30 Hr vs. 8Day - How to tell?

Discussion in 'Wood Movement Clocks' started by mtfinger22, Jan 28, 2008.

1. mtfinger22 Registered User

Jan 28, 2008
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#1
I have tried searching on this but can't seem to find my answer.

I'm looking at picking up a clock. The person selling it is not sure if it's 30 hour or 8 day (the clock needs some help). It's spring wound, not chain driven.

I thought there was a way of looking at the going train and determining if it's a 30 hour or 8 day movement.

Here is a picture of the movement:

How do I tell?

Thanks!

2. jmclaugh Registered User

Jun 1, 2006
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#2
Hi and welcome to the MB,
A 30 hour movement will nomally have 3 wheels in the train while an 8 day one has 4. If in any doubt aqssuming it runs get them to wind it up and wait to see how long it runs. HTH.

3. Thyme Banned

Sep 18, 2006
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#3
Measure the width of the spring. If it is 3/8", it is a 30 hour movement. If it is 3/4" or greater, it is an eight day movement.

4. mtfinger22 Registered User

Jan 28, 2008
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Thanks for all the great information!

The owner of this clock sent me some additional pictures and gave me the layout of the going train. I believe it to be a 30 hour clock.

Spring barrel gear - gear/pinion - gear/pinion - escape wheel/pinion = 4

The post above says 3 = 30 hour and 4 = 8day. I think that assumes that you don't count either the spring gear or the escapement wheel. I just found something that says 4 = 30 hour and 5 = 8 day, but I think that includes both the spirng gear and escapement.

Can anyone confirm the above information?

The gear on the spring barel is directly driving the minute hand. I read somewhere else that this typically means 30 hour. All of my 8 days clocks have a gear/pinion combination between the spring gear and the minute hand pinion. I have 2 30 hour clocks and they both directly drive the minute hand off of the spring gear.

I didn't get the width of the springs, but looking at the pictures they are around 1/2" or so (hard to guess). I don't see them being 3/4" or bigger.

Is my determination of 30 hours sound right?

5. Tom McIntyre Technical Admin Staff MemberNAWCC Star FellowNAWCC Ruby MemberSponsor

Aug 24, 2000
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#5
I cerainly have not seen all the clocks, but I have never seen an 8 day spring driven wooden works clock. I would be very surprised to see one made in America. Did they make such things in the Black Forest or elsewhere in Europe?

6. mtfinger22 Registered User

Jan 28, 2008
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The movement pictured is German (Black Forest).

I don't know the answer to your question, but based on some information I found earlier today, *most* Black Forest wooden plate clocks (the workings are brass/steel) are 30 hour, but some can be 8 day.

I'm not an expert. I just believe everything I read on the Internet!

7. Mike Phelan Registered User

Dec 17, 2003
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#7
It is indeed a very common type of Black Forest clock, and is definitely 30-hour. You only have to look at the fact that the arbor on the countwheel pinion is next to the barrel.

Earlier BF clocks had wood arbors, even earlier they had wood wheels and verge escapements.

Avoid bushing mania on these clocks - a recipe for disaster!

8. chrsvor25 Registered User

Jun 16, 2005
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30 hour springs are really small, don't take up as much space on the movement. and not as wide. 8 day springs are otherwise.

9. Mike Phelan Registered User

Dec 17, 2003
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#9
Indeed that is so, chrs; they need more power for the extra wheel in each train.