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- Dec 26, 2017
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That's pretty interesting material. Non-metallic, insulating, and very hard. Thanks for the info!
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Making parts for an antique radio
- Thread starter Mike6158
- Start date
That's pretty interesting material. Non-metallic, insulating, and very hard. Thanks for the info!
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- Feb 1, 2015
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- 9,615
Garolite, aka Bakelite, was an early plastic, second only to celluloid, and was widely used in electronic equipment from the beginning. It would be an appropriate substitute for the wood in the pulleys.
Plus, I really like the smell when it's machined but that's likely just me.............Bob
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- Mar 22, 2014
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- 847
Garolite (aka G10, FR4) is a common circuit board substrate and a structural material used in RF and high voltage electrical circuits. It is very abrasive to machine - a real tooling destroyer. I learned this the stupid way.
Restoring old radios looks like a lot of fun. I plan to restore some early 1950s vintage ham radio equipment some day.
Restoring old radios looks like a lot of fun. I plan to restore some early 1950s vintage ham radio equipment some day.
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- May 4, 2015
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- 3,583
In my teens I loved working on old radios and tv's . Now most of the things I had are worth tons of money. The old round tv with rotatable picture tube , and the little bakelite radio's ,tubes by the hundreds . All thrown out cause I got into motorcycles . Even had big console radios wood furniture , well made in America . We really were great I remember the tuner using pulleys on some I repaired . If your using brass you can make it last for another fifty years.
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- Dec 26, 2017
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- 60
Well... I spent about an hour and half in Fusion 360 plus about an hour with a set of calipers and the two pulleys and I have a drawing. There aren't any dimensions on the drawing because I couldn't figure out where Fusion 360 hides that command. I measured everything and it's within range of what I need it to be (bear in mind I'm talking 4 decimal places and I doubt if I measured that the original that well). Now I need to turn a couple of pulleys so I have the dimension I need for the spindle, and then make the spindle in Fusion 360 (for my own purposes). Then turn the spindle. It has a short bit of 6-32 threads on one end, a hex flat, and a spindle with a hole in the end to capture the pulleys. I have the hex stock I need so... onward through the fog...
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- Dec 26, 2017
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- 60
I figured out how to dimension the drawing and started making chips. I'm afraid the v-groove is going to be my nemesis... I plunged the tool in the photo in .030" (I had already backed out when I took the photo). I kept checking the flange width until it was close to the desired dimension and that's where I stopped. You're looking at two pulleys with a parting tool line between them and at the left side of the last pulley.
The groove is supposed to be about 160°, I'm not sure what the angle of the tool I was using is. I was thinking about changing to a parting tool and setting the angle of the tool to 79° (I know, not quite half but that seems to be what works dimensionally) and going in that way, but I only want 0.004" of width at the bottom and the parting tool is wider than that. I suppose I could thin it down on a grinder but I don't know how well it will hold up.
The other end of the rod has a #47 drill bit broken off in the end of it otherwise I might be farther along. Cheap bits and trying to hurry the last 1/8" teamed up on me. Stock is 5/8" silica bronze. Finished diameter is supposed to be 0.520" and I left it 0.002" larger. I didn't think the radio would notice the extra 0.002" in diameter. Lets hope these parts survive the final finishing operations
The groove is supposed to be about 160°, I'm not sure what the angle of the tool I was using is. I was thinking about changing to a parting tool and setting the angle of the tool to 79° (I know, not quite half but that seems to be what works dimensionally) and going in that way, but I only want 0.004" of width at the bottom and the parting tool is wider than that. I suppose I could thin it down on a grinder but I don't know how well it will hold up.
The other end of the rod has a #47 drill bit broken off in the end of it otherwise I might be farther along. Cheap bits and trying to hurry the last 1/8" teamed up on me. Stock is 5/8" silica bronze. Finished diameter is supposed to be 0.520" and I left it 0.002" larger. I didn't think the radio would notice the extra 0.002" in diameter. Lets hope these parts survive the final finishing operations
- Joined
- Dec 26, 2017
- Messages
- 60
Pulley's are done. Not perfect but they'll work.
Now for the part that I think is going to be the hardest. The spindle. 1/2" of shaft for the pulleys, 0.090" in diameter, followed by a 0.050" thick 1/4" hex (I'm using 1/4" hex stock since I don't have a mill), and 0.120" of 6-32 threads (I planned for a 0.050 gutter between the threads and the hex).
I think turning down 1/2" of brass to 0.090" is going to be pita.
Now for the part that I think is going to be the hardest. The spindle. 1/2" of shaft for the pulleys, 0.090" in diameter, followed by a 0.050" thick 1/4" hex (I'm using 1/4" hex stock since I don't have a mill), and 0.120" of 6-32 threads (I planned for a 0.050 gutter between the threads and the hex).
I think turning down 1/2" of brass to 0.090" is going to be pita.
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- Dec 26, 2017
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It turns out that it's not that making the spindle is not hard to do. I'm almost finished (maybe). The spindle is .020" too small... I made a parting tool cut .020" too deep but I planned to offset out .020" when I cut the rest of the spindle. Except I forgot to do that and made it all the same. The pulleys work but there's a little slop. It's not a precision device but it's the principle. The wood pulley's wobble a little too.
There's a bit too much thread, maybe 1/16" but that'll stick out of the bracket just a little and it's inside a case. I may file it down. And there's the gutter at the back of the threads. I used a parting tool. It should only be .050", same as the hex flat thickness.The original had a lock washer and about 1/2 the gutter width this one has.
The biggest screwup, maybe, is not drilling the hole where I need it in the end BEFORE I cut the spindle all the way down. We'll see how that goes, I may be making another one...
Drilling a .040 hole in a .070 diameter spindle didn't go very well, so I cut it off and peened it. The end pulley doesn't turn so I think I'll rebuild it. The right diameter spindle will make drilling the hole easier. I wonder if I should just groove it and use a really small snap ring? Nothing like practice to improve things...
There's a bit too much thread, maybe 1/16" but that'll stick out of the bracket just a little and it's inside a case. I may file it down. And there's the gutter at the back of the threads. I used a parting tool. It should only be .050", same as the hex flat thickness.The original had a lock washer and about 1/2 the gutter width this one has.
The biggest screwup, maybe, is not drilling the hole where I need it in the end BEFORE I cut the spindle all the way down. We'll see how that goes, I may be making another one...
Drilling a .040 hole in a .070 diameter spindle didn't go very well, so I cut it off and peened it. The end pulley doesn't turn so I think I'll rebuild it. The right diameter spindle will make drilling the hole easier. I wonder if I should just groove it and use a really small snap ring? Nothing like practice to improve things...