Hacking the Brother KM-950i

“Hack a knitting machine!” They said.
“It’ll be fun!” They said.

Well, I did get there eventually. But it was a battle just to get two-colour hacked knitting working (not of Mordor proportions, but still very big). I’d like to give you a quick introduction of the code and methods I used. I’ll be posting about upgrading to the multi-colour hack (ie, more than two colours) in the coming weeks. Stay tuned!

Back in 2013 when I lived in London I tinkered around with a Brother KM-950i knitting machine at the London Hackspace. Thanks to the awesome work by Adafruit there was a python hack available for the Brother KM-930e so I thought I could just dive in and make my own hacked knitting.

Cue proverbial rabbit hole.

Hacking a knitting machine involves talking to it using a modern day computer to upload and download knitting patterns from simple bitmap images. Think of it like turning a knitting machine into a printer. A very wooly printer.

While the Brother KM-930e hack got me 80% of the way to hacking the Brother KM-950i, there were a number of limitations I needed to address. I met the wonderful Sally Kentfield at the Brighton Mini Maker Faire who also hacks a Brother KM-950i but she prefers to use her husband’s GUI written for Windows. I opted to keep working on the command line Python hack as it works on any OS, being a Mac nerd myself. Also, command line > fun 😀

So my version of the Adafruit hack addresses:

  • A rewrite of writeSector to support the 32bit format of the Brother KM-950i (Brother 930e is 16bit).
  • Supply the blank pattern files instead of requiring them to be generated first. Thanks to Charles Yarnold we have the full set.
  • Support png file format.

You can find my code release here. Instructions for how to use it can be found on the Adafruit website.

The other challenge with knitting two-colour is the sheer learning curve with the knitting machine itself. You have to:

  • Find the right yarn – cone yarn 4ply or lower.
  • Setup the machine correctly – hello instruction manual!
  • Choose the right cast on and cast off methods – I cannot recommend Diana Sullivan’s YouTube channel  enough.
  • Choose the right colour technique to suit what you want to make…

Below are the fronts and backs of some sample swatches I made of the London Hackspace logo in four (very different!) knitting methods:

Left to right anti-clockwise: fair isle float pickup, intarsia, double jacquard, latched fair isle
Left to right anti-clockwise: fair isle float pickup, intarsia, double jacquard, latched fair isle

I lean toward double jacquard as my preferred method these days (thanks Sally Kentfield!) for its speed and flexibility, but it’s not an easy method to master. If the machine isn’t oiled and setup perfectly, things go wrong very quickly.

A few geeky scarves I’ve knitted in double jacquard with the 950i hack:

Cellular automata 150 scarf
Dragon curve fractal scarf
Recursively grown tree scarf






I hope this post helps anyone who’s thinking of doing some hacked knitting of their own. Let me know how you go in the comments below! Enjoy.

6 Replies to “Hacking the Brother KM-950i”

  1. Hi, Just came across your articles on hacking the 950i. I ‘graduated’ to a 965 and 970 years ago and gave my 950i away. I wish I still had it because I have a friend who is constantly having problems with hers. It is mostly to do with transferring data to machine via the PPD or the FB100 disk drive. I wonder if you have ever encountered such problems or maybe using your mac has avoided such difficulties. I have been looking for a code for the 950i which explains error messages. Have you found them? There are a few in the machine’s manual, but don’t really give the answers I’m looking for.

    You know so much more about the workings of the machine’s computer than I will ever. Do you think my friend would benefit from using your hacking technique given that she is over 80 and still very sharp?
    PS I loved the dj scarves you showed on the site.

    1. Thanks for getting in touch, Elaine! Sorry to hear your friend is having trouble with the PPD and disk drive. I personally have never used either of these physical devices (I haven’t even seen any come up on the second hand market) so it would be tricky for me to debug them.

      What your friend would need to know is if the problem lies with her PPD / disk drive device, or with her knitting machine. Is she able to upload patterns to your 965 using the PPD / disk drive? If so that suggests the problem is with the machine. If she is able to use a different PPD / disk drive with her knitting machine that suggests the problem is with the devices. She may be able to get in touch with her local Machine Knitting Guild to borrow equipment to test this.

      I see no reason why an 80yo can’t learn my hack – assuming her 950i is in fit, fighting condition 🙂

  2. Hi Sarah!

    Your update to the code is very much appreciated! Trying to follow the adafruit tutorial to hack our Brother 950i and got stuck at the backup stage. On the Brother 930 they press 552 and then the ‘step’ key. As you probably know the 950i doesn’t have one of those.

    Do you by any chance remember how you got around this step?

    Any ideas are much appreciated!

    1. Hi Ellen,

      Wonderful to hear from a fellow machine knitter! Do you have a Brother 950i instruction book handy? You’ll find all the backup and load instructions in there. Specifically pages 97 and 98 are what you’re after, operations 552 and 551 respectively.

      Best of luck!

  3. Dear Sarah, the link where you mention the KM 950i in the second paragraph is broken. Would it be possible to get that information somewhere? I am considering to taking up knitting machine hacking and would love to read what is behind.

    Your star map is just awsome, thanks for that.

  4. Hi Judith

    London Hackerspace has recently moved locations and one of their systems that is still on-and-off a bit is their Wiki. It’s going through a bit of an upgrade itself.

    I’ve checked it today and that site appears to be up and running.

    Just in case it isn’t, the relevant links to get you further are probably:


    Best of Luck!


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