sdedalus said:
Hi,
By v shaped I mean a cone, the ball will go nowhere. As the ball / shaft
interface is fixed, i.e. it doesn't slide, no lubrication for this point is needed.
(the point being if the cone is machined at the same time as the shaft it
should locate the ball by default very accurately in the centre of the shaft)
sreten.
FWIW,
I think if you want to go the DIY route on this, the likes of the bearing used the well tempered turntables are perhaps one of the easiest to make at home. Theres a bit of setting up, getting it all aligned, but its fairly easy to do well. Do a search for well tempered and it'll come up.
You seem to be diving in headlong to doing this, without really doing any much research on what the best builders out there do. I suggest you have a good look at teres audio to have a look at their bearings too.
Lastly, I believe you can buy a new bearing from rega for a P3 for small money (<$50). A very respectable bearing which would be hard to beat - esp. in the DIY stakes. I think I read somewhere that its good for upto 18lbs of platter.
The only thing with your teflon bearing is getting the tolerance right. You need virtually no play, but yet it must be easy to turn. This would be made a whole lot easier if you turned your current assembly upside down - housing in the plinth and shaft into the platter. Then you could fill the bearing cavity with a heavy gear oil which would help take up slack and also reduce any friction (I know, its teflon!). Stick with using the ball bearing in the cup at the end of the shaft. Make sure when you drill it out that its bang on centre.
Its sometimes not worth going the DIY route unless its for pig iron!!!
Fran
I think if you want to go the DIY route on this, the likes of the bearing used the well tempered turntables are perhaps one of the easiest to make at home. Theres a bit of setting up, getting it all aligned, but its fairly easy to do well. Do a search for well tempered and it'll come up.
You seem to be diving in headlong to doing this, without really doing any much research on what the best builders out there do. I suggest you have a good look at teres audio to have a look at their bearings too.
Lastly, I believe you can buy a new bearing from rega for a P3 for small money (<$50). A very respectable bearing which would be hard to beat - esp. in the DIY stakes. I think I read somewhere that its good for upto 18lbs of platter.
The only thing with your teflon bearing is getting the tolerance right. You need virtually no play, but yet it must be easy to turn. This would be made a whole lot easier if you turned your current assembly upside down - housing in the plinth and shaft into the platter. Then you could fill the bearing cavity with a heavy gear oil which would help take up slack and also reduce any friction (I know, its teflon!). Stick with using the ball bearing in the cup at the end of the shaft. Make sure when you drill it out that its bang on centre.
Its sometimes not worth going the DIY route unless its for pig iron!!!
Fran
almost unbelievable
I, almost, cannot believe that there is no such thing as "rest" (meaning: some left over) rumble noise being picked up and transferred to the pre amp on the diy turntable, be it wood or metal, especially when normal bearrings are involved.
I also wonder, maybe a bit too far fetched, but this is only because I copy thoughts of other participants here, the lack of constant density in this wood used in these turntables...
In my opinion the irregular density would be transferred to the motor with some hard to avoid vibrations ...
and, that is again in my opinion, just the top of the iceberg.
Jean-Pierre
I, almost, cannot believe that there is no such thing as "rest" (meaning: some left over) rumble noise being picked up and transferred to the pre amp on the diy turntable, be it wood or metal, especially when normal bearrings are involved.
I also wonder, maybe a bit too far fetched, but this is only because I copy thoughts of other participants here, the lack of constant density in this wood used in these turntables...
In my opinion the irregular density would be transferred to the motor with some hard to avoid vibrations ...
and, that is again in my opinion, just the top of the iceberg.
Jean-Pierre
Well,
as far as I can see it, the teres bearing is not actually inverted! What they do is mount the bearing so that most of the bearing is inside the platter and therefore and so it acts in a similar way to the inverted ones.
www.rega.co.uk is the website for rega in england, I'm sure they would help you.
On the subject of the teres platters and uneven density... well they don't just use a solid chunk of timber, they glue up many small lengths in different layers with different orientations so that any difference in densities are rendered negligible. Lead shot is also added as a dampener too.
Fran
as far as I can see it, the teres bearing is not actually inverted! What they do is mount the bearing so that most of the bearing is inside the platter and therefore and so it acts in a similar way to the inverted ones.
www.rega.co.uk is the website for rega in england, I'm sure they would help you.
On the subject of the teres platters and uneven density... well they don't just use a solid chunk of timber, they glue up many small lengths in different layers with different orientations so that any difference in densities are rendered negligible. Lead shot is also added as a dampener too.
Fran
I just noticed that about the teres. the first time I saw the bearing I thought the brass sleeve was mounted in the platter.
On the subject of platter materials, for about the same amount as a nice hardwood and about twice as much as birch plywood, I can get 8 14x14 sheets of .25" thick acrylic cut to within .015". Would a router and a good circular jig be capable of cutting an accurate circle from a 2" block of acrylic?
On the subject of platter materials, for about the same amount as a nice hardwood and about twice as much as birch plywood, I can get 8 14x14 sheets of .25" thick acrylic cut to within .015". Would a router and a good circular jig be capable of cutting an accurate circle from a 2" block of acrylic?
Here we have High End bearing
and link
http://www.hiendfi.com/phpBB2/viewtopic.php?t=823
from turntable
with two tonearms
An externally hosted image should be here but it was not working when we last tested it.
and link
http://www.hiendfi.com/phpBB2/viewtopic.php?t=823
from turntable
An externally hosted image should be here but it was not working when we last tested it.
with two tonearms
An externally hosted image should be here but it was not working when we last tested it.
I would say a lathe would be the only way of machining the platter, and when it trued after mounting, you would machine the centre hole and recess at the same time. Only way to get perfect circle with centre hole absolutely concentric. This applies to whether its going to be wood, metal or acrylic.
If you are going the wood route, birch ply is good with a layer of hardwood on the top, cocbolo is what teres seem to use. Make sure you glue it up in different layres to enhance stability
Fran
If you are going the wood route, birch ply is good with a layer of hardwood on the top, cocbolo is what teres seem to use. Make sure you glue it up in different layres to enhance stability
Fran
Re: 1st T/T
Quite so!
Although you can make it easier to produce a quality bearing of the type shown by HighTech here (or the Teres) if you don't bore a blind hole.
Here’s a version of an inverted bearing designed to be made as a “one off” that can achieve the kind of accuracy needed using only a small hobby-grade lathe. It would take some time but you could achieve a very high precision result using only traditional methods. I guess you work the dimensions around the available tools – like what size reamer you have available.
A – the shaft. Start with a length of precision-ground silver steel and you can achieve the finished diameter with only careful hand-finishing with 1200 and 2000 grade papers used wet. Get the final finish clearance to fit your bearing.
B – The bearing. Start with either brass bar or, better, aluminium bronze that’s available as thick-wall bearing tube. Would need to be carefully bored or reamed and then lapped to get the required accuracy.
C – platter mounting. Rather than turn the shaft in one, press fit this onto the shaft and then mount the shaft and finish-turn the mounting surfaces. You would need to be able to hold the shaft very accurately for the finishing, preferably with a collet.
D – Relieve part of the bearing surface, probably easier to relive the shaft than the internal bore. We don’t need all that surface area and it also provides an oil reservoir.
E – Thrust ball fits into tight recess. Needs to be accurately centred.
F – Thrust pad. Acetal is good for this, or could be phosphor bronze but needs to be softer than the ball. If you make it this “top hat” shape then both the contact faces can be machined in one, then the middle just parted off because it doesn’t contact anything.
G – Bottom plug threaded into the bearing. Supports the thrust pad and also provides an oil reservoir. You can get a nice accurate result because it can be machined in one go.
As for the platter, it's a part that needs access to a pretty large lathe and it needs to be fairly carefully machined. Any small error in the boring of the centre mounting will translate to a lot of runout at the edge.
tabarddn said:
Quite so!
Although you can make it easier to produce a quality bearing of the type shown by HighTech here (or the Teres) if you don't bore a blind hole.
Here’s a version of an inverted bearing designed to be made as a “one off” that can achieve the kind of accuracy needed using only a small hobby-grade lathe. It would take some time but you could achieve a very high precision result using only traditional methods. I guess you work the dimensions around the available tools – like what size reamer you have available.
A – the shaft. Start with a length of precision-ground silver steel and you can achieve the finished diameter with only careful hand-finishing with 1200 and 2000 grade papers used wet. Get the final finish clearance to fit your bearing.
B – The bearing. Start with either brass bar or, better, aluminium bronze that’s available as thick-wall bearing tube. Would need to be carefully bored or reamed and then lapped to get the required accuracy.
C – platter mounting. Rather than turn the shaft in one, press fit this onto the shaft and then mount the shaft and finish-turn the mounting surfaces. You would need to be able to hold the shaft very accurately for the finishing, preferably with a collet.
D – Relieve part of the bearing surface, probably easier to relive the shaft than the internal bore. We don’t need all that surface area and it also provides an oil reservoir.
E – Thrust ball fits into tight recess. Needs to be accurately centred.
F – Thrust pad. Acetal is good for this, or could be phosphor bronze but needs to be softer than the ball. If you make it this “top hat” shape then both the contact faces can be machined in one, then the middle just parted off because it doesn’t contact anything.
G – Bottom plug threaded into the bearing. Supports the thrust pad and also provides an oil reservoir. You can get a nice accurate result because it can be machined in one go.
As for the platter, it's a part that needs access to a pretty large lathe and it needs to be fairly carefully machined. Any small error in the boring of the centre mounting will translate to a lot of runout at the edge.
An externally hosted image should be here but it was not working when we last tested it.
Close enough to an Altmann bearing.
http://www.altmann.haan.de/turntable/
Take a valve guide and valve for an available car/ motor bike.
Machine off the 'valve' head (the large flat) (carefully, you dont want to mar the surface of the valve stem.
Machine a cap that will 'screw' onto the exterior of the valve guide (and hold the ball). Thread the inside of the cap.
Thread the exterior of the valve guide to match.
Drop ruby ball into the 'guide'.
Drill a hole into the valve stem for a roll-pin (or a simple groove for a circlip) to support the platter.
Assemble bearing.
Mount on base.
Easily available materials, small scale and simple machining = low cost.
Done.
Owen
http://www.altmann.haan.de/turntable/
Take a valve guide and valve for an available car/ motor bike.
Machine off the 'valve' head (the large flat) (carefully, you dont want to mar the surface of the valve stem.
Machine a cap that will 'screw' onto the exterior of the valve guide (and hold the ball). Thread the inside of the cap.
Thread the exterior of the valve guide to match.
Drop ruby ball into the 'guide'.
Drill a hole into the valve stem for a roll-pin (or a simple groove for a circlip) to support the platter.
Assemble bearing.
Mount on base.
Easily available materials, small scale and simple machining = low cost.
Done.
Owen
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