Pulley for AR-XA (and how to polish your spindle)

[gkimeng]

While we're on the subject....
What about the arm bearing?
(horizontal of course)

While mine is nowhere near in as bad condition
as the main bearing, it does need some work.
Its bad enough that it won't make for nice smooth
arm movement.

It can probably be made OK with just honing..
(I think)
But what if it couldn't?

Well, if you end up replacing the subchassis, you'll probably fix both problems at the same time...

Unfortunately, I think that even if the arm pivot doesn't spin at speed, all the same considerations are still valid.

[MuZak]

Well, if you end up replacing the subchassis, you'll probably fix both problems at the same time...

Thats assuming the replacement doesn't have the
same problems, and to the same degree.
...and with my luck.............

Unfortunately, I think that even if the arm pivot doesn't spin at speed, all the same considerations are still valid.

Well you'd know best..
So the criteria is?
Just smooth and shiny?

Bear in mind, that my purpose is not solely to remedy
my own problems in this instance, but to make
a contribution to the repair and maintnance of
the AR tables, so I'm looking to figure out how
to do this even if I don't wind up needing it myself.

[gkimeng]

So the criteria is?
Just smooth and shiny?

Very smooth and very shiny.

I think I already mentioned in some other post that one of my tables uses tungsten carbide balls (just a hair less hard than sapphire, but actually chosen because they were the closest thing in size that Smallparts had in stock at the time), and that this has made no obvious difference in performance. I think a mirror polish and good lube should do the job.

[MuZak]

Very smooth and very shiny.

I think I already mentioned in some other post that one of my tables uses tungsten carbide balls (just a hair less hard than sapphire, but actually chosen because they were the closest thing in size that Smallparts had in stock at the time), and that this has made no obvious difference in performance.

Actually, I think you mentioned that in 2 prior posts.
After the first, I thought, what a good idea and
promptly ordered one, particularly after seeing
the hardness rating.

A few days later I read the latter post, where you
mentioned no perf improvement and thought..
dang..

No biggie I guess and it can't hurt...
Larger size will cause taller VTA which is cancled
by using a thicker mat, which I likely will.
In a pinch.. the local ACE has standard size balls.

I think a mirror polish and good lube should do the job.

Ok, so how to get that mirror polish, and which lube??

[gkimeng]

Actually, I think you mentioned that in 2 prior posts.
After the first, I thought, what a good idea and
promptly ordered one, particularly after seeing
the hardness rating.

A few days later I read the latter post, where you
mentioned no perf improvement and thought..
dang..

No biggie I guess and it can't hurt...
Larger size will cause taller VTA which is cancled
by using a thicker mat, which I likely will.
In a pinch.. the local ACE has standard size balls.

Ok, so how to get that mirror polish, and which lube??

You probably should have ordered more balls in different sizes. Would have been an interesting take on VTA adjustment.

The story behind the balls is that I built a second TT table using spare parts, one of which included an XA platter, whose spindle is 1/4" too long for the TT subchassis bearing. So I cut 1/4" off the bottom of the shaft, and while relieving the cut end bored a new ball bearing well into it. So this table's platter ball is loose. The arm was yet another spare and there was no ball for it, so I put two new ones in the table, both the same size.

I polished the shaft of the vertical arm pivot by turning it against crocus cloth and jeweler's rouge. The well was polished by spinning the pivot shaft in it while still coated with the rouge. Then everything was cleaned and oiled. The oil is a black moly aircraft lube that I bring home from work; you can buy "black oil" from various turntable places that is essentially the same stuff.

[Alec124c41]

I'm having trouble understanding how 2 balls can work in a turntable bearing...
unless one is captive and centered and the bottom one completely fills the bottom...

Cheers,
Alec

[gkimeng]

I'm having trouble understanding how 2 balls can work in a turntable bearing...
unless one is captive and centered and the bottom one completely fills the bottom...

One is in the platter bearing well, the other is in the tonearm bearing well. One ball in each bearing.

[MuZak]

You probably should have ordered more balls in different sizes. Would have been an interesting take on VTA adjustment.

Probably... but at ten bux a pop, that wasn't
very likely..
Maybe down the line though.....

That reminds me...
The alternatives the offered were stainless or
chrome-moly.
Which is the better choice?
Not being sure of that was the main reason I didn't
order one in the correct size in addition to the
one I got.
They're only around a buck too..

The story behind the balls is that I built a second TT table using spare parts, one of which included an XA platter, whose spindle is 1/4" too long for the TT subchassis bearing. So I cut 1/4" off the bottom of the shaft, and while relieving the cut end bored a new ball bearing well into it. So this table's platter ball is loose. The arm was yet another spare and there was no ball for it, so I put two new ones in the table, both the same size.

Yes, I'd read that with interest in the afforementioned
post.

I polished the shaft of the vertical arm pivot by turning it against crocus cloth and jeweler's rouge.

At the same time?

The well was polished by spinning the pivot shaft in it while still coated with the rouge. Then everything was cleaned and oiled. The oil is a black moly aircraft lube that I bring home from work; you can buy "black oil" from various turntable places that is essentially the same stuff.

So heavy thick and black is the ticket for the arm
bearing as well...

There's also that GM differential additive.
Available at any GM brand dealer's parts counter.

As far as I can tell, its just a medium weight
gear lube mixed with a LOT of moly.

[gkimeng]

The alternatives the offered were stainless or
chrome-moly.
Which is the better choice?

The chrome moly would be marginally harder, but as I said, the choice of materials doesn't seem to make any difference in performance.

At the same time?

I started with dry crocus, then moistened the crocus with a drop or two of oil and added the rouge.

So heavy thick and black is the ticket for the arm
bearing as well...

The stuff I'm using is not heavy or thick. It's basically a 10W machine oil with moly added.

[MuZak]

The chrome moly would be marginally harder, but as I said, the choice of materials doesn't seem to make any difference in performance.

I guess I was thinking more along the lines of
which would be more slippery/shiny and stand
up better.

I started with dry crocus, then moistened the crocus with a drop or two of oil and added the rouge.

Ah! Very good to know.
Thanks

The stuff I'm using is not heavy or thick. It's basically a 10W machine oil with moly added.

That sounds like what Linn black oil seems to be.

[gkimeng]

Not to mention that due to side wall clearances, it's unlikely that the very top tangent of the lower ball will meet the exact lower tangent of the top ball. Ball on Ball has no advantage over ball on plate.....the tangent point of contact will be the same.......hence friction will be the same.

There is only one ball in each bearing. The platter spindle has been shortened and no longer has a captive ball at its end. The "second ball" in the table is the one in the arm bearing.

[LPM]

Well I’ve just completed the main suggestions on this thread for my XB and am really very pleasantly surprised by the results – in fact, rather astonished. In summary, I:
• Thoroughly cleaned out and re-oiled the arm well
• Same with the spindle and of course mirror polished the end and cleaned up the spindle shaft itself
• Added Marc’s () bearing plate
• Filled the pulley cavities with modelling clay
• Cleaned up and polished the pulley belt mating faces and spindle platter facings
• Installed a brand new belt
• Replaced the old RCA connectors as the old ‘grey’ lead with the additional ground wire had clearly broken internally and if moved would blast static through the speakers
• Added a sheet of 1mm thick butyl rubber on top of the base board
• Finally, added a Herbies Mat

The really obvious and quite profound improvements were firstly the far quieter background and almost complete absence of rumble. This I attribute to mainly to Marc’s bearing plus the ‘black oil’ I made up and used as recommended here. A special thanks by the way to Marc by the way for making this item available to forum members. Secondly, the slight but really noticable ‘flutter’ has been cured presumably by the new belt and pulley mod combination. Thirdly, and this is hardest to explain except through the combination of all of the work, the openness and clarity has improved out of sight. At long last, the slightly closed in sound stage and vague fuzziness that stopped it surpassing my CD source has been cured. Who knows how good it would sound with a better than standard arm. I’m very happy though.

[MuZak]

Congrats!

I always thoroughly enjoy reading about the massive improvements
and enjoyment folks get through applying these techniques.

Happy listening!

[rw_design]

This thread is probably the most comprehensive on earth for servicing and optimizing the XA. I have one I recently got that was well taken care of (its a time capsule) and I am slowly giving it TLC as I take it one step at a time learning all I can from you guys. Some of these techniques are amazing. The polishing for instance. Man.
Right now I am assembling the table and have started with the pulley which btw mine comes off easily too. It had some aluminum oxide on it which I have managed to remove with 2000 grit carefully. I have been polishing the surface of the crown carefully hoping for a lustre eventually. Worried a little about leaving anything in the aluminum that may migrate to the new belt I bought. The modelling clay is very interesting who would have thought of that? Also the tips on polishing the bearings and shafts and the wells for both the platter and the arm spindle. Scares me a little as I do not have crocus cloth. Have to find some of try something else. My Dad always said if you don't have the tool you need then make one!
My other challenge is getting the arm working right. I want it to be able to track at 1 -1/2 grams or so. This means disabling the damping. I have to find that thread as I must say I am having trouble understanding how the damping mechanism works or how to disable it and then assemble the spindle correctly. Its not just a matter of doing this or that its understanding what I am doing. Well I am sure we all think that way when we build confidence in our work. This is a beautiful thread really guys it is something to be very proud of.
Ron - Working on my XA.