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Union Graduate drive belt & turnbuckle queries


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Established Member
2 Oct 2013
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I recently bought a Union Graduate longbed that used to belong to Ray Key no less (thanks Paul Hannaby) and it's almost fully installed now. I've a couple of niggles to fix before I fully enjoy the machine:

When I first set it up there was quite a bit of vibration through the motor plate. I noticed that the turnbuckle was disconnected (one end not threaded in) and once this was re-connected most of the vibration is gone (now it oscillates a mid-range motor speed and mostly on the central speed). How does one set this assembly up for the correct amount of belt tension? Obviously I don't want to overwork the spindle bearings.

On to the V-belt - which size and spec of belt do people use on these? Mine is a 3 speed 'Variturn' pulley I think and it has an A66 belt on it, but I'm a bit concerned it's been overstretched due to the issue with the turnbuckle - the motor plate is not flat when fully tensioned. I also noticed that the V-belt doesn't fit all the way down into the pulley - is this normal? Is the alignment between the pulleys particularly significant regards vibration? It's quite a long belt travel, but obviously plumb travel will reduce vibration too.

Any other tips for nice smooth running of these machines?

Thanks in advance!

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