The TD124 Bearing and upgrades.
Above photo: As received the lower nylon bushing is missing..! This bearing won't be used unless new bushings are installed. The three threaded holes at the housing bottom are tapped by the factory for M3 x .5mm.
Above photo: the Bearing housing and it's end plate components disassembled.
Above photo: The Bearing housing, the remaining old Nylon Bushing and it's replacements; sintered bronze bushings. The sintered bronze bushings pressed in easily.
Above photo: The bearing housing with the new sintered bronze bushings installed.
Above photo: checking the bearing assembly for slop. With moderate pressure applied to the opposite quadrant, the indicator reads .001 inches of free-play. Note that the bearing housing is not filled with lubrication for this test.
Above photo: The assembled bearing housing with its new heavy bronze thrust plate. The nylon thrust pad was replaced with a piece of delrin cut to shape. Automotive gasket material was used to replace the original gasket. Longer screws were necessary. The thread size is M3 x .5mm. I sourced stainless internal hex cap screws (10mm grip length) from McMaster-Carr. The seal is oil tight.
Further developments 2008
As a refinement to the heavy thrust plate theme I drew plans for another heavy bearing cap.
This time the material chosen was gunmetal.* Gunmetal is an obsolete bronze alloy that was once used in the manufacture of cannons. Long ago. The US govt. bronze spec "G" recipe for this alloy is 88% copper, 10% tin and 2% zinc. The alloy is not in common use and can be hard to source. Once found, the alloy tends to be high priced. Nonetheless I did source a round bar of it; paying $105 for a 1 foot length of it. Then I found a local tool-maker to cnc machine a small order of these for me. The costs were not insignificant but the results can be appreciated in the photos.
The machinist told me that the alloy is very soft and requires special handling and cutting techniques in order not to distort or "mushroom" the material under the cutting forces involved. Also note, if you drop one of these to a hard floor surface, it will likely be heavily dented. It is that soft.
I like these parts and have decided to make these available commercially. If you would like one here is a link to my advertisement. If you would rather machine your own, go for it. In either case the consensus is universal, heavy bearing caps do improve the sound of a TD124.
footnotes:
 | * gunmetal. |
| Q: Why gunmetal? |
| A: There is a certain mystique surrounding this material among audiophiles all over the planet. In consideration of this I decided to make a small run of parts using the alloy. Sonic results are NOT disappointing. However I couldn't say that an end cap composed of this alloy will be a "better sounding" product than one produced from a different bronze alloy. What is known is that all material choices do affect the sonic qualities of our turntables in some, --perhaps large or perhaps small--, way. In the future I will offer bearing caps in different, perhaps less expensive alloys. |