Eureka Eureka repairs

[jkfabulos]

I am working on a complete Eureka disassembling and repair. I have run into a problem I cannot seem to solve. I cannot remove the "hair" spring from its end point mount. It appears that the mounting block is squeezed when a screw is run from the from side through into the back which has a split to anchor it. I removed the tension screw but the spring will not move. Am I missing something in this assessment?

 

[jkfabulos]

I put a drop of penetrating oil on the spring and it dissolved the rust releasing the spring from its clamp.

 

[jkfabulos]

I finished the restoration on this movement and got it running. It had a swing of about 240 degrees which was the same as before I tore it apart. I had an article concerning the repair of these movements stating it should be about 360 degrees swing. I tried every adjustment that was outlined in the various references and the swing improved only to about 280 degrees. In a totally unscientific test I decided to try Mobil one synthetic oil on the bearings and main shafts after cleaning out the original clock oil to see if that would change anything. I hooked it up to power and it still was at the 280 degree swing. To my total surprise the next morning it was swinging just a few degrees shy of 360 degrees.

 

[John Hubby]

Jim, an interesting story. I've not tried the synthetics yet with Eurekas but will do so on the next one to see if I get the same kind of results.

Could you post photos of the clock? I would like to add it to my database for these to include the case design and movement serial number. I've got 164 Eurekas now in the data and some interesting patterns about their manufacturing practices are beginning to emerge.

 

[jkfabulos]

It is marked 1906 #2937. It has only one extra flat spring on the fixed contact and looks to have been unmolested since factory assembly. Two balls in the window. Dial is solid not cut out.
I am waiting for a new glass crystal and repair of the minute hand to complete repairs.

 

[eskmill]

Jim's experience with the brand name synthetic lubricant is very interesting because it is an lubricant application to minimise rolling friction; not sliding friction.

I wonder if the original lubricant was a "natural" oil such as porpose jaw oil, a lipid. Lipids apparently change character on exposure to the environment to which they're exposed. Most become sticky, stay put nicely and don't flow. That character would or could affect the performance of roller and ball bearings.

On the other hand, the name brand synthetic Jim used, is a highly refined petroleum based oil that readily flows copiusly and does not readily become thick and sticky.

(brand name is purposely avoided.....we've had enough argument about it in my opinion)

Very interesting.

 

[John UK]

The swing on my Eureka varies from about 280 to not far short of 360 degrees - for no apparent reason. Its not temperature related, nor does it seem to be atmospheric pressure related, and I use the same single 'D' size alkaline battery. As a consequence it is a poor timekeeper!

 

[Ralph]

I'm a user of ATF... Type F and have used it on Eurekas and regular clocks for about 5 years, without any ill effects. It seems to stay put, just fine.

Ralph

 

[John Hubby]

It is marked 1906 #2937. It has only one extra flat spring on the fixed contact and looks to have been unmolested since factory assembly. Two balls in the window. Dial is solid not cut out.
I am waiting for a new glass crystal and repair of the minute hand to complete repairs.

Jim, thanks for the serial number and photos. This is the first Sheraton Pillar model (1911 Catalog No. 8) that Ive seen with the solid dial, also the lowest serial number of that model so far.

Regarding the fixed contact assembly, all the clocks I've worked on have only two springs. The longer contact leaf spring ("L" shaped), plus a single straight "helper" leaf spring. Apparently you have seen them with more than the two?

Post a photo after you have the job completed, these are very nice clocks.

 

[Mickyblueeyes]

Having bought a eureka Last october on ebay I spent many happy hours reworking the movement as it had a swing of about 180 and the timekeeping was quite eratic, Even after extensive work and a decent swing of around 320 degrees the clock was still a poor timekeeper and would easily be several minutes out over a week. The only solution was to design and fit an electronic quartz regulator, having done this the clock is now giving nearly a 360 degree swing and is accurate to within a second a month, the clock has been running like that since november last year.
I would however be interested to hear other peoples experience regarding the Accuracy of the Eurekas

 

[John Hubby]

Having bought a eureka Last october on ebay I spent many happy hours reworking the movement as it had a swing of about 180 and the timekeeping was quite eratic, Even after extensive work and a decent swing of around 320 degrees the clock was still a poor timekeeper and would easily be several minutes out over a week. The only solution was to design and fit an electronic quartz regulator, having done this the clock is now giving nearly a 360 degree swing and is accurate to within a second a month, the clock has been running like that since november last year.
I would however be interested to hear other peoples experience regarding the Accuracy of the Eurekas

Micky, your solution to timekeeping for Eurekas was also developed by Bryan Mumford (http://www.bmumford.com/) and for a time he made and sold both a battery powered voltage regulator and a transformer powered quartz regulator for Eureka clocks. The voltage regulator provided accuracy of something like a minute a week, the quartz regulator gave the same performance you have experienced. Unfortunately he is no longer making them, I think the market was too small so he didn't make any profit. Perhaps if you could post a description and diagram of what you made, others here can do the same.

My personal experience with using just dry cell batteries mirrors what you and others have reported, with accuracy not being all that good. I have found that putting four C or D cells in a typical battery holder (rewired for parallel connection) gives the best results with accuracy to about 2 minutes per week. I haven't tried using a transformer, perhaps someone else seeing this can report on how that works.

For interest and information, could you post photos of your clock including the serial number? That would be much appreciated.

 

[Mickyblueeyes]

Hi John, the eureka involved is serial number 1906 i have attached some pics of it.
The electronics involved in correcting the clock are not too complex I am considering posting details of it, but it involves a microcontroller device and a months software development to make it work so it is highly unlikely that the members would consider it worthwhile, but despite that the principles involved might be of interest.
Like Mumford if i marketed the product it would be unlikley to make a profit but it would be useful to some. All i can say at the end of the process is at least my clock works well now.

 

[John Hubby]

Hi John, the eureka involved is serial number 1906 I have attached some pics of it.
The electronics involved in correcting the clock are not too complex I am considering posting details of it, but it involves a microcontroller device and a months software development to make it work so it is highly unlikely that the members would consider it worthwhile, but despite that the principles involved might be of interest.
Like Mumford if I marketed the product it would be unlikley to make a profit but it would be useful to some. All I can say at the end of the process is at least my clock works well now.

Micky, thanks for the great photos. I've not seen this case before but it is a very attractive clock. This particular design isn't shown in the 1911 Eureka catalog but is similar to No. 12 that has fluted columns to both sides of the front door.

For info, the serial number is actually No. 7602, which is stamped just above the front bearing housing. 1906 is the patent date that is stamped on all the movements.

If you do choose to post the details of your controller device here that will be most welcome. I can see that it would be a problem to make it for general sales.

 

[Mickyblueeyes]

Thanks John yes your right i had so much trouble trying to get the picture clear especially as the 1906 doesnt show so well that i forgot it was the date!.
I have another area of interest in the Eureka story and that is battery life, I notice a lot of Eureka clocks have been fitted with diodes across the armature to save wear on the contacts due to spark erosion.
I have been thinking for some time that there must be a better way of using that energy rather than letting it dissipate in the coil, so here goes - if we remove or replace the diode with a higher voltage AC transil and design the controller to turn of the feed to the coil a short while before the contacts open then the energy in the armature could be saved in the controller power supply capacitors for the next cycle, this would require a half bridge design with steering diodes to take the energy back.
I havnt conducted any studies into how much energy could be saved this way but it seems like an interesting project, i am just wondering if anyone has tried this before. or has any thoughts on this.

I have included a PDF drawing of the controller circuit and the calibration interface used here to calibrate it, some pics of a prototype set are also included. to calibrate we used an off air frequency standard this gave us a one part in 100 million calibration reference.

 

[praezis]

Micky, thank you for the details of your circuit.
The idea of saving the stored energy of the coil is very interesting.
You asked for thoughts, here are mine:

In your circuit I cannot see how energy is saved. I suppose that it is just dissipated by D2, being parallel to the coil and conducting then.
If I am wrong, can you explain how it works?

But I see possibilities to save energy in your device (now consuming about 500uA as I suppose):
1. your quartz frequency (4MHz) is high for long term battery operation. Using a watch quartz (32kHz) would reduce current by 95%
2. Diode D1 consumes part of your battery voltage (0.7V)
3. Inverter stage TR1 with R3 consumes an average current of 20uA, also quite high.

Below I add a photo of my device for controlling electric clocks. It was designed to work with any battery operated clock, contact or transistor controlled.
Also for Eurekas, but unfortunately I did not yet get an Eureka for testing. A number of them already works with ATOs and Bulles.

Developing the software needed similar time as yours, but I was able to use parts of my earlier development, a controller that uses the national radio time transmitter for synchronisation.

Regards,
Frank

 

[Mickyblueeyes]

Hi Frank. There seems to be a misunderstanding regarding the circuit drawing i submitted, this drawing was for the prototype fitted to my own clock and doesnt relate to the question i was asking, thats why it doesnt have any of the energy recovery circuit details i described. The question was simply whether anyone had any thoughts on the question not on my prototype.

Your comments on my prototype are similar to the ones we had in the lab after this version was working, there are a few points that need clarifying.

1. Although the processor clock speed can be lowered it would be a struggle to get down to 32kHz as you suggested without losing a lot of the functionality that is built into it, the clock speed though is down to the application, if you simply want to create a gap in the supply every 2.66 seconds then yes it could be done.

2. Diode D1 is part of the circuit you assumed to be an inverter in fact There is no inverter circuit, the circuit you mentioned is actually monitoring the contact closure of the eureka so that it can be measured and controlled. The circuit is useful for eurekas not fitted with the suppression diode, the contact time is shortened so that the energy is dissipated using the on board diode, this circuit or another method will be usefull for implementing the energy recovery concept i originally posted about.

The 0.7V drop is a loss of energy though of the order of 20% but as the circuit is running at 3.5V a drop to 2.8V is not a bad thing.
When i first looked at this project i was looking to get a 12month operation from 2 D Cells, the processor wouldnt work down to 1.5 volts so a compromise had to be found, I know some suggest using a linear regulator circuit to compensate but I can see no harm in allowing the clock to be regulated at around 3V as long as the contact spark is controlled and the ballance wheel isnt allowed to over oscillate.

3. the few microamps used by TR1 R3 combination can be reduced but it is insignificant compared to the clock itself which takes an average 1.3mA (based on my own clock).

My question still remains regarding the energy recovery method i proposed in my previous post.

 

[praezis]

Hi Micky,
in fact I was in doubt if you were talking of plans or of your prototype. As you mentioned the Transil, that I also found in your schematic, I supposed the second.

Where do you get 3.5V from, don't you use batteries?
Decreasing supply voltage will affect the quartz frequency considerably.

1.3 mA is really heavy for an electric table clock. I knew that the electro-magnetic system has a poor efficiency, but did not expect that poor. Then you are not forced to save current in that extent.

I am focussed on ATOs mainly, they take about 40uA average, so I am not really satisfied with the 35uA that my device consumes. Here a watch quartz is a must. And you can do a lot between two contact actions if you use assembler (control the rate, measure and control the amplitude of swing, provide a rate tester etc.).

Now to your question. Problem is the reverse polarity of the surge.
My idea: a transistor switch on high and on low side (like your U1) of the clock terminals (coil). They must open at exactly the same moment to free the coil. A diode from O/P_0V to Batt+ and a diode from 0V to O/P_+ will feed the surge to C4 and charge it.
If the result is worth the effort must be investigated. In any case I am interested in your results.

Regards,
Frank

 

[Mickyblueeyes]

HI Fank,thanks for the response we appear to be on the same page, I also use assembly language to get the most out of the devices i find this is the best way and have been doing it proffessionally for 16 years now, with the microchip devices the instruction speed is 1/4 the clock speed so it can be a little restrictive, I'm not aware which devices you use.

The description i gave was for a half bridge with steering diodes this is basically the same as your description of the requirement and allows for the reverse polarity of the coil when the energy is released.

When i get the time i will try the idea and post the results.

 

[praezis]

Hi Micky,
on the same page indeed, I also use PICs. On my photo above it is a 12F675.
You are very right with restrictions, also beyond speed.

I would be interested in some data of your Eureka, if you have them.
The contact closing time, period of the swing (2.66s?), resistance of the coil, and its inductivity if possible.

Thanks and regards,
Frank

 

[jkfabulos]

Mr. Hubby per your request here is a complete photo for your records.
I am using a regulated 1.65 volt battery. I believe the battery uses a capacitor to make sure the voltage is constant over the life of the two alkaline "d" cells used.

 

[John Hubby]

Jim, thanks very much for posting your restored clock, beautiful! I mentioned earlier that your clock has the lowest serial number of the Sheraton Pillar design models (No. 8 in the Eureka 1911 catalog) I have documented to date. Also, it has a solid dial whereas the others seen all have the annular chapter ring style dial.

In reviewing my data, there is a clean break in serial numbers between the solid and annular dial fitted to the short movement Eurekas; the highest number to date with a solid dial is serial number 3046 and the lowest with the annular dial is serial number 3052, only six digits apart. Short movement clocks with lower serial numbers have a solid dial and all with higher numbers have the annular dial, with the exception of the gallery model (No. 15 in the 1911 catalog). All the tall movement models have a solid dial.

One question, where did you get the regulator battery? I would be interested to find some of those for my clocks.