Tiffany Tiffany Double Contact Movement

[Frank Manning]

Hi,
This one is the larger Tiffany with the double pulse. My question concerns that when it energizes the coil on each side it seems to stay in contact and keep the coil energized until it swings the other way. Wouldn't this make it go through batteries awful fast? It has a hum when against one side, which I assume is a dirty contact. I haven't taken it apart yet. Also, on one side in the rear it seems someone attached a hand to mate up with the large gear. Is that standard, or is replacing a pawl or something that is missing?

 

[eskmill]

Frank.

The tip of the contact as original would have a glass bead at the upper end. As the suspension rotates, the contact slides upward into the glass insulation and interrupts the circuit.

Some repairers have found that a "dab" of epoxy at the upper end of the "L" shaped platinum contact wire works as well as the original glass bead.

 

[Frank Manning]

Thanks Les.

That sounds pretty logical. When I get it out of the case, I will take a close look at that. I use epoxy often, especially fixing toys for the grandchildren. The glass bead being off might explain why it hums when against one side.

Frank

 

[fixoclock]

Frank,
The large hand added to the left side of the large ratchet wheel is not original. Its purpose is unknown except that it may be to add some friction to the rotation of the wheel. The anti-reversing pawl counter weight can be seen to the right of the large wheel and appears to be in the correct position.
The vertical impulse pin attached to the suspension spring is, in my opinion, the cause of your problems. It appears to be completely made of metal and has no insulated ( glass ) tip. It should be a silver tube with a glass tip. When the pendulum rotates it carries the impulse pin causing it to move from side to side alternatively contacting the two horizontal silver pins on the two long arms. The impulse pin silver tube contacts a horizontal silver pin closes the circuit, energizes a coil and activates the solenoid. The horizontal pin jumps up imparting a push to the pendulum impulse pin and at the same time moving up the impulse pin from the silver tube section and on to the glass section. Glass, being an insulator, immediately breaks the circuit and the magnet is de-energised. The pendulum reverses its rotation and the cycle is repeated on the other horizontal pin.
If the vertical impulse pin is not centered between the horizontal pins then the action will be "out of beat". This could buzz as the vertical pin may be permanently in contact with one of the horizontal pins.Also if the vertical pin is all metal, without an insulated top half ( glass tip ), then there will no "make & break" in the current flow and the pins will remain in a continuous contact and "buzz" as the current continues to flow.
Certainly the vertical pin appears to be not original as it extends below its mounting. It should be a silver tube with a glass tip. The glass tip must be tall enough to accommodate the jump distance of the horizontal pin when the magnet pulls the armature up.
I hope this helps to explain the somewhat complex operation. Setting up the eccentric arm guides at the bottom of the arms which hang down from the top of the movement and constrain the two armature arms is critical to the correct timing of the magnet activation and the impulse of the pendulum.
See the pictures below.

 

[Frank Manning]

Thanks Fixoclock and Les,

I had it all apart and did find the pin with the glass top. There appeared to be some wear on the side of the glass top, so I rotated it 90 degrees and tried again. One side was better, but the other side still stayed energized as the pin did not ride up the glass. Since I was able to turn the pin, I will try tp pull it downward in it's holder. There isn't any screw or anything holding it except friction. The holes on the side might have been there for a screw or something, but seem to be filled in now. If I can't pull it down, I will try dipping it in epoxy to make a longer glass top.

Frank

 

[fixoclock]

Frank,
I think you are going to have trouble until you change the shape of the insulated section of the vertical pin. The original silver tube and glas tip are shown below. The glass insulated section is not larger in diameter than the silver tube and this allows the horizontal pins to slide smoothly up without any hesitation or change in direction. The round lump on the end of your pin is going to force the horizontal pin to perform a horizontal action to get up and around the sphere.

You should remove the vertical pin and replace it with a silver tube and glass pin or something similar to achieve the correct action and impulse to the pendulum.

The pictures below are of an original impulse pin.

 

[Frank Manning]

Lindsay,

That sure is an interesting piece. I am not sure how I will ever make one of those. But, I get the message and will try something different. The clock does run well with what is there, but while the the side post is up on the epoxy the coil is still somewhat energized and I am nto sure why. The clock has been fitted up with one of those little 4.5 volt power units and was probably done that way because it used too many batteries. It seems that the epoxy is still transmitting some electricity. Do you know why the tube and the glass are bent?

Frank

 

[Frank Manning]

I checked out the current today. It measures about 50 miliamps in one direction and 20 miliamps in the other direction. It doesn't appear to have any current when it is up on the bead. On one end of the swing the hand seems to take a step backward, but it seems to be keeping time. If I have the balls all the way out and want it slower should I move the post down the wire a little? The clock is running on 3 "D" cells.

Frank

 

[Ingulphus]

Frank -

What 's the thickness of the suspension spring? Per John Hubby on the 400 Day board,

...stepping up or down one size for the suspension spring will result in a 4 minute per hour change in rate at the same pendulum setting. If the clock was running too fast with the pendulum adjusted to "full slow", then changing the spring to the next thinner size as you note would slow it down by 4 minutes per hour if you didn't change the pendulum setting. Ordinarily that will allow you to use the pendulum to do the adjustment, since most pendulums have a plus/minus adjustment range of 4 minutes change from full slow to full fast.

You can thin the spring carefully with emery if the next size thinner slows it too much.

Best regards,

Mark

 

[eskmill]

Frank stated: "It measures about 50 miliamps in one direction and 20 miliamps in the other direction."

I'd suggest that the current measurements may have been made with the pendulum in motion. Better to make the current measurement in a static mode with the contact bypassed and to compare the current/DC resistance of the electromagnets coils which should be equal.

As another subscriber has mentioned, the earlier and larger Tiffany Nerve Wind clocks with double contacts have shunt coils wound on top of the power winding. (neat idea but I'm not so sure the shunt is truly non-inductive) A problem with the shunt winding could possibly result in unequal current measurement.

And Frank, don't over look residual magnetism in the armature and cores of the electromagnets to assure that the armature isn't "sticking" to the core and giving the appearance that the contact doesn't break when the contact slides upward.

 

[fixoclock]

All 4 of my Tiffany 2x contact clocks have the original silver tube and glass impulse pin fitted and in all cases they are bent towards the front of the clock and towards the suspension spring. The only reason that I can think of for the bend is related to leverage.
Being bent towards the front the horizontal contact pins operate on the vertical pin closer to the suspension spring. This may help to eliminate wobble in the pendulum as the pin rotates in a smaller radius when bent towards the suspension spring.
I have found that when epoxy is used it only requires a trace of epoxy on the vertical or horizontal pins to prevent current flow across them. Make sure that all traces of epoxy have been removed by scraping/burnishing all the pins.

Good continuity at the contacts is related to contact pressure. That is how much force is being applied to push the contacts together. If you are getting different currents on the two positions then it could well be that the pendulum is out of beat. More pressure is being applied on one contact than the other. The very heavy pendulum supplies the pressure so if the clock is out of beat then less pressure is being applied at one contact than the other.
The knurled knob on the top of the suspension unit is held in place with a small set screw. Loosen the set screw and rotate the knurled knob to give equal over-swing on the pendulum. Over-swing on these clocks is the distance the pendulum travels after the contacts have closed. It is easy to determine the point when contact is made due to the noise made when the solenoid jumps.
Once you have these over-swings equalised then you can worry about timekeeping. None of the Horolovar suspension springs are suitable for this model Tiffany.

 

[Frank Manning]

Thanks everyone. You have given some great advice. It appears to be running and keeping good time, but I will check the overswing. I think these double contact Tifffanys are so much nicer than the single contact ones.

Frank

 

[Frank Manning]

Hi Fixoclock,

I have had the clock running now for a few weeks. I am having a lot of trouble getting it adjusted. I believe I have it in beat as far as I can estimate. The pendulum swings 2 + turns each time. It swings approximately 270degrees after each impulse. This isn't an exact measurement as I am trying to watch it as it swings.

I have previously shown a picture of the contact that is on the pendulum support. It appears to be made of brass as well as the contacts on the side. If I change these to silver will it help in the adjusting process? Also, I see where I can buy solid silver wire/rod about the right size. But, should it be dead soift, medium or hard? I never knew silver came in different hardnesses. For the rotating one I can machine down the wire and add epoxy about 030 thick and keep it in line with the contact surface if that would help. Keeping a little spindle in the center ought to give it some strength. Maybe it would help if a hole were drilled and a .040 steel piece inserted. Would you think that is necessary? I see the original one had a glass piece inserted.

Frank

 

[Ingulphus]

Frank -

If you don't have the Horolovar guide, this protractor is very handy for getting a torsion clock in beat. Print it (you may have to resize it), cut it out, and place it on the base, under the pendulum. Put a bit of tape or other marker on the outside edge of one pendulum ball and note the swing in each direction. (You probably are fully aware of all this, but if not...)

Best regards,

Mark

 

[Frank Manning]

Thanks Mark for the protractor, I hadn't thought of using one like this.

Frank

 

[fixoclock]

Hi Frank,

You say you are having trouble adjusting the clock. Just what are you having trouble adjusting, the beat or the timekeeping?

 

[Frank Manning]

Hi Fixoclock,

If we go back to one of your earlier responses, you said I would have trouble until I change the shape of the insulator on the vertical pin. Without changing it I had trouble adjusting the time even when I had it in beat. Yesterday I decided to take the pin out and remove the epoxy from the end. I believe the pin is actually a gold alloy of some type rather than brass. Then I turned down the pin in that area and reapplied epoxy followed by turning the bulb of epoxy down to be in a straight line with the pin. I had it running last night and was able to get it adjusted within one minute. I didn't measure the epoxy thickness, but I believe it is probably about .2mm. I will have to wait and see how well it wears.

Thanks for your advice.

Frank

 

[fixoclock]

Hi Frank,
I believe that by removing the lump at the top of the pin you have gone a way to eliminating your problem. As I pointed out before the lump was causing the horizontal pins to ride out and around the lump. The original glass pin is straight and equal in diameter if not a little smaller than the silver tube. The horizontal pin rides up the silver and glass smoothly.No lumps or bumps.
Your old lumpy vertical pin was going to be troublesome.
I'm glad to hear you are having some success now.
With fine tuning you will get good time keeping.
-> posts merged by system <-
Three double contact models and a single contact model.
I am searching for the elusive round topped mahogany cased model.
-> posts merged by system <-
An add for the early double contact models.

 

[Frank Manning]

I guess I don't have it right yet. The contacts that are in there appear to be a brass replacement and after a few days the pendulum swing started slowing down. I went ahead and purchased some silver wire and replaced all three contacts. My question concerns the posts on each side that have the guides in them. The area that the contact support rests against is eccentric from the screw thread. This allows them to be adjusted. What is the proper placement of the guide?

Thanks, Frank