opattapp12

[opattapp12]

Hi everyone,

I’m quite new to all of this, so sorry if these are very newbie questions! 
I’ve just inherited an old striking french clock from my grandparents, and got it running again. However there are 2 issues:

1. It didn’t have a pendulum when I got it, and it’s currently running about twice as fast as it should. Is this expected with no pendulum in place? And is it as easy as buying a replacement? 
 

2. The fly pinion/spinner (not quite sure what the proper name is) had broken and fallen out. When a strike of more than about 3 comes around, the strikes are very rapid and often miss several strikes. Is this linked to the fly spinner not being in place? Again, is this as simple as finding a replacement? 
 

Thanks in advance! 
Oli

[watchweasol]

Hi  The answer to both questions is yes,  without the pendulum there is very little control of the escapement and it will run rapid untill the mainspring runs down.  The Strike fly is in fact an air  brake which governs the speed of the strike train so the the strike count is even and controlled.

Depending on the make both parts are able to be found through Ebay and other sites, 

Have a look at the back plate of the clock and post a picture of it and close ups of any makers marks/medallions            .A.D.Mougin and Japy Feres were common makers.

I have some bits and pieces of french clocks so may be able to help.     cheers

[Nucejoe]

Welcome to WRT forum .

The shorter the length of the pendilum the faster it oscilates, same with hairsprings.

[Orologi67]

French movements are the most custom of the movements mass produced.  Do you have the fly and its arbor?  Best to have it sent to the machinist to have it repivoted.  If not then youll have to ask sellers on ebay to give you inside dimension distance of plate to plate to find a movement with the correct inside depth to cannibalize the fly and its arbor.  The fly has an eccentric bushing such that the meshing of the fly pinion and the 4th? wheel gear can be adjusted for mesh.

Also the pendulum is an easier fix however the outside diameter of the pendulum rod should be ever so slightly smaller than the inside dimentions of the crutch fork.  The weight of the pendulum bob also affects the rate.  So if you buy a new french style rod from the supply house, start long and work your way up cutting length until you find the sweet spot.

Its work.  Nothing is easy in clock and watch repair.  But when you earn the skills you will be rewarded

[oldhippy]

The steel used in these clocks can be extremely brittle; I doubt these days you will find anyone who can re-pivot the fly wheel. The pendulum should have the same numbers on it as the back plate, if it does that will tell you the pendulum is the original, those numbers are in a French measurement for the length of the pendulum.  

[jdm]

4 hours ago, oldhippy said:

The steel used in these clocks can be extremely brittle; I doubt these days you will find anyone who can re-pivot the fly wheel. 

I known one, but probably not for a long time. If one coming from wristwatches learns that fine art, will he/she become a clockmaker? A part of myself says that is the same as a watchmaker, another part says it is not.

Edited June 19, 2020 by jdm

[oldhippy]

I have in the past managed but I broke a few drills in doing so. Now with my eye sight I can hardly see the bloody pivot. 

[jdm]

11 minutes ago, oldhippy said:

I have in the past managed but I broke a few drills in doing so. 

Small bits need to spin real fast, even 5,000 rpm. 

[oldhippy]

Yep with my foot control lathe that wasn't a problem. 

[nickelsilver]

Drilling hardened steel and also small diameters is always an issue. If you do the math for proper surface speed at say 0.50mm you get figures ranging from 5k to 50k or more (especially dropping diameter down to say 0.25mm). Levin, as in the author and lathe manufacturer, put out a pamphlet way back in the 60s I think that broke that apart. Essentially they illustrated that at high rpm unless you can accurately feed a drill so it's taking x-amount of material off per revolution, you will likely fail. Also that materials respond differently at small diameters.

I have a cnc machine with a 10k spindle, and can tell it how much to take per tooth per rev, works great.

When hand feeding, lower rpm is really better. I generally don't go above 1.5k or 2k. If the tool isn't making a chip, it's rubbing, and rubbing work hardens most materials, which makes it harder to get through that skin, then with the added force boom it either implodes from a combination of worn tool (from rubbing) and impenetrable workpiece, or the tool manages to get through then takes a monster chip and breaks.

With tungsten carbide, even the glass hard French clock arbors can be drilled*. But it has to cut. In school we had hand cranked lathes, easy to make say 20 revs, pull the drill and check for/ clear chips, keep going to depth. Much preferable to make a hole in 10 minutes instead of 2, but not have to deal with a broken drill in the hole!

*back in the day the crazy guys would quench drills in mercury to get them hard enough to drill those arbors. Works for steel gravers too. Yes I tried.... (outside).

[rodabod]

On a not-very-expensive French clock and specifically for the fly, I would probably try bringing the temper down where I was going to drill. You’ll still have a nice hard, new pivot fitted after. 

I’m by no means a drilling expert, but my experience has shown me that you need to gauge the rpm and pressure according to hoe the work responds, and gauge how likely the drill bit is to break depending on its type. Although I use them, I hate carbide drill bits when they break and get lodged in place. Where possible, I use HSS-CO bits. 

[watchweasol]

Hi   what is the width between the plates, and can you post a photo of the fly shape and if possible the maker.   If you are in the uk Imaybe able to send you one.           Cheers

[opattapp12]

Thanks everyone! I’ll start hunting on eBay and hopefully both issues can be solved relatively easily  

[Orologi67]

Mike Loebakka can repivot a french fly arbor

[oldhippy]

5 hours ago, Orologi67 said:

Mike Loebakka can repivot a french fly arbor

Who is he?

[Orologi67]

He is an excellent machinist in the North East USA.   He advertises in the NAWCC mart paper.  Actually theres a couple machinists in the mart paper ive used to repivot such small arbors.

I can repivot certain things but when it come to the micro pivoting i send them off.  As with gear cutting.  Im not setup with a mill and id rather have a machinist with the experience do that.