Eminent Technology ET-2 Tonearm Owners

Ketchup, I am intrigued by your idea of shims replacing the O rings in order to increase the rigidity of the bearing. I am confused however. Don't the O rings need to remain in place in order to keep air from leaking out of the manifold? What type of shim are you referring to, that is both very rigid and will seal the outer diameter of the manifold to the housing? Are you suggesting to place shims inside the manifold housing, between the OD of the manifold and the ID of the housing?

Frogman,
The shims will not replace the o-rings- they will be added to a completely stock, unmodified arm. The way the arm is built, there is about 3/16" of "free space" between the manifold and manifold housing before the o-rings. To illustrate what I mean: Cut a piece of paper into a thin strip 1/8" wide and an inch long. Slide the piece of paper into the gap between the manifold housing and the manifold. It should slide in about 3/16" before it hits the o-ring. That space is where the shims will go. Here's a photo of my ET-2.5 manifold that shows the 3/16" gap:

ET-2.5 manifold

I like Richard's idea of making them tapered, but my OCD will have me constantly worrying that they have moved. A good compromise would be to make two of them non-tapered and make the third one tapered to apply the necessary force to lock the manifold in place. A small dab of silicone should hold the tapered shim in place and will be completely reversible.

Frogman - I used a cupboard door magnet. It had a pair of magnetic plates implanted edge on. You see 2 parallel edges exposed in a plastic case. I placed these on the plinth, under the bearing tube with the edges in line with the bearing tube, next to the manifold, on the other side of the manifold from the cartridge. Like this ( looking down the bearing tube )

O bearing tube
!! magnet(s)
-- plinth

Note that my modified arm cable loom exits the arm wand in front of the bearing tube, it does not pass though the bearing tube.

Very entertaining Chris, much mirth.

"I took one of the small circle magnets from the ET2.5 setup over to my Dynavector tonearm. What followed kind of reminded me of one of those horror movies –you know the one where the guy wakes up and finds himself magnetized in a kitchen; pots and pans, knives start flying towards him getting stuck on him as he ducks.

ok - no pots and pans or knives here. But I did LOSE the magnet as it flew out of my hand. I had to search to find where it had lodged itself."

Chris
I initially used one fridge magnet then went to multiple fridge mags. Finally using Neodymium before abandoning the idea.
I tried first at the counterweight end then transferred to the wand end. There are differences. Now the reasons for that could be a whole new controversial discussion.

Frogman
As per an earlier post, when I rebuilt the manifold I used 2 shims and one grub screw arranged at 120 degree increments each end of the manifold. This allowed for tightening by doing up the grub screws. Do this on a standard manifold at your own risk

Ketchup
You got me running to the arm to check these little screws. Still tight after 15 years, phew.

So now some may be asking why I haven't cleaned the sleeve in 15 years.
Well, we do have very clean air here in NZ.

With the air pump running I break the air line next to my pressure gauge and squirt in CRC CO contact cleaner. Then reconnect.
I have previously placed paper towels at each end of the manifold. Then move the spindle back and fwd.
The cleaner is forced thru the sleeve and its tiny orifices. Leaving them to be nice and clean

I do this approximately every 6 months with positive results.

Great thread and thank you to all that have contributed to this thread.
As a tangent tracking fan this ET thread is providing me with some very interesting viewpoint and insight on the working of this tonearm.