So things were moving along nicely, I moved from using header pins to using an M2 slot (which needs its own post) and changed a few things round, got the board ready for a second revision to be ordered, and every makers worst nightmare happened

After much searching there are similar connectors out there, but at different pitches, so wont work. Its possible to get custom connectors made, but thats not something im wanting to do right now, and so after all that faffing about the battery in an older post, that thinking is now moot!!

Going back to the much more common BL-5C wouldnt be impossible, but it poses many more problems

Connector hunt..

The reason i discounted the BL-5C initially was the fact that the battery has a 3mm pitch connector, and anywhere that sells connectors in reasonable quantity seem to sell 2mm, 2.5mm, and 4mm

The beauty of step files is that you can load them into cad and compare things that are teeny tiny. A 2.5mm connector has 1mm wide contacts, so that means that the gap between the outer contacts is 4mm, and the 3mm pitch connector means that the central connector is smaller than 3mm (but not buy much) so in a super hacky way that i dont really like, the 2.5mm connector might just work

It will be super reliant on alignment, but it might just be enough.

Re-think the case..

I would really like to make the case as simple as possible, ideally with no visible screws. The original plan was to have the pcb screwed to the back of the case. This had the battery bay within it, and therefore held all the power nicely in contact with the pcb. The front was then going to snap on using the usual arrangement of little clips as you get on most electrical devices.

After some googling of best practices on injection molding (thats the eventual goal) overhangs make the jig more complicated, and more complicated means more expensive, and more expensive is never a good thing!! Plan B was to have some screws in the battery bay to hold the front plate tight, and with the original battery plan, the screws were nicely spaced

Simply scaling that battery bay would mean that the area for screw attachment would be massively reduced, resulting in a larger portion of the front plate being un-supported.

Im currently bouncing round some ideas, maybe have the pcb initially screwed to the front of the case (which would actually be better for the keyboard strength) and then have a battery holder screwed to the back of the pcb, and somehow attach the back of the case without visible screws.. 

to be continued..........