Re-attaching fan blade

[Tinkering_Guy]

I have a 10" blower fan from an old computer that really pushes the air (about 250 CFM).  Unfortunately, one of the plastic blades has snapped off as shown in the really piss-poor photo.

I'm wondering whether this is something I can successfully repair with JB Weld (the blades spin at 1600RPM), or whether I might be able to make a completely new blade assembly, or whether I should just give up on it as anything other than a motor.

Any thoughts?

[Bernd]

Looks like a pretty clean break. I'd try some 5 minute epoxy. Might be a bit out of balance, but a little bit of filing would help bring it back into balance.

Bernd

[DMIOM]

It might also be worth stitching or stapling it with some copper wire

Dave

[Tinkering_Guy]

It's high-impact plastic, so 'stitching' it would involve some pretty fine drilling tasks.  However, doing something like that to keep the blade from shrapnelating if the join ever gave way would be a good idea.  Thanks!

[Dean W]

For a fan that spins at 1,600 rpm, I would stick to just gluing it.  JB Weld is good, strong stuff, and not very dense. 
File off the excess to try to maintain some balance, as Bernd suggests.  I think if you started adding much weight,
even a little bit, as you would in stitching to any one blade, it will soon start to vibrate quite a bit.

The safe thing would be to get a new fan, you know.  It's great to fix things though!
Making a new fan blade is surly possible, but again, balancing something 10" in dia for even that relatively low speed
might be beyond casual machining methods.  I'm a believer in the 'anything can be done' mantra.  Just depends
on how much time and money you want to throw at it.  Heck, I fix stuff out of pure meanness, sometimes.

Dean

[Bernd]

Heck, I fix stuff out of pure meanness, sometimes.

What? You get mean?

I can't believe that.         

Bernd

[Tinkering_Guy]

A new one is a fair chunk o' change.

I'll try JB Weld on it.  The angle of attack is about 40°, so I expect there'll be significant torque force placed on the joint.  That worries me a bit.  The assembly was injection-molded as a single piece.

Maybe a thin strand of wire circumferencing all three blade tips would provide sufficient relief..  I'll have to experiment.

Thanks!

[John Rudd]

If its plastic, can you obtain a small amount of the solvent type of adhesive used by those folk that make objects from Acrylic/Perspex/Plexiglas? (is Plexiglas real or was that something from Star Trek?)

I got some stuff called HCL it looks like water has no odour but is a solvent adhesive...When the lock broke on my Ford Mondeo ( Mercury to you guys...), I used the stuff to re glue the broken plastic tag...worked a treat and was as good as new...Becuase its a solvent it literally welded the broken part back on to the parent

[75Plus]

If its plastic, can you obtain a small amount of the solvent type of adhesive used by those folk that make objects from Acrylic/Perspex/Plexiglas? (is Plexiglas real or was that something from Star Trek?)

Yep, It is real and has been since 1933. Here is the details.

http://en.wikipedia.org/wiki/Poly%28methyl_methacrylate%29

Joe

[snub]

My favorite glue for joining plastic is 'cyanoacrylate', also known as Super Glue or Krazy Glue. I've used it to join PVC sheet, and even with right angle joints, it's way stronger than the PVC glue made for joining pipe. I use plastic a lot for mocking up projects. If anyone is interested, here is a link to a webpage where a guy experimented with different adhesives:

http://www.solarbotics.net/starting/200207_sintra/200207_sintra_adhes.html

[Tinkering_Guy]

I used some cyanoacrylate and added the blade guys, and it works a treat.  Again.

Thanks, all!

[Bernd]

Very good Tinkering_Guy. Now for the "how long will it last test".

Bernd

[andreas]

If the plastic is thermosetting you may be lucky,but if it`s thermoplastic.....no way
Andreas