TT bearing

Im going to make my own TT in the future and the bearing is the only thing i havent got a clue about.
I dont want to make one.
The only one i know of is the one teres audio have.
the plint is going to be heavy but the plasser is going to be around 5kg i guess
What options do i have??
 

DaveM

Member
2003-02-06 4:23 pm
Vermont
Wuffer,

You say this is for a first time turntable. That infers that this is not to be the last. I personally try to not cut any corners that I may think about later and say "Hmmmm how much better would it sound with that other bearing?". Just my 2 cents. Get a bearing that you know is worthy of your labor.

With that I know nothing of the BIX and how good it is.
 

DaveM

Member
2003-02-06 4:23 pm
Vermont
That is a good question. In fact it is one that I have been looking for the answer to for quite some time. I think in the end I will end up making my own. McMaster Carr sells high tolerance polished rod that make a perfect starting point. From there I have access to grinding equipment that I can use to make a bore as needed. I will probably go with an inverted bearing with a teflon pad and a ceramic bearing. Cut grooves in the ground rod for oil lifting. Is there anything much more? I don't know.

I still don't really know how tight the fit should be. Tight enough for minimal play and a wide enough gap for oil to be able to lubricate. .0005" gap? Beats me. I always look at the Teres bearing and think that it is a very solid design and a great compromise in terms of an inverted style bearing without the hassle of the oil grooves and oil bath.

Of course the issue with the design I laid out is access to the machines and expertise to make it well. I am fortunate and have access to the machines and someone who knows them well enough to keep my from making a hash of it. I am also fortunate to have had someone at work mistakenly order an piece of 6" X 12" X 12" black Delrin. That should make the best platter money can buy. I believe the material was $300. Delrin is often used as a replacement for metal parts when weight is an issue. Sounds like the next best thing to me.
 
Why the middle man?

Hi Folks, this is a really interesting topic - I'm glad I found you guys.

Here's my perspective: Why buy a VPI or Rega bearing? Are they special, or fitted to a mount or sub-platter that's easy to use? These are cost-constrained items that they're marking up before selling to you, so perhaps with some searching we can find bearings that far exceed our TT needs, and leave us never wanting for magnetic bearings again. Bearings have been improved so much in the last 20 years at every price point.

Here's an example. This bicycle bearing has balls that are round to 5 millionths of an inch - worth a Grade 5 precision rating. That's 0.000005 inches of wiggle. I don't think it gets much better than that.

"Starting with vacuum de-gassed alloy and hardened to Rockwell C-64, these super high precision races are cryogenically treated not once, but three times during the final super polishing phase."

http://www.neuvationcycling.com/parts_promos/bearings/ceramic_bearings.html

They want $100 for this (I think for a pair, actually). How much does Rega or VPI charge for a bearing, and can they claim this level of precision? Is there something that's special or more 'musical' about their bearings?

Of course, this bearing is not design primarily for axial load - I just picked it kind of randomly on the web to find an example of value outside the audiophile world. Then again, it's spec'd to handle 200lbs of cyclist going over cobblestones and jumping off the occasional curb, so it should support a 20lb axial load at 33RPM for a long time without problem.

There are other bearings designed for high speed that are very well balanced and incredibly smooth - capable of handling loads from all directions at 300,000 RPM in spindles like this:
http://www.sycotec.eu/drives/index.htm
My point is that there's a whole world of bearings out there beyond what mainstream TT manufacturers use, at reasonable prices. How much do you think the bearing in a $5,000 TT costs? Do TT manufacturers use the same bearing in their $1500 TT as their $5,000 TT?

Cheers,
Anthony
 
balls...balls...balls...

I had thought about using bicycle style bearings for a platter bearing.

It's not that they aren't any good, but that they are in fact are not designed for lateral thrust. One option may be a tapered headset type bearing using rollers, or loose pack headset bearings, races and cups. These bearings can take a ton of punishment. Hardened steel or aluminum races and cups, and order whatever spec bearing (as in the balls) one wants.

But a good headset is quite expensive.

As far as McMaster and Carr go, it is very possible to create an excellent platter bearing from their parts. However, the main body of the platter bearing needs to be very robust so as not to flex or have less than adequate support for the bearing shaft. The turntable specific bearings are not inherently better that other types, but well designed and constructed ones take this into account.

I think the idea of using someone else's bearing is the ease that many may be able to source them. Not everyone has the access required, or the skills required to build from scratch

I am currently working on a platter bearing for possible commercial use. So I need to consider the quality of the bearing, and it's vertical load capacity as well as an inherently stable housing. This is why I am looking at having a bearing made for me, but it will cost a significant amount to start and work out. And for a "one off" bearing the costs associated may be greater than purchasing an existing high quality bearing. If I could source an existing design OEM at what I think is a reasonable manufacturing cost, I'd go that route, even for the prototype work I am doing now.

stew
 

DaveM

Member
2003-02-06 4:23 pm
Vermont
The idea of a ball bearing is where I started my thinking and it was pointed out to me that turntable bearings do not use ball bearings traditionally. They are bushings riding on a single ball point. The reason for this is that ball bearings introduce noise. Think of having a single point that is carrying the whole load and spinning in place and compare it to, say 50 balls all spinning in a race. Those 50 balls are going to make tons of low level vibrations that will be picked up by the cartridge riding on the platter. Noise is of course the last thing we want in our platter. The whole purpose of a bushing is that the single high polished contact point reduces noise to a minimum and a high tolerance fit on the shaft/sleeve keeps wobble to a minimum.

This is not to say that you can't successfully build a bearing out of a roller or ball bearing, but I bet that a brass/bronze bushing with a high polished high carbon steel shaft riding on a high polished ball floating in an oil bath will beat it six ways from Sunday.
 
Dave, I agree...

I was responding directly to the question presented. And I can say that High quality bicycle bearings are very quiet. Loose ball bearing types will work, but there will be a significant amount of rumble (the old Garrards and Thorens use these types).

To add to you suggestions: a hardened, polished steel pad for the ball to run on.

stew
 
Mike Gergen said:
Another stupid question...
I've seen platters sitting on a single ball, with the ball in a mount of some type. What about a glass or quartz ball?

The finish can be as close or better than polished steel and there aren't any thermal issues with expansion/contraction.


Some of the high end bearings, are based on a ceramic ball.


Magura :)