Member postings for Sam Stones

Now that I have a decent steel wire drive between the main-spring barrel and the fusee, I found myself pondering over the possibility of setting the balance wheel screws to improve the clock’s timing.

As reported before, my version of John Stevens’ skeleton clock has several issues of time-keeping. My very simple attempts at torque measurement revealed the cause of poor time-keeping. Although crude, they provided enough information to show a distinct fusee inaccuracy, a situation which I’m no longer in a position to rectify.

A few months ago however, I commenced a series of tests and adjustments, and graphed the results. My final plot below illustrates two factors.

The heavy line displays daily errors. I took these at 5 am each morning based upon the assumption that they were perhaps the least affected by (Melbourne’s) ambient temperature variations. I was not serious enough to collect night-time readings. The caterpillars crawling up and down the slopes are the results of hourly daytime variations.

Given that the fusee does not accurately compensate for the varying output torque of the main spring, my intention was to set the timing screws on the balance wheel to the best compromise. After several weeks of timing tests and adjustments, I believe that I have set the mass of the balance wheel to the best compromise. Here are my observations:

• Over 8 days the variation ranged between +74 s and -79 s.
• When the main spring is fully wound, the stop-work mechanism fails to function.
• As the main spring runs down, the arc (swing) of the balance wheel begins to decline.

Until about day 6 or 7, the balance wheel arc (swing) appears to remain fairly constant.

My conclusions.

• I suspect that as the fusee torque varies up and down, there is a corresponding change in the friction at the locking and impulse faces of the pallets.
• I also suspect that there is a change in the mark/space ratio during the locking and impulse phases of the escapement.
• The fusee profile fails to accurately compensate for the output of the main spring.
• Selective use of the `flat’ portion of the main spring is not possible.
• The escapement is extremely sensitive to variations in the fusee torque.
• Balance wheel temperature compensation needs to be properly evaluated.

I shall now be content to wind the clock when it needs it, and set the fingers to the appropriate time.

Best regards to everyone.

Sam (aka Dennis) Stones

Melbourne

Sorry folks,

Where I wrote :-

... I also photographed the two wire terminations – `Thumb knots’ – for me the simplest way out to a less than ideal solution. Incidentally, this picture also captures (centre right), the stop-work iron and the associated `snail' hook." ...

This latter sentence applies to the first photograph.

Apologies! 

Edited By Sam Stones on 17/07/2014 05:57:45

Gentlemen,

Thank you for your many suggestions.

As a postscript to my `Fishy Story’, I can report that with multi-strand stainless steel wire installed between the fusee and the barrel and, after cleaning the pivots and pivot holes, the clock has responded well. If you haven’t been following the dialogue between my various interludes, the clock should run for eight days on one winding. It is no surprise therefore to know that it’s called an eight-day clock.

For the record, I photographed the fusee and barrel just as the clock was about to stop. You can see how, in running off the fusee, the wire has (neatly) arranged itself around the barrel.

I also photographed the two wire terminations – `Thumb knots’ – for me the simplest way out to a less than ideal solution. Incidentally, this picture also captures (centre right), the stop-work iron and the associated `snail' hook.

It looks like my wire cutters missed a few loose ends.

The correct way to terminate them is illustrated on page 106 of `Clock and Watch Repairing’ written by Donald De Carle (soft-back edition).

The following notes should also serve to highlight the fact (which I discovered some considerable time ago), that the 2” radius of the fusee profile does not accurately compensate for the output of the main spring. To determine the best contour, I should have done some homework back in the 70’s when I first began making the clock.

So here is what has happened since I set the clock ticking eight days ago:

During the first couple of days, I was pleasantly surprised to find that the clock was holding the time to within just a few seconds per day. Previously, its rate (beat) was all over the place, gaining as much as ten minutes per complete winding. I could never determine the real cause of the variation, and still can’t for that matter. What appeared to be happening was that when the balance wheel appeared to be sluggish, ie . swinging a total of less than 180°, the clock gained. I won’t go into my theory on that score, unless there needs to be some debate.

At about day three and still with the balance wheel doing a very lively (and greater than 360°, swing, the clock continued to lose. I felt pleased in some respects that the balance wheel was still romping along. By about day six, the clock had lost almost three minutes. It was then that I noticed that not only was it not losing, it was actually gaining.

On the morning of day eight, I waited for the clock to stop. My main purpose was to determine how far the fusee turned before the main spring ran out of puff. When the braided fishing line was doing the work, there could still be at least three full turns of line remaining wrapped around the fusee. More than likely this was signalling that after three years, the clock was in need of cleaning.

Shortly before the clock ran out of power, the total balance wheel swing was down to less than 90°, and within the previous twenty-four hours, had gained almost 60 seconds.

Over the past four years in particular, the whole process of building this clock has been quite a steep learning curve for me. I could not have got there without the very generous help from everyone who offered help and advice.

Good luck, and may none of your projects end up in the scrap bin.

Regards,

Sam

Edited By Sam Stones on 17/07/2014 05:45:15

John,

As always, you are very kind.

Although I had grown to like the yellow of the fishing line, I rather like the steel wire now.

By the way, I cleaned the clock and the chaps at the clock shop who supplied the wire, also pulled the main-spring out of the barrel for me. After I cleaned it, they put it back adding some special oil before they did. When I wound the clock, the extent of the swing of the balance wheel was most impressive.

I've not yet had a chance to adjust the beat, but overnight it had gained ten seconds, whereas before, it was all over the place.

Thanks again to everyone.

Sam

Edited By Sam Stones on 10/07/2014 03:38:17

Gentlemen,

I'm back with a (sort of) conclusion.

How much nicer it would look with a chain drive - but not for me.

However, following the failure of the fishing line which transfers the oomph from the main-spring barrel to the fusee, and with the gift of hindsight I decided to check a few facts.

And, I still have egg on my face over the aspects of creep.

With great respect for the late Mr Stevens, the following details may also offer reasons (in my situation), why I had a fixation on fishing line, and why any serious modifications (to my fusee) are now prohibitive.

It is worth noting here that I machined the fusee back in the early 70’s, not long after Mr Stevens’ article was published, and (as I’ve mentioned too many times already), I no longer have a workshop.

In his article commencing in February 1972, especially (Vol 138 Issues 3334 and 3435, Pages 139, 140, 168, and 169 of Model Engineer), Mr Stevens provided information (and dimensions) of:-

• The fusee and the barrel - [page 139];
• A recess in the edge of the barrel for the knot of a Nylon fishing line - [page 140];
• An improvised fusee cutter - [page 168];
• The 0.035” wide bull-nosed cutter for machining the fusee groove - [page 168];
• A recess in the fusee for the knot in a Nylon washing line - [page 169].

Incidentally, the space in the fusee recess is swept by the fusee ratchet mechanism during winding, so anything protruding (eg. a knot) is likely to interfere with the winding process.

It wasn’t necessary for me to build the fusee cutter. I simply set up my Myford ML7 to machine the spiral groove using the same template I had used to `swing’ the basic profile (a 2” radius). Using a cam follower principle between the cross-slide and the machine bed, the depth of cut was adjusted through the top slide. I’m no stranger to the intricacies of screw cutting, so this exercise was hardly challenging.

On page 140, Mr Stevens then goes on to say;

A key-hole slot is made near the front edge of the barrel tube and a crescent filed on the cover immediately beneath. This is to take a Nylon fishing line which serves admirably in place of the traditional gut.

On page 169 Mr Stevens then goes on to say;

“A hole about 3/64 in. dia. [about 1.2 mm], is next drilled from the outside [of the fusee] into this recess which is to secure the nylon line, and a space for the knot milled out. (The nylon cord is obtained in the guise of a domestic washing line from any hardware shop!).”

So I now realise that as an amateur clock-maker, that’s where my fixation for fishing line came from.

This photograph taken at the small end, is a rather `fuzzy fusee’ profile of the spiral groove as it currently appears. A 1 mm drill doesn’t quite fit, so it looks like I was fairly close to drawing.

In conclusion, despite a fixation on using a synthetic cord (fishing line), I eventually accepted the advice of a professional clock-maker and used multi strand steel.

See this second picture.

I’m not too impressed with the tail ends of the knots. My original method hid the line terminations.

As if all this wasn’t enough, I suddenly noticed in the very top LH corner of this picture that one of the pins in the first lantern pinion had worked loose. Oh dear! Or words to that effect.

Edited By Sam Stones on 10/07/2014 02:30:17

Gentlemen,

Thanks to all of you.

This veritable feast of advice leaves me gobsmacked.

Speaking of which, there’s now lots of egg on my gob. Fellow Victorian, John, was right in pointing out that I have been `attacked by the creep gremlin’. How could it be that I went ahead ignoring the creep characteristics of plastic fishing line while having sufficient knowledge about viscoelastic behaviour, especially of polyolefins and engineering polymers? I was even working in a plastics laboratory where the very 1000 hour creep tests were being conducted. The resultant curves became the very source of many of my designs. A maximum strain of 1% was my design benchmark, mostly relating to compressive and buckling phenomena.

How was it that I had a fixation about ultraviolet degradation? Well, it is Australia, and several of the plastics components which make up our north-facing vertical blinds have suffered from direct sunlight.

Wake up Sam!

OK! Humble pie eaten.

At 79, this will definitely be my last chance at fixing the problem. I’m now fully convinced that I need to switch to multi-strand metal coated or uncoated line, and as I’ve mentioned earlier my choice of terminations needs to be resolved. I am impressed by the sample line I was given, and expect that a simple loop crimped with a copper ferrule would be the way to go. This seems to be a common method amongst fishing experts. Unlike my failed method, hiding the terminations will no longer be an option. This afternoon, I’ll make another visit to Tackle World.

For the time being and to bring this up to date, I found that the line had thinned. This wasn’t all that obvious until I got down to taking the photograph. For the record, the thinned thread came from close to the break, and was subjected to the greatest tensile stress, whereas the thread below it came from near the fusee termination.

For the record, here's a picture of how I found the clock (and fusee line), after it stopped.

The badly frayed end must have received some bashing during the very rapid unwinding of the spring.

Thanks again to every contributor. It's been a lesson for me, I trust that it adds to the collective experience for model engineers everywhere.

I'll be back.

Regards,

Sam

Edited By Sam Stones on 04/07/2014 01:16:47

Gentlemen,

Thank you for your messages, they are greatly appreciated. I’d like to carry out a couple of tests before going any further.

Having said that, I’ve just arrived back from an interesting session with Tackle World in Cranbourne (Oz). They gave me a piece of fishing line to try which has a 90lb rating. I can only describe it as a multi-stranded steel core with a (tough to cut) reddish brown plastic coating. Its diameter fits in the fusee grooves perfectly.

Without too much thought when I was putting the finishing touches to the clock (over three years ago), I terminated both ends of the original (yellow) braided fishing line with (granny-knot) loops. These were threaded through holes in the barrel and the fusee. To prevent them pulling out, I inserted a tiny grooved peg into each loop. This worked well especially considering the limited space available. But that's what clocks can be like.

Knotting steel wire is not going to be so easy, and anchoring is where I need to concentrate.

Regards,

Sam

Hi Bazyle,

Thanks for your very prompt reply, and I appreciated your thoughts about the guaranteed breaking strength. I'd expected that with a 3 to 4 times `safety' factor, it was adequate. I certainly enjoyed your comment about the size of the fish.

I have been lucky enough to find a very helpful clock maker in Melbourne, who was generous enough to give me some multi-strand steel wire. Unfortunately, it is too thick for the grooves in the fusee, and I haven't yet figured out a simple way of anchoring the ends of wire. The existing method I've used, allows me to thread looped ends through holes in the barrel and the fusee.

The local fishing shop have invited me to come in and examine other types of line.

As I've mentioned, I suspect that UV has had something to do with it. In the plastics industry, the best and cheapest method of providing UV protection is micro-fined carbon black, so I'm wondering if black fishing line is available. I'll ask the local supplier shortly.

Thanks again,

Sam

Gentlemen,

I would welcome comment about using fishing line for clocks.

As some of you would remember, three years ago I finished building John Stevens’ skeleton clock and set it in motion. As an eight-day clock and being wound regularly, it has been running without a hiccough.

As you can see from my picture, I used braided fishing line to transfer the torque from the barrel to the fusee. The line is rated at 80lb, and my rough measurements suggest that the spring exerts a pull in the thread of about 10 to 12kg (22-26lb).

About a week ago, the clock stopped. The fishing line had failed while there was at least 80% of the spring’s energy remaining, ie. at almost the highest tension. Although I was out at the time, it must have caused quite a racket, probably scaring the life out of our dog.

While the clock has sat in the shade behind vertical blinds, I suspect that some UV has been getting to the fishing line. There are also limitation to thread/line diameter, and the method of attaching it to the barrel and the fusee.

Also, I have rather limited workshop facilities, so any serious modifications would be difficult if not impossible.

Before I buy more/better line, what are your thoughts?

With regards,

Sam

That's the beauty of this website Michael. Lots of interesting diversity.

I wouldn't miss it for quids. Well, dollars.

Sam

Brian and Gentlemen,

It’s interesting to note how this topic has swung towards optics and eyesight.

During the initial building of my skeleton clock some forty years ago (and certainly more recently), each part had to pass my visual scrutiny through a 3” or 4” binocular headband magnifier. It leaves both hands free although backache can develop while stooping over a lathe, etc.

Living in perhaps similarly rented accommodation, it would seem to me that restraining the spread of swarf in a domestic environment would require even more boxing-in than has previously been intimated. The stuff gets everywhere. Having a strong magnet helps a little with ferrous materials, but the rest . . . well.

By the way, keep magnets away from tools, otherwise that’s also where swarf will begin to reside.

When you’re machining and the cutter or drill starts to scream, how will noise affect the neighbours?

Good luck, and may all your swarf behave itself.

Sam

Brian,

From closer examination of your photographs, I would suggest that the left to right stiffness would benefit considerably from bolting a flat sheet of material across the entire back surface. That method avoids having diagonal braces running across otherwise useful storage space.

When I borrowed a small lathe, I had to stiffen up my existing (Bunnings) bench. Admittedly it was not as strong as yours.

I used 10mm MDF for the back and the ends. The difference was dramatic.

Regards,

Sam

Brian,

Are you suggesting that the bench uprights (legs) will be protruding above the surface of the bench? If so, they would present quite a working hazard.

I would choose to have the horizontal centre-line of the lathe at a height which allows my forearms to be horizontal while using the lathe. Of course, what you’ll be standing on comes into account too.

Regards,

Sam

Hi John ,

Adding to Michael’s moments, it’s worth noting that stiffness is proportional to thickness cubed.

Sam

Also from Melbourne

Gentlemen,

Around 1950 my father bought me a second hand treadle lathe. It was clearly for metal working, with top and cross slides, gears and a lead-screw. The flywheel was massive, but the flat belt either kept breaking or slipping off the pulleys. If you did manage to have your toe under the cast iron treadle, it was only the mass of the treadle which could clobber you. The linkage had been slotted for that very reason.

Unfortunately, the lathe was already knackered. The one-piece casting had split over the front bearing, and the three-jaw chuck was virtually useless.

Nevertheless, my school mate (a big lad who occasionally treadled for the headmaster), and I tried almost successfully to turn bits of wood in it.

Now here’s where you might find some additional benefit Gordon, the treadle pedal was wide enough for two.

For that extra tenth of a HP, you could invite a friend or SWAMBO to stamp on the pedal too.

Good luck,

Sam

I’ve heard of arc welding being referred to as electric glue.

Regards,

Sam

Then of course, having removed many of the parts, there’s HLR (Hidden Line Removal).

Thanks Michael,

The virtual reality (CAD) is a great help when testing the geometry of (say) an English escapement.

By the way, although my clock is now very real (see my avatar), and has been running for about two and a half years, it was only possible with the help of a lot of chaps via this ME Forum and other places.

Regards to all,

Sam

Ditto Andrzej.

Also from the Model Engineer, c.1972. This was compiled in CadKey (now KeyCreator).

Best regards to all.

Sam

Good morning Gentlemen,

How about a mill/drill (of Asian origin) with a 3mm pitch on the `X’ and `Y’ axis lead screws? I didn't realise this before I bought it, and it was fully installed.

I could have become used to the anomaly, were it not for the fact that the dials were marked 0 to 19, ie. 1mm equal to 6.66 graduation lines!!!

It wasn’t long before I had machined off the engraving and introduced a sensible scale.

Regards,

Sam