Replacement parts for 1920's Radio Headphones

Show off your FreeCAD projects here!
User avatar
The_ID_of_Ed
Posts: 4
Joined: Thu May 23, 2019 4:31 pm
Contact:

Replacement parts for 1920's Radio Headphones

Postby The_ID_of_Ed » Sat Oct 26, 2019 4:50 pm

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
EarCap Before.png (947.31 KiB) Viewed 1114 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
EarCaps new & old.png (933.12 KiB) Viewed 1114 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
New installed ear caps.png (896.46 KiB) Viewed 1114 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
EarCap Sweep Question.png (97.03 KiB) Viewed 1114 times

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

https://www.youtube.com/channel/UCtBGrx ... JbA/videos
User avatar
kkremitzki
Posts: 1796
Joined: Thu Mar 03, 2016 9:52 pm
Location: Texas

Re: Replacement parts for 1920's Radio Headphones

Postby kkremitzki » Sat Oct 26, 2019 5:02 pm

Wow, what a cool use of FreeCAD! How do those actually sound?
Like my FreeCAD work? I'd appreciate any level of support via Patreon, Liberapay, or PayPal! Read more about what I do at my blog.
User avatar
bejant
Posts: 5953
Joined: Thu Jul 11, 2013 3:06 pm

Re: Replacement parts for 1920's Radio Headphones

Postby bejant » Sun Oct 27, 2019 3:08 am

The_ID_of_Ed wrote:
Sat Oct 26, 2019 4:50 pm
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
Posts: 19703
Joined: Tue Mar 17, 2015 9:14 am

Re: Replacement parts for 1920's Radio Headphones

Postby chrisb » Sun Oct 27, 2019 6:31 am

The_ID_of_Ed wrote:
Sat Oct 26, 2019 4:50 pm
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.