Bandsaw Blues

[Sub MandrelParticipant @submandrel]

[Sub MandrelParticipant @submandrel]

I had a few troubles with my bandsaw (the standard cheap, 45 degree one) yesterday. I had to re-braze the blade twice, and it kept stalling and throwing the blade. I investigated more deeply than usual, and it turned out the driving wheel was moving in and out by over 1/8″ on its shaft. This movement has probably been there since new, and I suspect it has been the cause of a number of troubles

 

I ended up more or less dismantling everything at the driving end. The driving wheel had been forced on to a shaft that was too tight, with a key that was too big for its slot, the combination making it very hard to remove, even with my Trusty Picador puller. A side effect was that the worm wheel was free to move sideways as well, and as a result (or possibly partly because the shafts are too widely spaced) the gear has worn really badly – so badly that the oil was loaded with bronze particles and resembled liquid gold! Very pretty, but the tooth shape of the gear is so badly worn it now jams if run backwards by hand. Fortunately, now I have thinned the key and eased the shaft, the driving wheel runs fully home against its bearing and the worm wheel is in slightly better mesh. I still think the centres are too widely spaced, it would be an improvement if the bearings could be inside an eccentric spaced so the gear mesh could be adjusted.

 

After all this it appears to run OK, but when I tried to finish the cut (2 1/4″ diameter MS) the kerf had closed up, grabbed the blade and it threw itself.

 

ho hum, these things are sent to try us

 

But I recommend anyone whose bandsaw is a bit badly behaved, check to see if the driving wheel moves in and out, and also open up the gearbox and check the oil once in a while.

 

Neil

 

P.S. For all the cheap and cheerful nature of these saws, the main arm casting is a real piece of the foundryman’s art. It has a complex moulding line, lots of fiddly bits and the whole thing is only about 1/8″ thick.

 

Neil

 

 

[Terry LaneParticipant @terrylane]

After chopping out the original worm wheel on mine I replaced the gearbox cover with a piece of clear Perspex, with a 1’2″ x 26 tpi plug. I can see the oil level at a glance, and top it up without removing the cover. All this was several years ago, and no trouble in that department since. Just last week, however, I replaced both the driving and idle wheels as the flanges were worn to the point of almost not being there. The new wheels have cured the blade-jumping problems of recent times.

[Sub MandrelParticipant @submandrel]

Good idea Tel,

 

Where did you get the replacement parts from?

 

I’m still having problems – I don’t seem to be able to stop the blade slipping on the wheels without excessive tension, and every time it jams, it jumps off the wheel. (I’m using cutting oil).

 

Neil

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