Manufacturing update II
Time for another update. Most of the time since last have been spent on the enclosure. We have been working closely with the injection mold tool makers on getting all the parts in as good shape as we can. There are six parts to the enclosure. Five of them are good but the last part, the back of the enclosure, is a tough nut. I think we are on the sixth revision now and there are still issues with the manufacturability! Sigh. Sometimes you flush all you want but there is this one floater that just won't go down.
It's not so much that it is a problem to make it, we're trying to figure out how to make it without nasty parting lines on the A-surface. We have today and tomorrow to solve the rear part if we are to stay on schedule. No rest for the wicked.
The injection molded parts has the longest production time of all the parts that goes into the Kick. The factory have received a down payment on production and they have started up toolmaking for the rest of the parts.
We know a lot of you like a peek inside the sausage factory, so here are some pics from the design process for one of the parts, a button. There are two backlit buttons, the ON/OFF button and the Connect button.
This is the old design. The buttons are lit up from underneath so there has to be room for both the switch and two LEDs. The angle of incidence for the back of the button is such that the "total internal reflection"-effect causes the light to be reflected out the front.
To keep the buttons in place during assembly, we gave it hooks and corresponding slits in the PCB. This caused the molding to be more complex. Because of the hooks, it can no longer be made with a simple two-part mold. So the mold gets expensive. Unnecessary for this part.
Here is version two. We still needed a way to hold the buttons in place, so we added a slot and a piece of thin nickel-steel wire (nickel-steel wire is springy, like a guitar string).
This did not work very well. Here is a pic of the 3D printed test enclosure. The tactile feel is mushy, the button is wobbly and prone to come loose.
Also, the feasibility report from the factory pointed out that the uneven thickness of the part would result in sink and low yield. (When plastic cools off off it contracts a little bit. If the plastic has uneven thickness on the inside, you get sink marks on the outside.)
So we did a redesign. Both button tops are now in a single piece, making it easier to print the legends. The foot attaches to the inside of the enclosure with heat staking or acetone. The buttons are designed to allow the material to flex about 0.3mm and engage the switch. The PMMA (acrylic) is no longer a good choice as material. It is to brittle and would probably crack after a while, but we'll pick a more suitable material like clear PC or PP.
This is a cut through the case showing the new buttons and re-positioned electronic parts. The signal LEDs has been changed to a side-emitter type
On the electronics we have received the new PCBs and built up a new electronics prototype. (I mentioned last time that we had to do a redesign because of lead time on some parts.) The new electronics looks good, no major problems encountered so far.
About shipping details
We were about to send out for shipping details (your address etc.), but Kickstarter suggested that we hold off until we are closer to the shipping date. The reason is that people move. So we are going to hold off a while for the majority of you guys.