More Expert/EMG Questions on Horn and Bearings

[Garret]

Hello!

I have a few more questions for you all, now that I have recently acquired my Expert Senior, in addition to an Expert Minor that I found in North Carolina some months ago. Thank you so much for your thoughts in advance!

First question. What are the size of these ball bearings (I don't have a calipers, unfortunately)? Where can one get more of these balls? It seems there should be 34 in each race, but it seems the top race on my Minor was missing a few. Were these bearings standard across this type of tone arm and bracket?





Second question. Any thoughts on how to fix the paper on this horn? Is there a glue you would recommend, or method to tightening up the layers of paper?

[chunnybh]

I've found different size bearings even in the same arm, so firstly make sure they are all exactly the same size, then make sure they are all true and not worn or dinked. I tend to replace them all and keep the originals in a bag under the motorboard. I'm sure you will be able to find new replacements in a large hardware store. Take a few with you and they will measure them for you. Very important to the free movement of the arm and also to create an airtight seal. Don't forget the grease and make sure the new balls are stainless steel.

[Orchorsol]

Second question. Any thoughts on how to fix the paper on this horn? Is there a glue you would recommend, or method to tightening up the layers of paper?

I attended to small areas of flaking paper on all three of my EMG/Expert horns. My Mk VIII horn also had a small area where a sharp corner of an object had punched a hole right through and separated layers of paper, although the damage only covered about one square inch. It's now unnoticeable unless pointed out - there's just a slight indentation.

I mixed some white wood glue (PVA) with water (about 1:3) and gently wet the inner surfaces of the paper layers with the solution, using an artist's paintbrush. Over a period of half an hour to an hour, as the paper softened, I repeatedly 'moulded'/encouraged it into position, adding a little more glue solution judiciously where necessary. Painstaking and delicate, but effective. I made sure there was little or no PVA on the outer surface so that a few tiny dabs of brown stain would 'take' to the surface afterwards.

[emgcr]

What are the size of these ball bearings ?

I think you will find they were all standard 3/16ths originally---easily available. The tonearms are identical on Senior, Junior and Minor. There was a longer one made for the All Range but this is very rare and, in any case, the ball sizes were probably the same. A really important aspect to bear in mind is that it is easy to over-tighten when assembling. It is vital to tighten down the top race just sufficient to "nip" the balls so that they are neither too loose not too tight. The danger of too much pressure is that it is easy to indent the relatively soft brass bearing tracks after which it will be impossible to achieve a friction-free tonearm movement. Some models had a lock ring to fix the final setting whilst others had a radial grub screw.

[Nat]

I do minor restoration of torn pages in old books n(18th century). Book binder suppliers have a Japanese rice paper which is very thin, strong, and quite transparent after application. Might this make a good "final layer" in restoring these horns?

[Garret]

Everybody,

Thank you so much for the responses!

[Garret]

What are the size of these ball bearings ?

I think you will find they were all standard 3/16ths originally---easily available. The tonearms are identical on Senior, Junior and Minor. There was a longer one made for the All Range but this is very rare and, in any case, the ball sizes were probably the same. A really important aspect to bear in mind is that it is easy to over-tighten when assembling. It is vital to tighten down the top race just sufficient to "nip" the balls so that they are neither too loose not too tight. The danger of too much pressure is that it is easy to indent the relatively soft brass bearing tracks after which it will be impossible to achieve a friction-free tonearm movement. Some models had a lock ring to fix the final setting whilst others had a radial grub screw.

Graham,

I checked the bearing balls with a calipers, and they seem to measure just slightly less than ⅛". I think I'm going to get a micrometer for a more precise measurement and should get some replacement bearings from there.

[Garret]

I measured the bearing balls with a micrometer, and they are exactly ⅛". FYI.