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Tonearm bearing cones, black - polishable ?

master_fo

master_fo

Active Member
Hi, I am about to give another flush to my Empire 990 tonearm bearings.
This time I am thinking of also polishing the bearing cones.
On this tonearm, unlike the others I have seen, the main steel bar with the cones is black, not shiny as usual.
Can I polish this type of steel ?
 
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Black? Might just be black oxided for corrosion resistance or it could have been nitrided to make the surface extremely hard.
Is the surface rough or does it have wear marks? Not familiar with the Empire arms, have any photo's of the parts in question?

Billwojo
 
Looks a bit like black oxide finish. Thats not corrosion or dirt, too uniform. Appears to be a plating or finish of some sort based on the shiny bit there at the end. I suppose if you could pull the pin out and use a diamond hone or something to give it a very high polish finish while maintaining the angle it might help. Thinking chuck it in a drill as a small lathe and very carefully spin it against the hone to polish it. I'm assuming the bits that screw into that hole are an inverse of the pointy end?
 
gadget73 said:
Looks a bit like black oxide finish. Thats not corrosion or dirt, too uniform. Appears to be a plating or finish of some sort based on the shiny bit there at the end. I suppose if you could pull the pin out and use a diamond hone or something to give it a very high polish finish while maintaining the angle it might help. Thinking chuck it in a drill as a small lathe and very carefully spin it against the hone to polish it. I'm assuming the bits that screw into that hole are an inverse of the pointy end?
Click to expand...
Yes the bits that screw in are like a nut with circle bearings. unfortunately, to get this bar out would require complete arm disassembly. I suppose one can use dremel-like tool with a small felt polish head and a liquid metal polish. That certainly worked with another 990 tonearm and regular looking steel cone.
 
I'd be very leery of trying to do that freehand in place. Get the taper on that end messed up and it will quite likely cause more trouble than leaving it as-built.
 
This kind of finish is actually quite common on vintage tonearms. Of course, it affects the sensitivity of the bearings, which is why I always want to polish them to a higher finish.

But please, don't use any of the obvious hand tools for this. What you need to achieve is an even finish around the entire tip of the bearing cone, without any uneven spots,

The ideal would of course be to mount the cones in a lathe, and then do the polishing with the cone rotating in it. There you could use a set of lapping films, or a polishing compound on a bit of cloth. Lacking a lathe, mounting the cone in the chuck of a power drill is a good substitute. I both cases, wrap the back end of the cone in something to protect its surfaces from the chuck.

On those arms where you don't want to take the bearing cones out, as in the vintage Thorens arms, you can reverse the action. I usually make a thin roll of fabric, mounted in a suitable tube. Mount the tube in the chuck of the aforementioned power drill, add a polishing compound. Push the tip of the cone at the centre of the rotating roll. You may want to use a set of rolls with different grades of polisher.
 
tothmes said:
On those arms where you don't want to take the bearing cones out, as in the vintage Thorens arms, you can reverse the action. I usually make a thin roll of fabric, mounted in a suitable tube. Mount the tube in the chuck of the aforementioned power drill, add a polishing compound. Push the tip of the cone at the centre of the rotating roll. You may want to use a set of rolls with different grades of polisher.
Click to expand...
Thanks, the tube is a good suggestion. Unfortunately, on this tonearm, one can't really get to the cone on the other side without full tonearm disassembly (which is a huge no-no for Empires and cannot be accomplished without proprietary tools), so only one is really polishable.
 
Decided against polishing attempt - there seem to be no signs of wear from bearings on that black surface - let it be.
In general, flushing yields great result - this time I did it with Zippo fuel, and I observe a lot of improvement even now after about 1 year when I did flush with isopropyl alcohol.
This time I have also relaxed the nut that that keeps the platform in place, and rotated it a bit while flushing, also fixed back in different position.
Now it became obvious the anti-skate design is flawed - with zero weight and 'zero' antiskate, arm actually skates toward the center :) About 2 rotations of antiskate makes it OK.
 
master_fo said:
Decided against polishing attempt - there seem to be no signs of wear from bearings on that black surface - let it be.
In general, flushing yields great result - this time I did it with Zippo fuel, and I observe a lot of improvement even now after about 1 year when I did flush with isopropyl alcohol.
This time I have also relaxed the nut that that keeps the platform in place, and rotated it a bit while flushing, also fixed back in different position.
Now it became obvious the anti-skate design is flawed - with zero weight and 'zero' antiskate, arm actually skates toward the center :) About 2 rotations of antiskate makes it OK.
Click to expand...
Master fo,
Thanks for this post! I purchased a 598iii recently and could not get the arm to float level. Something in the gimbal didn't seem right. That black pin you referenced was actually loose. I pulled the set screw out to reveal the bearings. They are in good shape. I tweaked the tension of that set screw to get a workable tonearm.
Not 100% happy. I'm a little cautious of working on this turntable. That being said. Questions to you:
1) is Zippo fuel the beat way to clean that black pin? Will isopropyl achohol work too? Don't want to screw up the finish of this beauty.

2) what's the proper oil for that bearing?

Thanks again for the post and photos. Now I know what the inside of the gimbal looks like. Learning so much thanks to posts like your's.
 

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noted said:
Thanks for this post! I purchased a 598iii recently and could not get the arm to float level. Something in the gimbal didn't seem right. That black pin you referenced was actually loose. I pulled the set screw out to reveal the bearings. They are in good shape. I tweaked the tension of that set screw to get a workable tonearm.
Not 100% happy. I'm a little cautious of working on this turntable. That being said. Questions to you:
1) is Zippo fuel the beat way to clean that black pin? Will isopropyl achohol work too? Don't want to screw up the finish of this beauty.

2) what's the proper oil for that bearing?
Click to expand...
You can use a high grade IPO. The important thing is to use something that doesn't leave any residue. I often use a good contact cleaner spray for bearings i can't take apart.

Never any oil in tone arm bearings, unless you have explicit instructions from the maker, and the specified oil. Oils increase the starting friction of bearings, exactly the critical part of the movement in tonearms. Oil only improves bearings that rotate, which tonarms are seldom expected to do.
 
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