If it's OK to answer. Garrard used a Churchhill centreless grinder. - 80 dB is conjecture based on the 501. It possibly is better. It has to be somewhere about there as the 501 is - 78 dB with the motor running.
I do hope saying graphite as a cheap experiment is helpful to the TD124. It needs only woodworking tools to make.
I do hope saying graphite as a cheap experiment is helpful to the TD124. It needs only woodworking tools to make.
I think it would be worth a shot to try this at some point. I guess the one thing that leaves me somewhat curious/puzzled is I have used soft bronze thrust plates in my 124 in the past and saw no evidence of precession - i.e. the ball fit the indentation perfectly with no visible gaps. Am I missing something here or misinterpreting the results I see?
I will say that bronze thrust plate wore alarmingly rapidly however, enough that in a few months it wore enough to interfere with brake operation.. Not such a good idea. (Not my idea actually)
Simone Luchetti recommends a teflon (teflon like?) thrustplate and this is something I would also like to try at some point.
I will say that bronze thrust plate wore alarmingly rapidly however, enough that in a few months it wore enough to interfere with brake operation.. Not such a good idea. (Not my idea actually)
Simone Luchetti recommends a teflon (teflon like?) thrustplate and this is something I would also like to try at some point.
Would a very small ruby stuck on spindle shaft and Titanium alloy thrust pad work ? In TD-124 Is there enough gap between spindle shaft and thrust pad to sneak in a small ring magnet ? I had asked this in another thread, a bearing housing is typically 1 to 1½ inches cylinder, if we put in more material in its construction, would noise from bush and bearing be dissipated easily ? I presume function of all turntable bearing must be same. With advancement of materials and sciences there ought to be conclusive bush, ball bearing and thrust pad combination.
Thanks and regards.
Thanks and regards.
Does centreless grinding keep the bored centre hole exactly "on centre"?
I would expect that centre grinding would be required to keep the bored centre hole "on centre".
If the centre hole is exactly on centre and the ball sits inside that cup, then the contact point of the ball to thrust plate will be a point IF the thrust plate is exactly at right angles to the centre of rotation.
That's two conditions that must be met.
If one or both are not met exactly then either the ball wears a circular contact flat around the theoretical point or the thrust plate wears a ring around the theoretical point.
Both errors will give an increase in vibration as wear progresses.
I would expect that centre grinding would be required to keep the bored centre hole "on centre".
If the centre hole is exactly on centre and the ball sits inside that cup, then the contact point of the ball to thrust plate will be a point IF the thrust plate is exactly at right angles to the centre of rotation.
That's two conditions that must be met.
If one or both are not met exactly then either the ball wears a circular contact flat around the theoretical point or the thrust plate wears a ring around the theoretical point.
Both errors will give an increase in vibration as wear progresses.
Hi Andrew. Not exactly. The Garrard used a flat surface. The surface about 10 mm and the allowed error 0.0001" ( 0.00254 mm ). If I get it right that is 0.015 degrees. The other end is in a nylon ball socket to self align. Plessey reversed the idea in the 401 ( bronze dome that was the 301 ball ). This allowed lower standards to still work. 0.001" was the final standard allowed ( 10 times worse than 1955 ). That is 0.15 degrees ( where tan looks linear like a microphone pentode can ),
Precession was Linn's worry about the LP12. The running clearance helps it work. As luck would have it one has no choice. The 6 to 1 micron finish is because they can. As Rega say " People look for whatever reason so why not ". 1 micron is typical of a fuel injector or a JCB ram ! The JCB must be able to resist dirt and keep that finish to stop oil escaping ( Terry of Loricraft did earth mover repairs, often in the mud at 0C after midnight in the snow ). The on centres grinding often gives +/- 0.0001" and a ball is about the same. Thus one might get > 0.0002" as seating is never perfect. With 0.001" clearence the problem is minimised. SAE 30 seems about right to aid the centering. As Julian Vereker said the bearing spins like a childs top. The bearing would take 2 Rizla papers in the gap ( red ones I think ). When filled with oil the bearing is solid, when dry very loose. If you close the gap often the turntable takes 10 hours to get to speed ( Hysterisis motor). It slows in a few minutes to need 10 hours again. All very subtle. This is most likely why a 301/401 needs 5 minutes to gain 1% after switch on. Mr Verdier thought this a good thing and the eddy current brake also. Loading up the TC 124 brake in Verdiers oppinion helps the turntable cope with stylus torque variations called by some dynamic wow. Verdier pointed out that the oil and eddy brake are not exactly the same. However at any point on the graph they seem the same. So changing the oil and getting rid of the brake in Verdiers oppinion might not be a good idea and Thorens knew what they were doing. I have worked with the people at Thorens and will say they do.
As far as I understand the oil looks like tadpoles ( baby frogs ). They are in random distribution when still. As the spindle turns they swim in the direction of rotation. Although no real heat is involved this changes the resitance to movement. Some modern oils are not like this. Who knows how good they are. Motorcar oils are for > 30 PSi ( 2 Bar ) use. The aditives are too large for these bearings. Phosphor bronze dislikes this oil ( Esso research ), it forms phosphoric acid crystals. No lasting harm if washed out. Power station turbine jacking oil is OK( 1920's types ). ATF also. Never tried brake fluid, it might work. Olive oil seems likely.
Bronze seems to work well when looking bad. Hard points can work badly when looking good. That's where hardness and 1 micron do matter. The LP12 bearing looks like lead at the point. The finish is so good it looks darker. TD 160 looks different, I think it is important. I have an LP12 and TD145. It is surprising how they look mostly the same yet have a different sound. Noting the price the TD145 is my favourite, the LP12 is very much better on sound stage. As most of the LP12 didn't cost a penny more to make I suspect the point is the point. As Linns original advert said " A unique point in it's favour ".
TD124 and 301/401 are the same jump up from LP12 as it it is over TD145( 160 ). My TD145 has Linn springs, stiffer with no penalties. A good cheap upgrade.
Precession was Linn's worry about the LP12. The running clearance helps it work. As luck would have it one has no choice. The 6 to 1 micron finish is because they can. As Rega say " People look for whatever reason so why not ". 1 micron is typical of a fuel injector or a JCB ram ! The JCB must be able to resist dirt and keep that finish to stop oil escaping ( Terry of Loricraft did earth mover repairs, often in the mud at 0C after midnight in the snow ). The on centres grinding often gives +/- 0.0001" and a ball is about the same. Thus one might get > 0.0002" as seating is never perfect. With 0.001" clearence the problem is minimised. SAE 30 seems about right to aid the centering. As Julian Vereker said the bearing spins like a childs top. The bearing would take 2 Rizla papers in the gap ( red ones I think ). When filled with oil the bearing is solid, when dry very loose. If you close the gap often the turntable takes 10 hours to get to speed ( Hysterisis motor). It slows in a few minutes to need 10 hours again. All very subtle. This is most likely why a 301/401 needs 5 minutes to gain 1% after switch on. Mr Verdier thought this a good thing and the eddy current brake also. Loading up the TC 124 brake in Verdiers oppinion helps the turntable cope with stylus torque variations called by some dynamic wow. Verdier pointed out that the oil and eddy brake are not exactly the same. However at any point on the graph they seem the same. So changing the oil and getting rid of the brake in Verdiers oppinion might not be a good idea and Thorens knew what they were doing. I have worked with the people at Thorens and will say they do.
As far as I understand the oil looks like tadpoles ( baby frogs ). They are in random distribution when still. As the spindle turns they swim in the direction of rotation. Although no real heat is involved this changes the resitance to movement. Some modern oils are not like this. Who knows how good they are. Motorcar oils are for > 30 PSi ( 2 Bar ) use. The aditives are too large for these bearings. Phosphor bronze dislikes this oil ( Esso research ), it forms phosphoric acid crystals. No lasting harm if washed out. Power station turbine jacking oil is OK( 1920's types ). ATF also. Never tried brake fluid, it might work. Olive oil seems likely.
Bronze seems to work well when looking bad. Hard points can work badly when looking good. That's where hardness and 1 micron do matter. The LP12 bearing looks like lead at the point. The finish is so good it looks darker. TD 160 looks different, I think it is important. I have an LP12 and TD145. It is surprising how they look mostly the same yet have a different sound. Noting the price the TD145 is my favourite, the LP12 is very much better on sound stage. As most of the LP12 didn't cost a penny more to make I suspect the point is the point. As Linns original advert said " A unique point in it's favour ".
TD124 and 301/401 are the same jump up from LP12 as it it is over TD145( 160 ). My TD145 has Linn springs, stiffer with no penalties. A good cheap upgrade.
Nigel, this may be a bit off-topic as you're clearly talking here about oils used for the main platter bearing, while a synthetic oil I've come across is likely more well-suited to the E50 motor, but as you've mentioned the problems that might arise by using oils with certain additives and the fact that some oils are intended to be used in a pressurized, filtered system, I'd be interested in hearing your opinion of the Nye 181b synthetic oil, which I purchased some time ago with the intention of using it in my E50 motor. Nye offers a full line of oils, none of which to my knowledge have been put to use in the TD-124 to date. Here's a link to the spec. sheet.
http://productsearch.nyelubricants.com/pdf/TDS_English_SYNTHETIC OIL 181B.pdf
Sorry, here is the full line of Nye oils
http://www.nyelubricants.com/lubenotes/Lubenote_SinteredBearings.pdf
http://www.nyelubricants.com/lubenotes/Lubenote_SinteredBearings.pdf
It looks fine. The point I have been tying to get across is simple ideas work. What seems like the toys we played with when young is subtly different when a TD124. The oil, belt, thrust of a TD124 might cause 6 dB of noise. 6 dB is super turntabllle or OK turntable difference.
My TD 124 had worn motor bearings. 10 minutes work every 5 years would have prevented that. The TD 124 even has an oil hole.
Most synthetic oils are made from mineral oil base products. Hard to say if they really are different. Most sythetic oils are wrong for TD124 only because the use was not in mind when produced. Nye oils seem ideal.
I went to the Hoover Dam. They told me they had gone back to original 1930's oil as they had doubts ( Terre Esso 77 I think ).
As an engineer I make most of my money by being off topic. Often something I know about something seemingly unrelated is mathatically the same pattern. I was in a pub once talking like this with my friend who is a mathatician. A man came up to us and demanded how to fit a curve to business trends. I tried to say we always know afterwards the best curve. All I said is start and stop points are not known. Without that data nothing much can be said. Music is the same and in my oppinion that defeats digital systems. That's why so many samples might be needed. Jitter is mostly it hit the wrong point ( doubly worse on playback ). Equally bearing noise is a type of jitter. Worse is the level may not intrude into readings.
I wonder if a ball on a flexible tower would work ( TD124 main bearing )? The cup would minutely move on each rotation to halve the error. The longer the tower the better the result ? Magnetic levitation seems to have problems , I suspect noise works two ways and needs a mechanical ground.
My TD 124 had worn motor bearings. 10 minutes work every 5 years would have prevented that. The TD 124 even has an oil hole.
Most synthetic oils are made from mineral oil base products. Hard to say if they really are different. Most sythetic oils are wrong for TD124 only because the use was not in mind when produced. Nye oils seem ideal.
I went to the Hoover Dam. They told me they had gone back to original 1930's oil as they had doubts ( Terre Esso 77 I think ).
As an engineer I make most of my money by being off topic. Often something I know about something seemingly unrelated is mathatically the same pattern. I was in a pub once talking like this with my friend who is a mathatician. A man came up to us and demanded how to fit a curve to business trends. I tried to say we always know afterwards the best curve. All I said is start and stop points are not known. Without that data nothing much can be said. Music is the same and in my oppinion that defeats digital systems. That's why so many samples might be needed. Jitter is mostly it hit the wrong point ( doubly worse on playback ). Equally bearing noise is a type of jitter. Worse is the level may not intrude into readings.
I wonder if a ball on a flexible tower would work ( TD124 main bearing )? The cup would minutely move on each rotation to halve the error. The longer the tower the better the result ? Magnetic levitation seems to have problems , I suspect noise works two ways and needs a mechanical ground.
Thank you, Nigel. That's most helpful. With respect to modifications to the main bearing that you're suggesting might provide a meaningful noise reduction, I simply don't have the knowledge necessary to even hazard a guess.
I will note that there are at least two sources for new platter spindles/housings, but I believe the primary differences between those designs and the original are length, weight, materials. To the best of my knowledge the design with respect to the parts you mention, remains the same. Some of the people who machine and market these replacements may well be members of this forum & if so, perhaps will chime in.
Interesting comments, and some very useful insights. I'm going to be servicing the motor in my TD-124 MKII soon, it has never quite performed as well as I had hoped in terms of getting up to speed. (My other one is rock stable in a few minutes by comparison vs 20 minutes for the MKII motor) I am going to try the NYE oil I have based on Nigel's comments, and may possibly reinstall the original motor bearings as well. (They're not worn as the table had less than a 100hrs of use when I got it and had been dormant for 40yrs after that)
Nigel, what you think of silicon nitride balls on one of your suggested thrust plate materials? (Or for that matter teflon?)
My other comment would be I've not really found any evidence to date of precession on the thrust plates I've replaced, the balls seem to be very well centered. This is certainly the case with the two tables I own.
I'm using 30wt in one main bearing and currently 20wt in the other, but will probably go back to 30wt in that one. Oilite recommends 30wt oil for use with their 14mm ID bushings.
In terms of bushings they offer several different lengths, is the original optimum in your opinion - what is the impact on noise of using a slightly longer bushing in the top of the bearing assembly? (More/less/indifferent?)
Something to note is the ball centering approach on very early spindles differs significantly from later tables. (I worked on a unit with a serial number that puts it at the very beginning of production. I believe I posted a picture of that spindle here somewhere) The next oldest ones I have worked on had serial numbers in the 4000 - 5000 range and were essentially in the final configuration seen for the rest of the run. Bearing housing did not use a coined bottom in the earliest units either.
My other comment would be I've not really found any evidence to date of precession on the thrust plates I've replaced, the balls seem to be very well centered. This is certainly the case with the two tables I own.
I'm using 30wt in one main bearing and currently 20wt in the other, but will probably go back to 30wt in that one. Oilite recommends 30wt oil for use with their 14mm ID bushings.
In terms of bushings they offer several different lengths, is the original optimum in your opinion - what is the impact on noise of using a slightly longer bushing in the top of the bearing assembly? (More/less/indifferent?)
Something to note is the ball centering approach on very early spindles differs significantly from later tables. (I worked on a unit with a serial number that puts it at the very beginning of production. I believe I posted a picture of that spindle here somewhere) The next oldest ones I have worked on had serial numbers in the 4000 - 5000 range and were essentially in the final configuration seen for the rest of the run. Bearing housing did not use a coined bottom in the earliest units either.
Soak them in oil for a few hours first if they ar3e outside of the motor. Heat them up then let them cool ( 60 C ) . Work them in the sockets to be sure they move like eyeballs.
You now can laugh. I repaired a Bosch oven recently. The generic halfmoon 1700 watt element was glowing yellow red which would cause it to fail. It is now dull red as it should be. I suspect the fan had lost some speed due to sitting idle for over a year. The motor is a two pole of the exact same type as TD124 ( 4 pole ) with tidal flow bronze. I suspect the heat revived the oil to allow the increased speed. Problem is the fan was turning so all was thought to be OK. The generic is only 1400 watts ( 40 R cold 44R hot @ 240 V = 1300 ish ). This is a good move as it is more likely to survive. It takes a bit longer to get hot is the payback. The Bosch is $60, the generic $17. All I will say is the oven needs the fan to work much as a kettle needs water. A thermal switch on the motor plate switches the element off if the fan fails.
You now can laugh. I repaired a Bosch oven recently. The generic halfmoon 1700 watt element was glowing yellow red which would cause it to fail. It is now dull red as it should be. I suspect the fan had lost some speed due to sitting idle for over a year. The motor is a two pole of the exact same type as TD124 ( 4 pole ) with tidal flow bronze. I suspect the heat revived the oil to allow the increased speed. Problem is the fan was turning so all was thought to be OK. The generic is only 1400 watts ( 40 R cold 44R hot @ 240 V = 1300 ish ). This is a good move as it is more likely to survive. It takes a bit longer to get hot is the payback. The Bosch is $60, the generic $17. All I will say is the oven needs the fan to work much as a kettle needs water. A thermal switch on the motor plate switches the element off if the fan fails.
Be careful of PTFE as it is super hard ( yes ) yet it has lubricity. As said the ball can be rotated if it is a mistake. Nylatron also perhaps ( graphite-nylon )?
Getting the bush size right is a question. Thorens would have tried many ideas to get it right. I did use plain bronze once as do Rega. It is fine if the oil is sealed in. Phosphor bronze is to allow going dry. Never machine oilite bearings. Even experts get it wrong. As luck has it Thorens use off the shelf sizes. Garrard used 4.91mm in the motor. It has no metric nor imperial reason to be that size. Possibly they used 5 mm stock, hardened , lapped , and ground as it is said ( the order seems wrong, that's how it was said ). Garrard were also clock makers , this is not unknown for clock companies. It means only their spare parts used.
Getting the bush size right is a question. Thorens would have tried many ideas to get it right. I did use plain bronze once as do Rega. It is fine if the oil is sealed in. Phosphor bronze is to allow going dry. Never machine oilite bearings. Even experts get it wrong. As luck has it Thorens use off the shelf sizes. Garrard used 4.91mm in the motor. It has no metric nor imperial reason to be that size. Possibly they used 5 mm stock, hardened , lapped , and ground as it is said ( the order seems wrong, that's how it was said ). Garrard were also clock makers , this is not unknown for clock companies. It means only their spare parts used.
I've reconditioned bushings before so the procedure is very familiar, with the exception of genuine oilite bushes many of the ones I used were not oil impregnated when they arrived here. I heat the oil to roughly 60 C and put the bushings in and then allow the oil to cool to ambient before removing them. This has worked quite well.
I am a terrible machinist with a small machine shop in my basement. Some day I will get going and learn how to use my mill and lathe properly. I do know that machining bushings is a no no.. lol
I'm fairly good at rebuilding the E50 motor, done a lot of them, and can usually get them pretty quiet. I am very suspicious of the replacement bushings I have used - while quiet the motors seem to take much longer to come up to speed than they should based on the one motor I have that still has its original (and good) bushings.
The stock main bearing thrust plate is a concave shaped nylatron disk to conform with the dished end cap I mentioned previously, and in well maintained machines the contact patch has a diameter of about 2mm or less, and is perfectly round.
My one experiment with bronze thrust plate (integral with the end cap) ended after less than a couple of months as it was wearing very badly - the balls are quite hard and I've never seen one with damage (using a 9X loupe to examine) except in the case where the bearing ran totally dry, but then there was a lot of other damage as well.
I am a terrible machinist with a small machine shop in my basement. Some day I will get going and learn how to use my mill and lathe properly. I do know that machining bushings is a no no.. lol
I'm fairly good at rebuilding the E50 motor, done a lot of them, and can usually get them pretty quiet. I am very suspicious of the replacement bushings I have used - while quiet the motors seem to take much longer to come up to speed than they should based on the one motor I have that still has its original (and good) bushings.
The stock main bearing thrust plate is a concave shaped nylatron disk to conform with the dished end cap I mentioned previously, and in well maintained machines the contact patch has a diameter of about 2mm or less, and is perfectly round.
My one experiment with bronze thrust plate (integral with the end cap) ended after less than a couple of months as it was wearing very badly - the balls are quite hard and I've never seen one with damage (using a 9X loupe to examine) except in the case where the bearing ran totally dry, but then there was a lot of other damage as well.
Nigel, as you also mentioned having worn E50 bushings, can you clarify that in this instance, the "stock sizes" you reference are those used in the main, not spherical with collar design used in the E50?
Additionally, with respect to the desire to avoid cut Oilite bushings (which I certainly agree with), am I correct in assuming you either produced or obtained proper pressure cast bushings to replace the worn ones in your E50? If there is a source for these bushings, it has eluded me and many others. To the best of my knowledge all of the bushings currently produced specifically to accommodate those of us rebuilding E50 motors are cut, and may well be, as Kevinkr alluded to, the cause of less than optimal results.
Any insight as to how we might obtain proper E50 bushings (when the old ones cannot be put back into service) would certainly be appreciated.
Me also. I do the rough ones then get someone to do it for me who can make it look good. Seems if I don't do the rough one no one does. I do somehow know how to make it work OK regardless of how it looks.
Nylon likes water. It grows. Sometimes it is a bad choice. Put it in water overnight then machine it if for bushings.
The Loricarft PRC was my design ( and that of Percy Wilson and Keith Monks ). I am an electronics engineering with pieces of paper for electrical engineering. One day I said to one of the staff to teach me the lathe. He said he would show me how to sharpen a cutting tool and set it. Then he went to lunch. I redesigned the machine to suit my self taught skills. When a proper engineer took over he said he would change nothing as my way was also the most logical. My lack of skills meant easy to make. I have repaired motorcycles. I guess they showed me the way. I do find electronics people a little bit wrong by always being right. Mechanical engineers are different.They know it might not work and are willing to say so. That makes them more skilled because they usually know how to solve it. The reason plan A is tried is simple is best and often cheaper. Plan B is if 90% sucessful. Electonics mostly is make it twice to twenty times as complex for reasons unknown. My guess is to look original.
Nylon likes water. It grows. Sometimes it is a bad choice. Put it in water overnight then machine it if for bushings.
The Loricarft PRC was my design ( and that of Percy Wilson and Keith Monks ). I am an electronics engineering with pieces of paper for electrical engineering. One day I said to one of the staff to teach me the lathe. He said he would show me how to sharpen a cutting tool and set it. Then he went to lunch. I redesigned the machine to suit my self taught skills. When a proper engineer took over he said he would change nothing as my way was also the most logical. My lack of skills meant easy to make. I have repaired motorcycles. I guess they showed me the way. I do find electronics people a little bit wrong by always being right. Mechanical engineers are different.They know it might not work and are willing to say so. That makes them more skilled because they usually know how to solve it. The reason plan A is tried is simple is best and often cheaper. Plan B is if 90% sucessful. Electonics mostly is make it twice to twenty times as complex for reasons unknown. My guess is to look original.
Quite a lot is by looking at books of parts . One thing I did was machine an old bearing and press fit the smallest one in that will fit. For example 5 x 8 x 10 mm bearing used to save a worn bearing. Drill 7.7 mm into worm 5 mm hole , drill oil holes in criss-cross to aid oil transfer from felt pads , ream 8 mm. Press in oilite bearings pre soaked. When I say press I mean using finger and thumb. If not the bearing closes. That's one way to save a bearing. $1 to perfection. I had some bronze bushes made by a new process. Sorry to say no good. The pressed power ( cheap ) ones are better. If the Garrard there is a chance the 4.91 mm shaft can be removed . The rotor could be reamed to 5mm. > 64 Rockwell ( C ) 5 mm stock shaft of 1 micron polish can be bought from some suppliers. Standard oilite 5 x 8 x 10 could be used. The shaft end must be to a good standard. The pulley will just about ream as the dia at 50 Hz is circa 6.33 mm. 5.3 mm 60Hz is difficult. On the Garrard 501 I use a 6 mm shaft as the pulley. This needs 52 Hz from the PSU. I took the garrard design as something I should not change. This means I keep as near as I can to the original. 6mm casued some of us to be worried. They thought 5 mm better ( drag ). If 5 mm 62.4 Hz. The reason I choose 6 mm was it was almost the pulley size. I thought it might grip better.