Bronze Bushing

[TEACLOCKS]

This is the only Bronze bushing it this movement, There are others.
But this is the only pivot destroyed.
The other bushings are fine, There are other bearing holes warn, but no other pivots warn.
Do you think the Bronze bushing was to hard ?

 

[kologha]

Jewels are much harder than bronze, so I doubt it was the hardness.

 

[J. A. Olson]

This is a French Vedette chime movement from the 1930s. Without photos of the entire movement of clock, there isn't much else to say.

I have one Vedette from the 1920's which has been running strong for many months now. It is a good quality clock and really stands above its regional competitors of the period. I don't remember finding any bronze bushings anywhere.

Clocks do not wear consistently. Some get it far worse than others, even among the same design and age.
One aspects towards severe wear is the springs 'clunking' suddenly due to not being able to unwind at a steady rate. This is normally caused by dry lubricants binding the spring or the spring being misshapen.
Some movements take the 'clunks' better than others. Most European chime movements are not among those.

 

[Willie X]

My stance is that bronze is better as long as it has good lubrication. Without oil, the pinion is quickly scored and the wear process is off and running at a faster than normal clip.

Isolated wear is a fairly common occurrence. Here is a photo of a 31year old Hermle 150. The general wear is none to slight, except for S3F which is toast and then some. All pivots and other pivot holes (bronze and brass) are in good condition ... this just happens sometimes. Willie X

all

 

[R. Croswell]

This is the only Bronze bushing it this movement, There are others.
But this is the only pivot destroyed.
The other bushings are fine, There are other bearing holes warn, but no other pivots warn.
Do you think the Bronze bushing was to hard ?

If this is the only bronze bushing in this movement, then it was probably added during a repair. Very likely the pivot was filed or buffed or polished or burnished when the bushing was installed, perhaps nothing was done to the pivot surface. And the bushing may have been broached and may or may not have been burnished (smooth broached). It is also possible that abrasive polishing compounds used to polish the pivot were not removed and became embedded in the bushing. Had the pivot been properly polished/burnished and a brass bushing installed, this pivot damage very likely would not have occurred. While there does seem to be a correlation, there are other possible explanations so, so one example does not a proof make.

Are bronze bushings too hard? Bronze comes in many degrees of hardness, all softer than steel. Bronze bearings and bushings have been used for years in all sorts of machinery and would theoretically seem to be ideal for longer lasting clock bushings, especially in the lower train where the loading is heavy. Hermle has apparently gone to bronze bushings for 2nd wheel pivots in some of their clocks, but what does a huge German clock manufacturer know, they seem to have a long record of shooting themselves in the foot.

There are a lot of hearsay conclusions circulating about bronze or brass based on casual observations where not all variables were controlled or even know. At one time I used mostly bronze bushings and as far as I know these clocks are still going, at least they haven't all come back to me with massive pivot failures. That being said, over the years I have seen more pivot damage in other clocks that I service where bronze bushings were used. I finished an Ansonia last week and the only pivots that I had to turn were in what I believe to be bronze bushings. Someone on this forum a few years ago arguing against bronze bushings said, its easier to replace a bushing than pivot. There is obviously something going on here that sometimes causes premature pivot failure when bronze bushings are used. Seems to me that if it was just the bushing being bronze, we would see this almost all the time. I can provide no proof one way or the other and I'm sure the arguments will continue. Me, I now use brass bushings exclusively unless the original maker used or recomends bronze.

Sorry for the long dissertation which is what I think and nothing more.

RC

 

[Dick Feldman]

It is very gracious of an expert like RC to say, in essence: I don't know.
Best,
Dick

 

[Willie X]

I would add that Hermle has done a massive experiment with conclusive results.

Pre 1988 they used a soft steel pivot (some were plated) running in a brass plate and had a constant and on-going problem. It was not uncommon for some early 1970s clocks to wear completely out in 4 to 10 years.

Around 1988, in came the large bronze bushings and redesigned 2nd wheels with hardened steel pivots. This made the problem disappear. The pivots are actually 2mm standard needle bearings pressed into the larger arbors.

I've installed many of the new 2nd wheels on brass bushings, or sometimes one brass bushing and one plate hole that is simply broached to fit the new pivots larger diameter. No more problems here.

This doesn't exactly solve the brass/bronze question but it does tell you what Hermle did to fix it.

Note, older electric clocks usually get zero service and last a really long time, running moderately hard pivots on bronze bushings. The rotor has a constant supply of oil.

Draw your own conclusions ...

I made my 'delusion' years ago.

Willie X

 

[velocityloop]

Hi Willie
What does S3F identify? Is there a list with this nomenclature for clocks?
Thanks

 

[Willie X]

'S'trike train
'3'rd arbor up from the bottom.
'F'ront plate.

This simple system can locate any pivot, in just about any clock.

Willie X

 

[velocityloop]

Thanks Willie.

 

[bkerr]

I agree with the post above and would like to double down on the the condition of the pivot. First of all, one bronze bushing would likely indicate a repair sometime in the past. It may be possible that when the repair was made the pivot surface condition was not addressed. Brass v/s Bronze is really second on the list. Either material will not hold up to a bad surface pivot very long. One indicator that I have noticed is just looking at the plate. If you see black grime, pivot poop it is likely the pivot is bad, which can be caused by lack of lubrication and dirt. I purchased two scopes this year to really get a good picture of the clock or watch that I am working on. It is amazing what you can see beyond a loop. Burnishing the pivot for me is a must now ( did not always subscribe but that is the journey of learning) There have been many post about burnishing and it is worth the time reading them over. Willie also mentioned electric clocks. I am sure I have not done as many as others here but I believe that the train seems to wear less compared to an American made spring powered clock because there is less torque applied to the train by the power source, i.e. spring

 

[CTMusicStraps]

I would add that Hermle has done a massive experiment with conclusive results.

Pre 1988 they used a soft steel pivot (some were plated) running in a brass plate and had a constant and on-going problem. It was not uncommon for some early 1970s clocks to wear completely out in 4 to 10 years.

Around 1988, in came the large bronze bushings and redesigned 2nd wheels with hardened steel pivots. This made the problem disappear. The pivots are actually 2mm standard needle bearings pressed into the larger arbors.

I've installed many of the new 2nd wheels on brass bushings, or sometimes one brass bushing and one plate hole that is simply broached to fit the new pivots larger diameter. No more problems here.

This doesn't exactly solve the brass/bronze question but it does tell you what Hermle did to fix it.

Note, older electric clocks usually get zero service and last a really long time, running moderately hard pivots on bronze bushings. The rotor has a constant supply of oil.

Draw your own conclusions ...

I made my 'delusion' years ago.

Willie X

Thanks Willie,
I’ve wondered when the line was drawn between 1980’s-1990’s concerning the harder steel pivots in Hermle movements. I recently received a 1990 Hermle 461-853 BS (Westminster chime only version of the 1161), and was wondering if it would still have the softer, nickel platted pivots that had been known to fail more often.

I’m in a valley of decision on the brass vs bronze but your information makes good sense. Smooth, properly oiled and fitted pivots work well with bronze or brass it seems.

Experienced clockmaker, Al Takatsch, in his instructional videos mentioned that if pivots are properly polished to a mirror finish and given the proper end shake and tilt, they need little oil and last much longer.

RC’s comments were very reasonable as well.
CT

 

[R. Croswell]

Just an observation, most clocks from various makers over the years were made with brass plates and no bushings, and some used soft pivots and some used hard pivots. To make things more confusing, brass and bronze come in various degrees of hardness and some brass can be harder than some bronze. We speak of brass vs bronze because the bushing makers give us those two options, but what do we really know about the actual brass or bronze in the bushings offered.

The main issue as I see it with the Hermle movements with failing plated pivots, mostly in the lower train, is what to do about them. Hermle's solution was to replace the 2nd wheel pivots with supposedly harder pivots and offer bronze bushings. Where the new replacement 2nd. wheels are available, installing them with bronze bushings as the factory has done is one option that can be easily defended. The upper train pivots deserve close inspection and if the plating is beginning to fail, I just turn the pivot in the lathe to remove the plating, polish it and install a brass bushing. If there are no signs of impending failure I would consider leaving the sleeping dog alone.

RC