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  • ed_h's Avatar
    06-23-2017, 08:03 PM
    They are hawking a TV antenna. The pitch is made up of grains of truth or half truths with a lot of spin, but I saw nothing revolutionary or even...
    10 replies | 501 view(s)
  • ed_h's Avatar
    06-23-2017, 12:53 PM
    You're overthinking it. 341 g NaOH/3790 mL H20 = about 9% solution (w/w) Dan is certainly right about the hydration of the lye, and you could...
    25 replies | 724 view(s)
  • ed_h's Avatar
    06-23-2017, 12:38 PM
    The "outgassing" of acid is related to hydrochloric (muriatic), not sulfuric. Stored or properly charged lead acid batteries shouldn't pose much of...
    15 replies | 535 view(s)
  • ed_h's Avatar
    06-14-2017, 10:31 AM
    ed_h replied to a thread mass vs heat storage ability in General
    While the "planetary model" of the atom with its electrons in orbits around the nucleus may still be a useful picture for some things, it's pretty...
    18 replies | 977 view(s)
  • ed_h's Avatar
    06-10-2017, 08:46 PM
    Watch it to the end: https://www.youtube.com/watch?v=mTTuiE1_Oe8 Ed
    38 replies | 1689 view(s)
  • ed_h's Avatar
    06-07-2017, 02:51 AM
    ed_h replied to a thread OT: Copper corbels in General
    I've seen the word corbel quite a bit in a building context, often connected with stone or masonry work. You can buy modular corbel concrete blocks....
    35 replies | 2351 view(s)
  • ed_h's Avatar
    05-14-2017, 11:11 AM
    ed_h replied to a thread LED bulb resistor?? in General
    At zero length, material or temp wouldnt matter. Fabrication issues issues might be tricky, though. Ed
    35 replies | 2499 view(s)
  • ed_h's Avatar
    05-13-2017, 09:22 PM
    ed_h replied to a thread Electrical question in General
    True, but the fact that the OP explicitly called out 240 vac suggested to me that he was in the US or some other place where "normal" mains voltage...
    10 replies | 1058 view(s)
  • ed_h's Avatar
    05-13-2017, 10:43 AM
    ed_h replied to a thread Electrical question in General
    Far superior to what you have now. In fact, switching just one side of a 240 v supply is a really bad idea. Ed
    10 replies | 1058 view(s)
  • ed_h's Avatar
    05-13-2017, 10:37 AM
    ed_h replied to a thread LED bulb resistor?? in General
    You really need the LED specs to say for sure, but a 1K resistor should give you around 12 mA peak current, which should be fairly safe. You could...
    35 replies | 2499 view(s)
  • ed_h's Avatar
    05-12-2017, 12:59 AM
    I had a '74 Triumph TR6 that sat in my garage for over 30 years. Needless to say, the fuel tank spent most of that time empty. Yet when I removed...
    22 replies | 1915 view(s)
  • ed_h's Avatar
    05-09-2017, 03:22 PM
    The bushing you describe sounds like so-called "Super Oilite". It's a ferrous based, sintered, oil impregnated material. It actually has specs...
    15 replies | 1670 view(s)
  • ed_h's Avatar
    04-25-2017, 11:34 PM
    ed_h replied to a thread OT: Wood board load limit in General
    Yup, overbuilding a little is a good idea if you can. I built the house I live in, and some other assorted smaller structures on the property. ...
    14 replies | 1386 view(s)
  • ed_h's Avatar
    04-25-2017, 09:04 PM
    ed_h replied to a thread OT: Wood board load limit in General
    The 1/3 rule works well for 2 x 4, marginally for 2 x 6, and not very well for larger sizes. The strength of a beam is proportional to the width...
    14 replies | 1386 view(s)
  • ed_h's Avatar
    04-25-2017, 07:03 PM
    Mill scale is a complex of iron oxides not so different from rust. I find that rust removers work similarly for scale. Ed
    30 replies | 2433 view(s)
  • ed_h's Avatar
    04-25-2017, 04:26 PM
    ed_h replied to a thread OT: Wood board load limit in General
    I use this formula for thumbnail calculations: Max Load = (fiber stress x width x depth^2)/(9 x length) width & depth in inches, length in feet...
    14 replies | 1386 view(s)
  • ed_h's Avatar
    04-25-2017, 04:19 PM
    HCl is a gas and hydrochloric or muriatic acids are just HCl dissolved in water. This is what's behind muriatic acid's reputation for being able to...
    30 replies | 2433 view(s)
  • ed_h's Avatar
    04-02-2017, 11:43 AM
    ed_h replied to a thread The only way is up in General
    Good catch, Bob. I should have worded that a little better. Glad she doesn't follow this board. Ed
    21 replies | 2449 view(s)
  • ed_h's Avatar
    04-01-2017, 08:40 PM
    ed_h replied to a thread The only way is up in General
    Ha! Tell me about it! http://bullfire.net/Mill/Milling%20Machine.html I consider a basement shop ideal in many ways. My wife, not so much. ...
    21 replies | 2449 view(s)
  • ed_h's Avatar
    04-01-2017, 11:42 AM
    ed_h replied to a thread OT: Cool Mind Bender Video in General
    I believe thats a 2-D Hilbert curve. It's a 1-D curve that can fill a 2-D plane. I've not seen it generated that way. Thanks. Ed
    2 replies | 443 view(s)
  • ed_h's Avatar
    03-30-2017, 08:52 PM
    ed_h replied to a thread Electrolysis, and cast iron. in General
    My experience with ER would not support the claim of 1/2 pound of rust. It works and works well, but for me it seems to wear out fairly quickly. ...
    71 replies | 5573 view(s)
  • ed_h's Avatar
    03-30-2017, 06:45 PM
    ed_h replied to a thread Electrolysis, and cast iron. in General
    4) ER is also a good approach if you need to preserve zinc or other plating on a part. Most other methods will attack it. 8) I think Molasses may...
    71 replies | 5573 view(s)
  • ed_h's Avatar
    03-30-2017, 04:16 PM
    ed_h replied to a thread Electrolysis, and cast iron. in General
    I wonder if what some think is flash rust after a phosphoric acid treatment is really just some iron phosphate left after drying, which can present...
    71 replies | 5573 view(s)
  • ed_h's Avatar
    03-30-2017, 03:50 PM
    ed_h replied to a thread Lithium battery question in General
    You certainly could be right about what's used in power tools--I haven't taken any apart. I was just pointing out that the general heading "lithium...
    19 replies | 1419 view(s)
  • ed_h's Avatar
    03-30-2017, 12:42 PM
    ed_h replied to a thread Lithium battery question in General
    All lithium cell technologies I'm aware of require charge (and, ideally, discharge) monitoring at the cell level. Given that, lithium iron phosphate...
    19 replies | 1419 view(s)
  • ed_h's Avatar
    03-30-2017, 11:21 AM
    ed_h replied to a thread Electrolysis, and cast iron. in General
    I think this may have been mentioned before, but the black smut is probably one or more of the following: magnetite, a reduced form of iron oxide,...
    71 replies | 5573 view(s)
  • ed_h's Avatar
    03-30-2017, 11:05 AM
    ed_h replied to a thread Lithium battery question in General
    Some variants of lithium cell chemistry are much safer. E.g. lithium iron. A little less energy density, though. Ed
    19 replies | 1419 view(s)
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