German Blackforest clock mainspring

[wls1971]

I have a German black forest clock from around 1880 which I have serviced the movement was in very good condition and had a service mark scratched on for 8/2015. On cleaning the clock I removed the springs and cleaned, the pivots and pivot holes where in good clean condition not surprising as it had a recent service before so recently in the past. It is a stopper though I have inspected the obvious and found nothing lacking.

originally when cleaning the clock I removed the mainsprings inspected cleaned and oiled they looked like they had been fitted on the last service to me very new looking I did not however measure them, so I have removed the going train spring again and measured it the spring has a thickness of 0.30 the inner barrel diameter is 40mm I have read that a good rule of thumb with German clocks is that the thickness of the spring correlates to the inner diameter of the barrel so in this case the thickness of the spring should be 0.40.

I do feel that the issues with the clock stopping is a lack of power in the mainspring the pendulum amplitude is poor at best, is this rule of thumb accurate or should I work out the mainspring strength by other means ?

[oldhippy]

I have never heard of that saying. Could you take a photo so I can see the movement. There are so many German black forest clock movements I would like to see which type it is.

[wls1971]

O.k will have to take them tomorrow although I will say it's unusual it has three plates the mainspring barrel's are held by a separate plate, it was made by a very short lived manufacturer Fürderer Jaegler et Cie I've never seen a movement like it before.

[oldhippy]

Anything like this.

https://www.redriverantiques.com/listing/583335116/antique-wall-clock-furderer-jaegler-cie

[wls1971]

No its not that type the case is a black forest carved, rather like a picture frame, the movement is very thin with the mainspring barrels sticking out the back and held by a separate plate the following pictures are off the original ebay listing

 

[Lenj]

Beautiful clock..

[oldhippy]

A three piece plate movement. Good design for easy access of the springs. For a new spring, you measure the barrel in the normal way height and width of barrel and strength of spring. Do not be surprised if the strength does not match with what is obtainable today.  From the photos to me it is not clear if the depth of the pallets can be adjusted, are the pallets solid? If so, what about wear and wear on the escape wheel.  This will have a significant effect of the swing of the pendulum. Is the pendulum the original?   

[wls1971]

Well today I have had another look at the clock the pallets are solid they had light surface corrosion to the top but the faces are polished to a high mirror finish and look ok with no grooves worn into them on servicing the escape wheel teeth looked good, I also checked for any bent pivots and found none, The mainspring fitted is 20 mm in height 0.30 mm strength according to my micrometer and 1500 in length approx (difficult to measure a whole mainspring). The movement has a unusual lay out as far as the mainsprings are on a separate plate, the rest of the movement is very shallow, the pendulum is not numbered but I think it is the original. Please ignore the taper pins I have yet to cut to size.

I will have to assume that my original appraisal of the mainspring is wrong and it is in fact tired looking at cousins they list a 20 x 0.30 x 1550 x 35 mm or a 20 x 0.35 x 1600 x 40 mm these are the closet two mainsprings to what is already in the clock is 0.35 significantly stronger than a 0.30 ? because i'm tempted to go for that one as apposed to the 0.30 

 

[oldhippy]

That is a French movement. It is fitted with a self-beat because the crutch screws onto the pallets. It should be just tight enough so when you swing the pendulum a little it auto adjusts its self into beat. The teeth on the escape wheel the ones I can see in photo 3 7 and 8 are worn and will have an effect on the swing of the pendulum.   

It is a very good movement.

[wls1971]

French that's a surprise although  Fürderer Jaegler et Cie did buy in movements mainly Gustav Becker, whats the best way to deal with the escape wheel ? when I looked at it a thought it was ok but that's my beginners uneducated eye, will it require a new wheel cutting ? because that beyond my skill set at the moment ?

[wls1971]

Perhaps some of the techniques in this interesting article will help ?

http://www.nawcc-index.net/Articles/LaBounty-EscapeWheelProblems.pdf

[oldhippy]

With the new spring, see how it goes. If it stops, mark the escape teeth, start again and see, if it stops in the same place you now it’s that tooth. You could try stoning it with an a small arkansas stone or even escapement files, but be very careful. At best, have a new escapement wheel cut and mounted.

That pdf is very good.

[wls1971]

O.k will order a new spring will the 0.35 spring be best or should I stick with the 0.30 that is already fitted, I have some small triangular Arkansas stones so will do as you suggest if it continues to stop, I have found a site that will cut, cross out polish and mount a escape wheel they give £70.00 as a rough estimate,

I have some scrap movements laying around so will have a go at the techniques in the pdf on the escape wheels from those.

 

Many thanks for your advice

[oldhippy]

Small triangular Arkansas stones. That is the typed I used. That is a good price for a new wheel, sounds as if they will come in handy for you.

Sorry for the late reply I had friends visit me yesterday, I only see them once a year.   

[wls1971]

I've bit the bullet with this clocks escape wheel, I fitted a new mainspring which has made little difference so the problem was obviously with the escape wheel, on close inspection the tips of the teeth where worn and rounded, I've planished the wheel using a brass hammer to stretch it slightly then filed the teeth tips on my lathe using ceramic fibre files this has squared the tips off I did not feel comfortable drawing the teeth with pliers the planishing alone has done the trick. I then gently filed the faces of the teeth to remove burrs and defects the clock has now run all day without stopping I shall keep it on the bench a full week and see if it stops.

I have noticed it seems to run smoother and sound different from before there was a very slight judder in the action of the pendulum before amplitude as also improved slightly.

The clock does require a full clean again I've had it apart that many times over the last coupe of days I sick of the sight of it.

Fingers crossed this has solved it, if not I will get a new wheel cut.

[oldhippy]

Good for you.

Escape wheels can be nerve wrecking at times, one file on a tooth two much and its ruined.

[wls1971]

Just to update this the clock is now on its 8th day of running and apart from gaining 10 minutes over that time as run flawlessly, I shall strip it down again and re-clean and oil it and then regulate it, I will leave it to run till it stops the spring maybe slightly longer than that originally fitted so it will be interesting to see if I get 9 days from it.

And just to correct my thoughts on the clock as oldhippy stated the movement is French I had wrongly thought that Fürderer Jaegler et Cie where a German company they where not they are of French origin but did have production factories in Germany.

Edited August 8, 2018 by wls1971

[oldhippy]

Coming along nicely.