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

David G4EBT · 17th Sep 2021, 6:57 pm

They look spot on Mick and the radio looks bonny too!

The main challenge (apart from having one good knob to use as a pattern), isn't so much casting the knobs, but getting the spindle mounting hole to be perfectly concentric and exactly perpendicular to the knob. If it's just 1mm off centre when rotated, that become 2mm swing from side to side, which is noticeable - even worse if the spindle hole isn't knob.

It's next to impossible to drill a perfectly concentric & perpendicular hole in the knob with a pillar drill, less still with a hand drill, but by using a lathe as you did with your chum, it is. The brass insert can also be drilled either 1/4" (the usual size for vintage British or American vintage radios) or 6mm for continental ones.

As the casting medium I've had quite a bit of success using Plastic Padding two-part epoxy 'Super Steel'.

It sets rock hard, can be drilled, filed or turned.

17th Sep 2021, 6:57 pm	#6
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,763	Re: Making /casting knobs for the AWA They look spot on Mick and the radio looks bonny too! The main challenge (apart from having one good knob to use as a pattern), isn't so much casting the knobs, but getting the spindle mounting hole to be perfectly concentric and exactly perpendicular to the knob. If it's just 1mm off centre when rotated, that become 2mm swing from side to side, which is noticeable - even worse if the spindle hole isn't knob. It's next to impossible to drill a perfectly concentric & perpendicular hole in the knob with a pillar drill, less still with a hand drill, but by using a lathe as you did with your chum, it is. The brass insert can also be drilled either 1/4" (the usual size for vintage British or American vintage radios) or 6mm for continental ones. As the casting medium I've had quite a bit of success using Plastic Padding two-part epoxy 'Super Steel'. It sets rock hard, can be drilled, filed or turned. __________________ David. BVWS Member. G-QRP Club member 1339.