Hardware Case Study: Why Lockitron Has Taken So Long To Ship
Here are some other reasons:1- WiFi drains battery fast, therefore advertising instant WiFi unlocking was foolish, if not purposefully misleading from the beginning. (Look through their posts on HN when Lockitron was first announced and you'll see that they admit that instant WiFi unlocking isn't feasible yet that's not the impression they gave the backers)2- Determining intent (i.e. I want to unlock the door) through proximity is a fool's errand. You'll have an impossible time trying to get user's position right without multiple receivers and have to resort to wonky logic they use today which won't work for a vast number of people: if user A unlocks the door then ignore his phone until he exist... hmm what if user A enters with user B, or user A leaves though the car in the garage but wants come back through the door?3- BUILD A PROPER PROTOTYPE. It means critical functionality being there, like unlocking via BLE and unlocking via WiFi. Does it work reliably? No? Fix it. Don't promise anything! Don't put up a video until you have a proper prototype.Heck, you don't even need mechanicals. Light up an LED to indicate unlocking for all anyone cares. If it doesn't work here in your lab, it won't work out there. There is no magic fairy dust that reduces power consumption or makes something work at scale when it doesn't work in your lab.4- Knowing how to use an Arduino doesn't make you a product developer, just as knowing Javascript doesn't mean you can deploy a backend that supports 1M users and you only get to deploy it once. Pay an experienced EE or consulting company for 20, 30, 40 hours of work to review your design, plan, and feasibility.Done right Lockitron is about ~$25-$30 in parts + PCBA cost -- not considering mold amortization.5- Cameron enumerates a number of mechanical and electrical problems. The fact is you can get a number of low cost electrical locks from China today that have reliable turning mechanisms. It has been done. Those factories will gladly OEM an  entire lock for you -- or in this case just sell you the parts or the whole assembled mechanism. Tear apart a Kwikset keypad lock and see how few gears it has. Their main problem seems to be that they started with the wrong/inefficient mechanical design and tried to make everything fit that.There are lots of existing, inexpensive, gearboxes you can buy that would give you the torque you need. At worst you'd have to get a custom designed output gear. Even then there are many Chinese vendors who make gears. I've bought from them before. They have a large catalogue, and if you want something they don't have NRE is about $1200 + 4 week delivery.6- "The resulting power and torque requirements of our gear box required a number of changes on our circuit board that would have been nearly impossible to predict from our prototype units". This could have been avoided by buying the ANSI/BHMA deadbolt standard which specifies maximum torque required for the thumbturn. Add 25% safety margin and you should be good with virtually all locks sold in north america as they are ANSI/BHMA compliant.