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For those of you that have followed my Rek O Kut projects you know that I found micropolishing the main bearings to dramatically improve bass response, low level detail retrieval and reduce the noise floor. These are all very good things for an idler project.Here are some pictures for you to inspect.
Picture one is two Rek O Kut main bearings. The one on the back is a stock ROK LP-34 I just purchased a week or two ago. It shows an actual wear depression from the ball that rides between the bearing housing and the thrust surface of this steel bearing.
You can clearly see the natural state of the wear depression in the linked photograph. This will be machined down to flat and level and micropolished for my next project.
The platter in the foreground is the LP-743 which I am using for my RCM at this time. This was micropolished about a year ago.
You should also be able to see the very precise machining on the bearing in the back picture. It is superbly machined however it is unpolished.
The closer platter has a micropolished bearing.
To accomplish the polishing I removed the bearing by pressing it out of the platter. Then the bearing must be measured from top to bottom to find the lowest point. Then go back and polish the main bearing to bring the entire surface to the measurement of the low point.
This removes just enough material to get the surface polished and completely straight. You do not want to overpolish or other sonic nasties might intrude on your soundfield.
The polishing was accomplished by turning the bearing at 600 rpm in a lathe and running a polishing rig along the bearing running at 3k rpm. It requires just 20 minutes to get to the state you see here and much of this time is spent measuring.
The thrust plate is micropolished to a high luster.
Then drop in a silicone nitride ball from McMaster.com or a similar supplier and be ready to say oh my gawd.....
The sound is simply stunning from this simple tweak. I have more photos for you if you want them. Send me an email to jim_howard_pdx@yahoo.com for more details.
Cheers!
- http://i10.photobucket.com/albums/a150/tubesforever/Idler Project/pollishedbearings005.jpg (Open in New Window)
Follow Ups:
must have a precise instrument I suppose
Not so expensive purchased from a tool shop. You can pay more and get a better looking piece but if both meet the same accuracy you can save the money for the polish and polishing wheels.
As an example, if the overall bearing was machined to be .499 of an inch. It will probably vary and be .499 to .4989 or .4988. (Hopefully it will be at least this tightly machined!) You just have to measure the whole length to see where the low point value is on your particular bearing.Then polish the entire bearing to that low point. We do this for crank shafts all the time. Micropolishing = horsepower and performance longevity. That and main bearing alignment is critical as well.
Thanks for posting. Looks like it would make alot of difference with one as bad as that. Mine (B-12GH) is not nearly as bad. It has a small nick but otherwise looks alright. Still, I may look into this, as well as the silicon nitride ball, in the future if I can't banish the remaining noise. It really isn't all that bad on mine. I hear it (the noise, that is) between cuts and on the lead-in and lead-out grooves. I'll wait, however, until I get the Lenco up and running. I want to have at least one idler TT going while I work on the other one so I don't have to go back to my belt drive. You probably know what I mean! Thanks again.
My subsonic reinforcement is good to 18 hz in my apartment. So I can hear the hall breathe. If the idler intrudes into that sonic field I get a bit testy.The polished bearing provides less frictional loss and resonance from the main bearing. This gave me tight and extended bass. The silicone nitride ball gives me less friction on the thrust surface which means I can now hear auditory cues like the direction a cello is playing toward the microphone. If the mic is stand mounted I can hear the cello sway side to side while it is played. This level of detail is very intoxicating.
Normally you have to plunk down 5k or more to hear this clearly and realistically. The Rek O Kut can deliver this and the platforms are still reasonably priced.
I found my Rek O Kut to have significantly better bass response than other idler platforms on a recent trip. I think the superb bearing and 7 lb platter work very well together to deliver the information in the grooves.
I gotta get this LP-34 running this week or next. I love my thread drive but for rock and roll the idler reigns supreme.
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