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AndyHull

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Everything posted by AndyHull

  1. I picked up a couple of accessories for the microscopes. This was another bargain bin item from ebay. I'm pretty sure they are Russian (Lomo) and originally part of a larger set. The x8/23 is very sharp and clear and has a built in measuring graticule. The small plastic container has a second graticule, this one is a 15x15 square grid. This grid alone is worth twice what I paid for the whole lot, and the x8/23 goes for more than three times what I paid for everything. Second hand optical items are always a bit of a gamble, but these were all reasonably clea
  2. You could easily hide a small LED driver in the case. They are tiny, and would not look out of place in this Heath Robinson contraption. You could even hide it in its own Mechano or wooden box. https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=led+driver&_sacat=0&LH_TitleDesc=0&_sop=15&_osacat=0&_odkw=3v+transformer I assume the clock has some switched contacts, so you could use those to switch the low voltage output to drive a suitable LED bulb.
  3. Very nice. Notice that the mechanism looks very similar to the design of the Metamec, including an almost identical low friction bushing on the rotor. The coil is even larger, presumably using slightly coarser gauge wire, and is therefore probably even less efficient. The motor in these probably consumes something of the order of 2 to 10 watts, most of which is lost as heat. While this is not a hug amount in the grand scheme of things, it is many orders of magnitude greater than a quartz mechanism or even a transistorised coil oscillator one. Because the coils run warm, and because
  4. This Metamec design does look like something from the 1930s in the sense that it does not self start. I have heard that Metamec used designs and mechanisms from Smiths, so this may be based on one of their designs, and therefore may not have been cutting edge technology for the time. Most later designs use shaded pole synchronous motors, and typically only run in one direction, these older designs can be spun backwards which obviously leads to the hands tuning the wrong way (travelling backwards in time is always hazardous ). The modern designs also typically don't operate the motor c
  5. The earliest mine could be is around 1947, since that was when Metamec was founded, but it is more likely that it is from the early 1950s. I'd love to see a few pictures of the 1930s models. Who made them and do they work? Electric clocks have been around a lot longer even than the 1930s, but the first synchronous mains clocks date from around then. https://en.wikipedia.org/wiki/Electric_clock Many years ago (back in the early eighties) an Engineering firm customer of ours in Glasgow was closing down, and moving out of an old Victorian building. Bolted to the wall in their ha
  6. If any body is interested in monitoring the grid frequency to get an idea of how accurate (over the long term) these synchronous clocks are, you can watch the deviation in real time and view graphs of long term accuracy here. https://gridwatch.co.uk/frequency?old= Currently (pun intended) we are looking at an average of around ten parts per million, which compares pretty favourably with a typical watch quartz crystal figure of around six parts per million. Not bad for a piece of mass produced 1950s technology, although you have to bear in mind that in the 1950s the grid fre
  7. With just one coat of shellac, its still looking a little patchy and a shade or two too light, but the general colour isn't bad. I'll let this finish set up, and apply a few more coats tomorrow and see if it blends down to something close enough to the original for me to call it finished. If not, then I'll sand it down some and push the base colour a little darker. The good thing about the colour is its pretty dark, so it should be relatively easy to match. Pushing things a little darker is always a lot easier than trying to go the other way.
  8. It could be quite a hazardous occupation, not just because of the remoteness and the weather, but in the case of a lot of early light houses, mercury was present in relatively large quantities. The huge glass lenses were floated on circular trough of mercury to allow it to rotate on a frictionless mercury bearing. Bear in mind that the lens might weigh something of the order of a couple of tons. One of the lighthouse keepers tasks was to ensure that the mercury was free from contaminants, so periodically some of the mercury would be decanted off and strained through a cloth filter to remove th
  9. I little bit head scratching and a lot of whittling and fettling today, followed by a lot of sanding and no doubt a lot more head scratching when I try to match the colour and the look of the grain. I was initially going to attack a piece of wood with a router bit, but the shape is a lot more organic than I could muster with any of the bits I had, so I decided to drill a hole and chip the rest away with a mitre saw and a fret saw. I've wisely decided to perform this operation in the log shed, as it is producing a lot of sawdust. Some from the block but probably just as much from the
  10. If you are really in to light houses, you also have the option of staying at one (once the covid restrictions are lifted of course). "Rua Reidh Lighthouse, near Gairloch in Wester Ross, stands at the entrance to Loch Ewe, at one of the most dramatic and remote locations on the north-west coast of Scotland, with breath-taking views across the Minch to the Isle of Skye, the Shiant Isles and the Outer Hebrides" .. or of course there is the Scottish Museum of Lighthouses.
  11. I resisted the urge to bid on this item, tempting though it is, I don't have the room for it. Can any of you tell what it is? If you are interested, it has been re-listed. https://www.ebay.co.uk/itm/174606630912?ViewItem=&item=174606630912
  12. Buttoned back up and ticking away nicely. I wonder how many of these are still running? Some Metamec history.
  13. The coil from @JohnD arrived in the post and set about modifying the metalwork to allow it to squeeze in place of the original. An hour or so of careful filing and Dremel work and it now fits like a glove. I also took care to ensure that the new wiring is double insulated with a few patches of Kapton tape, a nylon bushing to replace one of the original brass nuts and some heat shrink sleeving ensuring that there is little chance of this ancient synchronous motor giving anyone a shock, even if the thing is dropped or the wires are pulled. I can't remember where I got the strange dayglo green
  14. Petroleoum ether is sold on Ebay, so not difficult to get. Indeed, however not everybody lives in a country where ebay or Amazon operates, or where suppliers will ship to, or at least ship to at a realistic price, so for those readers, you may need to substitute one of the above suggestions.
  15. Indeed, however if you can't get hold of "petroleum ether" lighter fluid is a reasonable substitute. If you are doing things professionally I would stick to quality products, but for the hobbyist, lighter fluid works. You could also use "white gas" Coleman stove fuel or similar. https://en.wikipedia.org/wiki/Petroleum_ether https://en.wikipedia.org/wiki/Naphtha
  16. I'm tempted too, since I've nothing to loose. Let me sleep on it, I still haven't entirely given up on the idea of unwinding and re-winding the existing coil. I suspect that wont work, but I'll look at it tomorrow. Would there be any possibility of filing some notches in the coil you have, or is there not enough "spare" plastic?
  17. Hi Andy, overall length of the plastic former is 29.89mm, width 18mm x 19.6mm, with 17.5mm x 20mm over the thickest part of the coil windings. The rectangular slot through the former is nominally 8mm x 6.5mm Nope. Just too tight. The maximum that you could squeeze in is 28.34mm without filing the plates Close, but no cigar. The other dimensions would not be a problem, but unless I could loose 1.5mm over the length, then it wouldn't work. Here are a couple of additional pictures, showing the rest of the mech. and the coil gap.
  18. Let me check if that might just squeeze in to the space.
  19. What are the dimensions of the ones you have? If the iron core would fit through the hole, and the coil would squeeze between the ends of the plate, it might just work. 6.1K sounds about right, I was going to guess about 10K Ohms as coils on similar items (washing machine solenoid valves for example) draw about 24ma consuming about 5W roughly, which means the coil DC resistance is probably of the order of 10K. I might explore using one of these, if I have a scrap one lying about, either as is, or winding its turns on to the metamec former.
  20. A good question. It looks like trouble. I pulled the coil out and unpeeled the top layer to see whether I could simply resolder the feed wires to the coil, but as you can see, despite my best efforts this was not successful. Initially I was hopeful, as the original feed wire had broken from the tab due to corrosion caused by the ancient rubber insulation decomposing and absorbing moisture. The problem is though, that this corrosion may also have affected the inaccessible inner feed wire. It appears therefore that the break lies either on the bottom attachment (which would necessitat
  21. Metamec becomes radio active. The electric mechanism on the second Metamec has a blown coil, so while I figure out if I am willing to try stripping the motor down and repairing the coil (unlikely, but I may give it a bash), I thought I'd see if I had any quartz mechanism in case I need a plan B. After much rummaging through spares and a quick trawl through the junk in the attic I found what I was looking for. An "Atomic" (Radio controlled) quartz module with the correct reach to fit in place of the old workings. I fitted the radio quartz module to a piece of clear plastic
  22. Reading about the Timex Hopalong Cassidy watch, sent me down a rabbit hole via Kelton watches, the French Timex arm to these articles, which you may find interesting. https://translate.google.com/translate?sl=fr&tl=en&u=https://fr.wikipedia.org/wiki/Histoire_de_l%27horlogerie_%C3%A0_Besan%C3%A7on https://nhujzchxszmfjwodqweptl7jha--fr-m-wikipedia-org.translate.goog/wiki/Lip https://nhujzchxszmfjwodqweptl7jha--fr-m-wikipedia-org.translate.goog/wiki/Revenu_(métallurgie) https://translate.google.com/translate?sl=fr&tl=en&u=https://fr.wikipedia.org/wiki/Histoire
  23. Are you sure this is the cause? I think if it looses power it is more likely to be the click spring. If this is badly worn, it will release or slip when the power in the mainspring increases. Does it manually wind without slipping? If not, the click is worn.
  24. One other thing to check. It is possible to fit the plate that holds the oscillating weight two different ways. In other words, the plate is not symmetrical. If you screw it on in the wrong position, then the pawls will be in the wrong position and the weight will not work correctly. I have done this a couple of times, however in my case the weight wouldn't turn correctly either when the movement was cased. If the case has more space though, then it might be possible to case the movement and still have the plate on back to front. Also check that the spring for the pawls is correctly fi
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