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Showing content with the highest reputation on 02/06/2019 in all areas

  1. 1 point

    How to control the speed of a lathe

    The V.T. 230 means that it is designed for 230V nominal mains voltage. i.e. you can plug it in to the wall. The H.P most probably relates to electrical horse power (slightly different, but not by much from mechanical HP). If we assume 1/12 HP is in electrical horse power, then we can convert that to Watts. 1/12 HP = 0.083333333 HP That equates to around 65W so that little triac board should easily be able to cope. If on the other hand, it is 1/2 HP, then we get 373 W, which the board should still be able to handle, but might make it run slightly warmer. You can protect the outlet with a 5A fuse in your mains plug, and even in the unlikely event that the board throws a hissy fit, it won't do much more than let out a slightly pathetic puff of smoke, and pop the plug fuse. Actually it will probably trip the breaker in a modern household, since if you so much as sneeze next to a modern household breaker it will trip . Either way, fit a 5A fuse to be on the safe side. One other thing the fuse will do, I suspect is pop if you stall out the motor. Better that than burning out the field coils I would suggest. If you saw in the bigclive video, you can (very carefully with a suitably insulated screwdriver) adjust the minimum speed to avoid the motor "chattering" and overheating if you try to run it too slowly. We can re-visit this when you come to test the thing. Incidentally the fuse wont stop you from getting a shock if you do something stupid (but the breaker might), its purpose is to stop you burning the house down, or blowing up the breaker in the local substation. Electrical horsepower to watts One electrical horsepower is equal to 746 watts: 1 hp(E) = 746 W So the power conversion of horsepower to watts is given by: P(W) = 746 ⋅ P(hp)
  2. 1 point
    I’ve just looked at the tech guide (I’m working on one of these myself at the moment so had it to hand - and I’m assuming that a 2892-2 is the same as 2892A2) and I think you are right, looking at the guide I ‘think’ it should be where I have circled in red... I stand to be corrected though. Sent from my iPad using Tapatalk
  3. 1 point
    for this I highly recommend the consew motors. they are DC servo, so when you set a speed, it stays that speed - more load, it sends it more juice to keep rpms consistent. they're cheap, like $120 US. Its a very simple mod to convert them to speed control via a rheostat if that's your preference (done it, literally takes on rheostat wired in place of the hall sensor). Also, they are powerful. 3/4hp. That doesn't matter much at speed but when you electronically reduce speed (DC or VFD) you won't have much low rpm power unless you start with a lot. (with electronic control power goes down as speed is reduced) Thinking this through, maybe what is best is a rheostat control up top and a foot operated on/off switch? I've got up top speed control and its a pain constantly reaching to turn the motor on/off to check things
  4. 1 point

    2892 Watch cases

    I believe the ST1812 is a clone of the the 2892-A2 ... an 11.5''' movement. Unfortunately getting a case for these seems problematic. You could look out for a second hand complete watch (that uses the 2892-A2, ST1812, or SW300) to use the case from but that would then presumably defeat the purpose of you getting the movement only to work with! There's no reason you can't get a not-necessarily-designed-for-the-2892 case however ... your main lookout is going to be the stem height expected. Perhaps your best bet is to seek out a 2824 case. There are plenty out there and in your 40mm preference. I mention this calibre because there is only a 0.3mm difference in stem height which you may be able to 'get away with'. Otherwise you're looking at needing some kind of dial ring / spacer. The movement holder that may come with the case may also need some adjustment to cope with the thinner 2892-A2 movement.
  5. 1 point

    Should I be worried about radium?

    i studied this quite extensively since i use to have cancer and received radiation treatments, and i work on vintage military watches which always contain radium. Radium can not be absorbed through the skin so touching is not much of a risk as long as you are not licking your fingers or picking your nose after handling a radium dial. but there are two ways to absorb radiation from lume. 1: Ingestion- through this process 80% flushes out from digestion. 20% gets absorbed into the blood and is distributed to organs and eventually will metabolize in the bones like calcium. It will then break down over a period of months in the form of both alpha and beta. 2: Inhalation- 100% absorbed through the lungs then 20% broken down through liver. 80% will metabolize in bone. it will still break down the same way but will take longer because more has been absorbed. so contrary to popular belief radium will not stay in the body forever, therefor limiting how much and how often you are exposed to it will determine if you are at risk. the story of the radium girls. these women who would sharpen their paint brushes laced with radium with their lips to keep the tips sharp for luming watch dials ingest a whole lot of hot radium per day. at least 100-200 dials per day, then they started realizing that it would glow so they thought it would be cool to use it as make up. and not all of these women ended up with cancer. so short answer is a definite NO! do not worry. just use gloves and a mask if you feel like you want to be careful. and DONT lick the dial LOL
  6. 1 point

    Some Of My Watch Lathes

    I honestly don't know how many lathes I have. About 5 years ago it was over 70. Counting Turns and Jacot lathes I am sure the number is well over 100. Some of the real expensive ones such as the larger size Derbyshire and Levin instrument lathes, a double pedestal Boley production Lathe and several more Levin WW (8mm and 10mm) lathes were not in the pictures. I also have two Sincere lathes. One I bought brand new years ago and another I purchased recently that is going to have to be restored. If I have time I will post pictures of these at a later date. I have been collecting these for the past 45 years and have no interest in selling them; at least not for several more years. david
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