Gear pair with no keyway, slipping

[rcx132]

I bought one of these "Chinese standard pattern" metal mitre bandsaws. Same saw is sold under many names. It was an absolute delight to use, it cuts quietly and no sparks. But today it had a total loss of power, the motor turns but the blade will only move if there's no load.

I took it apart despite warranty as I'm curious. Theres a pair of gears.... holding one gear using copper clamps I can still turn the other gear. I used a float and separated the two and there's no keyway. Surely this isn't an attempt at a slipper clutch or something?

Edit: I've cleaned the gears and applied loctite because I need it to live on another few weeks. The quality of these things is bad, the casting is ultra thin, missing bolts, stripped threads, one bare live wire floating around.

 

[Pete.]

Failed press fit. I'd glue it on with a couple of tig welds.

 

[frank horton]

as above or bearing fit Loctite....

 

[Agroshield]

...bearing fit Loctite....

Bearing fit loctite is normally 641 medium, for when disassembly is needed for servicing. For this, the green 601 high strength (never-comin'-apart) might be better.

 

[RichardM]

I'd give the supplier a call, they may send you a replacement and not want the old one back.

 

[rcx132]

@Pete. that could be it. Unfortunately there's no way to Tig it. I'm so disappointed, it was

I'd give the supplier a call, they may send you a replacement and not want the old one back.

I've emailed the supplier and will see what they say. The machine has a three year warranty so despite the poor build, it does work well, so I'll hang onto it. I've seen Warco do a steel construction mitre band saw for £400 but other than that I haven't seen any quality bench top mitre band saws in the £200-£400 range. Now that I've been spoilt by the low noise of a band saw I don't want to go back to a grinding disc chop saw.

 

[Chippie]

Better to have something slip, than a blade jam and motor burning out…

 

[rcx132]

Bearing fit loctite is normally 641 medium, for when disassembly is needed for servicing. For this, the green 601 high strength (never-comin'-apart) might be better.

So the well out of date loctite 270 I've had for 15 years didn't hold. I've just ordered the 601.

 

[Agroshield]

I've just ordered the 601.

Have a little read of the design guide. There is an optimum clearance/film thickness for the loctite to develop its best strength. If it is a failed press fit, you might end up having to sand the ID of the gear to open up the clearance.

See: https://www.scribd.com/document/487749534/LOCTITE-Retaining-Brochure-F-pdf

I cannot find a direct pdf download just now and it is >4Mb so too big to upload here.

 

[rcx132]

Better to have something slip, than a blade jam and motor burning out…

Yes, a proper slipper clutch that can take it, and not two metal surfaces which will quickly become even looser. Some tools also detect high loads and cut out to protect the motor.

 

[Ruffian]

I had similar with my parkside one.

Managed to put a proper nugget in the shaft with a chisel to peen it to pinch it up.

 

[rcx132]

I had similar with my parkside one.

Managed to put a proper nugget in the shaft with a chisel to peen it to pinch it up.

Was yours the same model of saw?

 

[Ruffian]

Looks similar but slightly different,
But it's just about trying to increase the friction.