rjs

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  1. rjs

    Burners 101

    Not necessarily, in a motor that can be reconfigured to run on 230 volts the field windings that were connected in parallel are reconfigured in series so a 115 volt motor that drew 15 amps and was splitting it between the two parallel winding inside (7.5 amps each) when reconfigured for 230 volts now drives the same 7.5 amps through both windings which are now in series. W = V * A W = V * V / R W = I * I * R In English: Watts equals current times voltage Watts equals Voltage squared divided by resistance Watts equals current squared times resistance Heating would be caused by the inefficiency of the motor (resistance in the motor windings, eddy currents in the laminations etc.) As long as it doesn't reach overheating temperatures minor inefficiencies in a hand tool are of no importance since they are almost always turned off, however overheating can let the magic smoke leak out. When a motor of a given horsepower is rewound or reconfigured to run on 230 vs 115 the current will be halved but the reduced current will be going through twice as much length of wire. A perfect motor would have no resistive component to its impedance, no friction in its bearings, and would not heat up at all (good luck finding one of those.) Bob
  2. rjs

    Burners 101

    "What makes this 280-watt tool so surprisingly strong is that it runs from 220V, instead of the much weaker 110V circuits:" Electrical power is measured in watts: volts times amps equals watts double the voltage at half the amps equals the same watts. Much of Europe runs on 220-240 volt wall power. Doubtless that unit was manufactured for that market. People who live where wall power is 120 volts would be well advised to stick to 120 volt angle grinders most of which are rated at 400-700 watts. Bob
  3. rjs

    Burners 101

    Mclendons? They were great back in the day. Bob
  4. rjs

    Burners 101

    So my mother used to teach school in the mid west back during the depression and had the following students; Heck, Gee, Gosh, Golly, and a girl named Ima Cow What were those parents thinking? Bob
  5. rjs

    Burners 101

    Yeah, I wish I had had that chart back in the middle 1990s, I still remember destroying a brand new 1/4-28 tap trying to tap a piece of hot rolled steel with a pilot hole diameter of .206 inches. & no I do not remember where I got that .206 from perhaps it was printed on the tap? The vendor honored the guarantee but he was grumpy about it. Regards, Bob
  6. rjs

    Burners 101

    the listing you quoted is for a bottoming tap. Those things are hard to start without going in first with a tap with a tapered lead in like this one . http://www.ebay.com/itm/HSS-Right-Hand-Tap-1-4-27UNS-Taps-Threading-1-4-27UNS-High-quality-1pcs/152391238235?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D41375%26meid%3Db18bd6e275114845b583bd79088c8598%26pid%3D100005%26rk%3D2%26rkt%3D6%26mehot%3Dlo%26sd%3D301840549163 Bob (who, in the past, has been shipped the wrong tap even when he ordered the correct one)
  7. rjs

    Burners 101

    concerning 1/4 x 27 tpi taps: https://www.amazon.com/HSS-Right-Hand-Thread-Tap/dp/B008AT64P8 about $18.50 with the shipping and it says it is high speed steel Bob
  8. I searched for gasoline explosions and got one hit which I described in my previous post. A search for gasoline fires turned up no hits although from personal knowledge I know of two both happened a long time ago and both involved the destruction of a vehicle. Ono of those was probably arson, the other may have been caused by an accident. (car was in the middle of the road on fire.) I have driven my share of flaky old beaters over the years and never had an incident. A search for garage fires got some hits, remarkably few considering the abundance of gasoline powered vehicles around. As long as I am beating the safety drum I have another point to make: refillable Propane tanks should always be transported and stored in the upright position. If one is on its side and the over pressure valve vents it will vent liquid propane and you will get a much bigger surprise.
  9. No argument about that but I does give a bit of warning, gradually increasing odor etc. When the over pressure valve on a propane tank pops you get exactly zero warning. You go from no problem to a possible face full of fire faster than you can say "[email protected]#$". I did a web search on Kitsap and propane explosion and found not only the one I referred to earlier but two others as well. A similar search only for gasoline explosion only turned up one and it involved drunken sailors and a camp fire so no surprise there. Of course as the saying goes "YMMV" Bob
  10. No I have never done that. (never had enough room in the garage.) But I do not see what that has to do with anything. Sad to say I did not. I was opening up a new piece of property then as well as working full time and I had bigger fish to fry. What I did do was watch like a hawk whenever my tanks were being filled after that and (substantially later in life) made the decision not to store (in use or not) propane tanks in enclosed spaces. Not sure what happened but Kitsap county had a couple of people killed this year from a propane explosion. The house was destroyed and the noise was heard by people a long way away. Bob
  11. R.E. propane tanks inside: Back in the late 70's a propane dealer over filled the tanks for my travel trailer. The next day (warm and sunny) I was outside and heard a loud "pop"from the direction of the trailer front. I looked and saw a brief cloud of vapour at the tanks. I kept my eye on it and it happened several more times before it stabilized. No harm done but I sure would not have cared to have that happen inside my shop with a lit forge sitting there.Those tanks, in use or not, belong in a well vented outdoor space. Bob
  12. One place to get it is at the auto parts store, Look at the labels on the various snake oil radiator stop leak products, read the fine print and you will find it. Bob
  13. rjs

    Burners 101

    Thanks you inspired me to do some more reading. Again from the dreaded wiki (https://en.wikipedia.org/wiki/Adiabatic_flame_temperature ) I fond the following: "In the study of combustion, there are two types of adiabatic flame temperature depending on how the process is completed, constant volume and constant pressure, describing the temperature the combustion products theoretically reach if no energy is lost to the outside environment." So either the they contradict themselves or the value I quoted earlier was not a constant pressure value. In any case lets go with 4532 F for this discussion. the point I was trying to make was the theoretical value for acetylene Is over 900 f higher than the value for propane. BTW any time I see a completely round number like 2500 C given I am suspicious that it may have been rounded off. But In the end the stuff is just too expensive to use for general blacksmithing (at least where I live) and I am sure it would quickly destroy any refractory we pointed it at. So if we were to build the torch that Mikey spoke of (high velocity air acetylene) it is safe to assume the the resultant temperature would be lower than 4532 F bob
  14. rjs

    Burners 101

    wiki gives 4593 F for acetylene in air