Miniature carriage clock

[Stuart2]

good afternoon, i have recently come across a miniature carriage clock, i have put it on the timegrapher it is producing a nice 18000 per hour however it appears to be gaining about 20 minutes per hour. There are definately no teeth jumping and it is a very consistent gain. I have no idea of the history of this piece or whether it is the original platform. Any ideas would be much appreciated

[RichardHarris123]

I've no idea @oldhippyis your man.  I have replied because I'm interested to find out. 

[watchweasol]

Hi with a gain like that on would suspect a sticky balance spring , coils sticking, or running out of flat and again catching. Best to remove the movement from its case and make a close inspection.  The pictures are not very clear for diagnostic purposes

[oldhippy]

This is a genuine French carriage clock. It sounds like it has what is known as a sticky hairspring, could be dirt on it or it is magnetized. So that is the first step to take. I notice the back door glass is broken you need to get that sorted as dirt and dust will easily get in. The click spring is not original, I don't think I have ever seen one that big in a small carriage clock. Not sure about the platform. I need to see the movement out of its case, the screws I can see on the platform don't look right they look modern cheese head type which I wouldn't expect to see.

Edited April 8, 2023 by oldhippy

[nickelsilver]

Sounds to me like the platform was replaced with one with the wrong tooth count on the escape pinion (or the pinion/escape wheel assembly was replaced with the wrong one). If it was set up for an 8 tooth pinion, and someone managed to fit a 6 tooth pinion, that works out pretty precisely to 20 minutes per hour gain. If it was something else you wouldn't see a clear 18,000 beat on the machine. 20 minutes/ hour is 28,800 seconds per day fast- no machine would read it as 18,000 bph.

[oldhippy]

It certainly will be an odd one if it's not 8 tooth pinion.  

[Stuart2]

Morning all, i have now taken the platform off of the clock the escape wheel has 15 teeth and 8 leaves. The platform has made in switzerland on it. Any ideas.

[oldhippy]

That is want I wanted to see. That is the original platform. Poor time keeping will be down to a dirty hairspring or as I said before it could be magnetized. Clean the hairspring in Ronsonol lighter fluid and dry it with your bench blower. Make sure the tools you are using are not magnetized, now use tweezers or an oilier gently push the coils so they touch one another and see if they stick if they do then the hairspring is magnetized and you will need to demagnetize it. I would also put the pallets and escape wheel through. I would also clean all the platform and you will need a Pocket watch oil for the platform. 

[nickelsilver]

I still think it's a gearing issue. If it's showing a "nice 18,000 per hour" it would be very odd for it to gain 20 minutes per hour; 20 seconds, maybe (but it would still show up as almost +500 seconds/day, more than some timing machines can read). If you get it apart, it would be interesting to see what the calculated BPH should be. 8 leaf pinions are standard, but they can go as low as 6 and as high as 10; and 18,000 BPH is standard, but you can sometimes see lower counts (haven't seen higher yet). I trust OH's judgement, but in the even the platform isn't actually original, it may have had a cylinder escapement before, for example, and those sometimes use a lower beat rate.

 

If it was intended for a 14,400 BPH escapement (just an example), all else the same (escape pinion tooth count), that would already cause a 15 minute gain per hour at 18,000 BPH.

 

To calculate, start at the center wheel (which makes one turn per hour). The calculation is wheels multiplied together, times 2, divided by the pinions multiplied together (not including center pinion). So: center wheel, third wheel, 4th wheel, escape wheel, x 2 / third pinion x 4th pinion x escape pinion. For example: 80 x 75 x 80 x 15 x 2 / 10 x 10 x 8 = 18,000 .

[Stuart2]

Hi all, i have taken the whole clock to pieces and counted all the teeth. Centre 70, 3rd 60-8, contrate 48-7, escape 15-8 i have done the maths and this comes to 13500 bph however if i change the escape wheel pinion to 6 leaves it gives me 18000bph. So am i looking for a new escape wheel and pinion or am i looking for a complete platform? 

[oldhippy]

8 leaves is the normal on the escape wheel. 

Have a look here. this will help.

https://www.m-p.co.uk/formulae/pivcount.htm

[nickelsilver]

32 minutes ago, Stuart2 said:

Hi all, i have taken the whole clock to pieces and counted all the teeth. Centre 70, 3rd 60-8, contrate 48-7, escape 15-8 i have done the maths and this comes to 13500 bph however if i change the escape wheel pinion to 6 leaves it gives me 18000bph. So am i looking for a new escape wheel and pinion or am i looking for a complete platform? 

That's a good question. I don't see any new platforms available with pinions other than 8 leaf. A 10 leaf popped up on Ebay. Looks like it really does need 6 leaves though; 7 gives 15,428.5714, haha (I'm sure you saw that already). 13,500 BPH is very odd, pretty impossible that was the original beat rate.

[oldhippy]

Silly me how come I missed this. I need shooting.

This is not the original platform but a replacement. The giveaway is the screw holes that hold the platform to the movement, there are only two in the platform, the movement has 4 screw holes which carriage clocks should have.   

So you will need a new platform. I see you have done the Math. Meadows & Passmore is the place to go. I have looked on there site and they are closed for Easter but I would think they should be open tomorrow.  

[Stuart2]

Good evening, thank you for all your help i will now set about sourcing a new platform.

[nickelsilver]

Oldhippy, I think you may forgotten more than the rest of us will learn!

[oldhippy]

I get quite a lot of senior moments these days.

On a more serious note. Replacing the platform with a new one will decrease the value of the clock.   

[HectorLooi]

But the clock came without the original platform anyway. Putting in the correct platform and making it run properly, shouldn't that increase it's value?

[oldhippy]

It took me a while before I noticed the old platform was not correct, however it did match to the movement. As I said before that is what I expected to see. A new platform will stand out like a sore thumb, the finish will be entirely different, it will have modern shock system. This is an example of a modern platform.   

[MikeEll]

I have a very similar miniature carriage clock by Angelus, made in France.  The escapement wheel has 15 teeth and a 6-leaf pinion.  It's a beautiful clock that looks as though its been tinkered with by the previous owner.  It looks as though it's lubricated with a tine of 3in1 oil.  Everything, including the mangled-up hairspring, was dripping in oil, and the pallets had a jewelled lever missing.  If I can find a new replacement, that would be a bonus; otherwise, I'll be giving it a serious look under a microscope to try and rescue the existing hairspring and replace the jewel.

[oldhippy]

How about some photos of your clock?

[MikeEll]

7 hours ago, oldhippy said:

How about some photos of your clock?

Of course, here it is.

The hair-spring is in pretty bad shape and you may notice one of the pallet jewels is missing.  I'll be giving the hairspring some attention under a microscope and then will see about a replacement jewel.  Might end up looking for a replacement platform escapement if I can find one.

 

Edited January 29 by MikeEll

[nevenbekriev]

The slot for the missing pallet stone seems to be bent - opened. Be verry carefull when closing it, as it is easy to break. Put something just a little thinner than the stone in the slot to limit the closing.

The hairspring is repearable, it is big, so charge with patience and go ahead.

[MikeEll]

34 minutes ago, nevenbekriev said:

The slot for the missing pallet stone seems to be bent - opened. Be verry carefull when closing it, as it is easy to break. Put something just a little thinner than the stone in the slot to limit the closing.

The hairspring is repearable, it is big, so charge with patience and go ahead.

yes, thank you for the tips.  I'll be approaching this very carefully. 

[MikeEll]

so, I managed to straighten out the hairspring reasonably well.  That just needs running through the cleaner now.  Also managed to fix the bent pallet stone slot ready for a new stone.  Latest problem though, despite being extremely careful refitting the hairspring to the balance cock, the screw that fastens the hairspring stud to the cock snapped off with nothing to grip it with.  Any tips for removing these?  I was thinking of cutting a fine slot across the top of the broken screw and trying to unscrew it that way. 

Edited February 2 by MikeEll

[oldhippy]

If there is nothing to grip. How are you going to cut a slot. From the photo I can't see if it is protruding or not.