Setting dpi in Inkscape for ScanNCut Canvas

If your Inkscape SVGs are showing up in Brother’s Scan-N-Cut Canvas as 3% smaller than they should, you need to read this.

In an earlier post I wrote about the troubles some people (me) have with size issues when loading SVG files they’ve made in Inkscape into Brother’s ScanNCut Canvas conversion program. Inkscape defaults to 90 dpi, and Canvas defaults to 96 dpi, for some combinations of hardware and software. So for some unlucky folk, the sizes are off by 96/90 or roughly 3 percent.

Thanks to a comment from John Scibran, I was motivated to have another go at fixing the problem.

What do I need to change?

The correct way to solve this would be to edit the Inkscape configuration file units.xml. Sadly, both the 32 bit and 64 bit Windows versions of the current stable release of Inkscape just ignore units.xml. That is the problem.

Inkscape’s latest development build, on the other hand, applies units.xml just fine. So by editing the values in that file, I can get Inkscape to let one inch be 96 internal units. Then when I specify a one inch square in Inkscape, it gets written to the SVG file as 96 units square, which Canvas reads as being exactly one inch. QED.

The current development build for Windows at the time of writing is a file called inkscape_r13149-201403142012.7z. That ‘7z’ suffix means it’s been compressed with 7zip so you need a decompressor that understands that format. Once you decompress the .7z file, you can drill down to edit ./inkscape/share/ui/units.xml, and fix the values so they all use 96 dpi instead of 90 dpi.

Then you can run Inkscape from the Inkscape.exe file and check that your units work the way you expect them to.

What magic numbers do I need to use in units.xml?

These are the figures I’m pretty confident I’ve got right:

  • in    96.0
  • mm 3.779527
  • cm   37.79527
  • m     377.9527
  • ft     1152.0

These are the ones I’m not so sure about. For em, en and ex, I’m not sure how Inkscape uses them, so I can’t really test them.

  • pt   1.33333
  • pc 16.0000
  • em 1.06666
  • en 0.53333
  • ex 0.53333

If all this sounds too hard, or you don’t want to risk using a bleeding-edge development build, you can still use the simple workaround of scaling the whole SVG before saving it from Inkscape.

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Sharing and selling ScanNCut cutting files

Brother’s Customer Support people got back to me quick-smart, yay!

Here — for context — is the question I asked:-

If I create a project on ScanNCut Canvas, using entirely my own uploaded SVG files, and then download the resulting FCM file, does Section 5.2 forbid me to sell or give copies of that FCM file away? Even if they are entirely my own work?

Here is the reply from productsupport@brother.com.au:-

We checked with our HSM team – they advise as follows:

If someone has created a design and it is not copied from someone else’s design you can sell the design and share the design. This design that they create will belong to them

I don’t know what an ‘HSM team’ is, but I applaud their wisdom! Of course, this only applies when the design is all your own work, not if you include any of the predesigned stuff that comes with the machine. Permission to reproduce that would be a different issue, and one that I specifically did not ask about, to keep the issue simple.

So now I know I can freely give out or sell copies of my own ScanNCut-compatible Inkscape designs, in SVG or FCM format, without fear of lawyerly interference.

Thanks, Brother!

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ScanNCut Canvas Terms and Conditions of Use

I’ve signed up to use the ScanNCut Canvas web service. It lets you upload SVGs file then manipulate them as if on the bed of the ScanNCut, then download the cutting file in Brother’s proprietary FCM file format. It’s a workable way around the lack of direct connection between the ScanNCut and a PC, for people who prefer to design on a full-size monitor instead of a cell-phone display. It is a little fiddly, but it works.

However. The Terms & Conditions of Use concern me. Especially section 5: ‘Restrictions on Use’.

Section 5.3 states:-

5.3 Unless expressly set out in these Terms of Service, you may not assign, copy, create derivative works of, distribute, lease, loan, modify, pledge, rent, sell, sublicense or otherwise transfer, directly or indirectly, the Services, or any part thereof (including, but not limited to, the Content) to a third party. You are prohibited from reselling or acting as an intermediary or service provider for the Services or any part thereof.

It worries me that Brother may consider that the FCM file is part of ‘the Content’ of the service, since their software generated it, albeit from the SVG files I created.

If I create a project on ScanNCut Canvas — using entirely my own uploaded SVG files which I’ve created in Inkscape — and then download the resulting FCM file, does Section 5.2 forbid me to sell or give copies of that FCM file away? Even if they are entirely my own work?

That seems unconscionably harsh. And a great way to kill any chance of a vibrant community building around the machine. Surely Brother want people to love their machine, and build a giant public library of stuff to cut with it. Look at how important the Thingiverse community was to the success of Makerbot. So it would be stupid and self-destructive for Brother to forbid the transfer or even sale of such files. The more patterns people cut, the more consumables — mats and blades — they buy from Brother.

This matters to me right now because I was in the middle of setting up a public GitHub repository of SVG and FCM files from my experiments with Inkscape and the ScanNCut. Now I’m not sure that’s legally safe. So maybe I can only upload SVG files optimised for Canvas import, and let people do the conversions into FCM themselves?

I’m not even sure where to ask this question of Brother. Everything I try on their websites seems to assume I’m reporting a malfunction, and sending a message to technical support. So I’ve done that, even though I’m not sure how much an Australian sewing-machine support technician will know about the Intellectual Property decisions of a major multinational corporation. Maybe he/she will pass the question up the line and I’ll get an official answer.

I’m not holding my breath.

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Making ScanNCut Canvas designs in Inkscape

Before you get carried away using your Brother ScanNCut machine to cut out objects you’ve carefully designed in Inkscape, do this simple test * :-

  1. Use Inkscape to create a simple one inch by one inch square. Save the file as an SVG.
  2. Create a new project in ScanNCut Canvas. Import the SVG file from step 1.
  3. Click on the newly imported rectangle, and read the width and height dimensions from the screen.

If Canvas says the rectangle is 1.0″ by 1.0″, congratulations, all is well.

If, as I suspect from the behaviour on my machine, Canvas says 0.937″, then you have a problem. Anything you design in Inkscape and convert with ScanNCut Canvas will be exactly (90/96) times smaller than it should be. (My carefully designed watercolour filofax-compatible pages won’t fit on the ring-binders.)

A Simple Work-Around

Scale the whole object up (by 96/90, or 1.066666), either in Inkscape or in Canvas. Every time. :(

So What Is Wrong?

The simple answer is that SVG is a unitless standard. There is no information in an Inkscape SVG file that says what any given unit of length represents.

Inkscape defaults to 90 internal units per inch. When you selected ‘inches’ as your measurement unit, and created a 1″ by 1″ square, Inkscape converted that into its own internal units, and made it 90 units by 90 units. You can see this by opening the SVG file in a plain text editor. The width and height values are clearly set to exactly 90.

Canvas (at least on my machine) defaults to 96 units per inch. So when Canvas reads in a SVG file with a rectangle that is 90 x 90 units, it thinks of it as being just under an inch each way, since an inch square to Canvas is 96 x 96.

I can’t yet see any way to tell Canvas what units per inch to work with. I can see how to tell Inkscape to use 96 units per inch, it just doesn’t seem to work! There are two files (‘units.txt’ and ‘units.xml’) in the Inkscape system that supposedly let you set your unit relationships. Sadly, at least on my version of Inkscape on Windows 7, both of those files seem to be ignored in favour of the default values of 90 units per inch.

So until a better version of Inkscape comes along, or Brother gives us an Inkscape-friendly import option, we’ll have to manually scale things up by 96/90 each time.

* If anyone needs more detailed instructions on how to do this, tell me in the comments and I’ll write a more complete tutorial on getting simple Inkscape designs to cut on your ScanNCut. Right now I’m concentrating on learning enough Inkscape to make things look pretty as well as the right size :)

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Posts on creating stuff from my other blog

Since I’ve declared that Brazen Artifice is going to be about creating stuff generally, here are some links to posts – including 3D printing ones – from my other blog, Strangeness and charm.

A post on why most men don’t sew.

Undercoating 3D prints with acrylic paint.

RepRap Magazine for DIY 3D printing fanatics.

DIY sound synthesis with CMOS chips.

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Brother Scan-N-Cut and Expanding My Focus

As you can see from the date on the previous post, it has been over a year and a half since I last wrote a new post on this blog. Despite this, Brazen Artifice has been getting steady hits all this time, so I hope my ramblings have been useful to folks. But I’m ready to branch out. Please let me explain.

My 3D prints are not smooth enough

There are two major reasons why I haven’t been so obsessed with my 3D printer lately:

  • 3D modelling with open source software is hard to learn. That is only overcome with lots of practice. And I haven’t practiced enough because I lack motivation. And I lack motivation because …
  • the surface finish of extruded-plastic 3D printers is … um … characteristic. It is bumpy and ridged, like a topographic map cut out in layers. There is not much I can do to improve that without post-processing the prints – coating them with paint and texture compound and other messy manual things which are not easily repeatable.

So I’ve been looking for a way of crafting cool exotic-looking artefacts that requires less mess. I think I’ve found it. And I think it’ll integrate well with my 3D printer output.

Paper craft and manual die-cutting machines

Recently I met Chrissie, a lovely lady who is setting up a Steampunk-inspired clothing store in a town near me. I love steampunk and goth fashion and gadgetry. I love the brazen, happy I’m not mundane creative vibe. Chrissie asked me to 3D print some gear wheels for decorating her cool steampunk hats, which was no problem. She’s quite happy to do the messy paint application bit. In fact, she happily paints on people with an airbrush, so messy paint-on-fingers is second nature for her. She’s setting up a website to support her work, and I’ll add her to my blogroll when she’s ready.

When she saw the gears I printed for her, she had another request. She has a manual paper die-cutting machine, a Sizzix Big Shot. It uses a variety of dies and texture plates to cut or emboss flat things ranging from tissue paper to heavy card to thin metal like aluminium flashing. The results are really cool. She wondered if I could 3D print an embossing plate for her, with her business name printed small enough to fit on merchandise tags.

So I said “Sure, I’ll have a go at that!”

Off to teh interwebz, to find out what would work on her machine. Lots of watching YouTube videos of scrapbooking crafters using die-cutters. I’m a tool junkie. I could see the potential, but also the limitations of template based machines – you can only cut shapes you have bought templates for. One particular packet of templates in my local Spotlight store was over $150. Expensive. (No link because Spotlight’s web site is pathetic). Which is why Chrissie asked me to 3D print something that would have worked much better as a commercial template, except that no such template existed or ever would exist.

But wait there’s more (as the evil American-made infomercial YouTube videos would say. Grr. Not all internet research is fun.) I discovered an alternative to manual die-cutters.

There are electronic cutting machines.

Basically like an extrusion 3D printer, but in 2D and with a very small, very sharp knife instead of a nozzle. Computer-Numerically-Controlled Cartesian robots dedicated to cutting out shapes from flat surfaces. Astonishingly precise.

Sign writers use them all the time for cutting vinyl lettering and logos for signs. Advanced scrapbookers and card makers use them for cutting shapes for their saccharine-sweet photo displays. Some tabletop wargamers use them to automatically cut out the print-and-fold scenery and buildings for their miniature figures to fight around. Paper engineers use them for prototyping their popup card designs. OK, now I’m getting seriously interested.

At the high end of the market, these things can be huge and have seriously industrial-machinery prices.

Down at the bottom end of the market, things are getting really sophisticated, and cheap, and easily available.

Brother’s Scan-N-Cut Electronic Cutter

Cutting to the chase, I bought this machine over the counter from my local big-box craft and sewing store, Spotlight. Recommended retail price is $600 Australian, but the man who was showing it to me pointed out that as a member of their VIP Club loyalty program I was entitled to a coupon for 40% off the price of any one item. So the price to me was $360. Sold! (I think the coupon deal expires in 12 days.)

It was only released late last year, and already the interwebz is awash with videos and blog posts about it. It is marketed at scrapbookers and quilters, who want to cut out very precise shapes from paper, card, and fabric.

But it has much more potential than that.

  • It has a built in scanner, so you can scan your own hand-drawn designs, folding templates for packaging, clip art from books like Dover’s public-domain collections, paper dolls, or things you’ve printed off on a regular 2D printer. Then it’ll detect the edges and cut out the shapes.
  • You can design things in any software that can output vector graphics in SVG format (like my favourite, the open-source Inkscape). Then use Brother’s free-by-registration browser-based web-service ScanNCut Canvas to convert them to the proprietary format cutting files for the machine.

<RANT_MODE_ENABLED>

WTF? Yeah, it sucks that the cutting file format is proprietary. And that you can’t do the conversions on your own PC. And it really sucks that the web service won’t work in Firefox. I mean, how is that even possible! Firefox can do anything! I’ve had to install Chrome (from Google, the New Evil Empire) just to use this one feature. And you have to agree to Terms of Service to use this feature that should have come with the machine!.

I’m hoping Brother will see the light and realise that they can’t expect to be – and don’t want to be – the gatekeepers of what can be cut on my personal cutting machine. The smart move would be to make it as easy as possible for people to make and distribute cutting files, to build unstoppable community momentum.

What if their lawyers decide they need to implement some sort of Digital Rights Management system. Error 666: The submitted cutting outline is similar to a [Dalek | Transformer | Disney Character | Marvel Character | Weapon | Unlawful Sexual Act]. You have violated your Terms of Service Agreement. The Copyright Police of your Country of Record have been informed. Have a Nice Day.

The product manual has a small section titled Unlawful Use of Scanning Equipment, with a short “non-exhaustive” list of things which it may be unlawful to produce copies of. Like Immigration Papers and Currency!. I’ve never seen a scanner manual give a warning like that before. Just how stupid do they think their target demographic is?]

<RANT_MODE_DISABLED: RESUMING POLITE DISCOURSE>

So this is why I’m expanding the focus of this blog

As I said, I’ve never been happy with the visual texture of my 3D printed pieces from my RepRap printer. But I love the texture and appearance of paper cut-outs. Childhood memories of Asterix The Gaul cut-out villages probably had some influence here. And I love the smooth glossiness of photographic paper. So I’ll combine them all.

Imagine 3D automata – gear wheels and camshafts and conrods powered by hand cranks or electric motors or servo-motors or the wind – roughly painted in grungy metallic acrylics, with perfectly 2D printed cut-out decorative plates of Victorian clipart glued or bolted to the moving parts. The mechanical skeleton made of plastic, the skin of paper or transparent plastic or even fabric. Sounds like fun to me.

Now I love the name of this blog. I’ve used Brazen Artifice as my identity all over the web. I always like names to have multiple layers of meaning, and Brazen Artifice is all about creating boldly, and building fantasy, regardless of the opinions of others. I’m not going to give up using the name just so I can keep it exclusively for 3D printing.

So from now on, this blog is officially about the processes of creating stuff, no matter how I do it or what tools I use.

And if you subscribed to my blog feed because you are fanatically obsessed with desktop 3D printing, I hope you’ll still find useful ideas now and then. Because my 3D printer is one of my favorite tools. But honestly, since I hadn’t posted in 18 months, you can’t be any worse off than you were yesterday!

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3D printed bronze artefacts now commercially available

Despite constantly wishing for it (and even naming my blog after it), printing objects in metal is not possible on the sort of 3D printer I’ve built. But i.materialise.com has much more money than me, a much bigger R & D budget, and much more expensive printers. They can print stuff for us in BRONZE!

I can design something in free software (Blender, OpenSCAD, FreeCAD, or TinkerCAD, for example), iteratively print prototypes in plastic on my printer, and then send the perfected digital model to i.materialise for them to print for me in bronze! This is just awesome.

Check out the announcement on i.materialise’s blog, and especially look at the print of Whystler’s ‘Tiki Chess Queen’. Magic. I wonder what their prints look like in the unpolished state?

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