Identification of Half Moon Marks Around Pivot Holes

[Vint]

Could someone please tell me what purpose these half moon looking marks serve on a clock movement plate?
What tool was used to stamp these markings? I’m attaching a photo showing these marks at S4, T3,T4. I have a feeling it may be part of the bushing process. Thanks.

 

[Micam100]

INSTEAD OF the bushing process. Punched where they have marked with an X to close up the holes.
Michael

 

[MartinM]

In lieu of bushing, some simply punched the plate on the side of the hole that was wearing to upset the metal towards the worn hole. Everything from a simple dimple punch to a point to tools more purpose built to deface the plate as in your case.

 

[Cespain]

They could have been scribed by a depthing gauge in preparation for rebushing. The idea is that you use the depthing gauge to find the precise gap between the pivot holes on the plate where the hole is not worn, i.e. if the worn pivot hole is on the back plate then you use the front plate and vice versa, of course if the pivot hole is worn on both plates this procedure will not work. You set the gauge to the gap between the mate of the worn hole and another nearby hole then keeping the gauge fixed at this gap you move to the plate with the worn hole and place one of the runners in the same nearby non worn hole and use the other runner to scribe an arc across the worn pivot hole. You repeat this process with another nearby hole so that you end up with two arc criss-crossed across the worn pivot hole and this should be where the centre of the worn hole was. I know it sounds complicated but I saw it being demonstrated by an experienced clockmaker and it really does work. I'm not sure if it is better or faster than using a centering punch or just a visual determination of where the center should be.

 

[wow]

They could have been scribed by a depthing gauge in preparation for rebushing. The idea is that you use the depthing gauge to find the precise gap between the pivot holes on the plate where the hole is not worn, i.e. if the worn pivot hole is on the back plate then you use the front plate and vice versa, of course if the pivot hole is worn on both plates this procedure will not work. You set the gauge to the gap between the mate of the worn hole and another nearby hole then keeping the gauge fixed at this gap you move to the plate with the worn hole and place one of the runners in the same nearby non worn hole and use the other runner to scribe an arc across the worn pivot hole. You repeat this process with another nearby hole so that you end up with two arc criss-crossed across the worn pivot hole and this should be where the centre of the worn hole was. I know it sounds complicated but I saw it being demonstrated by an experienced clockmaker and it really does work. I'm not sure if it is better or faster than using a centering punch or just a visual determination of where the center should be.

 

[wow]

This procedure is very unprofessional. It is done to avoid disassembling the movement and doing it right. If an experienced clockmaker does this, he is doing shotty work. That movement in the photo should be disassembled, punch marks repaired, thoroughly cleaned, bushings installed, pivots polished, and everything else inspected and repaired if needed. IMHO.

 

[Cespain]

In fairness to the clockmaker involved he had the movement disassembled at the time, it was an old unused one and he was doing this just to show me one of the uses of a depthing gauge - I was on a training day with him. I can testify that he does excellent work and have used him to do repivoting and making arbors for me since then. I had just remembered that the marks left round the pivot holes were similar to those described by Vint and offered this as an explanation.

 

[novicetimekeeper]

Punching to close up pivot holes was an accepted practice once. Did those semi circular punches exist for anything else, I don't know? I've seen them done all round making a flower pattern.

I think it is something that has been done for centuries.

 

[wow]

Punching to close up pivot holes was an accepted practice once. Did those semi circular punches exist for anything else, I don't know? I've seen them done all round making a flower pattern.

I think it is something that has been done for centuries.

Good to know the clockmaker does it right. My dad worked on clocks in the 60’s and 70’s. He was taught that way and did it until he was able to get a hand bushing tool. Once he learned how to bush with the tool, he quit punching. I get punched movements often. Most of the time I am able to hide the punch marks with the new bushing.

 

[Thomas Sanguigni]

I recently worked on a Gebr. Kuner cuckoo clock. It had so many punches, drill holes and chisel marks that it bent the plates inward and locked the movement. The work was performed by a hacksmith in 2009. The clock had not been running very well. I get scared when I see these marks.

 

[howtorepairpendulumclocks]

Yes. These are as above, punches or in this case, chiselled marks to re-configure depthing. Personally, I just shrug my shoulders in terms of doing anything about them i.e. actively hiding them. What is done is done and actively hiding them is just another form of change. Passively hiding them through the process of bushing is a different thing. I was once giving a lecture and a member of the audience went berserk when asking me "what was I going to do about the punch marks around a clock pivot?" of a slide I was showing. I said,,, "nothing". They say "I would drill and plug them and refinish the plate". It was at that point that the penny dropped for me....

Sorry, bit of a tangent but when I see those marks, I always remember that story. )

 

[Vint]

Thank you all for the information as it helps me understand what these markings are.

 

[bikerclockguy]

This procedure is very unprofessional. It is done to avoid disassembling the movement and doing it right. If an experienced clockmaker does this, he is doing shotty work. That movement in the photo should be disassembled, punch marks repaired, thoroughly cleaned, bushings installed, pivots polished, and everything else inspected and repaired if needed. IMHO.

I have encountered punch marks on several of the clocks I’ve worked on; some looked amateurish, while others were well-placed and seemed to accomplish the intended purpose. I had always assumed that bushing pivot holes was a fairly recent(1960s or later)repair method, and that these earlier clock repair people just used the methods that were available and accepted at the time. After reading all of the criticisms here, I have to ask...how long have pivot bushings been in the mainstream of clock repair? I used “mainstream“ to avoid replies saying the earliest known use was when Grog the caveman whittled a hickory bushing for his rock clock in 900BC...

 

[shutterbug]

I think bushings have been around as long as the watchmakers lathe - prior to WWI. But not everyone had a lathe then either, and there was probably the same controversy then as there is now. The punching method cannot preserve the proper center location of the hole unless it is skillfully done. If you see the "flower' pattern all around the hole, you can bet the center is no longer positioned where it was when new.

 

[howtorepairpendulumclocks]

Bushings have been in the mainstream of clock repair for hundreds of years. There was a lot of interest in this in the eighteenth century in relation to "what material is best for bushings/bearings" etc. I imagine brass bushings in iron frames and brass bushings in wooden frames go way back.. There point here (...I think) is the context. The context in which the clocks are perceived and the context in which we interact and intervene with these objects changes all the time. Yes, an objective, evidence-based, peer reviewed study of historic bushing methods would be useful and interesting. The point of bushing or punching-up, if the aim is to maintain or return the object to working order, is to put the mobiles at optimal centre-distance. Not to put them back in their original position per-se. We cannot put them back ), only bring about more change. Throughout the nineteenth and twentieth centuries the hand-made clocks industry in Europe (with a few notable exceptions) declined to the point of virtual extinction. The motivation, background, socio-economic environment of the people on this forum and the people who repair clocks today is immeasurably different from those that went before. Personally I see no point in damning the work of the past. It is what it is and is fascinating. The attitude and equipment we adopt today seem to be from the post WWII era. Very few people today seem to move pivots by punching-up. This was apparently a reasonably wide-spread method and therefore has validity in some historic context. No amount of drilling-out and plugging or bushing or re-finishing plates oblierates this work, it just layers change on top of change.

 

[MartinM]

We already have technology sufficient to recreate a plate, complete with stamps using a few different technologies. When entering a predefined program in a CNC or 3D print device becomes the accepted norm, bushing plates will seem like the work of witch doctors. Be kind to those who came before and had limited resources available to save a clock.