Koma standard

[Dells]

Hi all
I am putting together a Koma standard torsion clock that I got as a bag of bits, it runs fine after a service but without the Hands on, but when I install the hands it stops, ( when I do the hand nut up the hands are quite tight)
So have I got the order correct? Intermediate wheel washer goes over the centre wheel first then the cannon pinion then the hour wheel not forgetting the minute wheel then hour hand then the second hand then a flat brass washer then the hand holding washer then the holding nut.
If this is correct then what would make the hands tight ?
Dell

 

[KurtinSA]

I think you don't have a "clutch" that works with your minute hand. You need a setup that is tight enough to keep the minute hand from falling, but loose enough so that you can turn the minute hand along with the cannon pinion. I think there are at least three ways to create a clutch. A dished football washer at the base of the minute arbor (ok, maybe even a thin flat washer first), a domed or wavy washer under the hand nut, or a special cannon pinion with is pinched in order to create drag on the minute arbor. There may be another one with the Schatz Type 53 where there is a physical clutch between the plates.

Not sure why you're calling it a intermediate washer first over the arbor. The intermediate wheel is off to the side of the center arbor. Maybe that's the issue. You have two flat washers at either end of the minute arbor. When the hand nut is tightened down, it squeezes all that together with no give.

Kurt

 

[Dells]

Hi Kurt
The enclosed picture is the clock in question from 10th edition repair guide it shows 26 and I presume it goes behind cannon pinion as that is 27 but the hands only show 43-44 no flat brass washer but if I fit hands without it hands just drop but with it it is to tight.
Dell

 

[KurtinSA]

Weird that #26 is called the "hour wheel spacing washer". It doesn't touch the hour wheel/pipe...I think it's there to keep the cannon pinion from wedge or catching on the shoulder of the minute arbor. #23 is the intermediate wheel which steps down the once per hour movement of the cannon pinion to drive the once per 12 hours hour pipe.

I would guess then that #43 hand washer is not doing its job. It should be crushable to some degree to allow pressure to be put on the cannon pinion but not too much to lock things down. Of course, you've looked closely to see that the minute hand doesn't touch the hour pipe.

Another discussion about the minute hand tension on a Koma, only it's more loose.

Koma is sending me into a coma

Kurt

 

[Dells]

Well Kurt
According to the link in your last post it seems that the brass washer and the spring washer goes behind the cannon pinion, but I can’t see the flat brass washer on the exploded diagram.

 

[KurtinSA]

Maybe others have some thoughts. But I don't see how the "clutch" system works if you don't have a compressible part of the stackup on the center arbor. If you're having to tighten the hand nut far enough to keep the minute hand from falling, but yet that causes binding when turning the minute hand, then something is not correct or missing.

Kurt

 

[clksmyhobby]

I have one Koma standard, plate no. 1395, that runs fine after typical cleaning and lube. Rotation is about 330 degrees.

The illustration in the Horolovar book does not show the tension washer (curved, football shape) that goes between the cannon pinion and the flat washer (#26?). The tension washer goes curved side out against cannon pinion, pointy ends on the washer. My clock does not have the hand washer (#43). With the hand nut tightened fully, the minute hand moves with some light resistance.

Some one before me (found it 2011) used an antiquing paint on the base, and I left it that way.

 

[KurtinSA]

Interesting...none of the other Koma pictures (miniature and midget) show the "football" shaped tension washer. I have a few Koma clocks but none have needed to come down for repair so I don't know how they are configured. Also, they are either miniature or midget so they might not be good for comparison.

I just took the dial off a Koma miniature...plate 1398. It's a "hurt clock", missing the minute hand, washer, nut, blocks, etc. At any rate, there's nothing between the cannon pinion and the shoulder on the arbor. No washer of any kind anywhere. Again, not a good candidate for comparison.

Kurt

 

[clksmyhobby]

Dells,

Can you describe the hand washer? Is it flat or domed?

I just looked at my one Koma miniature, plate no. 1398. It does not have anything behind the cannon pinion. The hand washer is partially domed, but flat across the middle, possibly deformed after many nut tightenings. The fully tightened hand nut hits the shoulder on the center wheel shaft and makes the minute hand movement very stiff. Turn the minute hand counterclockwise a bit, the nut loosens a little but still holds the minute hand firmly.

Took the flat and tension washers off the standard clock and put the hand washer from the miniature on the shaft. Tightened the standard hand nut and had very stiff minute hand movement. Turned the hand counterclockwise, the nut loosened too much and the minute hand flopped around. Maybe the standard clock's hand washer is different from the miniature. Or ..........

The hand nut on the miniature clock does not allow the nut to fully thread onto the shaft. There is a hole completely through it that closes down very small on the outside. So it will only tighten so far on the miniature and not nearly far enough on the standard. The stadard hand nut threads fully onto the shaft and extends through. Perhaps it is not the correct nut and should be made like the miniature one. Then the correct hand washer would make it work without the flat and tension washers. Someone in the past found a way to get around that issue with the tension washer arrangement.

Will check my stock for a different hand nut and correctly sized dome washer. Maybe a fully domed hand washer will work with the existing nut (not turned too tightly of course). Nothing to lose as the clock works fine with the tension washer arrangement. Now it is a curiosity that begs examination.

 

[clksmyhobby]

Forgot to add something. The standard clock seems to run fine with the hand washer from the miniature and the hand nut tight against it.

 

[tracerjack]

From the illustration of the movement, the flat spacer is needed to keep the center cannon from rubbing the plate and/or jamming on the center minute arbor. So I would try the order as flat spacer washer, center cannon, hour wheel, hour hand, minute hand, domed washer then hand nut. My feeling is that the domed washer is either not correct or perhaps misshapen, since you mentioned that the miniature domed washer gave the correct tension.

 

[clksmyhobby]

tracerjack,

The cannon pinion sits on the shoulder of the center wheel shaft and away from the plate on the miniature. Same fit on the standard with the tension arrangement removed. But the spacing washer that is not installed on my miniature may help provide better operation, as the designer probably knew. Will try that. Thanks for the observation.

Can't find in my regular stock a different hand nut or domed washer for the standard yet. Time to check my parts/donor clocks.

 

[KurtinSA]

In thinking about all this, I thought I read somewhere that people make their own tension washers. They don't have to be football shaped...they can be round but they must have a concave shape. So, one must have the ability to punch out small circles from a thin sheet of steel, put a hole of the right size in the center, and then put the curve in the washer. I don't have the capability to do that...I bought a variety of tension washers from The Horolovar Company...that has been very helpful.

Kurt

 

[clksmyhobby]

Dells,

Try removing the flat brass washer between the hand washer and the minute hand. Also, does the spacing washer rest on the shoulder of the center wheel shaft?

Kurt - I missed your comment about the spacing washer in your second post. Speed reading has its drawbacks. I have fabricated tension washers by bending flat washers, but have not really been satisfied with the results. And I have no equipment to properly make one. So I buy them or rob them from donor clocks.

 

[clksmyhobby]

Installed a flat "spacing" washer on the miniature clock. Minute hand even tighter when nut was tightened. Still backs off when hand is turned counterclockwise. Found an incomplete miniature movement, plate 1398 (on my donor shelf since 2013) that had a curved spacing washer. Installed that on the miniature clock and viola! Hand nut stays put when minute hand is moved either in either direction.

This has been very enlightening. Thanks for all the input and to Dells for the original post.

 

[Dells]

Hi all hope we are all keeping well
I have the washer 26 on diagram and I am sure it goes behind cannon pinion I also have as in picture,

from left to right minute hand, flat brass washer, brass dome washer, brass nut, if I leave flat brass washer out hands just drop if I put it on in the order in picture hands are tight .
Hope that makes sense Dell

 

[tracerjack]

I got a little lost here between Dells and clksmyhobby as to which Koma standard needed help. Has it been sorted out yet?

 

[tracerjack]

Hi all hope we are all keeping well
I have the washer 26 on diagram and I am sure it goes behind cannon pinion I also have as in picture,
View attachment 581843
from left to right minute hand, flat brass washer, brass dome washer, brass nut, if I leave flat brass washer out hands just drop if I put it on in the order in picture hands are tight .
Hope that makes sense Dell

Oh, here we go. Posted too soon. In your photo order, you are putting the flat brass washer on after the minute hand? I thought according to the book that the flat washer went on the center arbor underneath the cannon pinion.

 

[clksmyhobby]

Dells,

I agree with tracerjack that the flat washer does not go on after the minute hand. It should be under the cannon pinion. That puts in in the configuration shown on the Horolovar book diagram. It should work as it is the factory combination. If that proves not satisfactory, you may want to try a curved tension washer instead of the flat one.

tracerjack:
Dells was the original post and I compared his standard clock against mine. I found the curved tension washer with large flat washer under the cannon pinion on mine, and it operates fine. Tried configuring my clock like his and I could not get the minute hand operation correct - either too tight or too loose. I will keep mine configured with the tension washer arrangement.

KurtinSA mentioned his Koma miniature hurt clock for configuration comparison. I also have a Koma miniature that operates but had minute hand tightness problems. It was configured just like the diagram in the book with flat washer, but the hand nut would rotate when the minute hand was moved. I had another Koma miniature movement (different back plate) that had a small curved tension washer behind the cannon pinion. I moved that to my miniature clock and now the minute hand operation is perfect.

It appears that at some point, Koma changed the configuration and added the tension washer. Or previous owners decided to change it. Not sure about that, just happy the clocks like it.

 

[Dells]

Thanks for replies
If I put the brass flat washer over the centre shaft then the cannon pinion instead of the spring steel washer where would the steel washer go and it looks like ( 26 ) in the picture in diagram and why would the diagram show 26 spring steel washer then (27) cannon pinion ? also if I put the steel washer after the minute hand then dome washer I can’t see it would make any difference but I will give it a go.
Dell

 

[clksmyhobby]

Sounds as though you have an extra washer - the brass one. Should be flat steel washer - cannon pinion - minute hand - hand washer - hand nut. Can't see where the brass washer would go.

 

[clksmyhobby]

Is your steel washer curved?

 

[tracerjack]

[/QUOTE] .....tracerjack:.Dells was the original post and I compared his standard clock against mine. I found the curved tension washer with large flat washer under the cannon pinion on mine, and it operates fine. Tried configuring my clock like his and I could not get the minute hand operation correct - either too tight or too loose. I will keep mine configured with the tension washer arrangement. .[/QUOTE]

The fault was mine for not paying attention to the names. I agree that there is one washer too many, the brass one. Someone might have put it on the hour hand to increase the tension, having the same problem as Dells - too loose without it. If a domed washer is not doing the job of putting enough tension on the minute hand, then I would think a either 1) a higher domed washer, or 2) a thinner added brass/steel washer, or 3) an added football washer might give the tension needed when placed after the minute hand, then tightened with the hand nut. Numbers 2 and 3 would most likely need the domed washer too. As for sanding a washer down, I once had to sand down a replacement ratchet wheel. Took a while - actually a long while, but in the end fit perfectly.

Adding the football washer after the steel and then the cannon pinion as you did might also work for Dells as well.

 

[clksmyhobby]

If the football tension washer is used, there needs to be a large thin steel washer on the shaft first. All the football washers I've seen have holes larger than the shoulder on the center wheel shaft. The pointed ends of the washer rest against the larger washer.

 

[Dells]

I have another Koma standard that was working fine apart from a bulge in mainspring barrel ( so it only ran for about 3 months) and I have removed face and this is what it has on it ( see picture) first the thick brass washer then the egg shaped spring washer then the flat steel washer with cannon pinion, totally different to the diagram in 400 day clock repair guide.

Dell

 

[clksmyhobby]

That's exactly what my Koma standard has installed. Hope you get yours operating to your satisfaction.

 

[Wayne A]

Currently working on a Koma miniature and here is the way I found it.

 

[KurtinSA]

Just finished (re)overhauling a Kern & Söhne and found the same tension washer and flat washer arrangement. If the tension washer was next to the cannon pinion, its tips would catch on the leaves of the pinion so the flat washer has be located as in the picture to prevent that.

Kurt

 

[clksmyhobby]

Interesting. Mine has the flat washer first, then the tension washer with tips on the flat washer, curved surface on the cannon pinion. I'll check my Kerns, standard and miniature, later today.

Mike

 

[clksmyhobby]

Kern standard, plate no. 1404, c 1949: same arrangement as Wayne A's Koma miniature and KurtinSA's Kern.

 

[Dells]

I seem to be taking one step forward and two steps back here, the clock I am working on has a flat steel washer ( I thought it was spring steel but when I inspected it under magnification it was just marked be the cannon pinion teeth) so it is just flat steel I also have a flat brass washer but I don’t have the spring steel egg shaped washer that my other Koma standard has as can be seen in post 25 the steel washer I have matches the diagram ( 26) so maybe there is a few years between the build dates .
Dell

 

[KurtinSA]

Are you the first one into this clock since the factory? If not, then previous repair people have created the situation you're in. You did say it was a bag o' bits.

Kurt

 

[Dells]

Hi Kurt
I don’t know about that, the only thing I know is the person I got it off said that he had taken it apart very carefully and made sure he put everything in the box because he was going to do it himself but said after he had stripped it he decided it was to much for him so he gave it to me.
Dell
Edit I have found a round spring washer in my spares box and I am going to try that later.

 

[MartinM]

If any of the washers are able to fit over the step on the center arbor, it/they are probably not original. Here's how it should be assembled. While it might be okay to switch the positions of the steel flat washer and "football" washer, you may run the risk of damaging the fat end of the cannon pinion if there is a burr on the football washer.

 

[clksmyhobby]

MartinM,

The football washer installed on my Koma standard will rest on the shoulder of the center wheel arbor. But if I arrange them as you have diagrammed, the flat washer's location prevents installation of the intermediate wheel. The standoff for the intermediate wheel is very short, so I returned it to the original configuration. I did not detect a burr on the football washer. Thanks for the info.

The only football washer in my parts supply had a larger hole than the one installed on the Koma. Will check it against my Kern standard just for curiosity's sake.

Dells - let us know how yours turns out. As you note, I am "still learning".

 

[tracerjack]

So I took apart the two Koma standards I had to see what kind of tension configuration they had. One is plate 1395B. It had a football washer, tips pointing up, thin flat steel washer, cannon pinion, hour wheel, hour hand, minute hand, small slightly curved brass washer, then hand nut. The second is a Demmler import, but matches plate 1395A. That one had thin steel washer, cannon, etc, brass washer, high domed brass washer, then hand nut. Seems to me several configurations were used by Koma, and within reason, what ever gets the proper tension will work.

 

[Dells]

Thanks for all replies
I have robbed an oval spring steel washer as in post 27 from a scrap clock and so far it is running fine so hopefully it is sorted.
Thanks for all the replies Dell