View Full Version : Townshend Avalon bearing
Hello!
The reason for opening this thread is to know about any possible different versions of the Townshend Avalon bearing.
I'm taking care of an Avalon turntable I bought some time ago and part of the bearing (shaft) is much different from what's described on the Townshend bearing reconditioning instructions, also it does look fairly tweaked...
It looks like a large mid section had been thinned further, perhaps in order to ease the oil going upwards, but what's more strange is the top which is not flat, but having a conical portion with a cup in the mid.
This makes the 8mm ball to be placed between two cups: this one on the shaft and the other one at the tip of the M5x5 grub screw, even thought the ball does not tend to move inside of the sleeve...
Sorry for the low quality mobile photos, but these will serve anyway.
It's easy to conclude that the ball does bear lots of friction while rotating inside of this cup on top of the shaft.
Please tell me what do you think of this, when comparing with other Avalon bearings you may have seen before, or even own(ed).
Needless to say that any help will be much appreciated... :)
Thanks a lot, cheers, JPB
Crumbs, it's looks a bit knackered!
Crumbs, it's looks a bit knackered!
Hi!
Please note that the larger diameter portions on the shaft are well polished.
Only the thinned portion in between is a bit rough, which is not necessarely a bad thing as it can ease to keep the oil up there.
On the top, it's not worn so that's not a dimple but a machined cup at the center of a conical inner sector (please check the vertical cross section sketch below).
11005
Thanks, cheers, JPB
potatoha
17-11-2013, 23:57
Mine, Elite Rock MK2, has a different bearing shaft as well. It does have a conical top, but without the cup like yours. :scratch: Max changes lots of things as he goes along. One time, when I tried to replace my platter with a new one, it didn't fit because the spindle hole size was different!!! BTW, how did you take out the bearing shaft? I always thought mine was stuck to the plinth?
Hi,
I'm afraid that bearing does look knackered. It looks as though the bearing shaft has been run without oil for some time. The face surface is supposed to be flat so that the contact area between the top of the shaft and the tungsten ball bearing is minimised. My avalon looked like that at one point and the contact surface of the ball bearing was rough and worn.
I think the self lubrication design of the bearing is poor - they all seem to go like that eventually. You could rotate the ball to present a new contact surface (or replace it) and have the bearing face resurfaced and polished to a flat finish or you could try a ptfe 'pill' on top of the bearing shaft instead - I found some on ebay... you will need a few as they don't last.
Max admitted to me that this part of the design it wasn't his finest hour, and the material choice and oiling design is poor. Do you have a precision engineering company near you? They may be able to either refinish it or possibly make another but I suspect it won't be cheap. Does your platter rock? If so the bronze bushing of the sub platter may also be worn. If so, I'm afraid It may be curtains.. The turntable will still play, but won't ever sound as it should.
Sorry to be the bearer of bad news...
postscript - I had another look at your pictures, and it is possible that the design changed. I can't remember exactly what mine was like, but I don't think the top of the shaft being domed as yours appears to be. Mine didn't have a cup when I got it, but it did by the end! That was definitely due to lubrication problems. Check the ball bearing for wear scars, and replace it if it doesn't look perfect. You could also try something like a light weight gearbox oil as I think light machine oil doesn't work in this application.
Alex
Hi John!
Thanks for your reply.
I strongly doubt the current bearing in this Avalon is fully original as it does not make much sense in having the ball placed between two cups (one on top of the shaft, the other one at the tip of the adjustment grub screw).
This shaft would only make sense if using a smaller diameter ball and a thrust bearing on top of it (but then it would be hard for the oil to get there, I think...).
As for your question, please refer to the first photo showing all the bearing parts:
The aluminium oil cup sits flush to the plinth upper surface and is attached underneath by that large (24mm) nut.
The shaft is attached to the aluminium cup through the hole at the bottom, using the shown nut and antislip shim.
Your Elite Rock Mk2 bearing may have a diferent layout, I guess... :rolleyes:
Thanks, kindest regards, JPB
Hi Alex!
Thanks for your contribution.
I added that cross section sketch to make clear that all those weird features on the shaft are not due to any wearing.
And yes, I'm considering to flatten the top of the shaft and replace the steel ball for a ceramic one, so I guess that much different hardnesses will prevent wearing.
I can do this myself as I do own an Emco Unimat lathe (albeit disassembled at this moment), but firstly I want to make sure I'm going the right way and want to understand what happened...
By now there is not noticeable play in the bearing, even in dry status, so when correctly set up using a good oil (most probably synthetic 5W30) I guess there will be no problem.
Thanks, best regards, JPB
potatoha
18-11-2013, 10:04
... you could try a ptfe 'pill' on top of the bearing shaft instead - I found some on ebay... you will need a few as they don't last
Hi Alex,
What's this ptfe 'pill' you mention? I'm quite intrigued. The tip of my bearing shaft has a pin head size dimple and was thinking of sanding it. If this ptfe thing can reduce friction, I'd really like to try it on my deck to hear if it brings any sonic benefits...
John
Hi Jose,
Just to be clear, I wasn't talking about the side profile of the shaft - I think these are tapered to make it a little easier to fit the bearing. I remember it being a real pain in the ass to get the quantity of oil just right... several goes at adding oil, seating the bearing, getting the air out and checking that the oil level is at the right level on the bronze sleeve. If it is too low then you won't have oil between the ball bearing and the thrust surface.
I wouldn't recommend a ceramic ball - this will wear the shaft more than a steel ball. I would keep using steel balls, but get a few spares and replace them once in a while. A carbide ball won't wear at all (probably), but will chew a nice hole in the shaft in short order.
I cannot see why a cup would be machined in the top of the shaft - you are trying to minimise contact area between the ball and the thrust surface, and a dish will add significant friction because of the increased contact area (you don't want this!). I suppose it is possible that the bearing design was modified during production- have you seen whether the ball and the dimple on the top of the shaft match precisely? If it is significantly larger than the ball bearing then maybe it is there to help retain a small oil bath to reduce wear. is the ball scuffed or marked at all?. Mine was definately flat on the top surface orginally, and a pimple emerged as it wore down.
You could try flattening the top of the shaft out and use a high film strength oil - machine oil is too thin for this turntable. If it is too thick you will never be able to release the air trapped in the bearing shaft. If you reduce the deck height of the top of the shaft you will probably need a longer grub screw to prevent it falling out of the bottom of the spindle.
If you do want to try a different thrust washer, you could try a hard ceramic or tungsten washer with a matching ball bearing. Dissimilar hardness is a bad thing in a ball bearing. If you want anything to wear out it wouild be the ball not the thrust surface as the ball is easily replaceable but the thrust surface of the shaft isn't.
Good luck with your repair.
Best regards,
Alex
Hi John,
It was simply small 'pill' of ptfe that provides a new thrust surface. A steel ball will make a dimple, but it has good lubricity, so the friction is still manageable. I bought mine from eBay, but I think audio origami may be able to provide them.
The jury is out as to what a thrust washer should be made out of - Ideally, the bearing ball or shaft point and the thrust surface should be infinitely hard for an infinately small contact area. Unfortunately the contact pressure would also be infinately high, so oil couldn't lubricate it as it has finite film strength. I found this thread on Vinylengine http://www.vinylengine.com/turntable_forum/viewtopic.php?t=21055 where there is an interesting discussion on the subject. Some say that PTFE is completely unsuitable for bearings, but I did use it and it worked while I had my avalon.
Regards,
Alex
Hi Jose,
Just to be clear, I wasn't talking about the side profile of the shaft - I think these are tapered to make it a little easier to fit the bearing. I remember it being a real pain in the ass to get the quantity of oil just right... several goes at adding oil, seating the bearing, getting the air out and checking that the oil level is at the right level on the bronze sleeve. If it is too low then you won't have oil between the ball bearing and the thrust surface.
I wouldn't recommend a ceramic ball - this will wear the shaft more than a steel ball. I would keep using steel balls, but get a few spares and replace them once in a while. A carbide ball won't wear at all (probably), but will chew a nice hole in the shaft in short order.
I cannot see why a cup would be machined in the top of the shaft - you are trying to minimise contact area between the ball and the thrust surface, and a dish will add significant friction because of the increased contact area (you don't want this!). I suppose it is possible that the bearing design was modified during production- have you seen whether the ball and the dimple on the top of the shaft match precisely? If it is significantly larger than the ball bearing then maybe it is there to help retain a small oil bath to reduce wear. is the ball scuffed or marked at all?. Mine was definately flat on the top surface orginally, and a pimple emerged as it wore down.
You could try flattening the top of the shaft out and use a high film strength oil - machine oil is too thin for this turntable. If it is too thick you will never be able to release the air trapped in the bearing shaft. If you reduce the deck height of the top of the shaft you will probably need a longer grub screw to prevent it falling out of the bottom of the spindle.
If you do want to try a different thrust washer, you could try a hard ceramic or tungsten washer with a matching ball bearing. Dissimilar hardness is a bad thing in a ball bearing. If you want anything to wear out it wouild be the ball not the thrust surface as the ball is easily replaceable but the thrust surface of the shaft isn't.
Good luck with your repair.
Best regards,
Alex
Hi Alex!
Thanks for the new post and advice contained.
So the same as me, you also don't see what the benefit is into having a cup for the ball, instead of the usual flat surface to be sure that the contact is minimized.
Having this cup there, equals to increasing drastically that typical wear dimple which is carved after some time.
Furthermore, this cup machined at the center of that low profile cone has not been correctly achieved: not only it is a bit rough, also it does not match the 8mm ball radius, so the ball earned a circular mark, and will again, and again...
Then, despite any possible design change, there is a mismatch (or mixmatch?) of two different concepts.
But to have a smaller ball would imply that we'd also have a thrust plate on top of it, but then how would the oil get up there?! (Unless assembly would be done upside-down, oil kept by vacuum as in other turntables)...
The correct amount of oil and the trapped air inside of the bearing are also concerns...
But perhaps this can be improved somehow.
Thanks for your help and wishes once again, kindest regards, JPB
Hi Jose,
Maybe the dimple is there to increase the centering action on the ball, but I don't understand why it would be smaller than the bearing. If I understood you, the ball bearing has a circular wear mark all of the way around the circumference. That is very odd - it suggests that it wasn't put there by the ball but I don't understand the design concept at all.
Regards,
Alex
Here you go guys, hope this helps in some way
1101411015
Thanks, Steve!
As you can see on my first post, it was exactly because this shaft does not match at all the design shown in those instructions, that I decided to open this thread, to know about any possible design changes, etc.
But thanks all the same obviously! :)
@ Alex: Yes, the cup is even more "closed" than the ball radius, hence the circular wear.
But as far as I know the 8mm size is the correct one for the Avalon ball (perhaps on the more expensive Townshend turntables too...) also because it's slightly "grabbed" by the upper section of the sleeve given the very tight tollerance.
So the intended rotating point for the ball is its "south pole".
But not on this bearing, the ball rather rotates on its "south polar circle" it seems... :scratch:
Cheers, JPB
Here you go guys, hope this helps in some way
1101411015
I have an Avalon and my bearing looks exactly like the one in Steve's illustration. I opened it up about 6 years ago for routine maintenance and there was a dimple worn on the flat surface. After a conversation with Max, I had it machined level, replaced the ball and it was back to normal. The problem is finding someone to machine it flat. When you dismantle the bearing assembly there is practically nothing for the lathe to grip. A small dimple is of no consequence if the oil and oil level are correct as the bearing will then self lubricate. A new ball would probably have a greater effect on sound quality.
However, the bearing + ball on Ortofan's turntable looks rather odd. Is the ball original? Has anyone asked Max? I suspect it may be an 'improved' version which has not stood the test of time and I think it would perform better with a ball which was smaller than the cup. It would self centre and should generate much less noise. If the cup is too deep, then perhaps reduce the shoulder height to get the required clearance.
I have an Avalon and my bearing looks exactly like the one in Steve's illustration. I opened it up about 6 years ago for routine maintenance and there was a dimple worn on the flat surface. After a conversation with Max, I had it machined level, replaced the ball and it was back to normal. The problem is finding someone to machine it flat. When you dismantle the bearing assembly there is practically nothing for the lathe to grip. A small dimple is of no consequence if the oil and oil level are correct as the bearing will then self lubricate. A new ball would probably have a greater effect on sound quality.
However, the bearing + ball on Ortofan's turntable looks rather odd. Is the ball original? Has anyone asked Max? I suspect it may be an 'improved' version which has not stood the test of time and I think it would perform better with a ball which was smaller than the cup. It would self centre and should generate much less noise. If the cup is too deep, then perhaps reduce the shoulder height to get the required clearance.
Hi Stuart!
Thanks for your contribution.
The problem with a smaller ball, is that it will be no longer "grabbed" by the rotating sleeve, but probably by the shaft's top cup instead, so it would be needed a thrust pad above the ball, but then no big chances of any oil getting up there...
Also, when I do introduce the shaft into the sleeve without the ball (same as if a smaller ball), there is a very slight play, but not with the ball in its correct place.
So the full 8mm ball is needed to completely eliminate play in the bearing, as the upper section of the shaft is slightly short of the 8mm, certainly to ease lubrication to get upwards.
I did ask Max Townshend about the bearing but could not get much detailed, conclusive responses as sometimes his answers are less than telegraphic... :)
But he did confirm that it should be a 8mm ball with the M5x5 grub screw adjustment on top of it.
Thanks, kindest regards, JPB
Hi there!
Yet speaking of Townshend turntables, here you've got what seems a good deal, for anyone nearby:
http://www.ebay.co.uk/itm/171182073816
Enjoy, cheers, JPB
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