Help Calendar dial drive mechanism

[Old Farmer]

I have an old (1700's) English clock with a calendar dial behind the clock dial that has no apparent drive mechanism. The calendar digits indicate that it turns counterclockwise, as seen from the front. There are 30 teeth on the as shown in the photo. There is no sign of any levers or gears that drive the calendar wheel. Does anyone have any ideas on what might be missing? View attachment 677996

 

[bruce linde]

yes… but we need to see photos of the front of the movement. where those pieces would go

 

[Old Farmer]

yes… but we need to see photos of the front of the movement. where those pieces would go

Attached is a photo of the front of the movement.

 

[Uhralt]

The wheel that drives the calendar seems to be missing. there is an empty hole under the snail where the post for that wheel might have been. Can you post a picture from the side of the movement so we can see how the space between snail and the front plate looks like? There should be a wheel that would drive the missing wheel.

Uhralt

 

[novicetimekeeper]

Yes I guess that empty hole is where it went, I imagine the wheel to drive it is under the snail, there would be a flag on the missing wheel to engage with the calendar ring and move it once per day. The calendar ring will have 31 numbers on it.

 

[bruce linde]

looks like the repaired tail rack might interfere with it... and, what's the pin on the hour/snail cannon?

 

[novicetimekeeper]

looks like the repaired tail rack might interfere with it... and, what's the pin on the hour/snail cannon?

Did see the pin, but the snail goes round twice in 24 hours, the date only moves once. The flag will have a cutout to miss the snail and the racktail.

 

[bruce linde]

right... so what's the pin for?

 

[Old Farmer]

The wheel that drives the calendar seems to be missing. there is an empty hole under the snail where the post for that wheel might have been. Can you post a picture from the side of the movement so we can see how the space between snail and the front plate looks like? There should be a wheel that would drive the missing wheel.

Uhralt

Attached is a photo of the side of the movement. There is another similar hole in the front plate at the edge of the rack lever mounting post, near the edge of the time gear (not visible in the photo). Both holes appear to be approximately 3.5 mm with coarse threads. The pin on the hour/snail cannon holds a clip in place on the back side of the hour gear. Hope this all helps.

 

[novicetimekeeper]

in that side view you can see the teeth to drive the calendar wheel.

 

[Old Farmer]

in that side view you can see the teeth to drive the calendar wheel.

Yes, I noticed that in looking closer at the side view photo. I'm hoping someone has a similar clock with the missing parts in place so I have an idea of what I need to come up with to make it work. Thanks for your comment.

 

[Old Farmer]

in that side view you can see the teeth to drive the calendar wheel.

I measured the gear behind snail that probably drives the calendar wheel: 32 mm diam., 26 teeth, 6 mm thick. Your comments helped me take a closer look at the movement and see things that I didn't notice before. Thanks for your help.

 

[novicetimekeeper]

You can buy the wheels to fit.

 

[LaBounty]

One can also purchase a proper suspension unit and pendulum rod . What's there now might work but the original arrangement was simpler and all one piece.

Tall Case Grandfather Pendulum 4-1/2" x 33"

33" long threaded steel rod, brass rating assembly, suspension spring and a 4-1/2" diameter cast iron bob. 2-1/2 pounds. Ships in 2 cartons.

timesavers.com

Regards,

D.

 

[Jim DuBois]

here is a movement front view, photo poached from another thread. But it clearly shows the calendar drive wheel and flag that engages the calendar ring on the dial/

 

[Old Farmer]

here is a movement front view, photo poached from another thread. But it clearly shows the calendar drive wheel and flag that engages the calendar ring on the dial/

View attachment 678043

Amazing! That's exactly what I was looking for! Thank you so much. Your photo is nearly identical to the movement I am working on. Is that some sort of a ratchet lever on the lower left side of the calendar drive wheel? If it is, that would explain the threaded hole in that vicinity. Now, I just need to come up with the gear and pinion. Thanks again.

 

[Uhralt]

here is a movement front view, photo poached from another thread. But it clearly shows the calendar drive wheel and flag that engages the calendar ring on the dial/

View attachment 678043

Yes, that picture shoes very well how things should look like. If you want to get the missing wheel made you should re-count the number of teeth of the wheel shown in side view, just to make sure. If there are indeed 26 teeth, then your new wheel needs to have 52 teeth in order to make one rotation a day. Measure the distance between the hole for the the post for the wheel and the outer diameter of the wheel behind the snail. Then add 1/3 of the depth of the teeth and multiply by 2. This is the diameter your new wheel needs to have. You will probably have to make the flag yourself unless you give the whole job to a clockmaker. There is some trial and error involved in getting the flag just right. People who cut wheels to order can be found in the NAWCC mart or sometimes on ebay. Also members here may be able to help.
Good luck,
Uhralt

 

[Uhralt]

Amazing! That's exactly what I was looking for! Thank you so much. Your photo is nearly identical to the movement I am working on. Is that some sort of a ratchet lever on the lower left side of the calendar drive wheel? If it is, that would explain the threaded hole in that vicinity. Now, I just need to come up with the gear and pinion. Thanks again.

There is no pinion involved. You need just the gear I mentioned above. The gear is driven directly by the wheel behind the snail and the flag drives the calendar.
Uhralt

 

[Old Farmer]

There is no pinion involved. You need just the gear I mentioned above. The gear is driven directly by the wheel behind the snail and the flag drives the calendar.
Uhralt

Yes, that picture shoes very well how things should look like. If you want to get the missing wheel made you should re-count the number of teeth of the wheel shown in side view, just to make sure. If there are indeed 26 teeth, then your new wheel needs to have 52 teeth in order to make one rotation a day. Measure the distance between the hole for the the post for the wheel and the outer diameter of the wheel behind the snake. Then add 1/3 of the depth of the teeth and multiply by 2. This is the diameter your new wheel needs to have. You will probably have to make the flag yourself unless you give the whole job to a clockmaker. There is some trial and error involved in getting the flag just right. People who cut wheels to order can be found in the NAWCC mart or sometimes on ebay. Also members here may be able to help.
Good luck,
Uhralt

Thanks so much for your information. I'm sure it will be very useful in procuring a gear. Instead of pinion, I meant to say gear shaft. I expect to use a threaded shaft to screw into the plate. Thanks again for your help.

 

[Old Farmer]

Amazing! That's exactly what I was looking for! Thank you so much. Your photo is nearly identical to the movement I am working on. Is that some sort of a ratchet lever on the lower left side of the calendar drive wheel? If it is, that would explain the threaded hole in that vicinity. Now, I just need to come up with the gear and pinion. Thanks again.

I am looking for brass plate to make the gear out of. On-line I've seen some Chinese-made brass that is 62% Cu. Is this material going to be hard enough or machinable for making this gear? Also, I am looking for a gear cutter. I have seen single-tooth cutters somewhere, but can't find them now. Are the multi-tooth ones a lot better for a project such as this? I'm sure they are a lot more expensive, but maybe they are the only practical tool for this project.

 

[novicetimekeeper]

Buy a trashed clock movement you can use the plates. For thinner pieces trashed dials are good.

 

[Jim DuBois]

I have not had good results with brass sourced from China. The brass I have from there was tough, stringy, and certainly did not cut cleanly. You can buy small amounts of sheet brass, 1/2 hard engraving brass, or free machining 360 is usually quite good, from McMaster-Carr stateside. Sheet Stock | McMaster-Carr It is entirely possible to shop make a fly cutter to make wheels, but that may not be something you can readily do with the tools and experience you have today. Merritts used to sell single tooth cutters, don't know if they still do or not. Also, you can buy superb multi tooth cutters from Thorntons in England.

 

[Old Farmer]

I have not had good results with brass sourced from China. The brass I have from there was tough, stringy, and certainly did not cut cleanly. You can buy small amounts of sheet brass, 1/2 hard engraving brass, or free machining 360 is usually quite good, from McMaster-Carr stateside. Sheet Stock | McMaster-Carr It is entirely possible to shop make a fly cutter to make wheels, but that may not be something you can readily do with the tools and experience you have today. Merritts used to sell single tooth cutters, don't know if they still do or not. Also, you can buy superb multi tooth cutters from Thorntons in England.

Thank you so much, Jim. I'll check on those references. You've been a great help.

 

[novicetimekeeper]

The advantage of reusing scrap dialplates and movement plates is you get the right colour of brass for replacement parts. You just need them to be from a similar period to the clock you are restoring.

 

[Old Farmer]

Yes, that picture shoes very well how things should look like. If you want to get the missing wheel made you should re-count the number of teeth of the wheel shown in side view, just to make sure. If there are indeed 26 teeth, then your new wheel needs to have 52 teeth in order to make one rotation a day. Measure the distance between the hole for the the post for the wheel and the outer diameter of the wheel behind the snail. Then add 1/3 of the depth of the teeth and multiply by 2. This is the diameter your new wheel needs to have. You will probably have to make the flag yourself unless you give the whole job to a clockmaker. There is some trial and error involved in getting the flag just right. People who cut wheels to order can be found in the NAWCC mart or sometimes on ebay. Also members here may be able to help.
Good luck,
Uhralt

Attached is a photo of the gear (driver gear) that drives the calendar drive gear (driven gear). It is 32.3 mm in diam. and has 27 teeth. The minor diam. of this gear (diam. at the bottom of the teeth) is 25.5 mm, making the depth of the teeth 3.4 mm. The width of the space between the teeth at the bottom of the tooth groove is 1.59 mm. The spacing between the centers of the gears is 46 mm. Using your info, this gives me a calendar drive gear (driven gear) diam. of approx. 62 mm with 54 teeth. The thickness of the drive gear is 6 mm. I estimate that I would make the driven gear 4 mm thick. I would like to try to make this gear if someone can tell me where I can get a gear cutter with a "semi-involute" shape, or tell me where I can find a shop that might make this gear for me.