Theoretical Best Unipivot Bearing Height

[Brf]

I've wondered if there was a default "spike height" for the tip of the pivot post, measured from the mounting platform base. It kind of always bothered me that with being able to change not only the height of the bearing cup, but also the pivot spike height, there never really would be a predictable frame of reference for this sort of thing.

IME, the factory set default height works well with 90% of all cartridges. A space of approximately 1/8 to 1/4" between the azimuth ring and dog leg platform is what I would consider the factory default position. The vast majority of VPI users will never have to touch the bearing bell adjustment set screw.

[tony22]

Thanks Brent. Boy it's good to have you around!

[suntea]

I've wondered if there was a default "spike height" for the tip of the pivot post, measured from the mounting platform base. It kind of always bothered me that with being able to change not only the height of the bearing cup, but also the pivot spike height, there never really would be a predictable frame of reference for this sort of thing.

IME, the factory set default height works well with 90% of all cartridges. A space of approximately 1/8 to 1/4" between the azimuth ring and dog leg platform is what I would consider the factory default position. The vast majority of VPI users will never have to touch the bearing bell adjustment set screw.

I have the parts and am getting ready to replace the old well pivot point with the new one to accept a 3D arm on a Classic 3. When the new pivot point is screwed in will it automatically get to the 1/8 to 1/4" height just be tightening the screw or will I need to adjust it? This whole thing makes me nervous and just want to make sure. Thanks.

[Brf]

I've wondered if there was a default "spike height" for the tip of the pivot post, measured from the mounting platform base. It kind of always bothered me that with being able to change not only the height of the bearing cup, but also the pivot spike height, there never really would be a predictable frame of reference for this sort of thing.

IME, the factory set default height works well with 90% of all cartridges. A space of approximately 1/8 to 1/4" between the azimuth ring and dog leg platform is what I would consider the factory default position. The vast majority of VPI users will never have to touch the bearing bell adjustment set screw.

I have the parts and am getting ready to replace the old well pivot point with the new one to accept a 3D arm on a Classic 3. When the new pivot point is screwed in will it automatically get to the 1/8 to 1/4" height just be tightening the screw or will I need to adjust it? This whole thing makes me nervous and just want to make sure. Thanks.

There is only one way to find out and that is to go ahead and perform the swap out. Don’t worry if it requires adjustment as the forum members are here to support you through the process.

[suntea]

(quote) I have the parts and am getting ready to replace the old well pivot point with the new one to accept a 3D arm on a Classic 3. When the new pivot point is screwed in will it automatically get to the 1/8 to 1/4" height just be tightening the screw or will I need to adjust it? This whole thing makes me nervous and just want to make sure. Thanks.[/quote]

There is only one way to find out and that is to go ahead and perform the swap out. Don’t worry if it requires adjustment as the forum members are here to support you through the process.[/quote]


Thanks BRF. I did indeed change it out. I am now making the adjustments on the spike height, etc. Looking forward to the 3D arm!

[suntea]

IME, the factory set default height works well with 90% of all cartridges. A space of approximately 1/8 to 1/4" between the azimuth ring and dog leg platform is what I would consider the factory default position. The vast majority of VPI users will never have to touch the bearing bell adjustment set screw.

I have the parts and am getting ready to replace the old well pivot point with the new one to accept a 3D arm on a Classic 3. When the new pivot point is screwed in will it automatically get to the 1/8 to 1/4" height just be tightening the screw or will I need to adjust it? This whole thing makes me nervous and just want to make sure. Thanks.

There is only one way to find out and that is to go ahead and perform the swap out. Don’t worry if it requires adjustment as the forum members are here to support you through the process.

Help! A problem has occurred. My plan is to have different cartridges on each arm and swap back between the new 3D arm and my original JMW steel arm (both 10 inch) using a Classic 3 table.

I have successfully installed the new pivot spike and my cartridge on the 3D arm and it sounds great. The problem is when I put the steel arm on, the arm lift is rendered useless because the arm is well below the LP height when resting on the arm lift in the up position. I have tried changing the bearing bell housing height by turning the screw with the hex head wrench but still will not change anything relative to the arm rest. Saturday I put one of those small sticky coaster pads where the arm meets the arm rest. That worked as far as getting the arm lift to work with this arm, however, everything sounded lackluster even at the right VTF and VTA! I put the 3D arm back on and everything sounds great again.

Are these arms not really compatible? It doesn't seem I should need to change the arm rest height just to swap arms. How could this be affecting sound quality?

Am I missing something?

[Brf]

The original JMW 10.5i metal tonearm was designed to have a rubber bumpon installed where the tonearm and the lift platform engage. The new 3D tonearm does not have a rubber bumpon as the tonearm's barrel ferrule is built up via 3D printing.

The 10-3D should sound better than the 10.5i but is should not be a night and day difference. I would play around more with the 10.5i setting before settling in on a conclusion.

[suntea]

The original JMW 10.5i metal tonearm was designed to have a rubber bumpon installed where the tonearm and the lift platform engage. The new 3D tonearm does not have a rubber bumpon as the tonearm's barrel ferrule is built up via 3D printing.

The 10-3D should sound better than the 10.5i but is should not be a night and day difference. I would play around more with the 10.5i setting before settling in on a conclusion.

Thanks for the reply. I will reapply the small sticky coaster pad on the metal arm to resolve the arm lift issue.

I rechecked the settings on the metal arm and they check out fine. I will now clean my tonearm leads and cartridge connectors and see if that helps. Do you recommend deoxit for this or alcohol? Thanks again!

[Brf]

You can use 3M Silicone rubber feet Bumpons for your tonearm. Most Hardware stores carry them.

[suntea]

You can use 3M Silicone rubber feet Bumpons for your tonearm. Most Hardware stores carry them.

Thanks - I will get those.

Any suggestion on what to use for cleaning the cart leads/pins? I have both deoxit and alcohol but have never done this before.