Inkjets are actually really fascinating technology. If you squint a little it's like a CRT monitor that sprays ink instead of electrons. But for the average consumer they're just not worth it except in niche situations. I have a black and white ~~inkjet~~laser printer. I printed a page for the first time in 7 months yesterday. It printed perfectly the first time. No print heads to clean, no dried ink, nothing. It just works. Hard to compete with that.

I often wonder why people think they have to start from scratch and build an entire printer. Few people's printer problems are printer problems. They're usually problems engineered into the printer at the firmware level. The stuff that actually does the printing is dumb components that do whatever you tell them and mechanical engineering someone else has already done for you. Right down to the commercially available connectors that connect the dumb components to the broken-by-design control board.

Why remake the entire printer instead of just the control board?

Not to mention, you can add features that should be there on every printer but that no manufacturer has considered including. Like an emergency stop feature for when the printer gets a corrupted print job and starts printing out as many blank pages as it can with the occasional page with a single line of gibberish. Tell it to stop, and it actually stops and spits out whatever sheet of paper it's working on at the time. No holding down the power button. No clearing the jam that results. No uselessly canceling the job at the source. No questions asked. Just stop printing, clear the paper path, ignore the rest of the job, and lie your ass off and say you finished the job so no software gets any funny ideas about resending it.

Pretty sure you can find schematics to make a BT100 printer somewhere ( https://en.wikipedia.org/wiki/BT100 ). You wouldn't want to, but you can.

More seriously, I think the main problem is simply achieving a usable resolution for a 3D printer is way easier than for a 2D one. Hence why the real hard part (the print head) is using an HP cartridge instead of rolling out their own here. Given my quick googling, it's usually that or building an inaccurate pen plotter and calling it a printer...

Tons of 2d printer challenges.

The ink jet head at a resolution of <50um (as opposed to 3d printing resolution of usually >200um)

Combined with printing on many different surfaces and such: cardstock, printing paper, glossy, weights, stickers, etc...

This project "cheated" (I mean that not in a negative way, tons of open source hardware projects use proprietary components, my own does too for now) by using a proprietary ready-mades printhead, which saves the most cost and effort of the whole machine, and is the component that causes the most issues, generally.

I definitely want to try this out too.

Can you elaborate on the paper alignment challenge? Why is it difficult to do and why this roll solve the problem?

You can follow the project here: https://hackaday.io/project/202990-open-printer

Exactly stop looking at it as a bunch of faults, look at it as a proof of concept. The bubblejet ink -- I'm sorry, the inkjet bubble -- will pop eventually!

I believe the idea is you would refill the original cartridge. You can get refill ink and a type of syringe to put ink back into the original cartridge. Those have been available for a while.

Actually kind of a necessity.

With an inkjet, most of the 'difficult' engineering and manufacturing is in the print head. The rest is just a basic x/y bot to move the head and paper around- easy engineering and manufacturing. They use someone else's print head so they get around all that. That makes this a fairly easy design- just figure out how to trigger the cartridge nozzles when the head is in the right spot, write some code for rasterizing the image into print strips, and you're done.

With a laser, there's a lot more work. You need an entire optical system (laser, spinning mirror, etc), you need high voltage stuff to charge the drum, you need a high wattage heating coil for the fuser, etc. There's a lot more engineering and coding work involved and more manufacturing also.

Bring back dot matrix printers and continuous feed paper!

So close, yet so far....

While the firmware could be using a classic software license, in the hardware world these licenses don't mean much. Afaik Creative Commons licenses are what's generally used for open hardware

It's open source. So even if it had it you could remove it.

What's this? I've never seen yellow dots on stuff I print

Edit: looked it up, intresting and definitely a bit disturbing from a privacy perspective. Particularly that it was kept secret until 2004.