Corroded main bearing - ideas?

[j beede]

I am restoring a 1970s vintage British turntable that has been in storage for a decade or longer. Things are going fairly well so far.

The main bearing well is an aluminum/brass/bronze hybrid with the aluminum forming a "collar" at the top of the well. That's where the problem is. The aluminum has corroded a bit and is dragging on the spindle. I tried cleaning the well and re-lubing, then letting it run for a couple hours to see if this would lap the corrosion away. It did not.

I thought I would check in here to see if you have any ideas as I cogitate over some options (none of them great):

-Apply lapping compound to the spindle and spin away
-Phosphoric acid to chemically remove the oxidized aluminum
-Brake cylinder hone

FYI: The finish on the spindle looks flawless. The bearing well below the aluminum collar looks good as does the thrust ball.

 

[bbftx]

Is there any way to eliminate or replace the aluminum part of the assembly? Aluminum is not a good material to be used in any way for a bearing assembly like this.
An oxidative layer is formed very quickly on aluminum in the air, so your problem won't go away as long as the aluminum is in the mix. It's also relatively soft and might be so easily deformed in this application to always be subject to dragging on the spindle.

A photo of what you're looking at might help folks offer some alternatives.
Good luck
B B

 

[Galu]

Please tell us which turntable you are restoring.
Someone may have prior experience of that particular model.

 

[russc]

Usually the aluminium alloy would be the cast support housing with the bronze bush being the running surface. Therefore I would have expected the aluminium to be clear of the spindle. If the aluminium has "grown" with corrosion then carefully applying a suitable diameter drill to trim it back, avoiding the drill grabbing and running into the bronze bush should do the trick.

 

[ralphfcooke]

If it is a comparatively high quality turntable I would not use a drill to open up the aluminium. On 'thebay' you can buy adjustable reamers at a very reasonable price. Measure the aluminium and buy a suitable reamer, that way you can do a decent job.