Here is a little project to make an integrated 3D printer controller that can be sold as a kit or home-built for around $40.

The original intention was to include this printer controller as part of a kit for a sub-$200 DIY 3D printer that folks could buy and then assemble at class sessions led by famed collector of 3D printers, Albill.

== About the Name ==

[[Image:Sandwich.png]]

== Design Goals ==

Hobbyist-friendly

free and open design

~$40 BOM

Capable of running the Marlin firmware

Support for 3 Axes with end stops, a stepper extruder, a fan and a heated build platform

== Approach ==

All design work will be done in the hobbyist-friendly, free version of Eagle CAD

All work will be done using a public repository on github

The design will be based on hobbyist-friendly through-hole parts.

== Progress ==

=== Design ===

A millable layout is available in the [https://github.com/atom-bomb/sandwich sandwich github repository].

The design is based on an ATMega 644p and the bleeding-edge Toshiba TB6600 motor controller.

A nice thing about the TB6600 is that it has internal voltage regulators for the logic voltage so there is no problem with powering the motor controllers before the microcontroller boots.

Unfortunately, the documentation for the TB6600 is a little bit lacking so it’s not clear how much current the internal regulators can support. Hopefully this won’t be a problem.

=== EVT0 ===

Thanks to davr’s suggestion of using [http://freerouting.net freerouting.net] and also thanks to the milling and drilling capabilities of [[Guido|Guido]], I’ve made a first prototype:

[[Image:Sandwich evt0.jpg|640px|Sandwich evt0.jpg]]

In hindsight, milling the board with Guido may not have been the greatest idea. The end mill was pretty worn out by the time I was cutting the second side and some of the traces were damaged. Also, there was no easy way to plate the through holes so I had to solder both sides of the board for every connection.. kinda tricky.

Fortunately, I discovered that part of my ground plane was disconnected. After some hacking on the bottom of the board, the machine boots and is able to control steppers. There still may be a problem with the power net because a few times in testing it seemed that the power supply for the printer I was testing against went into thermal shutdown.

=== PVT0 ===

Thanks to some lessons learned and a much nicer board made by our friends at [http://oshpark.com oshpark], I have a production prototype:

[[Image:Sandwich pvt0.jpg]]

So far, everything seems to be working on this design.

Note the attached [http://www.amazon.com/Elesonic-Vomaxtech-Pl2303hx-Module-Converter/dp/B008AGDTA4 TTL->USB serial adapter].

The design has been updated to include some improvements in the silkscreen layer.

== What’s Next ==

#Make a 3D print using a Sandwich-equipped MakerBot Cupcake
#Experiment with some cost-saving part swaps listed on [https://github.com/atom-bomb/sandwich/issues github]
#Figure out FOB cost
#Find out how long it takes a normal human to populate a board
#Figure out whether to fund production with pre-sales through kickstarter or just mailing lists and message boards
#Make some assembly and use directions
#Put a working Marlin configuration on github

== Links ==

The current design is [https://github.com/atom-bomb/sandwich here on github].

[[Category:Projects]]