IanMac Bearing

[Andrei]

This follows on from the thread: Can you improve the Stock Bearing. IanMac has done an interesting mod on the stock bearing but it should have a thread of its own.


For those who have not followed that thread the short point is that IanMac has essentially used a Teflon, a known slippery material for the thrust-pad. In principal this seems a brilliant and obvious idea and surely can only reduce rumble. The problems, if I understand it correctly, were twofold. First Teflon is not hard enough, and second keeping this material in place would require a new housing. The first problem Ian has solved by using a very hard type, called Peek. Second, his engineering skill have enabled him to make a housing.


Below is a comparative picture.


[IMG][/IMG]




The Mike New bearing is on the left, a stock bearing in the centre and the IanMac on the right.


I've had my IanMac bearing for quite a while now and I have decided I will keep using it. I have done a comparison of four bearings spin down times. When I say 'four' I have tested the IanMac Bearing twice, once as supplied, and then in a bath of oil. Here are the results.


[IMG][/IMG]


Each entry is an average of five readings. Larger numbers are better. I have done the test for each bearing in four scenarios. Twice with platter only at 33 and 45 rpm. And twice with a 5mm Achromat, 180 gram LP and the Michel Clamp. So at 33 rpm with platter only the IanMac bearing takes a little over 20 seconds to stop spinning. This is an improvement over the stock bearing.


Subjectively the IanMac bearing seems to have improved over the weeks I have had it, so maybe there is some benefit to running it in, though I did notice an improvement over the MNB straight out of the box as it were. I am not sure about the oil bath. I think improved slippery oils would help if it was a metal against metal bearing / thrustpad contact. But with Peek I am not so sure.


I have taken some readings in Audacity. I have used the silent groove on The Ultimate Analogue Test LP by Analogue Productions. They look like this in Audacity:

[IMG][/IMG]

I have taken Plot Spectrums from the Analyze menu. But I do not know how to interpret them. Anyone know what they mean and what are the best paramaters to choose.

[IMG][/IMG]


The net result is that I will be using IanMacs bearing from now and in due course will put my MNB up for sale. I will continue to experiment with different lubricants. I have a suspicion though that it may be best without any lubricant.

[Audio Al]

Did you include any bearing contact size / friction calculations / measurements ?

[Andrei]

Did you include any bearing contact size / friction calculations / measurements ?

No. What would you calculate and measure?

[Audio Al]

No. What would you calculate and measure?

I'm no engineer , however from memory i did see some images of the Mike New bearing out of the housing and the spindle is bigger ( tried to find the photos )

If the mass of the bearing spindle is bigger in a bigger housing surly it will have a larger contact area , spindle to housing contact , this will add friction and will result in shorter run down time , Is run down time relevant ? as its only running time accuracy that counts , The 1210 has a fine direct drive motor that copes with the bigger bearing and different types of platters and can maintaining speed accuracy ( just my opinion as a numpty )

[Andrei]

Peek is a good choice, as peek ceramic bearings are quite common.
I would suggest that your choice of oil is not the best.

It would also be interesting to compare the funk bearing, as this is another proven combination of materials.

I don't know what oil it is but it is the oil that was supplied by Mike with the MNB.

The Funk Bearing is extremely interesting and a polar opposite of Ian's approach. Peek is very hard but relative to Sapphire it is soft. One method is to obtain the benefit of a hard substance, and the other is to obtain the benefit of a slippery substance. Different approaches. I would certainly like to give Arthur's bearing a go but I suspect the use of Sapphire makes it expensive.

I'm no engineer , however from memory i did see some images of the Mike New bearing out of the housing and the spindle is bigger ( tried to find the photos )

If the mass of the bearing spindle is bigger in a bigger housing surly it will have a larger contact area , spindle to housing contact , this will add friction and will result in shorter run down time , Is run down time relevant ? as its only running time accuracy that counts , The 1210 has a fine direct drive motor that copes with the bigger bearing and different types of platters and can maintaining speed accuracy ( just my opinion as a numpty )

This is all tricky stuff for amateurs like you and me. I think the larger area would therefore spread the weight and produce less friction, or at least less friction per given area, just say sq mm for example. As against this there would be, as you say a larger area. I don't know if they are equally relevant. It is interesting to compare the readings for the IanMac bearing with and without added oil. The oil seems to make for some drag and that is why the readings are for a shorter run-down time. That is ok by me if the rumble is actually less. The motor of the SL1200 copes with this bit of drag without issue. The most significant comparison is between the IanMac (without oil) and the stock bearing. What is shows to me is that there is less friction - it is as simple as that. In fact my subjective listening is that it is quieter.

This leads to the Audacity readings. I was hoping to get some objective idea of the noise floor of the rumble with the IanMac bearing compared with other options. Really I am just looking to find the quietest bearing.
I should say that is not necessarily the be-all and end-all. The MNB does seem to be good for extra weight of heavy platters, mats and and record pucks. There is an obvious disadvantage of extra weight, but likely outweighed (sorry) by the benefit of more inertia.

[CageyH]

Peek is a good choice, as peek ceramic bearings are quite common.
I would suggest that your choice of oil is not the best.

It would also be interesting to compare the funk bearing, as this is another proven combination of materials.

[Stryder5]

Peek is a good choice, as peek ceramic bearings are quite common.
I would suggest that your choice of oil is not the best.

It would also be interesting to compare the funk bearing, as this is another proven combination of materials.

Just a quick comment about PEEK, it is an engineering thermoplastic, not ceramic. There are different grades of PEEK, there is a bearing grade, carbon fibre reinforced with graphite and PTFE lubricants, this offers the lowest friction coefficient and machinability of all the PEEK grades.

Not trying to tread on anyone's toes, just correcting a misconception that PEEK is ceramic.

Ianmac may already be using this grade.

[CageyH]

The ceramic comment was referring to the other part that makes up a bearing.

[Stryder5]

The ceramic comment was referring to the other part that makes up a bearing.

I'm really interested in this, what part?

[dimkasta]

Further on the lubrication matter, I recently read that motor oil has cleaning additives that can be corrosive to plastics. So use my previous suggestion of BP vanelus with care.

I also read that people had very nice results with more viscus oils or even greases like gearbox/differential lubricants (SAE 80). Has anyone tried something like that?

It might make sense for the bearing, especially with its bigger tolerances. I m not so sure about the thrust pad though.