December 3, 2012 at 5:15 pm #3623Ed KrausharCVRS Member
I picked up this Stewart Warner at an auction some time ago. It had seen some poor storage conditions and required refinishing.
I still have to fix the warped lid.
The radio was made in the USA and sold by Pudney Brothers in London, Ontario according to the decal inside the lid.
Generally the chassis was in pretty good shape, but one audio transformer was open. This was rewound. The single dial tuning knob is linked to the three tuning capacitors with brass bands.
The pot metal pulleys had deteriorated and needed replacement. They could be machined out of aluminum but they were quite thick. Aluminum like that is costly and should be cut from rod to fit into the metal lathe.
I decided to try an experiment. I have cast zinc into parts before using zinc salvaged from newer scrapped items. It melts quite easily on a hotplate in a stainless steel pan. The old original pot metal should not be re-used. The material was easy, the mold was the problem.
In this case I used a wood mold. Three pulleys were needed so I took a piece of hardwood and drilled cavities into it using forstener bits about 1/4 inch larger than the required part. Two pulleys were the same and I drilled one hole for each of them. The third was larger. The pulleys were stepped in size and the flat bottom holes were made by the forstener bits. Each hole was drilled into two sizes to fit the steps.
Wood contains a lot of moisture so the mold had to be baked to dry it out before casting the zinc into it. The pour was made and after the smoke had cleared and the zinc had cooled I split the wood block to release the parts.
The pulleys were cleaned up, sized and center drilled on the lathe.
Attachments:December 10, 2012 at 8:28 am #3647Bob MasseForum Participant
Great story Ed. Nice job, radio looks great. How about a pic of the new pulleys?
Bob MasseDecember 10, 2012 at 5:13 pm #3649Ed KrausharCVRS Member
I should have taken a picture when I made the pulleys. I won’t now as it is a big job to get into them.
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