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Re: New Member

Steve Berger
 

Hi Larry,
I have an extra casting available if it might help your project along.
Best regards Steve
AZ, USA



On Mar 8, 2019, at 7:44 AM, highpwr via Groups.Io <highpwr@...> wrote:

Thank you for the invite to the group.  Residing in the USA there is not much local activity in Synchronome collecting and restoration so I decided that building a Synchronome from scratch would be a worthy and interesting project.  I have not done much on the project lately but did manage to build a gravity arm, solenoid parts, turn a pendulum bob from cast iron, acquire invar rod and a working synchronome slave dial.  I am now waiting for a resurgence in my interest level (too many other competing projects and hobbies).  Maybe joining this group will help me restart my Synchronome build.

Larry <IMG_20141229_130635_190 _3_.jpg>


Re: Reinventing a Synchronome

John Haine
 

Oops on the diode - thanks.

Actually the on-board Arduino pullup is 20k, so the effective pullup will be ~12k, giving a wetting current of ~0.5 mA.  We'll see how that gets on.


Re: Reinventing a Synchronome

neil
 

Hi John,
                Looking at your clock pulser - a couple of suggestions:
 the diode D1 across the clock dial is back to front.
I would suggest 1k pullups in place of the 22k at R6 and R7, because the 22k will only give you about 0.2mA of switch current which is too low.
A protection diode across the LM7809 is a good idea and will protect it from reverse polarity if the input supply goes below the volatge on C3.

cheers
Neil
On 10/03/19 1:27 AM, John Haine wrote:

To avoid making the thread very long with photos etc I've created a folder over in "Files" called iSynchronome, and to get the ball rolling uploaded the initial schematic for the electronics which I now need to get on and build.


Re: Reinventing a Synchronome

Darren Conway
 

Hi

It seems to me that you are using so little of the original clock you could have done it without a donor clock.

--

Dazz

Virus-free. www.avast.com


Re: Reinventing a Synchronome

John Haine
 

To avoid making the thread very long with photos etc I've created a folder over in "Files" called iSynchronome, and to get the ball rolling uploaded the initial schematic for the electronics which I now need to get on and build.


Re: New Member

James Kelly
 

Hi Larry

welcome to the group, looks like you’ve made a good start, hopefully you’ll feel inspired to finish you’re project.

ATB

Jim


New Member

highpwr@...
 

Thank you for the invite to the group.  Residing in the USA there is not much local activity in Synchronome collecting and restoration so I decided that building a Synchronome from scratch would be a worthy and interesting project.  I have not done much on the project lately but did manage to build a gravity arm, solenoid parts, turn a pendulum bob from cast iron, acquire invar rod and a working synchronome slave dial.  I am now waiting for a resurgence in my interest level (too many other competing projects and hobbies).  Maybe joining this group will help me restart my Synchronome build.

Larry


Re: Reinventing a Synchronome

John Haine
 

That's what I'm hoping!  Time will tell.


Re: Reinventing a Synchronome

Rob
 

Thanks John,

Good old Araldite, sticks anything to anything else :-)

Regards

Rob

On Thu, 7 Mar 2019, 21:15 John Haine, <john.haine@...> wrote:
Rob, the CF is 10 mm OD tube, 8 mm bore.  There is a 25 mm slug of 8 mm aluminium rod araldited into the bore at each end.  At the top there's a 3 mm cross hole with a bolt through it that holds the rod into the lower chops of the suspension.  The bottom slug has an M4 rating screw tapped and loctited into it.  As the inside of the bore is quite rough, and I believe the CF is laid up with epoxy, I'm hoping that the lower joint will hold but may drill another cross-hole for a pin just in case.  


Re: Reinventing a Synchronome

John Haine
 

Rob, the CF is 10 mm OD tube, 8 mm bore.  There is a 25 mm slug of 8 mm aluminium rod araldited into the bore at each end.  At the top there's a 3 mm cross hole with a bolt through it that holds the rod into the lower chops of the suspension.  The bottom slug has an M4 rating screw tapped and loctited into it.  As the inside of the bore is quite rough, and I believe the CF is laid up with epoxy, I'm hoping that the lower joint will hold but may drill another cross-hole for a pin just in case.  


Re: Reinventing a Synchronome

neil
 

Hi John
I have also been working along similar lines, but all home made. Hopefully yours will be running before mine is.  I have 3 optos ( as seen in the pix) to sense the BTD of the pendulum but also to detect when the amplitude falls off to a preset point, when i will impulse the pendulum again magnetically. ( an electronic Hipp toggle if you like)  The coil is on the LHS with the LED across it is the impulse electromagnet, which "sucks in" the steel rod.  I'm using an Atmega micro, not the Arduino, but same thing. Just different language.  The bob is a massive chunk of cast iron on a brass sleeve for temp compensation, on a 3/8 invar rod. The suspension I built along the lines of the recommendations in Matthys book Accurate Clock Pendulums, but in hind sight it could be better. I have had it running, but other things have got in the way, and at the moment its a project still. 
Neil
New Zealand.
On 08/03/19 8:16 AM, Rob wrote:

Hi John,

 I am interested in this project. I was wondering how you are going to connect the bob onto the carbon fibre rod. I have been interested in cycling for many years and there it has always been a task to bond carbon an steel or aluminium together. I would be interesting to see how this project ends up

Regards

Rob Lockyer


Re: Reinventing a Synchronome

Rob
 

Hi John,

 I am interested in this project. I was wondering how you are going to connect the bob onto the carbon fibre rod. I have been interested in cycling for many years and there it has always been a task to bond carbon an steel or aluminium together. I would be interesting to see how this project ends up

Regards

Rob Lockyer


Re: Reinventing a Synchronome

John Haine
 
Edited

Thanks for the positive comments.  Carbon fibre has a near-zero coefficient of thermal expansion - there is some discussion over on the NAWCC discussion boards, and though the coeff is variable between materials it is generally better than invar.  It is liable to absorb moisture slightly, which means its weight can vary, but what this does to timekeeping I have yet to work out.  I do have a spreadsheet that takes into account all the material densities and shapes to calculate the period so it would be simple to do (in fact I ought to sooner rather than later).  It's also MUCH cheaper than invar.

Edit: Now done the calculation.  According to an NAWCC post the maximum weight gain of CF due to absorbed humidity is 0.2%.  Plugging this as a density gain in my spreadsheet gives a change in pendulum period of 1.9 microseconds, which I think I'll forget about!  The thing is, carbon fibre is so light anyway, especially compared to the bob, that its contribution to the MoI is minute - so changes to density also have a small effect.

Actually the opto will tell the Arduino when the pendulum reaches its extreme of swing, then the Arduino works out when to place the pallet, but will do this on the dead roll before the impulse so the exact impulse timing depends only on the pallet profile.  That's the theory, anyway!


Re: Reinventing a Synchronome

 

This is just beautiful. The development of the pendulum clock was driven by clockmakers relentlessly trying to stop the pendulum doing too much work so that the pendulum would just do the timekeeping. It reached its pinnacle with the Synchronome and its successor the Shortt-Synchronome. None of the developers in the past had access to optoelectronics but now we do.We could interact with the pendulum without touching it. How elegant to just use an opto sensor not only to count the number of beats but at the right time to drop a gravity arm and pick it up.  Do keep us posted as to how you get on and I'll be very interested to see what sort of accuracy you get from this modification that approaches the Shortt-Synchronome. You can even get a seconds signal from this.  Wonderful.


Re: Reinventing a Synchronome

John Hutchinson
 

That's an interesting project :)
Why CF for the pendulum rod? Better coefficient of expansion? 


Re: Reinventing a Synchronome

John Haine
 

That should say that the opto will pick up the pallet at the extreme left hand swing!


Re: Reinventing a Synchronome

John Haine
 

I forgot to mention that the cam follower is a 6 mm ball race with its inner bolted to an M2 screw through one of the holes that used to be used to attach the ebonite insulator on the back of the gravity arm.  Stepper motor is an "08" size.


Reinventing a Synchronome

John Haine
 
Edited

As I'm making some progress on my reinvention (if I may be so bold as to call it that) I thought that I'd post some pictures of the story so far.  I acquired a 'Nome round about the beginning of January, in not bad condition but lacking the pendulum and pallet, with the intention of using the parts that I had to make a clock on the same principle but updated.  Apart from the fun of doing my own thing, I wanted to make something that would be quieter and maybe better appreciated by the domestic authorities.  Apart from making a pendulum with a 7 kg cast iron bob and carbon fibre rod, the main differences are:
  1. The same basic impulsing system is used, but with a pallet shaped based on FH-J's theoretical description in Electric Clocks, as proposed I think by William Shortt.  This is designed so the impulse roller is placed gently on the pallet just before the impulse is applied, on a surface that is a circular arc struck from the pendulum pivot.  As the pallet moves further, the roller slides down a ramp shaped to give a smoothly increasing then decreasing force, around the centre of the swing, then the roller ends up on another dead roll, from which it's picked up just after the impulse.
  2. The count wheel is replaced with an opto interrupter, which will (if I can squeeze it in) sense the end of the pallet at the extreme righthand swing.  Swings will be counted by an Arduino, which will generate an impulse every N swings where N may not be 30; plus a pulse to drive the slave clock every 30 seconds.
  3. The gravity arm will be controlled by a spiral cam on the shaft of a small stepper motor driven from the Arduino, so as to place the impulse roller on the pallet just before the impulse, and lift it off just after.  Because the roller touches down and is lifted off when on a dead roll the impulse timing should be pretty insensitive to the exact moments of touchdown and liftoff.
So far I have made the pendulum, pallet + collet, the stepper mounting and the lifting cam, and a new cock for the gravity atm pivot that's much thinner than the original to make more room for the pallet collet, so all the main mechanical components.  Here's a photo of the assembly - there are more in an album under photos.  You can just see the spiral cam poking out of the side of the motor mount, which itself sits on two pillars set in holes on the bedplate that used to hold terminals.  I have accumulated a collection of 'Nome components that should not be needed, which will be looking for a good home.
.
With the basic mechanics built, now I need to start thinking about the Arduino.  I'll post more as the story progresses.

And sorry about the major surgery to an innocent Synchronome!


Re: New electronic Hipp Toggle clock project

John Haine
 

No, I'm afraid it's not supposed to!  I'm going to start a new build thread about what I'm doing, will explain there.


Re: New electronic Hipp Toggle clock project

wwwrogerj.codotuk@...
 

Hi John..It's probably me...but they don't look like the pallets in a Mk2 'Nome...Or a Mk1 'Nome..The "ramp" face of a Mk1 is rounded slightly across the width although the Mk2 doesn't seem to be. Thickness of blade is 5.9mm..Is yours a bit thinner ?
I have a horrible feeling I'm not seeing something I should, but here goes anyway...Nice work BTW..

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