ssmith,
Did you complete your bearing ?
If so are you happy with it?
What parts did you use (Part number if possible) and a drawing would be very helpful.
Thanks in advance BT
Did you complete your bearing ?
If so are you happy with it?
What parts did you use (Part number if possible) and a drawing would be very helpful.
Thanks in advance BT
toseland said:
Not finished, but I have some parts..... description is here....
http://www.diyaudio.com/forums/showthread.php?postid=741765#post741765
The s/s rod I got (0.50") slides nicely into the bronze sleeve with zero lateral play. However rotation is a bit sticky. There is a post somewhere noting that sintered bronze doesn't release its impregnated lubrification unless it rotates at high speeds (ie faster than 33.3 rpm....). I am now trying to source a cheap teflon tube to compare it with.
When I've worked out what works best, I have to get a wood platter made and then machined on a lathe and a perfectly concentric hole cut to insert the bronze/or/teflon sleeve into. That will be the hardest part methinks.
At the same time, I'm still undecided about whether to put the sleeve in the platter or the plinth (inverted).
It's a work in progress. At this rate expect a solution sometime in 2008.....
OK, here's a plan I made a while back.
the parts I eventually got (no part numbers, sorry, just stuff I picked up in a bazaar) have changed, notably with the sleeve having an ID of 0.5" and the rod having a diameter of 0.5".
The alternative I may end up doing is to get a teflon sleeve and fit that into the plinth, seal it at the bottom so it acts like a bath for lubricant (like special teflon lubricant).
This means I have to get a nice tight fit of the S/S rod into the platter. Not sure how.......
the parts I eventually got (no part numbers, sorry, just stuff I picked up in a bazaar) have changed, notably with the sleeve having an ID of 0.5" and the rod having a diameter of 0.5".
The alternative I may end up doing is to get a teflon sleeve and fit that into the plinth, seal it at the bottom so it acts like a bath for lubricant (like special teflon lubricant).
This means I have to get a nice tight fit of the S/S rod into the platter. Not sure how.......
Attachments
Years of experience with prototype work on centre lathes tells
me that unless you do the final finish turning with the complete platter/bearing assembled and clocked up in a 4 jaw -- It may well
throw ----The diameter of a vinyl platter amplifies any slight pressing assembly errors.
Thats why the shaft on my set up is integral with the platter and the double ball is in an iinverted top hat oil well.
( My opinion FWIW. )
Baggins.
me that unless you do the final finish turning with the complete platter/bearing assembled and clocked up in a 4 jaw -- It may well
throw ----The diameter of a vinyl platter amplifies any slight pressing assembly errors.
Thats why the shaft on my set up is integral with the platter and the double ball is in an iinverted top hat oil well.
( My opinion FWIW. )
Baggins.
ssmith: do be careful about placing any kind of seal on your shaft. Even the best of these can introduce rumble that defeats all of the effort of your design. Better maybe to use self-lubricating materials that will hold adequate libricant (a skin of teflon oil or maybe graphite) without the need for a seal.
Baggins: I for one would love to see a diagram of this arrangement.
cheers
jess
Baggins,
If the 2 ball bearings are made of the same material and hardend to the same hardness you MAY have a problem with microscopic galling on the mating surfaces.
It's usually best to use dissimilar materals or at least different harness materials in this application.
Good luck with your project,
Scott
If the 2 ball bearings are made of the same material and hardend to the same hardness you MAY have a problem with microscopic galling on the mating surfaces.
It's usually best to use dissimilar materals or at least different harness materials in this application.
Good luck with your project,
Scott
Thanks very much for the sketch, baggins. Looks like a nice, simple arrangement.
In view of andirocks comments, you might like to know that it is possible to find ceramic bearing balls. They are used in turbine engines (helicopters) and some other very high speed applications. I don't know exactly where to get some, (maybe a local aircraft mechanic could supply a few derated pieces) but a web search should turn up something.
Myself, I'm still working on a way to reduce or eliminate the side thrust imposed by the drive belt (string, tape, ???). I am convinced that this is the biggest remaining source of friction and noise in tt bearings.
Jess
You will find ceramic bearing balls at http://www.mcmaster.com/.
Their site is not responding at the moment unfortunately.
Jeff
Their site is not responding at the moment unfortunately.
Jeff
Hi All,
Firstly, this is not some esoteric high end project , it is a working turntable - a modification of an extremely low fi AMSRAD offering -
the AMSTRAD TP12D but it did have a competant looking arm which attracted my attention (remember when this was - 1970's) I was vindicated in my choice in that, after some mods ,I managed to succesfully play records (sic). using an ULTIMO 10x MC cartridge.
the limiting factor with the deck has always been the noise of the
cheap synchronous motor mounted via a clamp and some rubber grommets!! This is evident at V.HIGH volume settings.I cannot detect rumble as I understand it. I think I might just ay be able to detect the bearing noise if I isolated the motor with a remote mounting which I would do if there was room on the pull out shelf that houses this deck
BUT SERIOUSLY , WHAT LEVEL DO YOU GUYS PLAY YOUR VINYL??
I like it quite LOUD andf this beartings is inaudible!!
Firstly, this is not some esoteric high end project , it is a working turntable - a modification of an extremely low fi AMSRAD offering -
the AMSTRAD TP12D but it did have a competant looking arm which attracted my attention (remember when this was - 1970's) I was vindicated in my choice in that, after some mods ,I managed to succesfully play records (sic). using an ULTIMO 10x MC cartridge.
the limiting factor with the deck has always been the noise of the
cheap synchronous motor mounted via a clamp and some rubber grommets!! This is evident at V.HIGH volume settings.I cannot detect rumble as I understand it. I think I might just ay be able to detect the bearing noise if I isolated the motor with a remote mounting which I would do if there was room on the pull out shelf that houses this deck
BUT SERIOUSLY , WHAT LEVEL DO YOU GUYS PLAY YOUR VINYL??
I like it quite LOUD andf this beartings is inaudible!!
Well there you have nailed it, baggins - if it ain't broke, don't fix it! 😉
ME TOO!!!!!
Strangely, my Unity Rotary Platform (a '70s attempt at budget audiophile) has a real issue with rumble (the bearing shaft is long and too small a diameter for the weight of the platter (>30lb))
but it is most audible when I play it at medium to lower volume levels.
Jess
Just to be clear this bearing was not in the original Amstrad design.
Its so long ago Ive forgotten the original design ,this is what i came up with when I redesigned the whole platter /drive system to take advantage of what I considered to be a competent tone arm
(relatively speaking ). So I DID fix it so to speak!
Regarding searching out high tech ceramic balls ----- why ??
2 high carbon Hardened steel ball bearings are never going to spall
running in an oil bath @ 33.33333 rpm (excuse the lack of threes!)
the point contact has hardly any friction area !
Its so long ago Ive forgotten the original design ,this is what i came up with when I redesigned the whole platter /drive system to take advantage of what I considered to be a competent tone arm
(relatively speaking ). So I DID fix it so to speak!
Regarding searching out high tech ceramic balls ----- why ??
2 high carbon Hardened steel ball bearings are never going to spall
running in an oil bath @ 33.33333 rpm (excuse the lack of threes!)
the point contact has hardly any friction area !
baggins said:
The "small" area of contact must withstand a tremendous amount of force so the harder the contact area is, the better. I use Tungsten Carbide and Sapphire/Ruby in my bearing designs to minimize wear and friction over time. If your platter is of fairly light weight (2kg), Rockwell 68 ball bearings should be more than adequate.
To be honest the maths eludes me but assuming some slight compression of the balls I doubt if even in the worst case scenerio of a heavy (and mine probably weighs 8Lbs or so) platter they would flatten to the point of creating a large enough area of friction to generate enough heat for spalling or much noise for that matter!
I can only reiterate that this cloth eared old bugger hears far more noise from the motor (at what my wife considers excruciatingly loud sound levels) than from the bearing system.
I can only reiterate that this cloth eared old bugger hears far more noise from the motor (at what my wife considers excruciatingly loud sound levels) than from the bearing system.
Harley Davidson Bearing
Hello
I appologise if someone has already mentioned this in this thread (I haven't had time to read through all 8 pages!), but you should check out this TT which uses a cheap Harley Davidson valve as a bearing.
http://www.altmann.haan.de/turntable/
I'd like to build a DIY TT, but want to know how to build a platter, not too keen on wood, I fancy Acrylic/Perspex or metal... any thoughts... or threads!
Regards
Richard
Hello
I appologise if someone has already mentioned this in this thread (I haven't had time to read through all 8 pages!), but you should check out this TT which uses a cheap Harley Davidson valve as a bearing.
http://www.altmann.haan.de/turntable/
I'd like to build a DIY TT, but want to know how to build a platter, not too keen on wood, I fancy Acrylic/Perspex or metal... any thoughts... or threads!
Regards
Richard
Re: Harley Davidson Bearing
Hi richard, yes, it's been mentioned and looks interesting....
on the platter, yep, there are plenty of threads, and do a search and you may feel overwhelmed. But there are alot of ideas... rare tropical hardwood, wood, aluminium, concrete, perspex, delrin, melted vinyl records, plaster of paris... or any mix of the above as a sandwich.
The bottom line in many cases seems to be that you need access to a lathe/machine tools.
My advice, find the threads that interest you, click on "show printable version", then "show all XXXX posts on one page", then print it out and read at leisure. Saves you staring at a monitor for hours on end.
There;s one very long thread about a DIY TT here that took me something like 4 days to read.....
Richard Howell said:
Hi richard, yes, it's been mentioned and looks interesting....
on the platter, yep, there are plenty of threads, and do a search and you may feel overwhelmed. But there are alot of ideas... rare tropical hardwood, wood, aluminium, concrete, perspex, delrin, melted vinyl records, plaster of paris... or any mix of the above as a sandwich.
The bottom line in many cases seems to be that you need access to a lathe/machine tools.
My advice, find the threads that interest you, click on "show printable version", then "show all XXXX posts on one page", then print it out and read at leisure. Saves you staring at a monitor for hours on end.
There;s one very long thread about a DIY TT here that took me something like 4 days to read.....
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