Building a Better Colour Changer – Part 3 – Revising the design

Well, it’s been a while, but it’s well past time we had another look at the continuing saga of Circuit design and Colour Changers.

The good news is I haven’t been idle and now we’re up to like prototype 5.  The bad news is there’s still a bit to go before it’s reliable and repeatable enough that we can sell them.

Close though, I think we’re on the last but final!

So, as to delays……

One of the big problems with trying to capture a design process from start to finish is you end up with a hell of a lot of footage.

Turns out, editing hours of footage in to a watchable 5 to 10 minute video is something I suck at.  Inevitably when I promised myself I’d do it I sat down and promptly continued the design process again.

Which of course meant I now had even more footage.  Anyone who does the maths can see the problem with this.  So many hours of terrible, boring footage.

So here’s a peak at version……3….. I think.  Click on through for some of the videos I did actually did manage to finish!

I’m much better at Renders than Photos.

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Building a Better Colour Changer – Interlude – The KRC-1000E

Just as a little break from your regular program, I thought I’d talk about the $600 commercial alternative to our prototype.

The KRC-1000E is the rather catchy name for this unit, and my searching on the internet seems to suggest that it was most commonly purchased with the Brother KH-970.  This makes sense because from what I could find you can’t really program the unit as such.  There is simply a cable that plugs in to the KH-970.

Probably a good thing we didn’t spend any money on one for our KH-950i then.  It almost certainly would have been wasted money.

So, lets have a little look at what design decisions were made by a Japanese engineer in the 80’s vs an Aussie hacker in 2017.

So that’s what they look like! Thanks random internet search!

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Building a better Colour Changer – Part 2 – Firing the Lasers

Previously on “I’m cheating on my Colour Changer with a half made prototype”………

My first post on this topic was devoted to the Digital Side of designing a part.  It had lots of images, a fairly waffly bit in the middle where I admitted I hadn’t remembered to take images or notes and ultimately stopped before I put the rubber to the road.  What a cop out.

In this second part, there is still a bit of digital talk while I go through how I get my digital design from farm to table, but there’s going to be a hell of a lot of table too.  There may also be mixed metaphors.

I should also warn you, this is a bit of a long one.  On reflection, it should have probably been two posts.

This post contains 5 chapters (or steps, as it were):
In Step 1, I go in to a bit of detail on the digital steps I use to get to physical.
In Step 2, I put all the pieces together.
In Step 3, I give the project some smarts.
In Step 4, I attach it to the machine.
In Step 5, I cover some of the “corrections” I had to make.

As modern makers we’re really only presented with two approaches when turning our digital ideas into a physical reality,  Additive manufacturing and Subtractive manufacturing.  This project would suit either, I could have 3d printed these parts, CNC milled them or Laser cut them out of stock.  All are tools I have available fairly readily at the Connected Community Hackerspace here in Melbourne.

I guess I like the idea of vaporising plastic though, because friken laser beams is where I went without even a thought.

Hypothetically I could put lasers on this…..Stretch Goal?

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Building a better Colour Changer – Part 1 – Designing hardware

“Can we make an automatic colour changer?  And can we do it cheaper than $500.”

I think Sarah posed this to me as a bit of a challenge, coupled with a desire not to spend $500+ on a yet another add-on for her knitting machine.

Like a lot of things, I think the answer is “Maybe…”  I mean, I’m fairly confident, but as this is an ongoing project I’m still a little unsure.  Still, the render looks good, so that’s something!

Seriously, I’ve seen Kickstarter projects that don’t look this slick.

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Algorithms of Multi-Coloured Knitting

I’ve already posted about hacking a knitting machine to accept multi-colour patterns. Today I’d like to expand on that with some work I’ve done recently to improve the multi-colour algorithm.

When I knit in multi-colour I use a method called Double Jacquard. This involves the Brother KM-950i, ribber KR-850 and colour changer KC-900.

Different coloured yarns are held in the colour changer on the left. Moving the carriage right with one coloured yarn will simultaneously knit the yarn into the front (knitting machine bed up top) and back (ribber bed down the bottom) to create double-layered knitting.

The result is a multi-coloured pattern on the front and a simple pattern called Birds Eye to tie all the loose yarn together on the back.

Knitted pattern on the front, knitted birds eye on the back and purls in the middle. I also sell these personalized baby blankets on Etsy.

But we can do better than this.

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Hacking the Brother KM-950i to Knit Multi-Colour Patterns

I’ve previously discussed hacking the Brother KM-950i. The major limitation to this work was the hack only supported two-colour patterns. That’s like having a black and white printer when what I really wanted was a colour printer!

Two-colour patterns are quite simple. Each knit is represented in binary (0 or 1) for the two colours.

Output of a two colour pattern

So how could this possibly support multi-colour? It wasn’t until 2015 (2 years after my initial fork of the Brother KM-930e hack) when I had my first epiphany and a year later in 2016 when I actually knitted a multi-coloured thing. This upgrade to the original two-colour hack has been several years in the making!

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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.

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