Longcase Clock Striking Problem

bobbyd111

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Hello location England
I have been restoring clocks for a few years now And I'm not sure what to do with this one I hope you might help me.
I have replaced the click pawls and click springs
Some previous repairer has closed up all the bushes with a hole closing punch shame I have polished up the pivots, and for now have running.
The strike is out on the rack If I set-up @ 1'oclock works fine until around 10 o'clock and then misses 1 strike
and same up until 12 o'clock
If I re-adjust so that the 10 o'clock through till 12 works The next strike at 1 o'clock strikes 2 times and same up till around 4 o'clock
I don't think that the rack tail is original, the rack teeth look to be reasonable and the snail surfaces look okay
I hope that someone may have an Idea as to what the problem is
If you need any more information or photos I can do that for you
Thank you for Looking Robert.................

20210611_103517.jpg
 

shutterbug

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Set it at the 11:00 step. Center that one, and all the others will be right. The 11:00 step is the narrowest one on the snail.
If that doesn't work, then there's a problem with the rack tail. You might have to adjust it, or worse case, replace it.
 

bruce linde

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i just worked on a vienna regulator rack issue. rebushing the gathering pallet arbor helped, as did making sure the pin the rack pivots on was true and polished. this one had a broken rack that had been silver soldered back together and i had into adjust the angle of the end ever so slightly.

lots of magnification helps.

would love to see video so we could see what you’re seeing.
 

bobbyd111

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Hi every one, I have reset the strike on the 11 o'clock position still same fault
Attached a video of 11 o'clock strike (Don't no why no sound)
If I remake the rat tail it will have to be different or the fault may still remain any Idea's for this one
Thanks again Robert.................
 

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Simon Holt

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Robert, that video won't open for me.

The best way to make a video available for all to see is to put it up on YouTube, then put a link to the video in your message.

Simon
 

bobbyd111

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Thanks Simon
The video is I believe is an MP4 Thanks for letting me no
I will see if I can put it up on U/tube never done one before
 

shutterbug

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Works for me with sound. I count 11. Where does it fail?

Note: you have to have a MP4 player and tell the computer what to do with them when encountered. Windows should play them, but the file might be going to your download folder instead of opening.
 

bobbyd111

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Hello shutterbug thanks for your reply!
Counts fine 11 and 12 then at 1 o'clock counts 2
If you adjust the rack tail by bending ( 1 o'clock through to 9 o'clock is fine )
Then 10' 11'12' are striking with one less eg 10 strikes 9
I am thinking that who ever made the rack tail got it wrong (It is not original) And that the pin may be in the wrong position
Trouble is just about every thing done to this clock has been bodged Plastic metal etc
I am about to make a new rack tail, As described by Laurie Penman clock repair page 121
Thanks Robert
 

shutterbug

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Keep us posted on your progress, Robert. That's a strange one!
 

svenedin

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I had the same problem as you with an English longcase. The problem infuriated me. In the end up I gave up and took it to a professional clockmaker. He told me that the rack tail had been badly replaced and that the strike "geometry" was incorrect. By this he meant the angle between the rack tail and the rack. I notice your rack looks OK with all the teeth clearly defined but the gathering pallet looks a bit corroded which might or might not be anything to do with your problem. It has to accurately "gather" the right number of teeth.
 
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bobbyd111

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Svenedin Thanks for your reply
You are right the gathering pallet is corroded but the point where it inters the rack are good no rust or pitting
 

bobbyd111

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Thanks Mike I also think that the rack tail has been made incorrect
The rack tail is 50mm long
 

novicetimekeeper

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there is a detailed drawing of the geometry on the board in a sticky, drawing by shimmystep
 

bobbyd111

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Hello novice timekeeper Thanks for your reply and drawing I have the rack tail on the bench to unsolder
It' is a mess both soldered and riveted
Next free up so that I can properly make adjustment back on the clock
I will keep you all posted as I proceed Thanks.................
 

Ralph

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Matthew Read, a well regarded restorer in the UK, who was briefly posting here, has a youtube channel, where one of the videos discusses rack geometry and more. It may or may not give you some insight into your problem.


Ralph
 

Mike Phelan

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If it's possible for you to measure between the "1" step on the snail and the "12" step, and distance between 11 teeth on the rack, and also the length on the pivots of the rack between the toothed part and the pin that contacts the snail, the ratio should be the same. Does that make sense?
 

bobbyd111

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Hello Ralph thanks for your link to utube great video
Not sure how you divide by a recuring number my maths has always been poor
I will ask google how to? I am getting there
Thanks Robert
 

bobbyd111

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Hello Mike Thanks.
I'm afraid to say that I am not sure how to carry out the measurements
I will have another look later Meanwhile I have now made a blank rat tail and riveted to the rack
As can be seen by the photo the rack post is to short so a double set bend is needed to clear the high cams on the snail
I will have to sort this out as well (Meanwhile the time train is running even during all this work )

20210613_213337.jpg
 

svenedin

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Since you are making a new part, the pin in the rack tail should have a bevel. It is designed in this way so that should the strike fail it will clear the bevel on the snail and not stop the clock.
 

novicetimekeeper

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Since you are making a new part, the pin in the rack tail should have a bevel. It is designed in this way so that should the strike fail it will clear the bevel on the snail and not stop the clock.
Yes, the tail needs to be springy, or solid with a sprung tab like one of mine.
 

shutterbug

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It occurs to me that trial and error will get you the length you need. Cut a slot in the temporary tail and devise a moveable pin. Then you can fiddle the pin to a place where it works, measure it and make your permanent tail. I like doing the math, but not everyone does ;)
 

bobbyd111

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Hello shutterbug thanks for your reply
As you can see from the photo attached I have moved the pin both towards the post and away
Not the same as your method. Still the fault is the same Maybe I could move position more.
As you move through the hours the the rack lever drops in between the teeth and slowly moves out of position
Not sure what to try next
Thanks Robert 20210614_131218.jpg
 

shutterbug

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It could be the snail. Both components work together to make things work. Try doing the math that Mike mentioned above in post 19, and then check each step. You also could have an issue with the gathering pallet over or under lifting the rack. It's going to take some detective work :)
 

Ralph

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If the rack misalignment is moving at a linear rate, then I would think if it is an increasing rate, you would have to shorten the tail, if it is a decreasing rate, lengthen the tail.

All within limits.

As Nick pointed out, if you ignore the recurring number significance, and truncate it, it can introduce an error.

Is the snail and rack original?

Ralph
 

bobbyd111

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Hello Ralph Thanks for your reply
I have no Idea if the Rack and snail are original certainly the rat tail is not
In my collection I have a longcase clock that I can trace back through my family to its maker
I replaced the rack tail and 2 bushes no problem
I cant figure out if the linear misalignment is increasing or decreasing
Roughly 1-11 strikes ok 12 strikes 11 Thanks
 

Jaap

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The original clock was working, when it was made. I think you have a slip problem. The fall of the rack momentum could cause the slip problem.
 

Ralph

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It seems like the rack tail should be longer.... we're not talking much.

Does the rack detent fall cleanly into the tooth on the initial release of the rack. Where does the rack tail land on the step of the snail. When it's set up to strike 12 and the rack it released, is the rack positioned for the gathering pallet to gather 12 teeth, before latching?

As you manually advance the minute hand where does the tail land on the step on each successive step?

Ralph
 

bobbyd111

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Ralph thanks for your reply
I have made some more holes in my trial rack tail and increased the length Still same fault
The rack tail I set up to fall on the centre of the snail cams
As I manually advance the minute hand the tail lands on each successive step?
Rack detent falls cleanly into the tooth on the initial release of the rack @ 1 o'clock
And steadily gets worse as you go through the hours
If I slightly set the 1 o'clock strike off you can then get all 12 strikes meaning things are not far out
Thanks again Robert..............
 

Jaap

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How is the green lever fixed to the post? Maybe there is some room to wiggle.
 

Ralph

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I think your rack was replaced . Do you have clear pictures of it front, back and side. to see the craftsmanship. You will have to modify the rack or the snail.... to make them compliment each other.

Have you tried setting the hour wheel/snail timing at the 12 o'clock position, to make sure the rack tail drops in clean and exits cleanly.

BTW, if you changed the length of the tail arm, you should be able to detect a change in the limits of the arc of the rack's travel.

Ralph
 

bobbyd111

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Ralph thanks for your message
There is no craftsmanship in the rack or indeed any other part of the clock
The plates are out of square an not parallel and the list goes on
If I setup hour wheel/snail timing at the 12 o'clock position, 1 o'clock comes round strikes twice
Have it working now through 12 hours not perfect
When you say modify the snail do you mean filing a little of the 12 cam I think that would improve things
Thanks again Robert.................
 

shutterbug

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Filing the 12 does make sense if it's the only one failing, but be sure before you make changes that can't be undone.
 

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