Kundo Kundo Impulse purchase

[Dave T]

Stopped on my way home at a shop going out of business. Saw this sitting back in the corner all dusty and dirty.
Brought it home for $10 without even looking too hard at it. Figured I could have some fun trying to figure out why it wouldn't work. Couldn't get any reading on the coil, but did not show open??
So I finally tried a battery in it and it took right off! Cleaned up the glass dome, and haven't touched the rest of it yet. The hands are pinned, no nut? Wonder how old it is?

 

[Schatznut]

Nice find! Is this the zero-jewel or six-jewel movement? Is there a separate circuit card under the base or just a battery holder? Here's a copy of the US patent for the electromagnetic drive mechanism. Estimated date of manufacture would be between 1957-1967.

 

[Steven Thornberry]

I have moved this to the Electric Horology forum.

 

[Dave T]

It's a six jewel with just the battery holder.
Thanks for the pdf. I'll study it.

 

[Les harland]

Impulse buys like that are a gamble
Some you win some you lose
It looks like you have won there

 

[Dave T]

Les, I agree with you. I bought the clock assuming it wouldn't work, and just to have something to analyze and see what I could do with it.
Turns out, the clock runs fine but continues to gain a lot of time. I've adjusted the pendulum downward many turns now and it still runs fast. Beginning to wonder if it is just spinning on the pendulum rod?
I've studied the escape advance and I can't see that it is ever advancing more than one tooth at a time.

My only other experience with one of these is a Junghans ATO, and it was necessary to adjust the escape to avoid advancing two teeth at a time, and I've got it regulated real close now.

But this Kundo so far has me puzzled.

 

[Dave T]

Adjusted the pendulum bob clear to the bottom as far as it will go. Still runs fast.
Obviously adjusting the pendulum has no effect. I have yet to adjust the escape mechanism. But I haven't caught it skipping two teeth.

And I tried to measure the resistance on the coil, but get no reading with a digital multimeter. Might try the old Simpson and see what it tells me.

 

[Dave T]

Aside from tearing open the coil, I'm about to the end of options on this one. The clock runs fine no matter what I do but continues to gain.
I'm using a Duracell 1.5V and currently have it sitting outside the clock base, to eliminate any influence in magnetic direction.
The pendulum has good swing and appears to have equal swing on both side. I've made sure the clock is level.
I've adjusted the pendulum up and down with no change. I've adjusted the click upward to the point it won't catch the escape wheel. And then run it back down to be sure to catch just one tooth.

Tried to measure tolerances in voltage and amps, but can't get any logical readings. (to me). And I'm in unqualified territory here. I've studied pdfs for the circuitry and instructions posted but can't get any readings that agree.

This model is the one with all the electrical inside the coil. I am wondering if the germanium transistor, (if it has one) could be out of tolerance and making the clock run fast?
Would like to continue to pursue this one just to learn and see if I can correct it, but don't know what to do next.

 

[Schatznut]

Can you detect any evidence that the suspension spring has been replaced? The oscillation frequency is totally a product of the pendulum system and that spring is the only other variable besides position of the adjustment mass. The motor only gives it the impulse to cause it to run. If it is running at all there is nothing wrong with the motor and you can only make things worse by trying to open it up.

 

[Dave T]

That is good news, to me. I assumed that if it is running the electricals couldn't be an issue but wasn't sure about it.
Yes, I have looked at the suspension spring, and it looks all original to me and in good condition. There is an adjustment screw for it, but I haven't done anything with it and not sure what it's there for, or what to look for if I turn that screw.

 

[Schatznut]

I guess at this point you've got nothing to lose but to adjust that screw and see what happens. Can you post a link to a video of the clock in motion? These clocks generate so much power that giving them even the slightest nudge with the pendulum at rest should cause it to gradually start building momentum until the escapement starts tripping.

 

[Dave T]

Just took another look at that suspension spring, and as I said it looks fine. However..... I did see a problem with the other side of the escape wheel with what I call the drive wheel. Not sure what these parts are called, but the roller wheel riding on the adjacent wheel does not land in the same place every time.
You can tell by the way I write this I'm in foreign territory, but here's a video that shows what I'm trying to describe.

Kundo ATO

Kundo ATO runs fast!?

youtube.com

 

[Schatznut]

It is pretty erratic, and I think I saw at least one instance of its advancing by two teeth. You might take a slo-mo video to see what's going better.

 

[Dave T]

I think you're right. I posted it on youtube, but can't remember how to slow it down.

Kundo ATO

Kundo ATO runs fast!?

youtube.com

 

[Schatznut]

If you're using an iPhone, there's a slo-mo feature in the camera. It will start recording at regular speed and then go to slo-mo after a few seconds.

 

[Dave T]

Thanks, Found that option on my Android. I was trying to change it in Youtube, and couldn't find a way to do it.
So here's another video, not great but a little better. And according to what I see there is some aberration in that roller, but I don't think it's advancing more than one tooth at a time. Not sure yet.

 

[Schatznut]

I'd back out the stop screw on the escapement lever by a scant 1/8 of a turn and see how it performs. In your first video, it definitely hangs up a couple of times. This is counterintuitive at this point, but once you get consistent operation you will have one less variable to battle.

 

[Dave T]

Screw backed out. We'll see what happens.
I do think it's not gaining as much now. But I'm not keeping a chart. But, I will as soon as it get a little closer to keeping time.

 

[Dave T]

A day later, clock has gained 24 minutes.

 

[Mike Mall]

There are a few threads here from years gone by - that you may find thought stimulating.
Just search Kundo electronic runs fast.

 

[Dave T]

I think I've seen all of them. But I'll take another look. Thanks.

 

[Schatznut]

Is it possible that the pendulum hook is not fully seated on the pin on the end of the suspension spring? The root cause has to be making the effective length of the pendulum shorter than it should be.

 

[Dave T]

I just checked it and the pendulum is fully seated.
This question might be a little dumb and late, but the clock has not been cleaned, but does not look like it needs it, in my opinion. So, would a dirty clock of this type run faster?

 

[Mike Mall]

The roller / lock inconsistency certainly is a concern.
Why does it not land, and lock, the same way every time?
Are the teeth on the wheel irregular?
Is the roller's pivot binding, or loose?
Or by some odd chance is the pawl not pushing the wheel the same distance every time?
On the Kundo Electronics I own, that roller's operation is consistent.

 

[Schatznut]

Dave, your question is neither dumb nor late - in fact, it is a question that regularly surfaces when talking about many different types of clocks, and the answer is a bit nuanced with other clocks. With this one, the answer is no, it won't matter because the electromagnetic motor has so much power it overcomes virtually any drag in the mechanism. And the pendulum is quite heavy. Witness the fact that from a standstill, if you give the pendulum even a slight nudge, it will start to swing on its own, increasing amplitude until well beyond the point where the escapement starts tripping. I know of no other clock that will do that. I've got a couple of these clocks, and they all work like Mike's, as he describes above. There's something in the way the escapement is tripping that isn't right, but it's hard to see. Make yourself a nice long slo-mo video of it in operation and study it - hopefully it will give you some clues.

 

[Dave T]

Tried to make a long slo-mo but can't hold the camera steady in slo mo mode.
Anyway I do have a video, and I see that the roller cam is now operating properly. And the other day I did oil the jewels on that pivot. Evidently the reason for the erratic movement. It's okay now.
However.... the clock still runs too fast. And I've lowered the pendulum adjustment, just in case that might have been the reason.
The only thing I can think of now is to tear it down and clean the whole movement.?? Doubt that would make a difference.

Kundo runs too fast!

Can't figure out what to do next.

www.youtube.com

 

[Schatznut]

Out of curiosity, how fast does it run when you turn the pendulum adjustment all the way in the other direction? That would be an interesting data point.

Also, with a fresh battery in it, how much pendulum amplitude do you have? I'm looking at the two I have on the bench right now, and they both swing to within 1/4" to 3/8" of the sides of the motor housing. Can't see how that would make a big difference, but it would be another data point.

Re dismantling and cleaning the movement, I can't see what that would buy you, but you're running out of alternatives. If you do so, I recommend using camp stove fuel (outside!) as your solvent, as it does a good job and flashes off without leaving any residue.

 

[Dave T]

Out of curiosity, how fast does it run when you turn the pendulum adjustment all the way in the other direction? That would be an interesting data point.

Also, with a fresh battery in it, how much pendulum amplitude do you have? I'm looking at the two I have on the bench right now, and they both swing to within 1/4" to 3/8" of the sides of the motor housing. Can't see how that would make a big difference, but it would be another data point.

Re dismantling and cleaning the movement, I can't see what that would buy you, but you're running out of alternatives. If you do so, I recommend using camp stove fuel (outside!) as your solvent, as it does a good job and flashes off without leaving any residue.

First off, I appreciate you hanging in there with me on this one!

I'll start keeping a record of how fast it runs based on pendulum adjustment.

And the battery was new when I first got it, so I think it's still rather fresh. The amplitude is about 1/2" or so. But it looks good to me.

 

[Schatznut]

You've got a winner here; just got to figure out why it's running fast. The motor is good; the suspension spring isn't broken; everything is intact - it's in far better shape than most of my projects when I first get my hands on them!

 

[Jmeechie]

Screw backed out. We'll see what happens.
I do think it's not gaining as much now. But I'm not keeping a chart. But, I will as soon as it get a little closer to keeping time.

Hi,
Read through most of this post and my 2 cents on this is as previously mentioned, your occasionally probably grabbing or actually bouncing 2 teeth occasionally. The advance pawl should barely touch the next tooth on the return swing. You may need to tighten the screw more, raising the pawl more.
Also, if that locking arm/roller isn’t free it can cause issues. I just finished an ATO that was very dirty and it was irrational running at best! It had been running fast and they’d given up. After servicing the movement and adjusting the pawl depth and position I’m currently rating it out.
Cheers,
James

 

[Schatznut]

James, it might be helpful to Dave to enumerate what you did during the service. There have been quite a few of us looking at this one and we're running out of good ideas!

 

[Schatznut]

Dave, the 1/2" of pendulum motion amplitude you mention is relative to what? If it's absolute displacement from the rest position, that's pretty weak.

 

[Dave T]

Hi,
Read through most of this post and my 2 cents on this is as previously mentioned, your occasionally probably grabbing or actually bouncing 2 teeth occasionally. The advance pawl should barely touch the next tooth on the return swing. You may need to tighten the screw more, raising the pawl more.
Also, if that locking arm/roller isn’t free it can cause issues. I just finished an ATO that was very dirty and it was irrational running at best! It had been running fast and they’d given up. After servicing the movement and adjusting the pawl depth and position I’m currently rating it out.
Cheers,
James

James, thanks for this. My initial thought was the proper adjustment of the advance pawl. I've tried it in several attempts. And right now it's as high on the tooth as it will go without missing it altogether. The locking roller arm now appears to me to be operating freely, after I oiled those jewels on the pivots.
I've never had one of these apart, but doesn't look that difficult to me. Think that's my next step.

Dave, the 1/2" of pendulum motion amplitude you mention is relative to what? If it's absolute displacement from the rest position, that's pretty weak.

I'm estimating the 1/2" and I could be off, not sure how to get an accurate measurement. And as of relative to what, I'm looking at the distance of the pendulum curved bar that rides through the coil.
So, the 1/2" is from the end of the bar to the edge of the coil. Hope that makes sense.

 

[Jmeechie]

Shatznut, It was a complete disassembly of the movement, ultrasonic cleaning, inspection of all the pivots, gears, contacts. Found buildup on roller and between the teeth on several gears.

I was watching the slow motion video and noticed the pendulum is wobbling? Did you physically remove the suspension spring and do a visual?
So with the pawl all the way up, let’s try lowering it a little bit. It does look too high.
Here‘s the steps I’d suggest
1. with battery removed, manually move the pendulum from side to side slowly observing the pawl engagement. Adjust the pawl so on the swing to the right it is lightly touching the next tooth to be engaged. Also, ensure it pushes the tooth to far enough to allow the lock roller to completely engage and the pawl does not touch the tooth once locked by the roller.
2. Service the movement, completely disassemble, ultrasonic (or wash with alcohol), inspect all pivots for damage, gears, pivots and bushings for grime and reassemble. You’ll also need to clean the advance pawl assembly on the pendulum rod.
3. With the movement off, pull the suspension spring, inspect for breaks, warping. Also look at the clearances and fit of pendulum.
4. Install the battery and run the pendulum without the movement installed and visually watch the pendulum for any wobble, rubbing or touching.
5. Reinstall movement recheck pawl adjustment and run & time.
You’ll want to make sure the hands bosses are clean.
The confusing issue with these clocks is, they’re a push driven clock and everything is fixed, pendulum length and gear ratio. The distance of the swing and the 2 variables is swing width of pendulum and pawl depth engagement (double tooth).
Your‘s doesn’t have the hairspring on the gear locking arm to prevent gear bounce (primarily for the contact switch to prevent double contact).
Here’s my rules for ATO style (Bullè and Brillie as well) pendulum swing:
short swing = fast running
wide swing = slow running
and your swing looks excellent so I seriously feel the problem lays in the advance gear/pawl depthing.
Hopefully these steps will resolve The fast running movement.
Cheers,
James

 

[Dave T]

Shatznut, It was a complete disassembly of the movement, ultrasonic cleaning, inspection of all the pivots, gears, contacts. Found buildup on roller and between the teeth on several gears.

I was watching the slow motion video and noticed the pendulum is wobbling? Did you physically remove the suspension spring and do a visual?
So with the pawl all the way up, let’s try lowering it a little bit. It does look too high.
Here‘s the steps I’d suggest
1. with battery removed, manually move the pendulum from side to side slowly observing the pawl engagement. Adjust the pawl so on the swing to the right it is lightly touching the next tooth to be engaged. Also, ensure it pushes the tooth to far enough to allow the lock roller to completely engage and the pawl does not touch the tooth once locked by the roller.
2. Service the movement, completely disassemble, ultrasonic (or wash with alcohol), inspect all pivots for damage, gears, pivots and bushings for grime and reassemble. You’ll also need to clean the advance pawl assembly on the pendulum rod.
3. With the movement off, pull the suspension spring, inspect for breaks, warping. Also look at the clearances and fit of pendulum.
4. Install the battery and run the pendulum without the movement installed and visually watch the pendulum for any wobble, rubbing or touching.
5. Reinstall movement recheck pawl adjustment and run & time.
You’ll want to make sure the hands bosses are clean.
The confusing issue with these clocks is, they’re a push driven clock and everything is fixed, pendulum length and gear ratio. The distance of the swing and the 2 variables is swing width of pendulum and pawl depth engagement (double tooth).
Your‘s doesn’t have the hairspring on the gear locking arm to prevent gear bounce (primarily for the contact switch to prevent double contact).
Here’s my rules for ATO style (Bullè and Brillie as well) pendulum swing:
short swing = fast running
wide swing = slow running
and your swing looks excellent so I seriously feel the problem lays in the advance gear/pawl depthing.
Hopefully these steps will resolve The fast running movement.
Cheers,
James

Great information. I will step through this and try to get some answers and hopefully a good report. As for your first question, I have not removed the suspension spring.
I will first look at that and do step 1. ..removing the battery.
I did try lowering the pawl in minute amounts with no effect. I haven't noticed any pendulum wobble.

 

[Dave T]

Out of curiosity, how fast does it run when you turn the pendulum adjustment all the way in the other direction? That would be an interesting data point.

After 24 hours with the pendulum adjusted clear down it has gained 18 minutes.

 

[Jmeechie]

Dave I noticed the wobble on the slo-mo video you posted back on post #16. Watch the bob as it travels through the coil.

 

[Mike Mall]

After 24 hours with the pendulum adjusted clear down it has gained 18 minutes.

I have cleaned these before - very simple movement. There was some debate about whether or not, they should be oiled in earlier threads. I have oiled with no ill effects.

I've read that the whole pendulum can be adjusted slightly down at the yoke.

#19 & 20 Here

 

[Schatznut]

I have cleaned these before - very simple movement. There was some debate about whether or not, they should be oiled in earlier threads. I have oiled with no ill effects.

I've read that the whole pendulum can be adjusted slightly down at the yoke.

#19 & 20 Here

Thank you, Mike!!! That's the first thing I've seen in this thread that not only offers a plausible explanation, but a likely solution as well.

 

[Dave T]

By whole pendulum, does this mean the entire pendulum assembly? I can't see how you could lower it very much without disturbing the center opening in the coil where the curved section of the pendulum rides.

 

[Schatznut]

Let's do a little physics. For the sake of discussion we'll make the assumption this is a theoretically perfect pendulum. You will see in a moment that this simplification is safe.

If you're running 24 minutes fast in 24 hours, it means that you're running 1/60 too fast (1 minute = 1/60 of an hour). The length of the pendulum is proportional to the square of the time period (see graphic below), so the length the pendulum is too short is in the proportion of 1/3600 (this is the square of 1/60). Now the pendulum is approximately 6" in length. 1/3600 of 6" is less than 0.002", about the thickness of a sheet of paper. That's the distance the center of mass of the pendulum needs to be lowered to get this clock into regulation.

Relative to the bore diameter of the motor, this amount is insignificant. You are sooo close to having this one in regulation!

 

[Dave T]

Okay boys, Day one again. Removed the movement, cleaned it, didn't see anything that looked suspicious, BUT... the shroud that fits over the suspension spring was not exactly equally centered on the shaft. Not sure if this was inhibiting the suspension/pendulum swing or not. This picture was not taken from directly in front, but it shows the situation.

Won't know for a while if it keeps time now or not.

 

[Dave T]

4. Install the battery and run the pendulum without the movement installed and visually watch the pendulum for any wobble, rubbing or touching.

I forgot this step, but we'll see how it goes. The movement is so easy to remove and service. Should have done that long ago.

 

[sophiebear0_0]

The pendulum length calculation doesn't look right to me ?

The pendulum length is directly proportional to the square of the time period. If the time period id out by 1 minute per hour (=1.67 %) then the length difference will need to be approx (2*1.67) % = 3.34% to compensate

This would equate to an extra 0.2 inches for a 6" pendulum to slow the clock down by 1 minute per hour.

Its getting late here in the UK - so maybe my maths is deserting me. Perhaps someone could confirm.

Regards,

Peter

 

[Mike Mall]

By whole pendulum, does this mean the entire pendulum assembly? I can't see how you could lower it very much without disturbing the center opening in the coil where the curved section of the pendulum rides.

Yes - you could not lower that very much at all.
But lowered a single thread, would lower the center of gravity - many times more than using the bell shaped weight on the pendulum rod.
As I recall it isn't an easy task, it requires some disassembly.
I believe it should be considered a last resort.

The pendulum length calculation doesn't look right to me ?

The pendulum length is directly proportional to the square of the time period. If the time period id out by 1 minute per hour (=1.67 %) then the length difference will need to be approx (2*1.67) % = 3.34% to compensate

This would equate to an extra 0.2 inches for a 6" pendulum to slow the clock down by 1 minute per hour.

Its getting late here in the UK - so maybe my maths is deserting me. Perhaps someone could confirm.

Regards,

Peter

I'm not sure how math would work on this oddball of a pendulum. The vast majority of the weight is in the lower arc, but the adjuster is riding above on the rod. Figuring the center of gravity for this oscillator must be quite a calculation.

 

[Jmeechie]

That shroud would certainly act as a bumper and reduce the swing! I would suggest, pull the movement, centring the shroud and test running with the movement off to see if it’s hitting.
I wouldn’t try lowering the pendulum as I doubt this could be the isshe. These pendulums we’re factory set and I see no reason to try lowering or raising.

 

[Dave T]

Here’s my rules for ATO style (Bullè and Brillie as well) pendulum swing:
short swing = fast running
wide swing = slow running

As soon as I re-assembled this clock I could see a wider swing, and felt sure it would run slower. So far, it does!!! It's only been 8 hours now, but it's no longer gaining time. First time since I got it. Good news!

 

[Jmeechie]

Outstanding news! Sounds like you got it!
Yes so the shroud or I believe pendulum brace to protect the suspension spring for when you lock the pendulum for moving would have acted like an isochronal spring limiting the swing and caused a shorter arc and thus made a faster beat!
Now just double check the pawl adjustment and you should be good to go.
Cheers,
James

 

[Dave T]

Got up this morning and the clock was about two minutes slow. And after cleaning I moved the adjustor upward to what I thought was close to where it was when I bought it. This morning it had lost about two minutes. First time it ever ran slow! So I've adjusted it upward a little more.
Think I'm finally getting there.
I really think the pendulum brace off center, was the main issue all along. But I cleaned it at the same time so I'm not sure.