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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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15th May 2023, 10:35 am | #1 |
Triode
Join Date: Jan 2009
Location: Basingstoke
Posts: 17
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Fine wire gauge
I would like to try rewinding a coil from an old electric clock but how do I determine the gauge of wire needed? The original copper wire is very fine.
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15th May 2023, 10:40 am | #2 |
Hexode
Join Date: Feb 2007
Location: Chesterfield, Derbyshire, UK.
Posts: 481
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Re: Fine wire gauge
There is lots of advice on here on refurbishing electric clocks such as this:- https://www.vintage-radio.net/forum/...ad.php?t=74480
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15th May 2023, 10:44 am | #3 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,060
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Re: Fine wire gauge
Unwind a length, measure resistance and calculate the ohms per metre.
Then you can use wire tables to find the gauge - it's difficult trying to use a micrometer on really fine wire - especially as the enamel adds to the thickness and it's difficult to see if it's removed or not! |
15th May 2023, 11:25 am | #4 | |
Triode
Join Date: Jan 2009
Location: Basingstoke
Posts: 17
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Re: Fine wire gauge
Quote:
Much appreciated. |
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15th May 2023, 11:26 am | #5 | |
Triode
Join Date: Jan 2009
Location: Basingstoke
Posts: 17
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Re: Fine wire gauge
Quote:
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15th May 2023, 11:58 am | #6 |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,737
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Re: Fine wire gauge
When you say 'very fine' the finest SWG gauge you'll find is 50SWG - I doubt it's as fine as that.
Here are the SWG gauges from 40 to 50 SWG, in mm and inches: 40 SWG = 0.121mm / 0.0048" 41 SWG = 0.111mm / 0.0044" 42 SWG = 0.101mm / 0.0040" (4 thou) 43 SWG = 0.091mm / 0.0036" 44 SWG = 0.081mm / 0.0032" 45 SWG = 0.071mm / 0.0028" 46 SWG = 0.060mm / 0.0024" 47 SWG = 0.050mm / 0.0020" (2 thou) 48 SWG = 0.040mm / 0.0016" 49 SWG = 0.030mm / 0.0012" 50 SWG = 0.025mm / 0.0010" (1 thou) You'd need to measure the gauge (easiest on digital callipers). At Wires&Co (Retail arm of The Scientific Wire Co), in the sidebar menu under 'Copper', what you need is referred to as 'enamelled copper magnet winding wire'. It's best to get solderable enamelled copper, which you don't need to clean or tin. EG: 50 grams of 0.032mm (49SWG) Solderable Enamelled Copper Wire (approx: 139 km/kg, 21.25 ohm/mtr at 20C) To put that into perspective, 50 grams is only 1.76 ounces, yet it's 6.95 kms long. It would set you back £25.33 inc VAT: https://www.wires.co.uk/acatalog/SX_0032_0090.html When you've checked either the gauge or Ohms/Metre, you'll be able to search Wires&Co's website for the correct gauge you need. The less fine it is, cheaper it gets, (and of course the easier it is to wind), but the Ohms/Mtre drops significantly with each gauge. EG: 50 grams 0.050mm 47 SWG Solderable Enamelled Copper Wire (approx: 57 km/kg, 8.70 ohm/mtr at 20C) Price: £12.19 Exc UK VAT (£14.63 Inc 20% UK VAT) https://www.wires.co.uk/acatalog/SX_0032_0090.html Hope that helps a bit. Good luck with it Ian.
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David. BVWS Member. G-QRP Club member 1339. |
15th May 2023, 3:33 pm | #7 |
Triode
Join Date: Jan 2009
Location: Basingstoke
Posts: 17
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Re: Fine wire gauge
Thank you so much David for your detailed response. I didn't appreciate that I could measure the thickness with digital callipers, I thought the wire would be too thin. I've now measured the existing wire in several places and it pretty much consistently comes out at 0.05mm (so 47 SWG), and exactly the example item you described.
I'll now place my order with Wires&Co. Thanks again. Ian |
15th May 2023, 4:23 pm | #8 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
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Re: Fine wire gauge
Hi Ian, a micrometer is often better for the finer gauges and do not forget you will be measuring the diameter over the enamel. Wire tables will give you the bare size/ gauge number.
Using 0.071 or 0.063 and filling the bobbin will give you about 10,000 turns plus. This seems to work fine without needing too much precision Ed |
15th May 2023, 5:56 pm | #9 | |
Triode
Join Date: Jan 2009
Location: Basingstoke
Posts: 17
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Re: Fine wire gauge
Quote:
Thank you for taking the time to share your knowledge. Regards Ian |
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15th May 2023, 11:11 pm | #10 | |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,737
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Re: Fine wire gauge
Quote:
Good luck with the re-wind.
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David. BVWS Member. G-QRP Club member 1339. |
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17th May 2023, 9:52 am | #11 |
Octode
Join Date: Dec 2008
Location: Wincanton, Somerset, UK.
Posts: 1,757
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Re: Fine wire gauge
For these very fine guages you can expect the insulation to add at least 10% to the overall (measured) wire diameter.
See e.g. https://www.elektrisola.com/en/Produ...-Data#iec60317 |