Another interesting TT crossed my path recently, have not had one of these come my way before. Acoustic Signature Challenger II, a solid looking simple table that the owner wanted to change arms on.

What was needed was an armboard, and he was also concerned about the bearing. The bearing in these uses sintered oil impregnated bushes top and bottom in an alloy housing, with a plug screwed into the bottom that forms the thrust pad, its made from a material that AS calls Tidorfolon, vanadium, ferrite, teflon and titanium composition. Its quite soft to cut, but supposedly can deal with pressure from the bearing shaft and platter weight and offers damping and low friction.

The armboard sits on pillars that are bolted to a matching base that attaches to the side of the main solid alloy disc chassis.

The owner did not have much luck trying to order an armboard so I offered to take a shot at making one up based on the existing SME board he had. Below is the stock armboard assembly.

I got the owner to make a card template and tape it to the existing armboard, measure out the 222mm needed for the Origin Live arm, then send the whole assembly down, along with the bearing that we will touch on later.

We discussed materials, the stock parts are all alloy, there was also an option to do a delrin version. Of course you cannot say what the end result will be with each material, can only try, its all about synergy, arm type etc, I said I can do both and thats what I did!

The hole position is slightly off centre, which means rotating the board in the slots on the base will allow some fine tuning of the position in order the get that 222mm spot on.

I also knocked up a centre plug from some scrap which helps greatly in finding the centre of the hole.

With this out of the way the next step was to look at the bearing and work out a simple cost effective solution that maintained or bettered performance.

Next up was the bearing. The owner explained to me that he found it becoming quite noisy a few years ago, so had cleaned it and added a few drops of light oil, but it was quite mucky again when checked recently. Now the design is supposed to be service free and self lubricating. The oil impregnated sintered bushes and the Tidorfolon thrust pad at the bottom, running a steel spindle of 12mm dia with a tungsten ball pressed into the end.

It sort of reminded me of the 'lifetime' transmissions in cars, my feeling is there aint no such thing! Changing fluid and filter periodically in your lifetime tranny might actually get it to last a reasonable lifetime!

The spindle shaft has some fine wear at the upper bush area, not something you want to continue happening on your expensive TT, I suggested cleaning the bearing out and running it full of a high grade oil like the OL or Oracle oil. Owner has some of the vandenhul oil which should be more than good enough. But even with oil in it continued wear could be a problem, I remember how the hardened steel shafts used to wear in Tamiya RC cars if you used the factory nylon bushes, greased up or not made little difference. Yes vastly different rpm and load on an rc car 😁 but the shafts wore in a matter of weeks, this spindle has some light wear after 13 years of far more gentle rotation...

I suggested machining up a new bearing with the exact same measurements as the factory one, but with polymer bushes and thrust pad.

I got onto this and drew up the original bearing, then worked out a plan to make the new one.

Above is the new housing and some bush sleeves, next to the old bearing. I could see some marking inside the sintered bush, fine scratches here and there.

I figured there maybe other owners of this table out there who may want or need a new bearing so I made up a jig for doing the mounting holes, makes it easy to do them down the track. Jig has a spigot that drops into the top bush to centre is accurately.

Below is the final design with the final stack of bushes, spacer and thrust pad.

Now the bush material is an interesting polymer I discovered, and it must have been fate as the supplier was very close and a lovely bloke who was well versed in the industry. Its called Vesconite, a hard dense chemically inert plastic that has teflon amongst other things in it, is almost as slippery as teflon, machines much much better, and is extremely hard, working very well as a thrust pad.

I am sure some in SNA know about this material, not sure why it never came up in the past when chatting to my regular plastics suppliers but better late than never! I will be able to make thrust pads for the early Oracle bearings now, to replace the ceramic disc, this material should offer more damping vs ceramic, maybe not as brick wall inert as Delrin, but I feel its going to be very close.

1 hour ago, SonicArt said:

Next up was the bearing. The owner explained to me that he found it becoming quite noisy a few years ago, so had cleaned it and added a few drops of light oil, but it was quite mucky again when checked recently. Now the design is supposed to be service free and self lubricating. The oil impregnated sintered bushes and the Tidorfolon thrust pad at the bottom, running a steel spindle of 12mm dia with a tungsten ball pressed into the end.

It sort of reminded me of the 'lifetime' transmissions in cars, my feeling is there aint no such thing! Changing fluid and filter periodically in your lifetime tranny might actually get it to last a reasonable lifetime!

The spindle shaft has some fine wear at the upper bush area, not something you want to continue happening on your expensive TT, I suggested cleaning the bearing out and running it full of a high grade oil like the OL or Oracle oil. Owner has some of the vandenhul oil which should be more than good enough. But even with oil in it continued wear could be a problem, I remember how the hardened steel shafts used to wear in Tamiya RC cars if you used the factory nylon bushes, greased up or not made little difference. Yes vastly different rpm and load on an rc car 😁 but the shafts wore in a matter of weeks, this spindle has some light wear after 13 years of far more gentle rotation...

I suggested machining up a new bearing with the exact same measurements as the factory one, but with polymer bushes and thrust pad.

I got onto this and drew up the original bearing, then worked out a plan to make the new one.

Above is the new housing and some bush sleeves, next to the old bearing. I could see some marking inside the sintered bush, fine scratches here and there.

I figured there maybe other owners of this table out there who may want or need a new bearing so I made up a jig for doing the mounting holes, makes it easy to do them down the track. Jig has a spigot that drops into the top bush to centre is accurately.

Below is the final design with the final stack of bushes, spacer and thrust pad.

Now the bush material is an interesting polymer I discovered, and it must have been fate as the supplier was very close and a lovely bloke who was well versed in the industry. Its called Vesconite, a hard dense chemically inert plastic that has teflon amongst other things in it, is almost as slippery as teflon, machines much much better, and is extremely hard, working very well as a thrust pad.

I am sure some in SNA know about this material, not sure why it never came up in the past when chatting to my regular plastics suppliers but better late than never! I will be able to make thrust pads for the early Oracle bearings now, to replace the ceramic disc, this material should offer more damping vs ceramic, maybe not as brick wall inert as Delrin, but I feel its going to be very close.

Would you consider jumping online on Lenco Heaven and making some up for the Lenco bearing if its not too difficult?

Don't see why not, maybe shoot me a pm with a link to the correct thread and I will join up.