UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

kalee20 · 14th Jan 2021, 2:31 pm

If you have an insubstantial bobbin, you definitely need a good mandrel to support it!

A hardwood block, accurately cut to size, and with end cheeks to stop the bobbin flanges spreading, is very useful. With this, you can get by with thin card for bobbins (though I tend to use Nomex sheet, 7 thou' thick).

One matter: after winding, it is quite likely that you won't get the flipping thing off the mandrel. But don't panic: put it in an oven, raise to 120°C, leave for an hour, take out, put in freezer (in a polythene bag to stop condensation), leave a few hours, repeat... At one of the extremes, you'll find it will be loose enough to push out.

14th Jan 2021, 2:31 pm	#20
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,082	Re: Home made transformer If you have an insubstantial bobbin, you definitely need a good mandrel to support it! A hardwood block, accurately cut to size, and with end cheeks to stop the bobbin flanges spreading, is very useful. With this, you can get by with thin card for bobbins (though I tend to use Nomex sheet, 7 thou' thick). One matter: after winding, it is quite likely that you won't get the flipping thing off the mandrel. But don't panic: put it in an oven, raise to 120°C, leave for an hour, take out, put in freezer (in a polythene bag to stop condensation), leave a few hours, repeat... At one of the extremes, you'll find it will be loose enough to push out.