I've got a number of fairly high-quality DC fans (Papst, NMB, Panasonic), some of which are "Smart Fans" that I don't want to lose. All are plastic construction, not die-cast metal. I've noticed that on several, the supporting struts between the motor and frame have developed fractures. I've done some repairs with epoxy that seem to be holding. The body of these things seems to be made of some sort of polyamide (nylon?) with a lot of filler. The usual solvents (e.g. methylene chloride) don't make a mark, so solvent cement appears to be out of consideration. Am I wasting my time with 20 and 30 year old fans? Should I just scrap the lot and chalk the loss up to age? Experience of others would be much appreciated. --Chuck

Unfortunately many plastics do degrade with age (oehr factors, such as UV can speed it up, but they fail anyawy). It's one reason I prefer metal to plastic (although of course there are metal alloyst htat don;'t last too...) I've not seen thse fans, but can you strangthen them by taking them apart and fitting a metal plate overthe end, fixed to the frame and the motor end? There are plastic glues (not solvents) that are supposed to stick to any plastics (one even claims to sticl to ptfe!). One of those might make a stronger repair. Only you can decide what your time is worth. I know I'd have ago because for me, a couple days repairing one is worth less than the \pounds 20 that a new one would cost. Others may differ. I;'ve enver had this fault in a fan thouhg. Fan faults I've repaired incldue bad bearings, burnt out windings (yes, I have rewound one) and power transitor failure on the PCB (fortunately that one used discrete components, not an IC so it was easy to fix). You may have noticed i often include a scheamtic of the fan in my HP computer schemeatics... If a plastic part failed I give serious thought to either replacing it with metal (not an option here, you don't want to have to make the entire fan hosuing) or at least strengtheneing it with ametal plate. That's what I would do here as I suggested above. -tony

I had an old fan die in somewhat similar way. It had a Papst-type (external rotor) motor, the blandes were a plastic mouding that could be described has having a hollow cyclidriacl cetnre (which was pressed over the outisde of the rotor) with the 3 bl;ades integrally moulded with it. Anywy, the cylindrical section split down one side so that the blades fell off the rotor. That was one I didn't fix (althohgh I did use some of the parts as sapres ofr other siliar fans). -tony