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15-day Skeleton Timepiece

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Russell Eberhardt23/01/2012 10:46:15
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2720 forum posts
86 photos
After several years of model engineering and as my grandfather, great grandfather, and great great grandfather were all watch and clock makers I have decided to make my own clock.
 
I have chosen John Parslow's skeleton clock as it is described as being suitable for beginners to clockmaking and looks nice.
 
Having started it I have found that he assumes rather a lot of clockmaking knowledge so have been reading up on techniques and nomenclature. I have also found quite a few errors in the articles (some, but not all, of which were corrected in later articles) so I will note them here in case it helps anyone else:
 
1. The material list omits the brass for the minute wheel. This should be 1.5 in Dia. x 3/32.
 
2. The 4 mm winding key specified will not fit on the 0.18 AF end of the barrel arbor. The correct key is 4.5 mm.
 
3. The suspension spring should be part no. S5516.
 
4. The mainspring should be part no. 0321 204515.
 
5. He gives some rather odd dimensions for the bores of the wheel collets and pinions. I'm using the following drill sizes:
0.78 2 mm.
0.85 #44
0.112 #33
0.118 3 mm.
 
That's all for now - back to the workshop.
 
Russell.
johnp1023/01/2012 12:13:12
25 forum posts
4 photos
Hello Mr Eberhardt,
If you will kindly contact me at johnp10@ virginmedia.com I will endeavour to answer your queries.
Regards.
John Parslow.
johnp1024/01/2012 10:41:32
25 forum posts
4 photos
I must thank Mr Eberhardt for pointing out that a number of errors the have crept into the 15 day skeleton clock series in M.E. from 28 March to 15 August 2008.
Items 1,2,3 & 4 in Mr. Eberhardt`s list are correct as printed.
The drills that I used were standard Imperial sizes when the clock was first built but there is no reason that the sizes suggested by Mr. Eberhardt should not be used as long the diameters of their matching arbors are adjusted to fit.
John Parslow.
 
Mogens Kilde24/01/2012 16:56:40
60 forum posts
25 photos
Hello Folks
As Mr. Eberhardt has started this topic, I simply have to show my progress on making the very same clock.
 
Previous you all have been kind to give me some feedback on the tool making for the project.
 
 
In the building proces I have made metric design of all parts, as you might see the next step is the ThirdWheel section.
So far the project has been very interresting, so I would like to thank Mr. Parslow for his design of this clock.
 
Mogens
Russell Eberhardt25/01/2012 20:47:20
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2720 forum posts
86 photos
Morgens,
 
It's looking good so far.
 
John,
 
The drill sizes I came up with are the closest I could find to the decimal dimensions in the article. The metric ones are closer than the nearest number drills. Of course, as you say, it doesn't really matter as the parts should be made to fit.
 
A question when it comes to the pivot holes in the frames: I guess the holes are drilled to the pivot diameters and then opened out with a broach. My question is how much should they be opened? I have seen books recommending that the arbors should be able to tilt by about 15 deg. but the frame thickness must affect the amount of tilt for a given clearance. What would you recommend?
 
Russell.
johnp1026/01/2012 13:18:50
25 forum posts
4 photos
Hello Russel.
I suggest that you drill the pivot holes a few thou. less than the pivot diameter then broach the hole on the inside of the frame plates until the pivot will just fit into the hole. At this stage cut the oil sinks on the outside of the plates, lightly countersinking the holes first to provide a location for the d-bit. Now broach out the pivot holes equally on each side of the frame plate to give about 5 degrees of arbor lean in all directions. Fit the arbour and wheel into the clock frame and check that it spins freely. If it does`nt spin freely or stops with a jerk then one or both holes may be a little too tight. A final check is to fit the arbor and wheel in position then suddenly invert the clock frame When a click should be heard as the arbor drops taking up the end shake.
 
John.
Russell Eberhardt26/01/2012 19:58:27
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2720 forum posts
86 photos
Hi John,
 
Thanks for that.
 
Perhaps a silly question but:
I had a problem with a clock I repaired where I re-bushed a couple of pivot holes. It would run OK for a few days, then loose half an hour the next day, then run OK again. I found the problem to be that I had made the pivot holes too sharp on the inside edge and the pivots had a significantly rounded corner at the shoulder. This occasionally caused things to stick.
Would you recommend an undercut on the shoulder of thee pivot, making polishing difficult or a slight countersink on the inside edge of the holes?
 
Russell.
johnp1027/01/2012 14:14:45
25 forum posts
4 photos
Hello Russell,
 
Machine your pivots with a sharp internal corner and chamfer the arbor at about 60 degrees inc. to about 1 m/m diameter larger than the pivot , then c`sk the pivot hole just a few thou. to remove the sharp corner. This reduces the rubbing friction between the pivot shoulder and the frame plate.
 
John.
 
Russell Eberhardt27/01/2012 17:03:52
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2720 forum posts
86 photos
Thanks
 
Russell.
Mogens Kilde17/12/2012 07:06:48
60 forum posts
25 photos

Hello

Could someone (maybe John him self ) tell me the dimension of the main spring, for 15-day clock.

I know the part number is stated in the article, but still I would like to know the dimension

Thanks in advance

Mogens

roy entwistle17/12/2012 10:56:56
1440 forum posts

Hi The part no's of the suspension and main springs will depend on where they are puchased from

Roy

Mogens Kilde17/12/2012 11:13:52
60 forum posts
25 photos

Hi Roy

Thanks for your reply.

Exactly... Thats why I would like to know the approximate dimension, and experiment in the work shop

Mogens

RJW17/12/2012 12:44:30
343 forum posts
36 photos

Mogens, the part number is useless if you don't know the supplier to whom the numbers pertain!

If it helps, you will find that when buying mainsprings from a supplier, the dimensions you will use to select them from stock charts are:
(a), the internal diameter of the mainspring barrel
(b), the working depth of the barrel, which is internal measurement from the bottom of the barrel to the inside face of the barrel cap, you can get away with using a depth gauge using the seat for the cap as a datum!
Allow for working clearance inside the barrel when closed, the springs available will probably determine this, too wide and the cap won't fit, so select the size down where it will!

(c), the 'Force' or thickness of the spring, this is the main dimension you will need because you already have the others if you have the barrel to hand!

Meadows and Passmore usually have a good stock:
**LINK**

It's a bit of a faff going from their homepage because there's no direct link to their mainspring listings (robots), but click 'Buy Online' > Enter M&P Store > The Driving Force + enter 'mainsprings' in the search box > this will take you to their mainspring listings, you'll get an idea then of their sizing conventions and increments of dimensions between sizes, it's the same for all of the suppliers I've used.

John

johnp1017/12/2012 13:28:15
25 forum posts
4 photos

Hello Mogens.

Thank you for your query.

The mainspring that you require is available from Meadows & Passmore, Tel 01273 421321.

Part number 0321 204015

Dimensions, 20 x 45 x 45.

This was originally in stainless steel but a look today on M & P website seemed to indicate that is now only available in clock grade steel. This should be satisfactory.

Hope that this helps.

Regards.

John Parslow.

Bazyle17/12/2012 14:28:59
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6087 forum posts
221 photos

Russell has a number of progress photos uploaded. Just click on the link under his name on the original post. They demonstrate that clockmaking skill is passed down the generations so perhaps one day the relevant gene will be identified. Thanks for sharing.

Mogens Kilde17/12/2012 17:36:20
60 forum posts
25 photos

Thanks to you all, now I can go on with experimenting The last 40 mm dims. is that the outer diameter of the coiled spring when supplied ?

Mogens

RJW17/12/2012 19:30:28
343 forum posts
36 photos

Mogens, the sepc's given of 20 x 45 x 45 are:

20 = 0.20mm which is the thickness or 'Force' of the Spring,
45(1) = 45mm = 'Height' of the spring, which is the depth of the barrel with cap fitted and allowance for working clearance,

45(2) = 45mm = Internal diameter of the mainspring barrel!

The spring will be supplied fully coiled and wired, you will need a mainspring winder to release it from the wire so you can clean and lubricate the spring before fitting, and then to wind the spring again prior to fitting to the barrel.

Note that with both Height and Barrel diameter, for purchasing other sized springs, you will need to check which way round M&P specify those dimensions, I've numbered them 1&2 for the purpose of this reply only, they may be the other way round!

Spring 'diameters' are sized on internal barrel sizes, and have no bearing on the actual diameter  of the coiled spring you will be supplied with, it would depend how tightly M&P wound it before wiring it up!
Although it's most likely it would drop straight into a barrel, you wouldn't want to do that without cleaning any preservative and dust off, then lubing it first!

Hope this makes sense,

John

 

Edited By RJW on 17/12/2012 19:35:24

Mogens Kilde17/12/2012 19:42:56
60 forum posts
25 photos

Hi John

On the M & P website I find the following for the partnumber 0321 204015 :

HOLE END CLOCK MAINSPRING 20mm x 0.40mm x 40mm You will find other sizes of mainspring in chapter 15. Clock-grade steel.e

I believe this means that the thickness (Force) i 0.4 mm and that the width (barrel height) is approximately 20 mm, this leave the 40mm to be the inside diameter of barrel

Is this correct ?

Regards
Mogens

Russell Eberhardt17/12/2012 20:24:51
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2720 forum posts
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I believe the correct measurements are 20 x 0.45 x 45.

The M & P reference is 0321 204515.

Russell

RJW17/12/2012 22:53:33
343 forum posts
36 photos

Morgens, Yes you've got it, the figures Russel has since added are for the corrected mainspring, the decimal point was missing from the sizes in the reply I quoted from, and I never checked M&P's site first to confirm sizes beofre posting, apologies for any confusion!

John

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