VanguardAudioLabs
Member
If any of you follow me on IG, you've seen this project starting to take shape. I got a shattered vintage U87i from Cesar Mejia (Herbie Hancock's engineer). It had been a school mic at the school he teaches at, and…well, audio students ¯\_(ツ)_/¯ The capsule carrier head's plastic bits were beyond salvage. Even if I'd been able to plastic-weld them back together, there were too many missing pieces. I resolved to just measure, draft, and 3D print new plastic for it.
Hopefully you never need these files…but if you do, here they are for posterity.
NOTES:
Hopefully you never need these files…but if you do, here they are for posterity.
NOTES:
- I used PLA, 100% infill, and it's quite strong. Supports are a must, so make sure your support settings are dialed in well. Alternatively, you could use a site like Xometry and sinter them from Nylon.
- PLA may not be the best choice here for the Hi-Z area of the circuit. I may yet just send it to Xometry and have them do SLS Nylon, which I believe has a higher insulation resistance than PLA (along with better tensile strength). I'm not 100% sure what material Neumann was using, I imagine Klaus could tell us.
- The capsule pin holes I put at 2.4mm, even though original spec is a 1.5mm hole molded around the old pins. A few reasons: I'm going to use the original pins and JB-weld them in place. Also, my 8-year-old old FDM 3D printer kind of sucks, and I intentionally oversized the holes because my printer tends to print through holes about 10% small. The pin retention flares measured 2.2mm on my calipers for this mic.
Alternatives include shaping some brass socket head cap M1.6 or M2 screws, or brass pin nails, but that would require a different hole size. I've included the STEP files as well so you can modify them. - I'm doing something similar for the riveted-in switches. I had to drill out the old rivets. Instead of tube riveting and cracking the old plastic on the switches, I'm going to use the old rivets and JB weld those in as well. I also thought about tapping in new plastic-threaded screws, but I'm worried I'd break the old plastic on the switches, which already is showing some fatigue.
- This is for the opaque plastic of the early 70s mics. The clear plastic ones are a bit different and I suspect one day I'll need to model those.
- I made the capsule rubber slot slightly thicker. Neumann molded in a piece of what appears to be aluminum at first glance for this part. I made it a bit thicker to compensate for the strength difference, but left the set screw slot to hold the capsule in place. I'll probably tap in an extra set screw or two to hold the capsule rubber in place using self-tapping plastic screws, M2 x 3mm.
