ball bearings in clock making

[lperzy]

Can any one direct me to or explain how micro ball bearings can be incorporated in clock making? Purchased an IBM seth thomas master clock movement for parts and want to build a precision clock. Having a problem in figuring out how to install bearings on the great wheel and have the end shake needed but yet at the same time using the bearings for smooth and almost frictionless pivot points. The local clock shop man said that there were some clocks that were made using these items.

[lperzy]

Can any one direct me to or explain how micro ball bearings can be incorporated in clock making? Purchased an IBM seth thomas master clock movement for parts and want to build a precision clock. Having a problem in figuring out how to install bearings on the great wheel and have the end shake needed but yet at the same time using the bearings for smooth and almost frictionless pivot points. The local clock shop man said that there were some clocks that were made using these items.

[Chris McVetty]

I'll jump in here with my .02 worth and then run for cover!

My understanding is that ball bearings will not provide the smooth transmission of power that is needed for a clock to run well. The way it has been explained to me is that the ball bearings have a high resistance to starting to roll, which is not what a clock escapement that starts from a dead stop each beat runs best with.

Chris

[bil2054]

I think I would agree with Chris. The main reason for using ball bearings would be to accomodate high axial loading and/or high speed operation, which are not normal requirements for a clock mechanism. I would think that careful fitting and alignment of the pivots and bushings would serve best, unless you want to build a really cool tower clock. Hmmmmm... :biggrin:

Bill Miller

[john brendel]

Hi,
I think Chris is right. The additional surfaces of the bearings that would need oil would gum up the works. Particularly when you consider that the alternative is to use jewels, bearings seem like a cumbersome complication. John

[lperzy]

Chris
Since it seems like that the ball bearing idea is out where can I purchase large jewels for clocks??

[john brendel]

Hi Lperzy,
The old Swartchild catalog lists Seitz friction jewels with a maximun hole diameter of 1mm. These jewels were primarily made for watches. To my knowledge none of these jewels are being made anymore. This is in the range of the pivots on French clocks which can sometimes have much smaller pivots. I don't know what your background is but I have been repairing watches and clocks for about 8 years and I have a long way to go before I would consider undertaking what you are proposing. Good Luck John

[bil2054]

Hi, Lprzy,

www.industrialjewels.com (http://www.industrialjewels.com)

These folks manufacture jewels for watches, instruments, etc., and there motto is "Can do".
You might check with them to see if they can help

Bill Miller

[lperzy]

Thanks Bill. Looks like a good sight for jewels and thanks to everyone who contributed to this question

[John Hubby]

I generally agree with the points made re ball bearings on clocks. As an observation, the only commercial clock I am aware of that used ball bearings is the Eureka electric (1906-1910), which had ball bearings for the balance pivots. This application fits the comment about high loading, since the balance wheel on these clocks is quite heavy.

However, there are problems with these anyway especially if they have not been cleaned and lubed in a long time. The oil or grease used years ago tends to turn to gum and varnish, especially in these since the bearings are behind glass making the lube subject to UV exposure.

John Hubby dba Pas-Times
400-Day Clock Specialist

[Charlie Haywood]

Ball bearing are used on some modern clocks for the lower bearings and "pulley" bearings. See
Ball Bearings (http://www.erwinsattler.de/english/1799_1.htm) and

Ball Bearings #2 (http://www.erwinsattler.de/english/columna4.htm)

Charlie

[kirklox]

Hermle is now using a second wheel with hardened pivots and bushings. I would think this could be done thru-out the clock. You could also be real accurate in your pivot lengh and add Spring Steel covers like they used on the floating balance to limit the amount the arbors ride on the plates with the shoulders of the pivot. However, you would have to taper the ends of the pivots to allow minimal rotating contact.
All of this does not get rid of the biggest bugaboo in clock making and that is the various frictions that the gear teeth have in their rotation. They are not polished and the friction differences are fairly large from one area to another. You really can see that when you are checking the beat of an anniversary clock over a fairly long period of time. You will also notice a fairly large amout of pendulum rotation change.

kirxklox (Sam Kirk)
Web Horology MB (www.webhorology.com)

[bil2054]

Hey, I found a clock on Ebay that has ball bearings!
Ball bearing clock. (http://cgi.aol.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2154114960&category=3933) :biggrin:

Bill Miller
NAWCC Member #157710

[Bill Ward]

The friction is, at least in theory, independent of the area in contact, but depends only on the force applied (for hard surfaces, not if one indents or deforms). So the length of the pivot is immaterial. The endstones are sometimes used as dustcaps; otherwise the pivot might be pointed and actually bear on the stone. In that case, the advantage is that the lever arm acting against friction is shortened by the smaller radius.
But for each wheel, the real lever arm acting against friction is, as noted above, at the teeth. The latter is typically 1-2 orders of magnitude (10-100 times) greater. And the real bugaboo, also noted above, is the oil, which is why it's not advised for the teeth. It's unfortunately required to prevent pivot wear, while the teeth have the wear spread over a much larger area.
Anyway, ballbearings definitly reduce friction, as rolling friction is always less than sliding.
The key is to use them dry. The question is whether it's worthwhile; probably not on the higher pivots, since the force is so low.
Many engineers have looked at the use of modern materials for slow or intermittant motion bearings (like clocks); one solution is the use of bushings of ultra high density plastic, like polyethelene, sometimes impregnated with teflon, or just a teflon lubricant. Plastics sometimes have a problem with creep, but they don't dry out, amalgamate with dust, or have high viscosity and adherance which can glue slow or intermittantly moving parts together.

[bil2054]

I don't think ball bearings would be that workable on a clock of less than fairly heroic proportions, unless you got into some pretty technical micro stuff, like they use on the needles of the better chart recorders, etc. The newer plastic bearings look interesting, though, and might well be worth some further study.
The case against ball bearings is that, while the co-efficient of friction is about 1/10th that of a slide bearing, the moment of friction, (total friction), is a product of the coefficient and the bore size, plus a couple of other factors I don't recall. The point being that even the smallest bearings would probably be several sizes larger than the average clock pinion, thus negating alot of the friction advantage, not to mention the static friction in an impulse transmission system. Don't forget the added mass, too, which needs to be got moving on every beat. I'm not saying it couldn't be done, but probably not with your off the shelf ball bearings.
A slight retrencement, here; per the examples shown above by Charlie, ball bearings are perfectly reasonable in winding arbors, pulleys, and like mechanisms with fairly massive arbors, and which are not subject to the impulses of the escapement. Notice that the clocks cited have jeweled movements outside of the mentioned exceptions.

Bill Miller
NAWCC Member #157710
Bill's web page (http://bil2054.freeservers.com)

[This message was edited by bil2054 on February 12, 2003 at 22:49.]

[Bob Vasquez]

I restored a circa 1920's 3 weight Colonial GF clock that had bearings instead of bushings about 10 yrs ago. I couldn't tell if someone had added the bearings or if they were original. They were fitted quite nicely. There were two types of bearings, sealed ones and those were you could see the bearings. For the exposed bearings, there was lots of gunk in between the balls but cleaned up real nice. For the sealed ones, I couldn't tell you what the inside looked like but the outside did clean up quite well. The movement and bearings were all high end. For my repairs, I do complete take downs. The customer stills lives in the area and hasn't called about problems. Bob V.