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The Case for Clocks

Your help is needed!!!

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Sam Stones21/10/2010 23:26:03
684 forum posts
257 photos

My skeleton clock is rapidly approaching completion (see my various pictures). It will therefore become necessary very soon, to design and make a display case. Down here in Ozland, various ideas have been tossed around based upon traditional methods.

However, with a very limited budget and even more limited workshop facilities, I could use some help.

The overall dimensions of the clock are :-

Height = 300mm, Width = 180mm, Depth (front to back) = 160mm

Traditionally, a glass dome would be the ideal, but . . . !

Clearly, the clock must be accessible for winding, which is done from the front.

It would be nice if :-

1. The case could be made from relatively low-cost, easily worked materials, eg. Acrylic, although I don’t fancy my chances at succeeding with (invisible) glued mitre joints.

2. The clock could be seen through the case from every angle.

3. The case could `breath’ without dust penetrating to the inside, eg. filtered through a closely woven fabric. Possibly through velvet covering a base plinth.

4. For winding, the case was light enough to lift off each time. I don’t know for sure how long the clock will run on one winding, although I’d guess eight days.

Your ideas would be most welcome.



ady22/10/2010 00:17:40
612 forum posts
50 photos
I'll start the ball rolling

There are also acrylic plant bowls and fishbowls on the net.

Edited By ady on 22/10/2010 00:24:54

Sam Stones22/10/2010 04:19:29
684 forum posts
257 photos
That's a great idea gl, and thanks for getting the ball rolling !!!
I've still got a few friends in the plastics industry.
The acrylic covers you mentioned are just under size, but maybe an upside-down fish tank would do the job!?
DMB22/10/2010 08:59:13
958 forum posts
Hi Sam,
May I suggest a smart looking (Mahogany?) baseplate with 2 large flat "feet" at the ends, leaving an air gap in the middle. The cente area could then be bored with a matrix of air holes covered with green baize, velvet or similar material to act as a filter. Might be a good idea to nicorporate a small piece of Cedarwood to frighten away clth moths.
Hope this helps a bit.
Good luck,
DMB22/10/2010 09:03:55
958 forum posts
Sorry, I AM very good at spelling but fingers slipped when typing `incorporate` and failed to proof - read properly before posting. Disgraceful! especially as I wanted to be a compositor when leaving school! I failed to get an apprenticeship so I went into a factory and gained lots of ME knowledge by using different machines.
Niloch22/10/2010 11:39:43
371 forum posts
Hello Sam,
Many, many congratulations from a fledgling clockmaker on your progress so far.  I regret that most of the references that follow are British based, however, I hope they are of some assistance to you.
P.L.Rawlinson wrote an article in the Model Engineer for 03/02/2006 entitled Perspex Model Covers.  I believe Perspex is a brand name for acrylic, it may be known elsewhere as Plexiglass.
Please be aware that there is a scratch resistant variety of acrylic, the brand name here in the UK is Artshield and as you will have gathered one of its main uses is in the fine art framing world. 
Tony Jeffree wrote an article in the Model Engineer for 29/12/2000 entitled A Glazed Case for John Wilding's 3/4 second Pendulum Electric Clock.
If you have a few $A100,000 banked visit these dome makers!
I also found these suppliers after a rapid perusal of the web.
Finally, the references section here may be of further assistance.

Edited By Niloch on 22/10/2010 11:43:49

NJH22/10/2010 15:28:06
2314 forum posts
139 photos
Hi Sam
You have made such a nice job of your clock I think it needs some care with the case. Traditionally this type of clock seems to have a glass "bell jar"  though I expect this would be difficult to source and then prohibitively expensive. I don't think that a plastic cake cover would quite set your work off to best advantage!
Perspex is probably the best option and I did at one time make quite a few different sized boxes ( including some mitred joints ) which were then joined together (welded) with chloroform. This worked very well but chloroform is a very nasty substance and I wouldn't recommend its use at home. On first reading your post this morning I recalled seeing an article some years ago where the author made a very neat and attractive clock case from perspex sheet with small brass angle at the corners. This coupled with John's wooden base would, I feel , set off your clock very well. I have been trawling through my archive unsuccessfully for the article and then I see that Niloch has pinpointed one above  by Tony Jeffree and I think that is the one I had in mind.
So thanks to Nicloch from me too - I will also need a case sometime ( John Wilding's electric clock)  although with all the other projects probably not too soon!

Edited By NJH on 22/10/2010 15:29:59

Niloch22/10/2010 16:14:34
371 forum posts
Hello Sam and Norman,
I imagine that besides the difficulty in procuring any I can understand that chloroform might be frowned upon for bonding acrylic.
Try Tensol 12 though, my elderly canister shows it to be made by the Bostik Findley people of Leicester, LE4 6BW. (Sorry Sam, another British reference).  It contains  Methyl Methacrylate and Dichloromethane and the container has one of those big black crosses on a red ground on it with the word harmful underneath.
There is also the technique of flame polishing the raw sawn edges,; how do you do it?  Apart from intelligent guesswork, I haven't the foggiest ! 
NJH22/10/2010 17:20:51
2314 forum posts
139 photos
It is quite possible to finish sawn edges by filing first then using progressively finer  paper and finishing with increasingly fine grades of perspex polish to a (near) perfect finish. A special adhesive is also available (but again very nasty) and both products are expensive.
There is info here:-
See Sam - just when the end of your project is in sight another set of challenges emerge.
Oh well that's Model Engineering I guess!
All the best
Adam McCullough22/10/2010 22:27:12
10 forum posts
I think the glass bell/dome covers on a wooden base usually look great on clocks like this and show them off very well.  I'm very impressed by your work on the clock, it looks like it'll be beautiful.

If you have a university anywhere nearby, try to get in touch with their chemistry department - they should have a tech who can make glassware to your design for a pretty low cost.  My father studied chemistry in the mid 70s; at that time all the chemistry undergraduates had to complete a glassblowing course early in their degree, and there were some techs in the department who could do amazing things with glass.

Failing that, perhaps a scientific/pharmaceutical supply house?
As far as wood for bases goes, I've always liked walnut!

Looking forward to seeing your next photos,

Sam Stones23/10/2010 05:39:11
684 forum posts
257 photos


That has been a very pleasing set of responses to my posting.  Thanks to all.

They have created some additional thoughts, especially since I had some professional dealings with a local university several years ago. I just hope that my personal links have not dwindled too much.

Many thanks again for your comments.



Stub Mandrel23/10/2010 12:42:20
4307 forum posts
291 photos
1 articles
Visiting places that specialise in  pile high, sell cheap householdgoods (e.g. Latiff's warehouse in Digbeth) might turn up an imported clock or ornament in a  glass dome for a fraction of the cost of the dome alone.
The Harper31/10/2010 01:24:56
18 forum posts
12 photos
Hi Sam,
Following on from all the other ideas and tips etc.
If you are trying to machine Perspex  / acrylic try using WD40 as a lubricant, this will give you a very good clear finish to the machined edge, believe me it works. It is also very good for keeping the walls of holes clear when drilling.
A further thought for you case. Why not make a 'Four Glass' case, similar to a carriage clock? You could use a brass or hardwood frame that could be easily joined together and could include a pin type hinged door. It could incorporate a wooden base too. The brass or wood sections could be slotted to suit glass or acrylic. Plus you would still have a very visible timepiece that could be surrounded by nice clear glass instead of acrylic.
Sam Stones31/10/2010 03:14:19
684 forum posts
257 photos

Hello Paul,

Thanks for your comments about making a case for the clock.

I’m quite impressed that your ideas and description are so aligned with my own. It is however, hard to avoid the neat and clean line concept of a carriage clock.

My ideal, and as you suggest, would be a four sided `glass and brass' case, with the edges of the glass bevelled to add some prismatic colour. The vertical corners would be of slotted brass, suitably profiled to add further character. Similar in principle to a carriage clock, it would have a hinged front for winding purposes, while the top would be a sheet of brass with a central fretted-brass handle. The escapement needs to be visible, so I think that the top ought to be pierced somehow to let in more light, and preferably allow visual access. I suppose a fifth glass window, suitably bevelled and sealed at the edges, would provide this and some necessary dust protection.

While that would be my ideal, I have to admit that although the clock really deserves a quality case to show it off, we are on a very limited budget. That’s why I’m still looking at a plain acrylic case with mitred edges. Incidentally, I would have thought that WD40 would be a stress-crack agent for acrylic, but obviously you have found it to be OK!?.

On a totally different subject, I designed and manufactured a five-port micro-valve for microscopic research purposes. It featured an acrylic body (polymethyl methacrylate), better known as Perspex. The centre of the valve body was machined out to an accurate diameter of 9.5mm but, because I needed a highly polished finish beside an accurate diameter, I decided to lap the bore with metal polish. What happened during the initial development stages was amazing.
The surface of the hole crazed to a depth of about 2-3mm!
I was generating too much heat during the drilling and boring stages. By reducing to a much lower level the amount of heat being generated and pulling the swarf and lots of cold air through the ML7 headstock mandrel with a vacuum cleaner’s suction, stress cracking was eliminated.
The finishing steps included reaming with a brand new adjustable reamer, `lubricated' and cooled with clean, slightly wetted water, followed by lapping and polishing. This time, metal polish didn’t introduce the cracking.

By the way, I have occasionally noticed this same stress-cracking effect has introduced crazing to the edges of acrylic security screens, where human body oils and other substances have made contact.

We are getting there, but slowly.

You'll notice that I've added an extra image to my clock pictures. It's a 3D isometric like the HLR version, but converted to `Solid'.



modeng200031/10/2010 07:09:40
215 forum posts
1 photos
Another idea for you to consider is to use a set of photo frames to make a 'Four Glass' case. I did this for my ME clock but I guess this method might be only suitable for large clocks.
NJH31/10/2010 09:43:53
2314 forum posts
139 photos
Hi Sam
The story continues! 
I've used parafin as a cutting fluid on perspex which seems to work well, and as far as polishing goes,  perspex polish.
The manufacturer states :-
 Xerapol® Perspex polish   "The Perspex surface is lightly dissolved and polished with fine abrasive particles. During polishing, the edges of the scratches are rounded off and the fissure bottom is filled in. This returns the Perspex acrylic surface to its former smooth and shining glory."
I like the 3D image but Photoshop is a thief of time and should carry warnings for all model engineers!
Stub Mandrel31/10/2010 09:54:01
4307 forum posts
291 photos
1 articles
> pulling the swarf and lots of cold air through the ML7 headstock mandrel with
> a vacuum cleaner’s suction, stress cracking was eliminated
I've found the same approach useful when swarf is causing boring tool to bind in a tight bore.
Tony Jeffree31/10/2010 13:06:12
370 forum posts
6 photos
Sam -
I built a wall clock a while back (completed in Jan 2000) for which I built a case using glass and small section brass angle available from B&Q. The same constructional approach could be used to make a square or rectangular section "dome"; admittedly it would have brass corners, but it is easier to produce an acceptable end result this way than attempting to mitre joint acrylic sheet.
There is an article describing it here:

Stovepipe31/10/2010 13:37:12
196 forum posts
I hope you realise, Sam, that our esteemed editor probably has his beady eye on you as the source of a future ME article for this beautiful piece of workmanship (once of course you've made the case for it). Seeing the balance wheel and escapement photo underlines the intricacy of the craftsmanship. Not into clocks myself, but can admire the work that has gone into it.
Sam Stones31/10/2010 23:43:18
684 forum posts
257 photos

Hi Norman,

Thanks for your posting, especially your comments about Perspex.

I have to agree with you about Photoshop being a time thief. It also mops up a huge amount of disc space especially with RAW, which I now use almost exclusively. Just for the record, and because I’m a rank amateur, I transferred the skeleton clock image from Keycreator to Photoshop, switched it to jpg, then dropped the file size down to <500kb for ME purposes. Why? Because I don’t know a better way.

Hi Dennis,

I’ll keep a weather eye open just in case.

By the way, my first name is also Dennis. These days, I’m referred to as Sam (my middle name), but the reasons are long and tortuous.

Regards, to all,


Edited By Sam Stones on 31/10/2010 23:45:56

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