Custom Drop-In replacement PCB for Da Vinci Mini

Haha! Just kidding! I know this doesn't exist yet. So.... I'm going to make it. First of all I'll answer some obvious questions up front:

1. Why?

That's an easy one - DRM Filament(of course) and also... These printers have terrible support! Mine was bad out of the box and it took forever to convince them that the printer was faulty and not that I was just another yahoo who didn't know how to use technology.

2. Why the Mini? Nobody likes the Mini! Do this for the Jr or the AIO or any other printer than the Mini!

Well, the Mini was the first one I bought. I mainly chose it over the Jr based on a review that suggested that it prints slightly better quality. Also, it was about $20 cheaper or so, although when I saw that crappy fold it yourself front cover, I wold have gladly paid the $20 for the fully enclosed version.

3. OK, so why not dump the Mini, get a Jr and then do your project?

Haha, that's easy. It seems like people are dumping Minis left and right! I can't throw a rock on CraigsList without hitting a <$100 almost new Mini that people just like me got frustrated with when they realized that 3D printers, while priced like Inkjets of 10 years ago, aren't actually just plug-and-print user friendly devices. I'm still struggling with printing more than just test Cubes, D&D 20-sided Dice, and a couple of Benchys. That's mostly because the initial defect took all of the excitement out of me and I have doubts that I'll actually be able to print one of those cool, working(well, moving) 8-cylinder engine blocks I see online.

Still, the glut of dumped Minis got me a second mini for just $50. It still had it's original spool of transparent yellow which had only about 3m printed off of it! By this time I had learned how to level the X-arm and adjust the Z-height. Also had learned a few tricks with the bed sticking(kapton tape + thin layer of gluestick made by diluting with a few drops of water and spreading by hane to make just a slight "haze" on the Kapton). It's still a pain to get large contact prints off without wrecking the bed tape, but I'm working that out.

So I have 2 minis so I can experiment on one while maintaining a "golden unit" just in case. If I brick one, the spare parts and extruder are well worth the $50.

Also, since the Mini seems the least hack friendly, I figured I'd be doing a service to the other poor souls with Minis that are not easily modified.

4. Why not just install a Ramps board and be done with it?

If you ever met me in person for more than 5 minutes, you'd know. I don't just re-invent the wheel. I fabricate a shiny streamlined, user and programmer friendly wheel that looks like it always belonged there. Wait... That analogy got away from me. Anyway, I like to create what I'm calling(coining?): FactoMods. That's a modification that fits exactly where the factory part came from like it was always meant to be there. I pull out the digital calipers and measure the board, mounting hole locations, connector part numbers and locations, etc... I largely use what's already there, and make it (hopefully) better. Someone wth no hardware experience other than the ability to know how to gingerly remove and replace delicate connectors(particularly the flex cable), will be able to install one of these. If other smart people help write/port the firmware, they also won't have to know anything about firmware programming either. There's still the host side stuff (slicer, etc), but I'm thinking of leveraging Python to make something that works a little better.

So... This post covers the "Why" Next I'll get a little more into the "What"

Since i'm pre-answering the 5W's+H. I'll cover the rest here:

Who? : Why, me of course. An EE with over 20 years in the field. I've done everything from ASIC/FPGA design, computer motherboard design and integration, high speed I/O design and characterization, and most recently embedded architecture and design.

How? : As an independant contractor for a few years, I built up an infrastructure of design and test software and equipment. I have a commercial license for the Eagle-Pro PCB design tools, a decent 200Mhz Oscilloscope with SPI/I2C/CAN/LIN/UART decode modules, and a 235Mhz State/2Ghz Timing Logic analyzer. I've also got some pretty good soldering skills "for an engineer", and a small "Pizza" reflow oven.

When? : Haha. I have a lot of projects, A... LOT..., but this one will be getting a lot of attention in the next couple of months because it's new, and I like new things? Unexplored territory, for me at least.

Where? : Does it matter? Well, I am in the USA, if that matters...

IMHO reinventing the wheel or in this case a control board is not necessary the best path.
If you want to help yourself and others take the current version or an older one  of marlin and change it t run on existing OS hardware. then do a tutorial to show people how to rebuild there machines.
or sell ramps/arduino boards.  pre loaded with firmware. Nothing saying you can not sell Open source but  you must have the source code open and available.

IMHO the people that were sucked into a cheap plug and play machine may not have the time money or technical experience to build there own machine. Or rebuild the one they just bought.
There are lots of good boards out there but cost more than the cheap davinci. so the old  conundrum how do you make good stuff cheap or at least afordable.

Good luck with your endeavor. .

Oh, I'm actually not attempting to re-invent. I'm attempting to innovate and make something that is less Hack and more drop in improvement. I start in a virtual vacuum so my thoughts are not steered intentionally toward what has already been done. Also, as many 3rd rate 3D printer companies have proven, when you just copy another product without fully understanding the nuances(control systems, fluid dynamics), you end up making and selling a product you don't understand, and no surprise, it ends up being considered "crap".

Atmel 8-bit processor based? No thanks. Also, why would I want to be just another tutorial writer that shows you how to wire up rats nest? Again, I don't know the full specifics or capabilities of the ramps based hardware, but with an 8-bit MCU, I'm suspecting you can't just dump a job onto it and have it print. It's likely getting spoon fed instructions from the host. Again, I could be wrong and I don't even want to know as I want to embark on this with no preconceptions. Otherwise, I'm just copying, not innovating. That's the real goal for me. I'm suddenly curious about 3D printer technology and precisely how it works. What better way to learn than by making a platform. Since mechanical fabrication and ID are actually costly, why not use this cheap, troublesome-for-many, Mini and use it as a starting point? The people wth those machines, I'm sure would love to have a drop in board and not have to hack together a rats nest of harnesses. A solution for non-hackers if you will.

Never said I wanted to sell firmware. I would only sell the hardware. But I may develop my own set of APIs as well for myself or anyone else who may have innovative ideas they want to test out that don't fit in with the existing open source firmware platforms. Any engineer knows that there are potentially hundreds of ways to solve the same problem. I'm assuming we may not yet have found the best one for cartesian based 3D printing

Hence the drop in board. No rebuilding required. As far as cost, I'm hesitant to speculate this early in the project, but It will definitely not cost near as much as a new Mini. It will likely coat more than a Ramps + 4 Polulus, but should be competitive given the hardware features it will include.

Thanks , although it will take more time than luck, in this case. I kind of already have the hardware architected in my head...

The minimover app lets you set the machine to do PLA, ABS, and PETG. So again you technically are late to the game. All you are doing is just basically making an enclosed 32 bit machine such as my CT'c and the Azteeg X5.

IMHO if you are going to reinvent the the main board make it universal like the arduino Ramps so it can work  on any 3d printer.  I understand folks will have to work with the physical format a bit but we already have to do that with the ramps.

Marlin is already 32 bit comparable then  i is a matter of tweaking Marlin or repitier for the most popular printers. 
If i was developing a new board I woul make sure it is compatable with trinamic drives  they seem to be one of the up and coming technologies.

If you are anywhere close to Bel Air Md, come out to EERF and see what much of the rest of the world  is doing   http://eastcoastreprapfestival.com/

The minimover APP is nothing but an APP for your phone that allows you to buy blank NFC tags and program them with your desired settings and filament type. You then place it over the tag reader in the machine in place of the one on the spool. Then use the filament of your choice. There is no modification to the machine, no change in appearance or function or program. Just giving it a different tag to read.

Might be true, but I am pretty sure there are user doing ABS. Most people who buy these junk piles and decide to keep them usually print a new extruder and install a better hotend first thing. The stock hotends have a very well known history of constant jams. So you would most likely need to swap out your hotend as well in your project to be as fully functional as you want. Otherwise there is no real meaning to making an open source board since you would still be limited by the hotend.

If you want to design a board go for it . IMHO there is plenty of room for innovation. Just make sure you are making measurable improvements . This is a hobby how you go about it is your business. 
And do not take carl wrong he is just citing previous work  and trying to lead you away from pitfalls and redundancy.

Joe prusa has a a color changer built into his newest printer.

BNC sigma just released all the fies for there sigmax (Dual independant head}
And the folds at e3d are developing a 4 head tool change system.
And iirc the folks at ultimaker still have source files for there machines available.
you may want to take a look at this technology as well.

This is the beauty of open source you can improve on others work legally and help everyone in the process.

Whatever you decide have fun this is a hobby.