Junghans Spring Sizes

[f.webster]

In Steven Conovers book "Chime Clock Repair" this movement is called referred to as Junghans B-10 chime and strike model. The clock I have asked questions about model, year, etc. on a thread (https://mb.nawcc.org/showthread.php?44808-Post-your-JUNGHANS-clocks-here); but, thought here I might get this question sooner than later.

The springs are not original. This I know because they don't fit the barrels correctly (much too narrow) and they don't seem to be strong enough. It appears that someone used kitchen clock springs in a past repair.
My question is: What were the original springs' width, strength, and length?

I could do the calculations based on the barrel diameter, arbor diameter… and vary the strength (thickness) and find something that might work. I would like to start with knowing what the springs SHOULD BE.

Thanks for your help and inputs.

 

[Bruce Alexander]

Hi,

For whatever it may be worth, I worked on a similar movement (B-09) a few years back. The Chime Mainspring was set and so I replaced it with the closest match to the existing spring I could find, which was a Hermle MS from Timesavers, part 15930. http://timesavers.com/search.html?q=15930&go=Search

The Time and Strike Trains were adequately powered and their springs were in good condition so I didn't record the measurements of any of the mainsprings at the time. The Hermle did provide adequate power for the Chime Train through its week-long run.



Hope that helps a little.

 

[Billy]

I'm just now tearing down the same exact clock as Webster. My chime spring had a .875 x .022 x 56" spring in it. Don't know if was original or not. Guess I'm surprised a .015 would run the chimes.

 

[Billy]

The strike and time springs in my clock are .875 X .014 x 58". The clock did run and strike. The chime side was running in fits like there was binding. Now that I have it apart, I can see the barrel bushings are shot. So now I'm wondering if at some time someone put in a larger mainspring instead of fixing the bushings.

 

[f.webster]

I have now dismantled this movement's spring barrels. Unsure of what the thickness (strength) of the spring should be, I assumed that the chime and strike trains would require the same strength while the going train could operate on a weaker spring I found this held true when I measured the springs that were in the barrels. The going and the chime barrels were the same width and the chime barrel was wider. All three arbors were the same diameter. Placing this information into my 'spring calculator' I came up with the following results (in MM and IN)

MM	(W)idth	(T)hickness	(L)ength	IN	(W)idth	(T)hickness	(L)ength
Going	22.2	0.39	1973.3175		7/8	0.0155	77.74871
Strike	22.2	0.46	1673.03005		7/8	0.018	65.91738
Chime	25.4	0.46	1673.03005		1	0.018	65.91738

I am still looking for the original spring sizes. Suppliers carry springs that I could cut to length (according the above assumptions)and install into this movement that might work.

Feedback and comments please.

 

[Bruce Alexander]

I'm just now tearing down the same exact clock as Webster. My chime spring had a .875 x .022 x 56" spring in it. Don't know if was original or not. Guess I'm surprised a .015 would run the chimes.

It was closer to 0.016. That clock was done in June of 2012. That's not a long time but I remain in contact with the owner and there have been no complaints thus far. I don't know how much extra power the spring provides but it got the job done a lot better than the old one.

 

[f.webster]

Here is my thought: In Junghans A-10 movement all three barrels are the same size. The springs are different thicknesses. In the B-10 movement, I am supposing that the chime barrel is different sizes and the spring thickness should remain the same.

Others' thoughts?

 

[harold bain]

Frank, A10 and B10 are only date codes (first half and second half of 1910), and have nothing to do with the movement type.

 

[Billy]

Yup, what Harold said. Mine is stamped b10 and all barrels are the same size.

 

[f.webster]

I am not questioning the Junghans date stamp methodology. That quick answer appears multiple times on this message board. On this movement it is A12 (see image below).

As stated in my original post, I referred to this movement as B-10. Why? Because "In Steven Conover's book 'Chime Clock Repair' this movement is referred to as Junghans B-10 chime and strike model." In the other movement that Mr. Conover refers to in the Junghans chapter of his book, all the barrels are the same size. I speculate that the need for more power in trains was gained by an increase in spring thickness. In this B-10 movement, the chime barrel is wider; therefore, I speculate that the need for more power in the chime train was gained by an increase in the spring width.

I have seen both movements. I raised the question of original spring size when restoring a NOT B-10 movement (check message board history). Without an answer in either case, I have turned to calculating the appropriate spring size base on arbor and barrel dimensions.

 

[harold bain]

Frank, you must have a newer copy of Conover's book, as the movement isn't identified in the copy I have, and only one movement is shown, without the date code. Certainly Junghans made a lot of changes over the years with their chime movements. Conover may not know that the B10 designation is a date code rather than a movement model number.
There likely is nothing else on this movement to identify it by.
A look though our Junghans thread shows how our information evolved over the years regarding dating. Vic Tang deserves most of the credit for discovering the date codes on these movements.

I don't know of any mainspring data base for mainsprings for these clocks, so what you are doing is the best way to proceed.