I have a long term project underway to complete a Mk2 'Nome which has no Pendulum assembly. So far I have bought a rod and made a bob (from a ww2 brass shell case). Today in the post I received the suspension parts (chops) which leaves the Pallet as the final hurdle..The same mechanic whohas made the chops for me  may be prepared to make the Pallet and he now has the drawing for the Mk1 Pallet as detailed in "Electric clocks and how to make them. but....

Can anyone oblige with a drawing of the Mk2 Pallet ?

And any thoughts on wether the Mk1 Pallet woud work as it should in a Mk2 'Nome..Any advice gratefully received..Roger

Hello Roger, I'm having trouble attaching a picture to this reply so I will post in "Files" a copy of the design from Elliott Isaacs' articles in EIM, sometime in the 1950s I think - presumably that should be a Mark 2.

John.

Now uploaded.

Thanks John...I'll have a look at that later..Meantime I'll consult" Miles" as I have a feeling Mk2 clock was introduced early 1960's.. I had assume the Pallet re-design came at the same time that the whole movement was re-done...Roger

Dear Roger
So this is my first ever post on this site, although it's true that I have been suffering from this masterclock affliction for some years now, and observing with great interest all of the exchanges of information etc on here.

I have a Mk.2 clock here running in my workshop, and I have another earlier clock which is missing its pendulum. I made up a CAD model of the pendulum to allow me to make a new one. I based the model on an amalgam of:
- the HJ diagrams in "Electric Clocks and How to Make Them"
- the existing pallet on my Mk.2

Basically, I don't think there is much difference between these 2, except for 2 details:
1. The length of the cylindrical section is increased from 5/8" (15.875mm) to approx. 19mm. All of the pallets since the 1920s (according to Miles page 82) use a screwed bush for fitting the gathering wire, so I assume that this lengthening dates back to then, and so pre-dates the Mk.2 (which appeared early 1960s: Miles page 94) by a long way.
2. The horizontal distance of the impulse slope away from the vertical axis of the pendulum rod. "Electrical Clocks..." states this as a radius of 1/1/4" (31.75mm). However, on my Mk.2 clock this is more like 33mm. I am unable to say exactly why this change has been effected, since I have not carried out an exhaustive study different geometry of the various synchronome components as they have evolved through time. But it would seem logical to expect on the Mk.2 a corresponding increase in the horizontal distance between the vertical axis of the pendulum and the axis of the impulse roller (due to a change in the geometry of the cast back-plate?, or the gravity arm? or a bit of both? etc etc), which would make this lengthening of the pallet necessary.

The Eliot Isaacs sketch is much like that which appears in "Electric Clocks...", except that he has a slightly different position for the pivot of the gathering wire, but I couldn't see that this would make any difference as long as you are happy to make up the wire and then adjust its length to precisely suit the clock in hand for optomised performance. I have now made several of these wires, and personally I like to mount the jewel in a little turned cylinder, open at one end only, and with a screw (thread S0.80) which allows me to slide the jewel along the wire and lock it in place. In this way, very small adjustments can be made to the position of the jewel, and it is interesting to observe the notable change in amplitude produced by even a small change.

If you use CAD, I would be more than happy to let you have my CAD model of the pallet. However, I have to tell you that I am not a fan of imperial measurements, and so have rounded everything down/up to the nearest convenient metric sizes, including the threads.

By the way, have you ever wondered where all of the lost masterclock pendulums go to? I sometimes imagine a wee dingy old room, like a sort of masterclock pendulum heaven, stuffed full of hundreds of them.

Best regards
Stephen

Hi Stephen and John.
Very helpful post Stephen...welcome to the clock nuts...hope to hear more from you ! John, I've now examined the excellent drawing of Isaacs pallet that you uploaded and am pretty sure it's based on a Mk1 type. Both Stephen's dimensions and those in the drawing - plus examination of a Mk2 I have. The length is slightly longer than 1 1/4" and the collar of a Mk2 is 3/4" high.
I don't know if there are any  changes to the clock mech to deal with the extra length, but off hand I wonder if the lateral adjustment of the main pendulum suspension arbor would accommodate that.
An intersting feature of the Isaacs drawing that it seems to be made from three separate parts, silver soldered together..That seems like a good idea for construction where no access to a mill is available..
Yes please...I would like to have the CAD drawing you have made, Stephen. Upload to the files area or send by PM. I wouldn't understand it, but my cousin who may make it for me almost certainly will..

On subject of  the pivot screw for the gathering wire, I find it an awkward concept all round. I've only just noticed that the one I've taken from a working clock has a broken section in the "head" and, being on the back, of the pallet they are a pain to adjust. Not to mention trying to make unless you are a "proper" clock maker used to working in miniature. Which I'm not !.

Although I am actually trying to finish of a Mk2 clock, I also have a my first ever master clock which I bought years ago as a mechanism only - fortunately complete with pendulum. I eventually aquired a MK1 case and made a dial for it. So it has no great monetary or historic value and I've now "robbed" the Pallet from it it complete the other one.

So this pallet will now go into the "marriage" clock just for completeness..With that in mind I've allowed myself to think of 3D printing....now there's thought ! (But I haven't got one!!)

On the question of where do all the missing pendulms go, I suspect Sarah Moore...Perhaps there are pink painted bobs in Chelsea flats used a door stops or that other "artisan" has but a light socket on the top of the invar rod and they are upcycled as standard lamps.......and of course sold for £800 ish..Oh dear...I must watch too much daytime telly :-)

At least the bulb height won't vary much with room temperature...

Hello again Roger

Ok so my mistake, it would seem that the pallet collar remained at a length of 5/8" following the advent of the screwed bush for the pivot of the gathering wire. See on the hvtesla site: power station model/original synchronome literature:
http://www.hvtesla.com/masters/syncro_power_station_lit.html

Here he shows a mk.1 and a mk.2 pallet, both with the screwed bush. However, on the mk.1, the bush doesn't look great because it sticks out well beyond the bottom of the (shorter) pallet. So the lengthening of the mk.2 pallet collar to 3/4" (I had said 19mm which is 0.05mm less) would seem to be for aesthetic reasons.

Yes Roger, I agree that the screwed bush is a bit of a pain, in that you have to take the pendulum off to adjust it. However, I would defend it from the point of view that its presence greatly simplifies the manufacture of the impulse pallet overall, and I would suggest that this is very probably the reason why Synchronome introduced it. The original pallet as shown in "Electric Clocks..." is grand, but that wee fiddly bit on the back where the wire is supported is a right pain, and a fairly poor design if I may say so. Also, clearly no adjustment at all of the angle of the wire is possible with the original version, so the adjustable bush is a welcome improvement. Yes it is a fiddle, but you are only going to have to do it once. You can make the pallet and bush so that the threads are an interference fit, meaning that the bush is slightly tight in its threads but can still be turned. Otherwise, you can make the pallet and bush with standard loose-fitting threads, and then adjust the final position of the bush after tightening by fitting wee brass shims which are made up to suit. Also, keep in mind that this is only supposed to help you to roughly set the angle of the wire. The fine adjustment is the done by bending the wire. If someone has broken part of yours then I'd say that can only be down to extreme carelessness. Many of these poor clocks led tough, loveless lives, didn't they. Also, there is plenty of space behind the pallet when it is mounted in the clock, so you could certainly thicken up those parts of the head of the bush to make it more robust.

As regards the CAD model, Roger, sorry I should have been more clear. What I have done is to create a 3d CAD model of the pallet, so that I can use it as a basis for my own machining. I can certainly let you have this, but it will only be useful if you or your cousin has access to CAD software (Autodesk Inventor, Solid Works etc etc). I haven't actually done a corresponding machining drawing, although I'm sure I could draw one for you (version with bush, that is) if that were helpful. If so then let me know. I could do it in imperial, or rounded up to nearest metric sizes?

Stephen

Hi Stephen..My 3/4" was approxiamate..I just used a ruler to check if it was 5/8" !

It was only after posting my previous that I noticed that the both drawings mentioned, don't have the "screw" supporting the gathering wire at all ..

I'm thinking of ways to simplfy the constuction (for my cousin) so might suggestto him  that the Collar part is plain reactangular in cross section.This will leave a 90d corner at the abutment of the projecting pallet.

I may suggest to him that if the bearing hole is drilled 1/32"clearance and  I extend the length of the 1/32" wire to protude 1/4" from the front surface of the pallet....I (or he !) could make a small collar with 10Ba clamping screw.to hold it in place.

By rotating the position of this collar, the head of the 10ba screw could be arranged to be at the 5 o'clockish position to fix the rest position of the gathering arm by coming into contact with the 90d shoulder of the main rod collar. can anyone see a problem with this ?
I,m waiting to hear from my cousin about his access to CAD software.

Roger..

Worth noting that Fusion360 is available for free for hobby use.

Because I'm fairly new to this group I hadn't realised that a lot of the info I asked for is covered very thoroughly in a previous thread;  "Pallet Design" and I now have enough info to proceed.
Walking between two rooms to compare pallet shapes left me confused until I realised that the Mk1 clock I was looking at actually has a Mk2 pallet. Not surprising really when the youngest of these clocks are  50+ years old and have been "maintained" by diiferent people and companies over the years.
I note that one experienced contributor to the othere thread stated that there was little point in obseesing about the shape of detail like the inpulse curve, and pointed out that the Gents C7 has a straight profile impuse surface.

In this instance I'm not interested in making a repair that will pass as original so will use one of the drawings I now have from the various posts..

It has left me wondering however if the detailed drawing of the Mk1 type pallet taken from the "how to make" books (without the screw-head bearing for the gathering arm) was ever actually used in a production clock.
Roger

Yesterday I the site would not accept this image which I was going to add for interest only...but it's ok today..strange !
Top...a Mk1 and below, aMk2 Pallet.