Show HN: Printercow – Turn any thermal printer into an API endpoint • Hacker News Board

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#81

Post by namero999 » Tue, Jan 21, 2025, 9:02 PM UTC

mrtksn wrote: post #74

Okay, the question is: Can it print with a Cat Printer? You know, the cheap toy-like printers? Like this: https://www.amazon.co.uk/Portable-Instant-Bluetooth-Wireless... I was trying to hack mine to use it with an app I want to create for personal use. Currently only prints using the official Fun Print app over a bluetooth connection. There are projects[0]that are supposed to work with a cat printer but mine specific…

Funny, just today I finished reversing a similar toy printer, the "bear" printer, not the "cat" one, and writing a driver/library for it in Rust just for the sake of finally learning a bit of it.

Looking at the code you shared, it seems like the cat has quite a different protocol than the bear. The opcodes seem different, and there seems to be some sort of crc happening that is completely absent in the bear. So I doubt my code will work without major adjustments.

In case you missed it, the first link you shared also has a "test unknown printer", so maybe yours is just a minor hardware iteration but might work nonetheless!

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#82

Post by xp84 » Tue, Jan 21, 2025, 9:11 PM UTC

lionpixel wrote: post #4

ksdme9 wrote: post #3

The whole twitch demo thing is genius and fun. Do printer companies usually not provide a first party apps or integrations?

When it comes to regular ink/laser printers: yes. When it comes to thermal printers, you are normally left alone with just the ESC/P protocol, plus most printers handle the commands in a different way. The way I solved this issue is to write an image buffer directly to the printer, circumventing the protocol and always ensuring that prints look the same regardless of the printer.

Are prints as clear and as fast printing everything as an image? Or are there some tradeoffs?

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#83

Post by xp84 » Tue, Jan 21, 2025, 9:15 PM UTC

echoangle wrote: post #10

lionpixel wrote: post #9

Earlier quoted context omitted.

Indeed. But there are some good BPA-free alternatives on the market

Is there any way to verify that without getting a Lab to do an analysis? I'm not sure if I can trust stuff labelled BPA-Free from Amazon for example.

Yeah I would assume that given how easy it is to start a new Amazon seller account and how impossible it is for some random seller in China to face legal repercussions from the US, the likelihood of finding an “_____-free” item to actually be made of whatever the cheapest and most readily available formulation is. (Including the _____), is pretty high.

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#84

Post by RadiozRadioz » Tue, Jan 21, 2025, 10:34 PM UTC

Interestingly I made this same exact thing a few years ago for a company I worked at.

Raspberry pi connects to the printer, pi runs a daemon, Daemon connects to a central server and downloads stuff to print, server runs an API with a friendly endpoint.

Difference with mine is that I used CUPS on the pi and generated PDFs for it. I supplied a custom PPD to make the printouts extra crisp, but other than that the OS handled it for me. What I wrote was little more than a PDF generator and a basic spooler.

I can attest that this method is very reliable, if you're looking for confirmation that this architecture can be used in production.

I do question whether it's worth paying for this as a SaaS though. Speaking as someone who has built this, I'd probably build it again and it doesn't take long to get "good enough". The bulk of my time was spent on improving the printout quality from the built-in driver. Which was fun but unnecessary.

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#85

Post by PokeyCat » Tue, Jan 21, 2025, 11:22 PM UTC

Toxygene wrote: post #80

Very cool. I created a thermal printer project a few years back that prints (low quality) proxies of Magic: the Gathering cards based on the rules for "Momir Basic". It was a fun project, though formatting images to work with the various ESC/POS image formats was quite a challenge. https://magic.wizards.com/en/formats/momir-basic https://imgur.com/gallery/momir-basic-irl-g2S3hJT

Very cool! I did a similar project with an accompanying app that connected to one of these inexpensive printers over Bluetooth in order to play a Discord, Lord of Disharmony commander deck in person.

The portability of the whole setup makes it easy to bring to an LGS, it's always a treat to see people's reactions when I pull out the printer and they see how the deck works!

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#86

Post by e28eta » Tue, Jan 21, 2025, 11:58 PM UTC

long shot: I’ve got a USB-based ESC/POS printer, but couldn’t get my mac nor RPI to recognize it as a printer through CUPS.

The printer shows up in the USB tree, but (maybe?) needs a driver to be recognized as a “printer”? I was trying to follow tutorials that treated it as a line printer, but unsuccessfully.

Any idea how much luck I will have if I try this out? Does this project rely on working drivers? Or does it handle the raw USB communication?

It’s an IBM-branded Type 4610 Model TF6.

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#87

Post by heeton » Wed, Jan 22, 2025, 12:17 AM UTC

kube-system wrote: post #25

heeton wrote: post #14

Earlier quoted context omitted.

That study looked at 6 similar plasticizers. The alternative chemicals for thermal paper are totally different. That's not to say that they are guaranteed safe, but that study is inapplicable. E.g. one type of paper claims to use Ascorbic Acid (vitamin C). No idea what else is in it of course, but it's not a BGA-analogue plasticizer.

> E.g. one type of paper claims to use Ascorbic Acid (vitamin C). No idea what else is in it of course, but it's not a BGA-analogue plasticizer. How would you know it doesn't, if you don't know what's in it? Regardless, my point is that many BPA-analogue containing products advertise their BPA-free status.

My comment was that BPA is not used in thermal paper as a plasticizer, which that linked study was examining.

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#88

Post by heeton » Wed, Jan 22, 2025, 12:23 AM UTC

d1sxeyes wrote: post #35

heeton wrote: post #13

Earlier quoted context omitted.

Extremely shortsighted take. I currently use a local LLM to scan my notes, meeting transcripts, todo list and calendar. I currently have an iPad that displays some items (e.g. if I have important personal tasks to do today that I might have forgotten) and I would love it to be printed out like this. Nothing to do with generating novel text, it's just used as a flexible API to my existing text and items.

Is that handwritten notes? What LLM are you using for that and what level of accuracy do you get?

No, just computer notes. Currently on llama3.2 text-only 3B, running on an M3 Macbook Pro.

Accuracy is good for my limited use case (extracting context, giving me links and reminders).

It's not yet good enough (for me) at summarising larger notesets, it might miss out useful / pertinent things in a way Claude does not.

I'd also like it to be better at inferring partial context from audio transcriptions. But hey, it's an open source 2GB model running on my laptop, it'll get better.

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#89

Post by freedomben » Wed, Jan 22, 2025, 12:31 AM UTC

This is a great idea, and it looks like you've done a great job! I share your enthusiasm for these printers. I have a Rongta receipt printer sitting on my desk that I like to play with :-)

I have a business usecase for something like this (now that Chrome doesn't allow printing to ESC/POS), and exposing the printer interface as an HTTP API is a clever and great solution! But, sending the data through a third party is a complete no-go for us for reasons of compliance. For this architecture to work for us we would have to host it on our VPN and serve it from our own domain as our customers have a strict whitelist.

As cool an idea as this is, honestly though I don't think this should be a SaaS. Certainly it doesn't fit the typical mold of SaaS where there's nothing to install because it's all delivered through the web. Given you have to install a local Pi or other, you lose all the benefits of SaaS and also incur all the downsides of SaaS. It feels like it was shoehorned into a SaaS because otherwise it would be very hard to monetize. I don't blame you for that because it is indeed a hard problem to figure out how to get paid (in fact I've abandoned good ideas prevously because it was either SaaSify something that shouldn't be a SaaS or else face huge obstacles getting paid), but I wanted to share my thoughts honestly.

Re: Show HN: Printercow – Turn any thermal printer into an API endpoint

#90

Post by JJOmeo » Wed, Jan 22, 2025, 12:49 AM UTC

This could be plain software on any computer with network and a serial port. Not sure if the product is tied to RP hardware but it certainly wouldn't have to be. I work with thermal printers controlled by significantly less powerful hardware still running Linux, and still easily hit physical speed limits. I'd rather see this as a pure software daemon that can run anywhere.