Fine wire tensile strengths?
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From: Joe on 31 Jul 2010 01:35 On Fri, 30 Jul 2010 19:01:37 -0700, Ken S. Tucker wrote: > I've been asked to 'light-up' aircraft models, such as, > http://www.flickr.com/photos/35156618(a)N03/4754110575/ > > It is suspended from a rope. > I need to use very fine 120V wire (like magnetic wire), the model uses > 8# test monofilament right now and weighs 1/2 # , but a strong wind > requires that 8# test. Is there a table that gives wire gauge & tensile > strength? The current will likely be a max of 1/2 amp. Ken Resistance and stretch calculators for lots of materials can be found at <http://www.allmeasures.com/Formulae/>. Eg, click the Steel button, submit, choose resistance calculator, put in wire area and length, etc. Or click the Young's Modulus button, put in area, length, and load, then observe Change in Length result. Numbers in the ARRL handbook chart of breaking load for copper antenna wire work out to about 39000 psi for soft drawn copper wire and 65000 psi for hard drawn so perhaps use 2 strands of varnished #24 or #26 copper magnet wire. Those strength numbers are higher than Tim mentioned so run deadweight tests before testing with model. #26 is ok on ampacity. Copperclad steel antenna wire is two or three times as strong but only 40% as conductive. Offhand, 60W of lighting within a model sounds like a lot. Have you considered low-voltage wiring with high-brightness LED's?
From: Nunya on 31 Jul 2010 02:26 On Jul 30, 7:01 pm, "Ken S. Tucker" <dynam...(a)vianet.on.ca> wrote: > I've been asked to 'light-up' aircraft models, such as, > > http://www.flickr.com/photos/35156618(a)N03/4754110575/ > > It is suspended from a rope. > I need to use very fine 120V wire (like magnetic wire), > the model uses 8# test monofilament right now and weighs > 1/2 # , but a strong wind requires that 8# test. > Is there a table that gives wire gauge & tensile strength? > The current will likely be a max of 1/2 amp. > Ken The problem with all these replies is that he wants to pass 120V over a "fine wire". That will not get one much past about twenty feet before the line drop starts to show a huge drop. At least that is the idea I got. Otherwise why mention 120 V at all?
From: Grant on 31 Jul 2010 02:48 On Fri, 30 Jul 2010 23:26:44 -0700 (PDT), Nunya <jack_shephard(a)cox.net> wrote: >On Jul 30, 7:01 pm, "Ken S. Tucker" <dynam...(a)vianet.on.ca> wrote: >> I've been asked to 'light-up' aircraft models, such as, >> >> http://www.flickr.com/photos/35156618(a)N03/4754110575/ >> >> It is suspended from a rope. >> I need to use very fine 120V wire (like magnetic wire), >> the model uses 8# test monofilament right now and weighs >> 1/2 # , but a strong wind requires that 8# test. >> Is there a table that gives wire gauge & tensile strength? >> The current will likely be a max of 1/2 amp. >> Ken > > The problem with all these replies is that he wants to >pass 120V over a "fine wire". That will not get one much past >about twenty feet before the line drop starts to show a >huge drop. At least that is the idea I got. Otherwise why >mention 120 V at all? Current (1/2 A) is the important factor for drop, and 120V says he has lots of wiggle room for voltage drop, no? Grant.
From: Nunya on 31 Jul 2010 03:10 On Jul 30, 11:48 pm, Grant <o...(a)grrr.id.au> wrote: > On Fri, 30 Jul 2010 23:26:44 -0700 (PDT), Nunya <jack_sheph...(a)cox.net> wrote: > >On Jul 30, 7:01 pm, "Ken S. Tucker" <dynam...(a)vianet.on.ca> wrote: > >> I've been asked to 'light-up' aircraft models, such as, > > >>http://www.flickr.com/photos/35156618(a)N03/4754110575/ > > >> It is suspended from a rope. > >> I need to use very fine 120V wire (like magnetic wire), > >> the model uses 8# test monofilament right now and weighs > >> 1/2 # , but a strong wind requires that 8# test. > >> Is there a table that gives wire gauge & tensile strength? > >> The current will likely be a max of 1/2 amp. > >> Ken > > > The problem with all these replies is that he wants to > >pass 120V over a "fine wire". That will not get one much past > >about twenty feet before the line drop starts to show a > >huge drop. At least that is the idea I got. Otherwise why > >mention 120 V at all? > > Current (1/2 A) is the important factor for drop, and 120V says he > has lots of wiggle room for voltage drop, no? > > Grant. How high (long) would this line be? That too is a factor. And no... voltage drops with line length, not current. The line itself is a resistor, and that means that the other end of the line will see lower voltage.
From: Tim Williams on 31 Jul 2010 03:52
"Joe" <joe(a)somewhere.org> wrote in message news:i30cnt$d59$1(a)news.eternal-september.org... > Numbers in the ARRL handbook chart of breaking load for copper > antenna wire work out to about 39000 psi for soft drawn copper > wire and 65000 psi for hard drawn so perhaps use 2 strands of > varnished #24 or #26 copper magnet wire. Those strength numbers > are higher than Tim mentioned so run deadweight tests before > testing with model. 65 KSI is close to the ultimate tensile strength I saw; I specified yield strength, which is a little lower of course. The yield of dead soft copper is astonishingly low, it's like shiny pink clay. Only that, after you push it around a bit, it hardens up, and pretty soon it's so damn strong you can't bend it by hand anymore! Copper provides a particularly dramatic illustration of work hardening. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms |