star the process of documenting the GaG PCB assembly line

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+# Surface Mount Robot
+
+For a long time, we've hand-loaded prototypes and then sent production board
+runs out to one of several 3rd-party surface mount assembly shops.  We've
+tired of dealing with these assemblers, however, would like more control
+over the process, and are intrigued by the [OpenPnP](https://openpnp.org)
+project. 
+
+After playing around for a while with building a machine from scratch, Bdale
+was offered a surplus Philips (Yamaha) CSM84 pick and place robot.  This is
+a massive thing to make room for in a home shop, but as designed it's meant
+to be able to hold 84 reel feeders with 8mm width reels, has a conveyer belt
+for loading and unloading assembly panels, 3 placement heads, and very good
+fundamental mechanical accuracy and repeatability.  Unfortunately, the machine
+controller is 1980's era technology, and the machine isn't really capable of
+handling 0402 parts as-is.  The goal, therefore, is to convert the machine
+over to using a modern control and vision system running OpenPnP, capable of
+loading [Altus Metrum](https://altusmetrum.org) and other products that make
+heavy use of 0402 passive components, and fine-pitch integrated circuits.
+
+## Sub-Projects
+
+* The stock machine has a nozzle vacuum sensing board that uses an analog
+  amplifier and comparators to output 3 states per nozzle as a 2-bit digital
+  signal.  OpenPnP would rather have simple analog vacuum sensors on each 
+  nozzle, readable by one of the system's control interfaces, then implement
+  the thresholds in software.  That that end, Bdale designed a [replacement
+  vacuum board](https://git.gag.com/hw/csm84vacuum) that uses 3 NXP 4115
+  series analog output vacuum sensors, intended to be attached to three of
+  the "thermistor" inputs on the Smoothieboard that also provides axis servo
+  control.
+

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+# PCB Assembly Line
+
+In support of [Altus Metrum](https://altusmetrum.org), Garbee and Garbee runs
+an in-house printed circuit board surface-mount assembly line.
+
+## Machines 
+
+* [laser engraver](laser/)
+* [paste station](paste/)
+* [CSM84](csm84/)
+* [reflow oven](oven/)
+

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+# Laser Engraver
+
+Most of the printed circuit boards we load need to have a serial number
+associated with them.  After trying stickers, and spending years using a
+fine-tip Sharpie pen to write on a silk screen rectangle, we've decided to
+try a laser engraver instead.
+
+More details to come...

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+# Reflow Oven
+
+After placing surface-mount parts on boards either by hand or using the 
+[CSM84](../csm84/), the next step is to melt all the solder paste in a
+reflow oven causing all the joints to be soldered simultaneously.
+
+Our current oven is a T-962A IR oven modified with open source firmware
+and a number of hardware upgrades.  While it's been fine so far, on the 
+advice of friends with more experience doing this, we're currently gathering
+the parts to build a better reflow oven, and will document it here as we
+proceed.

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+# Paste Station
+
+After [laser engraving](../laser/) serial numbers on each board image in an
+assembly panel, the next step in our process is to apply solder paste to all
+of the pads on each board that we intend to populate with surface mount
+components.
+
+Initially, this was done "by hand" using a frameless stencil on a desktop
+with bits of scrap PCB to form a frame and bits of masking tape to hold
+things in place.  However, we've got a clever idea about how to do this
+better without investing in an expensive solder-paste stenciling machine.
+
+More details to come...