self sourced electronics

I want to self source the electronics for my first reprap for several reasons; cost, the diy feel of actually knowing how your machine works without any magical black boxes, and because I really want to learn what all those little greebles on boards are for. I read the fantastic "sourcing a 3d printer" article on the blog, read this: [forums.reprap.org], did my best to understand what the wiki pages were saying, plus looked a few other places, but I need some help. I'm looking in particular at Adrian's Ramps, Gen7, Sanguinololu, and DIY Ramps, but suggest anything else you think would be helpful. My questions were, once I've sourced all the parts, which will likely be cheapest? which is the simplest, easiest for a novice to understand? Which leads to the highest quality builds? What has the best controller software? Also, which is made with the least integrated circuits, ie highest percentage of discrete components to chips and controller boards? If you can answer any of these, I'd appreciate the help. Thanks!

Most folks recommend RAMPS. Buying a kit shouldn't prevent you from understanding it though. The schematics are published for both RAMPS and the Arduino Mega. Study those until you understand them. Whether you buy a kit or source it yourself, you'll still just be putting parts where the instructions say.

For me, buying kit form where possible dramatically increased my chances of actually finishing the project. I see a lot of Repstrap blogs started, not nearly so many finished. You know what works best for you on this count.

All of those work the same way, running the same firmware: an ATmega processor receives Gcode (instructions, such as "move to (X,Y,Z) extruding length E") from the host computer vis a USB-serial converter, monitors the temperature sensors and (if fitted) endstops, and sends step/direction signals to the 4 (X,Y,Z,Extruder) Polulu stepper drivers and on/off signals to the heater control MOSFETs.

Print quality and speed is hence likely to be similar for all of them (though I don't know of any actual tests of this), though Gen7 has the option of running the processor at 20MHz rather than 16MHz which may help at high print speeds.

RAMPS has the processor on an Arduino carrier board, which makes it more expensive but probably less work to assemble.

Sanguinololu/Gen7 put the processor on the main board; this is cheaper, but if the processor's internal memory is blank (as it will be when bought from a general electronics supplier) you will need a hardware programmer. If you don't already have this, either borrow one (since the firmware uses a bootloader, you only need the programmer once, and can later change the firmware without it), or buy a kit where this step has been done for you.

Sanguinololu is designed to be physically small to reduce the cost of having the PCB made professionally, while Gen7 is larger and single-sided to allow the PCB to be milled on a RepRap, but I don't know which comes out cheaper overall.

PiezoPizza, I think there is no single "the best one". All sets of electronics are similar, use the same CPU and almost all the same stepper driver chip, the "Pololu".

From the cost side, purchasing in single components is likely a bit more expensive than buying a kit. There are multiple sources for the small items and you have shipping costs for each of them. Unless you order additional parts, of course.

Regarding the PCB, you likely want a single-sided design without SMD parts. SMD can be done on the kitchen desk, but not many people feel comfortable with it. Purchasing a single PCB from a PCB manufacturing house is expensive, so your design of choice should be DIY-manufacturable.

Now, low integration is a rarely seen goal, most people tend to higher integration. To get something without the "Pololus" you likely have to design yourself.


P.S.: a few days ago I've seen an IC-less design with a functionality similar to the Pololus, including current limiting. It was a link in the Wiki to another site, but I can't find it any more. :-(

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

The only SMD component in any of these is Sanguinololu's optional FTDI chip, which you don't need if you use a USB-serial converter cable.

> Purchasing a single PCB from a PCB
> manufacturing house is expensive, so your design
> of choice should be DIY-manufacturable.

The Sanguinololu PCB alone only costs $11, the kit $55 excluding Polulus and USB-serial cable; how much do you charge for Gen7? Since this is piezopizza's first RepRap, they may well not be equipped to mill their own PCB, while toner transfer etching is said to be unreliable.

True, we don't know what tooling equipment PiezoPizza has available. Making a Gen7 PCB on a RepRap takes about EUR 3.- in material and 4 hours of work, I ask EUR 14.50 for it, about $20.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

piezopizza Wrote:
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> I want to self source the electronics for my first
> reprap for several reasons; cost, the diy feel of
> actually knowing how your machine works without
> any magical black boxes, and because I really want
> to learn what all those little greebles on boards
> are for.

I know how you feel!

I would suggest that you get a bigger arduino than mine though, the '328 is kinda limiting- it's big enough for teacup, but doesn't leave any room for things like SD support or per-motor enable lines. RAMPS is a popular electronics kit, go with that if the above looks a bit too scary

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Wooden Mendel
Teacup Firmware