Can you improve the stock techie bearing???

[Ianmac]

Have been away for a week and back onstream for a few days.
Continuing to do my research.
I find it interesting to note that very very few (if any) of the suppliers of goodies for these decks provide any measurements to back up their improved performance claims. Some of the reports on performance gains are so good it makes one wonder who really wrote them.


I have rebuilt a second bearing, the one I removed from my own deck.
Have spoken to a few Plastics Suppliers/Manufacturers support staff about the correct type of plastic to use. The bearing fitted to my deck at the moment uses Teflon, the second is fitted with Ertalyte and a member has kindly sent me a piece of Torlon.
The arguements re wear are noted but I am running my bearing fully immersed in a lubricant and this puts a slightly different perspective on the wear issue.

I am trying to establish a better way of measuring any unwanted vertical movement of the platter when rotating and looking for a reasonably long unmodulated track on disc
anyone help?
Has anyone done any work on the vertical movement induced by the motor itself - this must be there and is probably dampened slightly by a heavier platter. I must look at the servo itself and try and determine the frequency band any induced movement would be in.
Sounds like Im talking myself into getting a deck to use as a bench test unit probably a bit OTT at the moment. Im sure someone will already have looked at the servo issues. Just got to find their comments.

I want to experiment with different lubricants as I believe this may be more important than the precise type of plastic used on the bearing thrust plate.
Given a servo controlled motor the reduction in rotational friction is not my top priority but using the fluid to assist damping vertical shaft movement may be the way to go. I can accomodate this in my reworked bearing.
I am awaiting alternative fluids and a stock of Brass before proceeding further.
One member has already been in contact prepared to do some evaluation on a reworked bearing so by mid march we should have an unbiased second opinion.
Will report back as soon as I can.

[Mike_New]

Continuing to do my research.
"I find it interesting to note that very very few (if any) of the suppliers of goodies for these decks provide any measurements to back up their improved performance claims. Some of the reports on performance gains are so good it makes one wonder who really wrote them."
Ian old chap,
If you may care to bother to read through the over 110 pages of observations, comments and measurements on the "Mike new Bearing" thread, and about three or four other relavent threads on this forum (and elsewhere). You may conclude that the people who were making these observations "wrote them"
As the main single person who has probably done more for the developement of sensible and valid update options for the venerable SL1200 I find your seemingly uninformed observations somewhat puzzeling. As has been said so often in the threads mentioned, it is difficult nia impossible to catogorically state a set of meaningful figures over a range of conditions as it is I believe with any audio equipment.
Your attempts which follow many before you; to improve the basic bearing are laudible, if somewhat fruitless.
You see the basic problem with the "bearing" is not the pivot point that the shaft sits on but the rigidity of the actual bearing housing.
The shaft could sit/rotate on the top of Tower Bridge for all the bloody good it would do if the constraining bearing housing were not suficiently rigid and correctly enclosed to a high precision fit.
The pointless "experimenting" with different lubricants just boggles my mind. All they do is to help fill in the gap between the shaft and the bearing support.
Please understand that any movement of the platter in the vertical direction will be induced by the translation of the lateral rocking movement in the bearing to a vertical movement in the platter, such movement will be proportional to the radial distance as difined by basic trigonometry. You can do some sums on this if you wish to further your research.
Concernig the motor if you have ever investigated offering up the fero magnetic rotor to the stator coil assembly using a dummy platter centre-part and taper boss you will find that the radial magnetic field of the stator is such that it tends to pull the stator down onto the coils and consequently the bearing. This is clearly demonstrated when carefully placing a platter onto the spindle taper.
No amount of accoutical energy is going to cause the platter to move in the axial vertical direction.












Ian, old chap

[Ianmac]

Mike,
Thanks for your comment.
There is no need to address me as old chap , Ian is just fine.

Its nice to know my attempts to improve the basic bearing are laudible and will be somewhat fruitless.

It is very obvious to anyone with an engineering background that one of the issues with the bearing is its rigidity and I have addressed that.
I am also aware that one of the effects of the magnetic field is to pull the stator downwards and that the acoustical energy we are dealing with is unlikely to move the platter in the vertical direction.

The object of my excercise is to improve my Technics bearing within a limited budget and am very confident that it will be achieved.

[keiron99]

As has been said so often in the threads mentioned, it is difficult nia impossible to catogorically state a set of meaningful figures over a range of conditions as it is I believe with any audio equipment.

Is "rumble" an issue that upgraded bearings seeks to improve? This would be easily quantified wouldn't it?

[Ianmac]

Rumble is an issue that upgraded bearings should improve.
It is measurable -- In my humble experience everything in audio is measureable by one means or another-- designers dont just sit changing components and listening all day as some seem to think.
I have devised my way to measure "rumble" and I can see the improvement my "Laudable and fruitless attempts" at modding a bearing are giving over a given frequency range. I would like to improve this thus my seeking a disc with a large section of unmodulated track. We used to have one where I worked but I cant seem to find one today.

Currently running my second bearing with the Ertalyte thrust bearing. Results are identical to the Teflon pad.
I'm looking at the cost of a possible DIY excercise to build a few from new or donor technics bearings if we have enough interest, encouraging figures coming in well below what we see in the marketplace today.

[keiron99]

I am trying to establish a better way of measuring any unwanted vertical movement of the platter when rotating and looking for a reasonably long unmodulated track on disc
anyone help?

I'm not even sure I know what "unmodulated" means but maybe such a track is available on a test record like the HiFi News one?

[Ianmac]

Apols for the techspeak , I mean just a cut track with no sound. Used to use them years ago for checking rumble and noise on decks used in pro applications.
Ideally you want this across a whole disc so measurements can be taken across the whole platter area.
Ill check out the Hi Fi news disc

[rmsshipbroker]

I would like to improve this thus my seeking a disc with a large section of unmodulated track.

What about lead out grooves at the end of side?
They are unmodulated and go on.....and on....and on....
Excellent work on the bearing.
I look forward to reading more about your mods.

Edit: Sorry just seen your comment about needing it across the whole width, doh.
I think it's time I had some kip....

[Ianmac]

Have been away for the last 3 weeks but now back on stream.
I will shortly have a modded bearing available for anyone who wants to evaluate it. This will use Ertalyte as a thrust bearing and be capable of running in oil or silicon fluid as ones preference.
I'm currently using a low CST Silicon (CST is similar to SAE rating used for oil). As guide I'm using 50CST in my bearing and the silicon fluid used in my arm damper is 60,000CST ( very very thick). I will be getting some 250 and 350 CST fluid to do comparison tests.
Looking at the cost of producing the bits and modding a donor bearing, for a small batch of 5 or 6 bearings. Im certain these can be made for below one quarter of the price of the top end bearings in the marketplace.

[Marco]

Looking forward to seeing what you come up with, Ian

Marco.