG 15, but have drilled the hole 0.25mm too big for the fan to fit onto the motor shaft so it is now slightly loose.
...Will the glue be strong enough to hold this on?
...Will this cause too much vibration?
...is it possible to balance a fan once fitted?
Thanks
David Bevan
Mmm. I'd advise bushing it out and redrilling correctly
Fans aren't TOO bad on vibration as the diameter is small and the mass is low, but variations in te fan-to-duct clearance are I think, not good for efficiency.
Even a small diameter fan with a very tiny imbalance from being off center spun at 30,000 rpm is going to exhibit too much vibration. Not only will it lead to premature motor failure, but structural damage and terrible battery efficiency and reduced flight times. Rebushing is not likely to help because you will either need to fill the hole completely and find the EXACT center to rebore it, or the hollow bushing you put in is going to have ITS center offcenter by the same amount as the mis-drilled hole.
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One assumes he would chuck it in a lathe and redrill it properly. And balance it afterwards. Its not rocket science.
No.
Yes.
This should normally be done, but you won't be able to properly dynamically balance the assembly with the hole oversized.
--- Rich
I wouldn't assume that. He didn't drill it right the first time :)
--- Rich
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