MID, I'm here because I think what you are doing is great, and I am always interested in taking things to the next level.
I've got no secrets - I'll tell anybody who cares exactly how I make cups. I started with a lathe, chisels, and forstner bits. Realized really quickly that it was very time consuming to keep cups precise. Especially in the critical aspects of chamber dimensions and vent opening, etc. To evaluate how set A would sound compared to set B, C, and D was very time consuming, I had to mill all 4 sets on the lathe, which required a vast assortment of expensive forstner bits which were dulling out quickly, burning up my cups if my RPMs were too high.
Getting a CNC built and running was the solution to this problem. I have a friend who has helped me get this going and it has been a ton of work (not to mention $) for us both. They don't sell those cheaper engraving CNC routers with the necessary Z-axis range needed to mill cups, so this thing had to be built. That's DIY on steroids, let me tell you - some of the parts for the mill couldn't be purchased and actually had to be fabricated.
So now we're milling the critical parts of the cups with a CNC, and I still do the finishing/shaping of the outer flange part on the lathe. Having that provides a degree of precision where it counts sonically, that makes it possible not to have to wire up and listen to every single cup, because every cup from the same wood type and milling program is, well the same or pretty damn close.
My finishing process is deliberately kept minimal when needed for porous wood like honduran mahogany, I use as little shellac as I can, really just enough to seal the wood, so that the wood characteristics don't get covered up too much. A little bit of a beeswax/carnauba polish afterward, mostly for looks but also to fill in any pores that the shellac might have missed. Not sealing the wood is disastrous for this kind of application, you'd end up with headphones that might sound very different depending on the season and humidity in your house, etc. MID, you should know exactly what I'm talking about here.
None of my finishes are mirror polished, I haven't done a single cup with lacquer or polyurethane. The only way I would is if I got that as a request. To some my cups might look dull and boring as a result, but I did that for the sake of retaining the natural sound characteristics from the wood as much as possible, to me that was much more important.
Everything I've done has been thought out and deliberately geared toward sound characteristics. I'm pretty happy with what I'm able to get even from stock Grado drivers, the chamber dimensions I'm using squeeze a little extra bass out of them.
I've spent a couple months now staying up until 2am or later almost every night to learn, improve, fine tune, listen, tweak, etc. - and above all I unconditionally guarantee satisfaction, anybody for any reason doesn't care for the look, sound, whatever reason - they can return the cups for a full refund.
So what Chris said before does tweak me a bit, because he's being an armchair quarterback. I have worked pretty hard on the exact thing he mentioned - sound quality. My shapes and finishes are pretty simple and boring compared to other prettier stuff that is out there and 90% of my cups have been Hond. Mahog., so I'm obviously not totally focused on cosmetics. Anyway, I'm sorry to take away from the main purpose of the thread MID started here and I'll bow back out, I just want criticism to be kept fair. After going through the blood sweat and tears of getting the CNC finally going and doing the tuning work that I did, the previous comment needed to be challenged, because it's incorrect.
I'm sure I didn't find the holy grail that MID is working diligently toward finding with my current process, but it's still a marked improvement over the stock plastic and the result of a lot of hard work on my part. And I am always happy to share anything that I am doing with anybody here who wants to try it out for themselves.
