Bearings for Home-Built Conventional Tonearms

[PGEngineering]

Hello there!
I'm new to this blog, but thought I could throw something out to get some help.
I've built a couple of tonearms as a hobby, don't think there necessarily the greatest, they used a pinched ball bearing system using cup point set screws, but I want to use multiple ball bearings.
This is the first one I built 3 years ago:
PGE Homebuilt Tonearm - YouTube
Does anybody know a good supplier of very small bearings? The smallest I can get where I live are 1/4"outside 1/8" inside, there small but still mean the gymbal must be quite large to house them.
Or has anybody experimented with making their own bearings from scratch?
Patrick

[jlsem]

Jewel Bearings

Jewel Bearings | Swiss Jewel Company

Most high end gimbal type tonearms use these. You may be able to scavenge some from old analog kilowatt-hour meters.

John

[PGEngineering]

Ooh! that gives me some ideas, I didn't realize that many used jewel bearings, but makes perfect sense. I suppose any hard jewel stones shapped properly will work.
Thanks

[audiostar]

Did you also make your own turntable?

[PGEngineering]

I've been working on the table slowly. Got a large piece of 11 ply board to use as the base. But I still need to do quite a bit. I'm not sure at what radius the arm must mount yet, but I haven't decided on a total arm length yet. Also actually have to write the program that runs the speed control.

I've noticed that a lot of tables (well at least the ones I've taken apart) use bushings to support the platters. Is this because there is a problem with angular contact or thrust bearings? I've always seen then as superior.

[vinylkid58]

Originally Posted by PGEngineering

I've noticed that a lot of tables (well at least the ones I've taken apart) use bushings to support the platters. Is this because there is a problem with angular contact or thrust bearings? I've always seen then as superior.

Do you mean plain bearings vs caged ball bearings?

jeff

[kevinkr]

Originally Posted by PGEngineering

,<snip>

I've noticed that a lot of tables (well at least the ones I've taken apart) use bushings to support the platters. Is this because there is a problem with angular contact or thrust bearings? I've always seen then as superior.

Assuming you are talking about the platter main bearing - the issue revolves around very low frequency noise - caged ball bearings are much noisier than good vertical sleeve bearings with a single small ball running on a thrust plate. Better still of course is the air bearing - might be worth checking out.

[Mark Kelly]

I've never actually seen a gimbal (aka Cardanic) arm that uses jewel bearings and I wouldn't have thought they'd take the required loads : if you look at the load ratings on those jewel bearings they're very very small.

Everything I've pulled apart has used pivot ball bearings such as these from NSK Micro. To see the sizes you need to click on " Catalogue PDF mm Download" on the right side.

I've tried to purchase these in Australia with no luck - eveidently the local NSK distributor doesn't stock them. I've also asked Boca Bearing in the States, no answer yet. I used to know someone who worked in the car biz in Tokyo, I might ask him if he can find them.

I'm after BCF9 and BCF6 with the intention of substituting Si3N4 balls before use. Maybe if we get a group buy together we can get some traction with one of the distributors.

[PGEngineering]

@ Mark
yeah, that style of needle into concave race is the most common I've seen to. I'm guessing the jeweled bearings in arms are generally much larger than what is considered a 'common' jewel bearing. I've only seen jewel bearings from watch mechanisms, but I'm sure there are large variations around. The ones shown in the link posted by jlsem above, seem quite large indeed.
The BCF9 is very similar in principle to the bearings I'm using on the latest creation, except the bearing is complete, making the cone a non-bearing surface, and is actually just a 4mm cone-point set screw.
This is someones picture of them,
http://www.vxb.com/ball-bearings-images/fr133zz-1.jpg

I'm gonna try and think of a way to make these bearings since 1mm balls are easy to get by the 1000's online. but I like the idea of creating a order group for those micro nsk's. they look like the proper thing.

@ kevinkr
hmmm, that's what I thought, I like the air bearing idea. Gonna have to get some practice if I'm gonna make some bushings. Thanks! something else to look into.

[jlsem]

For the horizontal pivot I've seen those pivot ball bearings but with ruby balls as seen in my link. For the vertical pivot, plain endstone bearings are often used. I just saw a unipivot (very expensive) that used a sapphire endstone.

John