Bent pulley / motor shaft?

snap, crackle and pop
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Alec124c41
vinyl engineer
vinyl engineer
Canada
Posts: 23207
Joined: 28 Oct 2002 03:24
Location: North of Toronto, Canada

Bent pulley / motor shaft?

Post by Alec124c41 » 21 Jul 2008 22:26

I have seen a few posts querying the alignment of pulleys. I was given an old Thorens 150 a few years ago that had been transported in the back of a truck with the platter in place... at the start...
Visibly bent driveshaft!
Here's what i learned:
To check if your drive pulley is straight or wobbly, bring the point of a pencil slowly to the rotating bare pulley. If you get a pulsation, it indicates some eccentricity. The pencil will mark the high point.
Place a small block of wood against the high point, and tap it gently with a small hammer. Take your time. Many small taps and frequent retesting with the pencil can rescue even what looks like a write-off. The pencil test is quite sensitive, and you can get a very smooth-running result IF you don't damage the bearing. It is better to tap toward the side away from the spindle.
Alec, who can't leave anything alone. :{)

sq225917
senior member
senior member
Posts: 956
Joined: 17 Jun 2004 19:56

Post by sq225917 » 23 Jul 2008 02:43

nice pencil tip. if you clamp it rather than holding the pencil it removes the natural variation that the pulse in your finger provides, crazy eh, but it does make it move...

Alec124c41
vinyl engineer
vinyl engineer
Canada
Posts: 23207
Joined: 28 Oct 2002 03:24
Location: North of Toronto, Canada

Pencil

Post by Alec124c41 » 24 Jul 2008 22:01

In your hand you can feel any vibration caused by eccentricity, very sensitive and very simple. I go for simple every time - it suits me.
Alec

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