Replacement parts for 1920's Radio Headphones

[The_ID_of_Ed]

Hi FreeCAD folks, I used FreeCAD to design some replacement parts for some old 1920's Radio Headphones. Specifically the Bakelite ear cup's were broken, so restoring the headphones was going to be a challenge. So I designed some replacement replicas and made 3D Printed replacement parts.

EarCap Before.png (947.31 KiB) Viewed 3301 times

These ear caps were made for Brandes brand headphones made sometime in the 1920's

The ear caps are printed in two peaces then glued together, then sanding, paint and or epoxy the surface is smoothed out to look more like the smooth surface of the original Bakelite parts.

EarCaps new & old.png (933.12 KiB) Viewed 3301 times

Also a couple files are for 3D printing some sanding arbors, one is optimized for a lathe and another for a 3/8 drill chuck.

I have a YouTube video that goes into the details of making my ear cap replacements the video is at: https://youtu.be/-7h8EQaEMt0

https://youtu.be/-7h8EQaEMt0

The 3D printing files are at my Thingiverse page https://www.thingiverse.com/thing:3900510

New installed ear caps.png (896.46 KiB) Viewed 3301 times

The most notable issue is the threads are very fine and are close to the limit that can be printed with a FDM printer. I found using a lot more fan cooling, bit higher extrusion temperature and much lower print speeds helped the most. It seems also the age of the plastic makes a difference. New is best. They'll still be some light stringing at the threads to clean up.

It may also be necessary to adjust the scale slightly to get the best fit. So several printings maybe necessary to get them to work.


I also have a question on how to generate threads. I used the Sweep function to generate a helix sketch. But to create a solid I could seem to only get a single thread. So to produce more threads I had to clone and then offset the location. It worked, but I seem to be missing something on how to get the solid extrusion to follow the length of the sweep sketch. Any suggestions? Using ver .18

EarCap Sweep Question.png (97.03 KiB) Viewed 3301 times

I do other mechanical stuff on my YouTube channel that may be of interest.

https://www.youtube.com/channel/UCtBGrx ... JbA/videos

[kkremitzki]

Wow, what a cool use of FreeCAD! How do those actually sound?

[bejant]

I also have a question on how to generate threads. I used the Sweep function to generate a helix sketch. But to create a solid I could seem to only get a single thread.

For the Sweep Path, press and hold the Ctrl button and select the remaining turns one at a time in the 3D view.

Thanks for posting such a neat project!

[chrisb]

I also have a question on how to generate threads.

You have used the sweep from Part workbench, while your model is mainly constructed in PartDesign. I would recommend to make the sweep inside of the body in PartDesign workbench. Then you select only the object for the sweep path and no edge at all.

[The_ID_of_Ed]

Thanks for asking me the question about how well my 1920's headphones work. I really went to town to figure out in great detail how well they were working. Which as expected was not what they use to be. So lots more geeking out, I worked on tweaking them up to what likely they use to perform at.

Check out my first video on the performance evaluation.

https://youtu.be/ecz5mBA-L5c

The Second video goes into lots of detaile's on measuring magnetic strength and how to recharge the magnets.

https://youtu.be/s_nL7dkaNUI

If you only have a few minutes to spare the last 10 minutes, basically 40 minutes into the video has all the concluding meat to all that the videos build up to.

I'm very pleased with the headphones now. A lot of that is thanks to FreeCAD.

I very much appreciate all the efforts that go into the software project. It's come a long way and I get a lot out of it now.

Thanks again

- Ed

Wow, what a cool use of FreeCAD! How do those actually sound?

[Gregory son of Carl]

Wow! Those headphones are really from another world huh. Very cool project!