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National Electric Watch Cleaning Machine


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Well, where do I start? 

The speed control is a rather scary looking, three layer, open wound, wire-wound resistor/rheostat. As the mains connectors and the resistor itself is open from the underneath, that alone is enough to kill any chance of it meeting current standards. It would need to be completely replaced with an enclosed, mains motor speed controller to comply. Remember I did say 1940’s early 1950’s vintage for this machine. Not even close to 1970’s technology or practices.

The motor itself is fine and I will be inspecting the brushes and commutator as a matter of course.  But a quick visual inspection before purchase showed nothing for concern.

Here is a photo of the rheostat - in situ - for some idea... I have cut out some of the old wiring, which as you can see, is very old and fabric wound. I think Noah last used that stuff when he re-wired the Ark!

Bear in mind that this is what you are exposed to, as soon as you turn the machine over. This is how it was built! No guards or covers have been removed - none were ever built in. All that mains wiring and connections were visible and accessible at all times.

i will likely restore it as is, but then give some serious thought as to how to give protection from all that exposed stuff.

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Take it easy around that wiring, one thing I did think of after I posted is that some of the old wiring and indeed that rheostat may well contain asbestos. It will be safe enough unless you start chopping it about.

I would grab yourself a triac speed controller and bin the rheostat and its associated wiring.

There may be some suppressor capacitors that might need changing (although judging by the age of the machine, possibly not) and when the thing is running I suspect it will blast interference all over the radio spectrum, and buzz all over the local radio stations, but probably not enough to travel next door and annoy the neighbors.

 

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No suppression in sight. Again, typical of its age I guess. I am also a licensed Radio Amateur so well aware of looking out for and solving interference problems. As well as not annoying the neighbours, I have no intention of wiping out my HAM radios either. ;)

All those plates you see on the rheostat almost certainly contain asbestos as mentioned, but they are bonded into those plates and are in very good condition for their age. I have "fabricated" a plastic insulation shield that encloses the rheostat and provides much increased protection. Having said that - I have also, already ordered a more modern 240v motor speed controller as well which will arrive today. I'm pretty sure that even with the "new" protective cover - I still would feel uneasy putting this back into service, so will likely panel mount the new controller in the space vacated by the rheostat. I hope the measurements I took off the replacement are accurate, as it should be a straight swap (if I am lucky). I may even be able to use the original rotary control knob and maintain a bit more originality...

Anyhoo...

Having cleaned and painted the base (with rattle-can black Hammerite) I turned my attention to sourcing a replacement for the heater. My main design criteria was that It had to perform like the original, and fit in place of the original. Clearly finding a spare part (even if likely, which it is not, not without cannibalising another original machine and goes against the grain somewhat), would mean that I was re-introducing an old (unsafe) element, after taking away an old (unsafe) rheostat. This did not make logical sense. So something new was needed.

Thee replacement heating element for the Elma Super Elite (RM80/RM90 etc.) are still available and they look like they would do the job, but are £45.00 plus postage from everywhere I could find them.

This is the specification for the Elma Machine and a photo of the spare part. The spec. shows that the power consumption of the heater is 200W, which is important to know. A quick examination of the wiring diagram (found elsewhere on the forum) shows that the heater has no external temperature regulation circuitry, and therefore must regulate its temperature by itself.

I recognised the heating element (the rectangular thing) as they are the sort of heater used for equipment cabinets etc. for frost protection and providing other low level heating needs. They are PTC elements, available in a variety of outputs and crucially, can be switched directly across mains voltage and self-regulate their temperature.

They are easy enough to find as the likes of RS Components and Farnell (other suppliers are of course available). So - I ordered a 200W 240V element for about £23. This would provide the perfect solution for my application.

Incidentally - As the Elma cleaning machines themselves are somewhat "vintage" these days, their original spare part heating elements are also likely (if they are not already) to become rare things. Therefore, knowing how to source replacements is useful to know. The Elma spare part comes with the circular metal disk (heating plate), but having a look at how the element fits onto it, looks like it just slides into those two grooves.

Anyway - the solution to my National machine was sourced and the next instalment will cover fabrication and installation.

 

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I forgot to actually show the original heating element. So in the interests of full explanations and detail, here are some photos.

The first shows the heater in the base of the front right corner. It is normally covered by an alloy copy of the glass jars used for cleaning, but with no bottom. (You can see this in an earlier photograph.)

The heater is a circular, pot-ceramic element, typical of its age, and contains a long 'nichrome' wire element to provide the heat. It is simply switched across the mains input to provide whatever it's rated output was. (I have not been able to find this out, but guessed when looking at this machine's descendants, for it to be around 150W to 250W heat output.)

There was a simple protective mica disk over the element, once again something of a give-away as to the age of this design, and also again, not particularly safe, as the Mylar is quite flexible and it would be easy enough to lift up at the side of the disk and touch the element whilst at mains potential.

After disassembly. you can see the channel where the heating wire fits. As can also be seen, is the reason for the auction listing describing the heater as non-functioning. The coil was broken in many places and sections were missing.

Replacing this to get the National Electric Watch Machine's drying capability back in action, was seen as essential during my restoration/repair/refurbishment of this fine antique! (Slightly tongue in cheek there... :P)

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Some more of the "before" photos.

Rear facing shot.

Motor rating plate.

Swing-arm and clamp. Very old fabric sheathing on the twin-flex wires to the motor.

Rheostat housing and motor speed controller.

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Interesting, I may look at using a PTC heater on my 3D printer bed. I suspect that since it is a purely resistive load, it should be possible to use one of the inexpensive triac motor controllers and a few resistors and a NTC thermistor to give rudimentary maximum temperature control.  

Something like this.

https://www.ebay.co.uk/itm/NEW-200W-AC-DC-220V-77x62x6mm-PTC-Thermostat-Aluminum-Heating-Ceramic-Heater/262875357015?epid=892675962&hash=item3d34979f57:g:PhUAAOSwwVBbeDLn

... and this ...

https://www.ebay.co.uk/itm/Mini-DC-5A-Motor-PWM-Speed-Controller-3V-35V-Speed-Control-Switch-LED-Dimmer-A/254124806948?hash=item3b2b04d324:g:BLoAAOSwSYRbnMMT

 

...  controlled by a conventional relay by the 3D printer controller. I suspect it would heat a lot quicker and provide more even heat than the ubiquitous aluminium PCB types. 

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Last two pictures for now.

The cleaning baskets are what you expect from this machine and have been seen before on the forums. I was intrigued by these, as in most of the threads, it is said that they measured around 80mm or thereabouts, and that two of the current Elma parts dividers would fit inside the National's outer basket. This sounded like a good idea and I very nearly sourced a couple when I got the machine. I'm glad I didn't!

When I got it home, I measured it to make sure all was as I was expecting - but it was not. The overall diameter of these baskets is 64mm - the same as the Elma, therefore the Elma dividers could not fit inside the National Basket as it's internal diameter is only around 55mm.

SO - as others have posted, their models did indeed come with 80mm fittings, as evidenced by dimensioned photographs. It is also true that mine came with a 64mm fitting. SO, a little more digging may be needed to see what was fitted as standard.

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8 minutes ago, AndyHull said:

Interesting, I may look at using a PTC heater on my 3D printer bed. I suspect that since it is a purely resistive load, it should be possible to use one of the inexpensive triac motor controllers and a few resistors and a NTC thermistor to give rudimentary maximum temperature control.  

Something like this.

https://www.ebay.co.uk/itm/NEW-200W-AC-DC-220V-77x62x6mm-PTC-Thermostat-Aluminum-Heating-Ceramic-Heater/262875357015?epid=892675962&hash=item3d34979f57:g:PhUAAOSwwVBbeDLn

... and this ...

https://www.ebay.co.uk/itm/Mini-DC-5A-Motor-PWM-Speed-Controller-3V-35V-Speed-Control-Switch-LED-Dimmer-A/254124806948?hash=item3b2b04d324:g:BLoAAOSwSYRbnMMT

 

...  controlled by a conventional relay by the 3D printer controller. I suspect it would heat a lot quicker and provide more even heat than the ubiquitous aluminium PCB types. 

Are you sure? That linked PTC is rated for 220V AC or DC, but your controller is only rated to provide 3V to 35 DC output. My guess is, it's nowhere near the PTC's operating voltage.

That PTC element is designed for a 220V input. You either need a PTC with a lower voltage DC input, or a controller with a higher rated output.

This is the one I will likely use. its a PWM AC Motor speed controller. adjustable from 50v to 220v output and 2kW max. (Although I personally would take with a pinch of salt the 2kW rated output. Mind you, I only need less than 800 Watts or so anyway.)

 

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Well spotted. I included the wrong link. Something 220V AC rated, more like this perhaps (although I don't think I would try to crank the stated maximum 25A out of them) ->

https://www.ebay.co.uk/itm/2000W-AC-Motor-Speed-Control-Controller-Adjustable-Voltage-Regulator-50-220V-YJ/382850170457?epid=3020717857&hash=item5923a5fe59:g:gKQAAOSwAuZbN2gD
 

I already have a couple of similar ones "in stock" as it were, i.e. lying around in one of my component bins.

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Yes - I know what you mean about posting the wrong links... I won't go into a time when I posted the wrong link to something... Oops. :ph34r:

I think that one is the same as the one I am likely to use. And I agree about the power rating looking, well,  let's just say "optimistic" and leave it that. I think for the National Watch Cleaning Motor, I'm unlikely to need more than 100 watts of motor power anyway, so that would be more than adequate.

Thanks for the comments so far.

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I haven't pulled the trigger on a watch cleaning machine, yet, but if/when I do, I suspect I would go for something vintage, 'cos half the fun for me, is in restoring it.

I've still to bring home a colour laser printer I picked up on ebay, which is currently in my office, and which is no doubt larger than my wife expects, so I may need to wait for a suitable diplomatic cooling off period before I introduce any more junk useful items in to the mix.

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With the PTC Heating Element arrived, it was time for some metal bashing. 

Actually, it briefly got a bit more "high tech" that that. I needed to try and replicate the Elma Heater, based upon what the Elma spare part heater looks like from catalogue pictures. A quick estimation on my part seemed to indicate a mounting plate size of around 90mm diameter (the element being 75mm on it's long side). Where to sort it from? 

A quick conversation with an old work-mate turned up the opportunity for a catch-up and a bit of "metal bashing" for the cost of a light lunch.

A bit of mild steel around 1.5mm think was run through his laser/plasma cutter in no time and I had my mounting plate. Once back home, it was drilled to attach the heating element. So that job done, now to mount it in the machine.

In my opinion, it's not a bad replication of the original Elma spare part and I cannot imagine that it would be any less efficient.

SO - if you cannot get hold of the Elma Heating element, all you need is a relatively cheap PTC Heating element, and a good mate with around £35,000's worth of plasma cutter!

 

 

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Next up - mounting the heating element.

You might have noticed that the mounting holes (for the element into the machine), in my disk were not the same as for the Elma. Well, one look at the casting for the National Machine's base will explain that.

The whole base is a quite substantial, one-piece alloy casting. It must have been a sod to produce back in the days before computer aided design.

The original ceramic heating element, was secured by a single screwed bolt through it's centre, with an asbestos/ceramic tile between it and the metalwork on it's underside. Mine would have to attach by either two of three mounting points around its circumference. The pictures explain all.

A couple of drill holes later and I was done. The one thing I did not have to hand was some spacers to raise the heater away from the metal web of the base. I made do with an extra couple of nuts to provide the correct spacing, till I get some proper spacers. (He said - knowing full well, it will likely stay like that forever now...).

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With the element in place, it looks (almost) like it was designed that way. Well - a reasonable approximation at least.

I have used some fibre washers on the underside of the mounting points and under the securing bolts, in order to try to minimise heat conduction that would be present, if there were a metal to metal contact on the attachment points.

I also re-used the small, asbestos tile (about 25mm square) on the underside, which stabilises the off-centre mounted plate and sits between the PTC element and the web of the base. I have no qualms about re-using the asbestos tile, as it was in perfect condition, without any degradation. I may well choose to replace it, if I locate something else more suitable. But for now, it's not a priority.

The refurbished heater switch has also been remounted and can also be seen in this photograph. I could have replaced it with a more modern toggle switch, but to be honest, this one was in very good condition and after cleaning, performs flawlessly. It helps to preserve some of the originality of the cleaning machine.

 

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And the last one for today.

Now with the "drying chamber" in place, you can see the heating element nicely positioned at the base, and ready to perform drying duties.

Next - to cork, or not to cork... that is the question.

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Quote

Next - to cork, or not to cork... that is the question.

For that full authentic look,  I would cork...

https://www.ebay.co.uk/itm/Natural-Cork-Dining-Table-Placemats-Coaster-Trivet-Drinks-Mats-Surface-Protector/292834814624?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20170907081254%26meid%3Dc263661ca14641aa940435dac72c1951%26pid%3D100281%26rk%3D2%26rkt%3D12%26%26itm%3D292834814624&_trksid=p2045573.c100281.m3567

.. however plastic (a nylon cutting board, cut to size maybe), as that might be less inclined to get stained, would be my second choice.

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Good choice of options. I have a sneaking suspicion I may have a sheet of cork somewhere... I seem to remember it was about A4 sized and about 3mm thick. If I can remember what I bought if for originally, I may have a fighting chance of remembering where it was put...

:huh:

I also have some chemically resistant rubber somewhere as well... I know, I have some junk lying about the place!

It was used to line storage tanks and was chemicals and petroleums proof and also about 2mm to 3mm thick. I'm sure I have some offcuts somewhere in the shed. It would be ideal for seals in the jar lids.

I'm off for a rummage!

B)

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I have been doing a little research into these fine old machines and found some useful background.

The National brand was used by the company S.Lanzetter of Manchester. That much can be found out easily by simply reading the information on the makers’s plate. It seems that S.Lanzetter was one of the key members of the Jewish watch making and jewellers community in Manchester from around the turn of the 19th century. At the time, they were a very well known watchmaker’s materials and machinery supplier, and also responsible in their own right for patenting some key items. Such as this particular style of watch cleaning machine ( and other variants) from around 1945, electric soldering machines, and watch crystal cutting/grinding machines.

i managed to find a reference to a National Watch Cleaning machine that is retained in the UK’s History of Science Museum. I have included their extract for the item below. It describes the typical layout and functionality of this type of machine perfectly and mentions a spare rheostat, that seems to have been supplied with the exhibit.

I would be interested to know which company copied what, as the original Elma machines were pretty much identical, and it gets me thinking if the National, as well as later National designs, pre-dated them all? Who knows...

What I have further identified were other versions of what the manufacturer refers to as their “Model 1”. I have seen what appears to be later versions of model one that have an additional switch, which I presume isolates the rheostat and thus provides a proper off switch, rather than just relying on the rheostat being set to minimum (as mine is).

A further version of the model 1 additionally has a small indicator lamp on the rheostat housing, indicating if the heater is switched on. Again, mine does not have that. This leads me to assume that my model 1 is one of the early versions, which perhaps dates it to between 1945 to 1950. As this makes my machine likely to be around 60 to 70 years old - I feel like I am restoring something quite special, even though it is quite an ordinary machine.

I have also found an old advert for the National brand(as applied at the time) which may be an example of the advertising copy, as referred to in the science museum entry. This is really “of its time” and a delightful reminder of the whimsical advertising style, typical of the 1940’s and 50’s.

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This advert also caught my eye, for a couple of reasons.

Firstly, as it refers to 4 models of National Watch Cleaning Machine. I have now got photos of all four types and the similarities to any other machine I have seen (Elma etc.) are striking. Again leading me to muse over which came first.

The second point is in the detail. In the listing for the Model 2 and 3, they refer to both watch and clock baskets being supplied. This makes me wonder about previous posts on these forums, where others have said that their National Machines, had 80mm baskets, whilst the one I have, comes with a 65mm basket. I just wonder if the 80mm basket is therefore a clock basket and larger to accommodate the larger parts? It would seem to make sense, as whichever size of basket is used, the width of the jars supplied has to be suitable ( I.e. large enough), to accommodate the larger and smaller baskets. Certainly the jars on mine would easily be large enough to allow use of an 80mm basket.

Also, contemporary watch cleaning machines (Elma Super Elite, etc.) also seem to use 65mm  cleaning baskets, but their glass jars are all very much smaller than the early Nationals, and would likely not accommodate an 80mm basket size. I just wonder if the industry as a whole, just started concentrating on automated watch cleaning, and just let the clock works cleaning side of things lapse.

Makes you think...

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This is an advert for the four different machines, as originally conceived. As well as their own design for a crystal press and dies, and the watch crystal cutting machine.

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And finally, the last one. (Although many more can be found by scouring the Internet.)

this purports to be. Mark VI-C (I think). Now go on, look at it and tell me that this machine is not where Elma got their idea from! I just wonder if either the original patent that National took out on the machine ran out, or, if National allowed others to freely license the basic design? 

 

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A little further research and then on with the show...

A quick browse through patent databases, shows that one Saul Lanzetter applied for and was awarded a patent for this design of watch cleaning machine in October 1937. A brief narrative is reproduced here:

Quote

Apparatus for cleaning watches and other small parts. LANZETTER, S. Oct. 21, 1937, No. 28667. [Class 139] Apparatus for cleaning watch and other small parts in which the parts are placed in a wire mesh basket F mounted on the vertical spindle d of an electric motor D and adapted to be submerged and rotated in a plurality of vessels E in turn, the vessels being of square crosssection, is characterized in that the motor is mounted on a flanged plate c forming the lid of the vessel in use and having two or more depending baffles c<1> which assist turbulence.

Interestingly, the patent application is entitled "Improvements in apparatus for cleaning watch parts and other small parts of machinery."

It may be reading too much onto this title to assume that there may have been a previous patent, pre-dating this one, as this one refers to "improvements".

Also of interest, there were 2 patent applications from US companies in 1944 and 1945 which cite the Lanzetter patent, and three from Germany in 1956, 1960 and 1961 (only one of which was actually published), which also cite the Lanzetter patent as a reference.

Incidentally - the two US patents refer to machines which look strikingly similar to the National Model VI-C above, and the National No 4. machine in the earlier advert, showing the four jars side by side ( this seems to be referred to as a lab machine, rather than a repair shop machine).

Naturally, all patents or applications referred to above are now expired.

For me anyway, I think this may clear up which watch cleaning machine may have come first (at least in this machine format anyway): The S. Lanzetter National Electric Watch Cleaning Machine, circa 1937.

 

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Back to the job in hand.

I managed to find the cork I thought I may have had, lurking in a box under the stairs. It was the most part of an A4 sized sheet, so more than enough for my purposes - to sit the jars on whilst they are in the machine.

Looking at the metal bases, I really can't be convinced if there ever was any cork or any other material for that matter there. But for me anyway, the idea of the glass jars sitting directly on the metal base just seems wrong and I would prefer some cork there as a cushion.

It's about as tidy as it needs to be, given the shape of the metal webbing. I suppose I could have cut-out squares of cork, but then it would leave potential weak, unsupported areas of cork, which would likely need some form of strengthening.

Anyway - this application suits me and helps the jars sit a bit more stable in their locations.

Whilst I am in the vicinity, so to speak, I have also added an earth lead which will bond the chassis to the incoming mains lead, once fitted. This is visible in these photos.

 

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Next up is the motor speed control.

I did think long and hard about my original aim of maintaining as much originality as possible. And, there is no doubt that the original speed control rheostat was a) original and b) functional. But - as I was an electronics technician in an earlier life, and also health and safety professional in a more recent life, the safety aspects weighed heavily upon my concience.

Logic played it's part as well - with the original rheostat put back into service, albeit with some hand-made guarding to keep out the fingers of the unwary, it would be safe-ish, for me to use, as long as I kept my wits about me.

BUT NOT SAFE FOR ANYONE ELSE unaware of what was underneath.

Only the knowledge of what lurked underneath would be keeping me safe, but anyone else might not have a second chance.

As can be seen from the photo below, all of the wire on the resistors is not only unguarded, but within millimetres of the level of the base. Also, the incoming mains terminals to the rheostat are also dangerously unguarded.

With today's knowledge, it is difficult to fathom how this ever could have been considered safe to use.

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I certainly did not want to replace the motor, as this is so very visible, all attempts at maintaining the illusion of originality would fail. A solution to the problem could only be achieved with a safer, replacement speed control, which could work with the original mains voltage motor.

Fortunately, these are readily available in the form of a Pulse Width Modulated (PWM), motor speed controller circuit. These will take in the 220V incoming mains supply and provide a variable output of between 50V and the incoming supply voltage. These are well known devices and proven to work with even simple (old) motors.

So, a PWM circuit was obtained (at incredibly reasonable cost), and measured up.

In an attempt to at least have the "illusion" of originality, I was determined to use the original hole for the rotary speed control, as well as the original Bakelite control knob. With the shaft on the rotary potentiometer too short for this, I had to do some more metal bashing.

As can be seen below, I used the old rheostat as a donor, for a short length of it's shaft, which I would mate to the new potentiometer, allowing the Bakelite knob to operate. This was cut to shape and filed to mate with the new potentiometer shaft. This was then soldered together and thus ready for installation.

You can see in the photo, the size and technical comparison between the old rheostat and the new PWM controller circuit.

 

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