18th Century Repeater Missing Part Quandry

[dshumans]

Working on restoring this John Fladgate, London repeater, I have discovered a missing part that helps operate the half quarter strikes. I have never seen this type of repeater system, even in books. I finally have the repeater running and the hours strike OK, but the quarters do not and there is an empty post in the critical operating position where a missing part used to go. I am hoping somebody here has seen one of these and knows the missing part operation. Because it is very unusual, it takes some explaining.
Here is a picture of the under dial repeater after some cleaning and adjusting:

What is very unusual is that the hammer trip dogs do not have the common return spring so the rack teeth can pass and then trip the hammers upon the return. Instead, the trip dogs are lifted on their posts so the rack can pass and then they are let down into operating position to contact the rack teeth when chimes are required.

The trip dogs (red arrow) are held up by the trip bar (blue arrow) which is spring loaded to drop down to let the trip dogs into strike position, but is held in the "up" position by the all-or-nothing strike lever (green arrow). When the repeater hour rack is reached, the strike lever (green) rotates counter clockwise, letting the trip bar push the trip dogs down into strike position. This all works, but then the strike lever is just loose on its post and leaves the trip dogs to strike every tooth on the hour and quarter racks as they pass. That lets the hours strike fine, but then always strikes all the quarters because the strike lever is doing nothing.
When it is set to strike quarters, the 7 tooth half-quarter rack (yellow arrow) falls correctly and would run the chime lever which lifts the trip bar that in turn lifts the trip dogs at appropriate times to strike or not. However, that sequence doesn't work because the strike lever is doing nothing.

The missing part in question goes on the empty post (red arrow) next to the strike lever. The strike lever can swivel too far out of place, but there is a hold for a missing post (blue arrow) that I am sure is a limiting stop for the strike lever movement. The notch in the end of the strike lever is a steep angle that lifts the end of the trip bar, moving the trip dogs up out of the way of the rack teeth as they pass.
The main problem is that when the quarters are striking, they always strike far too many strikes. By adding a new limiting stop post to the blue arrow and applying light hairspring pressure to the strike lever, the lever works to control the trip bar, but still lets far too many strikes run. This is because the quarter strike rack teeth are passing the trip dogs before the half-quarter rack teeth are engaged.
I am sure that whatever part was on the empty post (red arrow) must lift the end of the trip bar until the half-quarter rack teeth engage by the tang of the strike lever. However, it is a mystery what that part may be. Hopefully, someone here can help.
Regards,
Doug Shuman

 

[gmorse]

Hi Doug,

You have a Stogden, which is well described in Richard Watkins treatise on repeaters. I have restored one of these in the past, I'll dig out some pictures and see if they fill in the gap.

Regards,

Graham

 

[gmorse]

Hi Doug,

Just a picture to be going on with:



I'll try and dig a little deeper.

Flipped to bring it into the same orientation as yours:



Regards,

Graham

 

[dshumans]

Hi Doug,

Just a picture to be going on with:

View attachment 722926

I'll try and dig a little deeper.

Flipped to bring it into the same orientation as yours:

View attachment 722929

Regards,

Graham

Thanks much Graham,
Same type, but different, as many early makers added their own twists. I can't determine on this one what keeps the trip dogs up from the quarter rack when repeating on the hour. That's my missing part problem.
Doug

 

[gmorse]

Hi Doug,

Forgive me if this is an obvious question, but do you have the hour and quarter snails aligned properly? On my example, there's a pip in one of the 4 lantern pinion pins under the quarter snail and a corresponding pip between two teeth on the hour snail wheel. If these aren't aligned nothing works properly.



Regards,

Graham

 

[dshumans]

Great question Graham. There is a pip on the hour snail teeth, but no pip on any lantern pinion post. I just have it aligned so that zero level of the quarter snail is aligned with the rack end just as the hour snail first changes to the next hour.
However, that can't change the issue of the trip dogs being in strike position when the strike rack passes them at the hour changeover.
Doug

 

[gmorse]

Hi Doug,

Another thought: just to clarify, have you taken into account that the quarter snail in this piece works the opposite way to the hour snail, so that the highest level of the quarter snail strikes the most quarters?

Regards,

Graham

 

[dshumans]

Yes, thanks. I have it such that just when the hour snail advance tang advances the hour snail for changeover, then the quarter snail rack reaches the first part of the deepest 8 levels of the snail. The problem is that it strikes 3 quarter strikes when it is activated at the hour changeover like that, even when I make the strike lever connect with each tooth as the quarters rack passes. I think maybe some missing part on that empty post worked to stop those strikes.

 

[gmorse]

Hi Doug,

I have it such that just when the hour snail advance tang advances the hour snail for changeover, then the quarter snail rack reaches the first part of the deepest 8 levels of the snail.

If I understand you correctly, you have it set up so that the quarter snail's smallest radius is in position when the hour changes?

Regards,

Graham

 

[gmorse]

Hi Doug,

Have a look at this video.



Regards,

Graham

 

[SKennedy]

Its a while since I've done one of thes so I'm trying to remember. Here's a photo of a 1/4 repeater though the fact yours is half 1/4 shouldn't really make any difference as the operation is essentially the same - to lift the dogs out the way at the right time.

 

[dshumans]

Its a while since I've done one of these so I'm trying to remember. Here's a photo of a 1/4 repeater though the fact yours is half 1/4 shouldn't really make any difference as the operation is essentially the same - to lift the dogs out the way at the right time.

View attachment 723010

Graham, Yes. Thanks for the video. That's how this one operates when I apply hairspring pressure to the strike lever. The quarter repeater photo is extremely close to the one here, except 3 teeth instead of 7 (plus the last tooth for all-or-nothing). This lifting arm lifts the trip dogs, but at the wrong time. If I take it apart and move one strike wheel pinion tooth farther on the strike rack, it changes the lifting arm timing, but makes the hours strike incorrect, or the strike wheel doesn't go far enough to engage the last 1/8th tooth.

 

[gmorse]

Hi Doug,

When you said you couldn't find any references to this type of repeating work, did you know about the Richard Watkins treatise on the subject? It's extremely comprehensive on most types and chapter 4 deals with the Stogden in depth.

Regards,

Graham

 

[gmorse]

Hi Doug,

Any chance of a video of it misbehaving?

Regards,

Graham

 

[dshumans]

Hi Doug,

Any chance of a video of it misbehaving?

Regards,

Graham

Graham, yes and I appreciate your help. Here are 2 videos. One with the 1st tooth of the repeater rack in the pip of the repeater pinion, and one with the 1st tooth one past the pip. With the tooth one past the pip, the hours strike correctly, but with the tooth at the pip the hours strike one too many. In both videos, the trip bar lifts before the trip dogs pass and it strikes quarters.
The all-or-nothing strike lever didn't work as received (missing piece problem?) and it also went up way too far and just flopped around. I put a small hairspring through the empty post to lift it so it would run against the quarter rack teeth, and I added a post in the empty hole as a limit to how far up the strike lever could go. First, some pictures:

With the repeater works removed, here is the rack tooth in the repeater pinion (red arrow) and the hairspring I added (blue arrow) to the empty post to make the strike lever work.

For the 2nd video, I moved the first tooth of the repeater rack one past the pip, which corrects the repeater time strike, but does not correct the strike bar error.

Video with 1st tooth in the pip


Video with 1st tooth 1 past the pip

 

[gmorse]

Hi Doug,

Two figures from the Stogden chapter of Richard Watkins' Repeaters, to help with identifying components.



Thanks for the videos. The first thing that occurs to me, (I nearly said 'strikes me' but I'd better not . . .), looking at Fig. 82, is that the red small all-or-nothing piece, (z), (I'm using Richard Watkins naming here), either in the figures or in my video in post #10, isn't spring-loaded, it's either blocking the all-or-nothing rocking piece, (M), or letting it fall and push down the hammer collets. It isn't supposed to oscillate.

Here's another video, this time striking 6 hours and 3 half-quarters at 0.3 x speed.



Regards,

Graham

 

[dshumans]

Hi Doug,

Two figures from the Stogden chapter of Richard Watkins' Repeaters, to help with identifying components.

View attachment 723144 View attachment 723145

Thanks for the videos. The first thing that occurs to me, (I nearly said 'strikes me' but I'd better not . . .), looking at Fig. 82, is that the red small all-or-nothing piece, (z), (I'm using Richard Watkins naming here), either in the figures or in my video in post #10, isn't spring-loaded, it's either blocking the all-or-nothing rocking piece, (M), or letting it fall and push down the hammer collets. It isn't supposed to oscillate.

Here's another video, this time striking 6 hours and 3 half-quarters at 0.3 x speed.



Regards,

Graham

Thanks much. The videos showed me what my problems were:
1. The all-or-nothing piece would not move out. As received, it was not moving out caused by the all-or-nothing lever under the main repeater racks not having enough pressure to move it, so no striking at all. Adding the hairspring made it move out so it would repeat, but always repeated wrong.
2. The rack tooth on the repeater pinion pip was wrong, and the now oscilating all-or nothing piece made the 1/8ths wrong. When I removed the hairspring and moved the 1st tooth on the repeater rack one past the pip, it now works! Many thanks for your great help! It's great to have people in NAWCC that have deep understanding of these and are willing to help. Is this a great forum or what?
Best Regards,
Doug

 

[gmorse]

Hi Doug,

Very glad you've solved it, well done!

Regards,

Graham

 

[Incroyable]

What was the purpose of a half quarter repeater?

They seem just as complex to make as a minute or 5 minute repeater.

 

[Incroyable]

What was the purpose of a half quarter repeater?

They seem just as complex to make as a minute or 5 minute repeater.

And not as convenient to calculate the time as either a quarter or minute repeater I should add.