Here’s another exciting update on the KNTRL9! I mainly have been busy with getting the knobs done and improving the software. Where in the beginning everything seemed to be going smoothly, the last month some things went a little different than how I’d hoped. But I guess that’s life and I’m positive the KNTRL9 will turn out great!
The fader knobs came in in two phases. First the inner plastic parts, and last week the outer metal parts came.
First, I’d like to explain why I have chosen plastic for the inside of the fader knobs, especially since everyone knows I wanted to avoid using any plastics at all. Unfortunately that turned out to be quite difficult.
The reason for this is that when trying to fit one metal part (the knob) onto another metal part (the slider potentiometer), it needs to fit exactly using something called an engineering fit. In my case, in order to be able to take the controllers apart for service, I would like to be able to take the knobs on and off without too much strength. Since plastic is more flexible than metals, it is easier to achieve a good fit, without using too much strength to attach the parts (using too much strength would also possibly damage the potentiometers).
So, I designed the knobs to be made out of two parts: the inner plastic part that fits the potentiometer, and a nicely polished aluminium outer part that fits on the plastic part. The problem was however, that the parts that were sent to me, were not polished :(. This was a mistake on the manufacturers behalf and they will send new ones in three weeks (which means unfortunately more delay).
I tried polishing it manually myself but unfortunately that didn’t work out at all (no change whatsoever).
Another challenge are the rotary knobs. Since the last batch turned out to be too big (a mistake on my side), I ordered new ones that should have the perfect fit. They came in recently but to my surprise, they also were too large and in two ways: The hole was both too deep and too wide. Now, this was a real downer for me, especially since I spent extra effort making sure that all the dimensions are correct.
So I started to look at the drawing again and noticed one very stupid, but subtle mistake: Each rotary potentiometer had four little “cleats” (?) of just 0.5 mm high. I had somehow missed these when I designed the controller. Because of these cleats, the whole panel was 0.5 mm higher above the PCB than expected and therefore, the knobs would just scratch the surface of the panel. My temporary solution (I of course also fixed the design): drill some shallow holes in the backside of the panel.
Now, this doesn’t explain why the holes are too wide as well. I specifically told the factory to use a specific fit, and that the diameter is 6 mm, which is also described in the potentiometer’s datasheet. When asking about it, the factory told me they’ve done everything according to my drawings. I’m still in the process of trying to figure out what went wrong and will call in some help from someone who works in the same co-working space as I am (he will be back from his holiday next week).
In the meantime, I will use hot glue. This will make sure the knob will stay in its place and won’t scratch the surface, which is fine for the prototype. If they need to be taken off, I can simply heat up the knob a bit to melt the glue.
Here you can see the cleats. I now adapted the design to include little holes in the panel. I will find another solution, since this will raise the cost per panel with about €20(!)
I will be honest: I am terrible at marketing. I’m trying to learn some of the principles but since I consider myself immune to marketing techniques (I mean, I really did need a new Novation Launchpad recently, that ad just happened to be there, I already had decided I would buy one), I have no clue how to approach all this.
So, I really need some help from my Clan (a word I learned recently ;)). If you like my product, you would really help me to spread the word: mention it here and there. If you know anyone that works for a music magazine, let me know!
Also: Did I mention that I have FREE STICKERS!! Drop me a message (firstname.lastname@example.org) and I will send some off to you. Free of charge.p>Most importantly: Subscribe to the mailing list!