Copying rare vintage radio knobs.
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Copying rare vintage radio knobs.
Hi,
I'm rained off; its another black hole and its cold so as I can't continue with my coffered ceiling I thought I'd spend a bit of time and add the story of how I made a set of wooden knobs for a vintage radio forum member who posted asking if anyone had some of these rare knobs?
Easy job and done in a few minutes? Read on. These knobs had to be octagonal in shape and any deviation on the flats would be painfully obvious so a lot of accuracy was required not only to get all the flats the same size but the front turned sections also needed to be concentric with the axis. I was supplied the only original knob the member had and set about carefully measuring it. Next I used "emachineshop" CAD to draw the shape allowing me to print out white paper templates which in turn were cut out using a pair of scissors.
Looking through my stock of hardwood I found a suitable length of dense tropical wood; species unknown but it would do. This was cut to size and the blanks marked out also their hole centres. The blind holes were bored axially in the big drill press using a 12mm Forstner bit ideally suited for such work but taking care not to go too deep and break through because the blanks would each be subjected to woodturning.
Radio knobs are cross drilled and tapped to accept a grub screw this being the means of securing the knob onto the chassis spindles. Brass round bar stock was selected; cut into lengths then faced and bored in the big Colchester Triumph lathe I owned at the time; the lathe an overkill big style being 3 phase running a 5hp motor. These brass inserts were then roughed on their diameter and in turn glued and pressed home into the wood blanks. Whilst the blanks were still connected together they were cross drilled and tapped at 4BA to accept grub screws. The blanks were then roughed out on the bandsaw taking care to leave extra material. Then each blank had a paper template attached using double sided self adhesive tape.
I had a home made 4" belt sander and this proved ideal for bringing the blank flats down to the template lines firstly with a coarse belt then fine sanding. This took care of the inserts and flats. Next to do was the turning; I mounted a Jacobs chuck in my Record Power DML24" woodturning lathe and into this chucked a short 1/4" diameter steel rod; each blank was then attached in turn using a grub screw securely to the rod and carefully turned matching the pattern of the original knob and sanded smooth under power.
The new knobs were then stained in Jacobean Oak and finished with French Polish (Shellac); the pictures show the original knob together with the new knobs; I didn't attempt to distress the new knobs they being honest copies. This small project was a delight for me to do but took quite a few hours to accomplish. I packed and posted the original and new knobs to the forum member with my compliments and he was absolutely delighted to receive them to complete his radio restoration. I gained a lot of personal satisfaction out of making the knobs and this was reward enough for me. I find on forums there are many genuine like minded people and it's good to be able to help each other out. This project fell just at the right time because usually I'm bogged down with jobs. I hope this is of interest as its unusual.
Kind regards, Col.
I'm rained off; its another black hole and its cold so as I can't continue with my coffered ceiling I thought I'd spend a bit of time and add the story of how I made a set of wooden knobs for a vintage radio forum member who posted asking if anyone had some of these rare knobs?
Easy job and done in a few minutes? Read on. These knobs had to be octagonal in shape and any deviation on the flats would be painfully obvious so a lot of accuracy was required not only to get all the flats the same size but the front turned sections also needed to be concentric with the axis. I was supplied the only original knob the member had and set about carefully measuring it. Next I used "emachineshop" CAD to draw the shape allowing me to print out white paper templates which in turn were cut out using a pair of scissors.
Looking through my stock of hardwood I found a suitable length of dense tropical wood; species unknown but it would do. This was cut to size and the blanks marked out also their hole centres. The blind holes were bored axially in the big drill press using a 12mm Forstner bit ideally suited for such work but taking care not to go too deep and break through because the blanks would each be subjected to woodturning.
Radio knobs are cross drilled and tapped to accept a grub screw this being the means of securing the knob onto the chassis spindles. Brass round bar stock was selected; cut into lengths then faced and bored in the big Colchester Triumph lathe I owned at the time; the lathe an overkill big style being 3 phase running a 5hp motor. These brass inserts were then roughed on their diameter and in turn glued and pressed home into the wood blanks. Whilst the blanks were still connected together they were cross drilled and tapped at 4BA to accept grub screws. The blanks were then roughed out on the bandsaw taking care to leave extra material. Then each blank had a paper template attached using double sided self adhesive tape.
I had a home made 4" belt sander and this proved ideal for bringing the blank flats down to the template lines firstly with a coarse belt then fine sanding. This took care of the inserts and flats. Next to do was the turning; I mounted a Jacobs chuck in my Record Power DML24" woodturning lathe and into this chucked a short 1/4" diameter steel rod; each blank was then attached in turn using a grub screw securely to the rod and carefully turned matching the pattern of the original knob and sanded smooth under power.
The new knobs were then stained in Jacobean Oak and finished with French Polish (Shellac); the pictures show the original knob together with the new knobs; I didn't attempt to distress the new knobs they being honest copies. This small project was a delight for me to do but took quite a few hours to accomplish. I packed and posted the original and new knobs to the forum member with my compliments and he was absolutely delighted to receive them to complete his radio restoration. I gained a lot of personal satisfaction out of making the knobs and this was reward enough for me. I find on forums there are many genuine like minded people and it's good to be able to help each other out. This project fell just at the right time because usually I'm bogged down with jobs. I hope this is of interest as its unusual.
Kind regards, Col.
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