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find exact center of tonearm bearing

My graham 2.2 bearing cap is a flat circle with no marks showing the exact center. When setting the distance between the spindle and this exact center I do not want to guess. I looked at many ways to find the center using rules and compasses and thought they would be difficult due to the bearing cap's small size. I just found an item from Micro Mark # 82285 for $18 which will work perfectly. hope this helps-i do not work for company. i may buy a bunch of these,rebrand them and sell them for big $$$ as is the audiophile way...just kidding. good listening to all.
rlw3

Showing 1 response by dover

dover
2,295 posts
 
If you use a set of dial calipers to measure the diameter of the bearing housing, then measure the spindle to front of housing instead -
The pivot to front of bearing housing distance should be :
Recommended pivot to spindle distance less ( 0.5 of diameter measured ) - assuming bearing is in centre of housing and that arm is level when you measure.
If you cant find the centre of the spindle then do the same - use dial calipers to measure the diameter. The centre is halfway. So you can calculate the distance from the edge of the spindle nearest the arm bearing to the front of the arm bearing housing.
The easy way is to do the calculations, then simply make a plastic ruler to the correct length - spindle edge to front of bearing housing.
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