Thread: Making a Faceplate Lathe

Rob & Wayne

I would suggest you consider some kind of positive tension (or retention) beyond gravity. A motor can give a very destructive 'kick', particularly in direct on line starting, or abrupt stopping scenarios. Think bent shafts, spindles and broken pulleys, gears or worse.

There's always the question of what should be the "weak link" in the event of overloading, and to my way of thinking it would be preferable that electrical overload (VFD, DOL or fuse) triggered first, followed by minor mechanical sacrificial elements like a shear pin.....even key's in shafts are designed to be sacrificial, although I've never seen a sheared key. I imagine the shaft and pulley/gear would be badly damaged either way.

Admittedly, when things go wrong, the simple inertial load of heavy components can wreak havoc before the electrical limits can take effect.

Regards
John

really enjoyed all that. fond of old machinery.

cheers mate

Originally Posted by jcge

Rob & Wayne

I would suggest you consider some kind of positive tension (or retention) beyond gravity. A motor can give a very destructive 'kick', particularly in direct on line starting, or abrupt stopping scenarios. Think bent shafts, spindles and broken pulleys, gears or worse.

There's always the question of what should be the "weak link" in the event of overloading, and to my way of thinking it would be preferable that electrical overload (VFD, DOL or fuse) triggered first, followed by minor mechanical sacrificial elements like a shear pin.....even key's in shafts are designed to be sacrificial, although I've never seen a sheared key. I imagine the shaft and pulley/gear would be badly damaged either way.

Admittedly, when things go wrong, the simple inertial load of heavy components can wreak havoc before the electrical limits can take effect.

Regards
John

Yes, those are quite valid considerations, John. In a "gravity" motor situation there's usually some type of slotted adjustment bracket where the motor position can be fixed to maintain the optimum belt tension, but this still wouldn't compensate for potential issues with any "kick" in the drive train. There's always seems to be an element of blind faith in these things, doesn't there? We generally just need to temper this with some basic common sense and precautions.

Wayne

Can't believe I missed this thread. Incredible stuff Rob.