Cockpit Clearances

By Patrick Fenner | Published 11th May 2012

Designing a cockpit to accommodate a range of rider sizes is more complex than laying out the controls to fit one rider; especially having a steering wheel control for such a reclined operator instead of underseat/tiller steering or a moveable yoke.

Rider Clearances

Rider Clearances

To account for different height riders while still keeping the rider’s eyeline above the height of the bulkhead, the seat back reclines, pivoting near the hip joint. All of the swept area must be clear of any other objects. Below the body swept area is space usable for luggage, except where the chain passes through.

To cycle, there has to be room for the rider’s legs to move as they pedal, so the swept area of the rider’s thighs has to be kept clear; the rider’s legs mustn’t hit the bulkhead, nor the steering wheel. Position of the steering column is not affected though, as the rider’s legs will pass either side of it.

Having a steering wheel in the cockpit with the rider in such a reclined position presents a trickier packaging requirement then underseat steering. Not only must the wheel be clear in the straight ahead position, it must also not interfere whilst turning, including the protruding brake levers.

As the body area pivots close to the hip position to accommodate different height riders and the wheel has no variation of position, the best position for the wheel is directly above the rider’s hips. Height of the steering column must be set so the wheel doesn’t impact the rider at the bottom and doesn’t hit the screen (with clearance for the rider’s hand) at the top. A lack of steering wheel adjustment means that there will be a variation in hand position depending upon rider height.

The low height of the cockpit area also means that full steering lock (>±90⁰) may bring the bottom of the wheel (and brake lever) close to the rider and the top of the wheel will obscure some of the rider’s forward vision. Though this isn’t too much of a problem, as full steering lock will only be useful at very low speeds (e.g. for parking or turning round) when the speed of reaction for braking is less critical. All normal riding should need much lower steering wheel angles.

Posted in Atomic Duck | Tagged , , | Leave a comment | Short URL: http://def-proc.co.uk/b/abfkb

Git Un-Merge

By Patrick Fenner | Published 4th May 2012

When I last merged a development branch of add-rel-lightbox into the master branch and realised that I’d not finished testing the changes, it was off to the internet to find out how to undo a merge. After a couple of goes at git revert -m 1 refused to do anything, and a little more searching, I found out that there are two types of merge: a Commit Merge and a Fast-Forward merge.

Once it was clear what happened during a merge, it was much easier to see how to go about undoing the change.

Commit Merge

Commit Merge

Commit Merge

When development has taken place on both branches before the merge operation, git has to create a new commit that mixes the changes.

Git will automatically try to make a commit, but using git merge -n (branch_name) or having merge conflicts will leave you to make a manual commit.

Fast-Forward Merge

Fast-Forward Merge

Fast-Forward Merge

If there’s only development in one branch, then when you make the merge, git will just update the head position for the receiving branch. The merging branch is then a sub-set of the history if the recipient branch.
Continue reading »

Posted in Computing | Tagged | Leave a comment | Short URL: http://def-proc.co.uk/b/qjfpg

Ce n’pas une entrée de blog

By Patrick Fenner | Published 27th April 2012

It’s crunch time for thesis revisions this week, so there’ll be no blog post.

Except this one. Which isn’t one.

Back next week.

As in: The Treachery of Images

Posted in Deferred Procrastination | 2 Comments | Short URL: http://def-proc.co.uk/b/yanyu

Dotsies on your Reader

By Patrick Fenner | Published 20th April 2012

Dotsies is probably the Dvorak of fonts — in a good way, of course. It’s better because it’s more compact; but they are both difficult to learn, very few people can use them well, and there’s no incentive to start learning them other than “they are better”. Though Dotsies is part of The New Aesthetic, so it could thrive. [I'm typing this with a Colmak keyboard layout!]

But, if you’re going to the trouble of learning a new skill, then you’ll want a way to use it in practice. Online, there’s the Dotsies reader and the bookmarklet; but as there are no books published in Dotsies yet, changing the font on some ebooks might be a good start. After all, Dotsies is designed for maximising screen estate.

These instructions are for a Sony PRS-505, though it should work for most Sony Readers, I’m changing fonts book-by-book, so there’s nothing scary like firmware flashing. These instructions use Calibre for the conversions, so you’ll need DRM-free ebooks; I’ve used the file from “A Princess of Mars” that I’ve used previously.

Dotsies on an ebook Reader

Dotsies on an ebook Reader

Continue reading »

Posted in Other Topics | 2 Comments | Short URL: http://def-proc.co.uk/b/bkmmp

add-rel-lightbox now using Simple HTML DOM

By Patrick Fenner | Published 13th April 2012

When I first mashed together add-rel-lightbox, I used regular expressions to control and replace the relevent parts. This was my fault. Regexes were the only tool I had. It was a bad thing. Parsing HTML with regex is wrong.

[…]using regex to parse HTML has doomed humanity to an eternity of dread torture and security holes using regex as a tool to process HTML establishes a breach between this world and the dread realm of c͒ͪo͛ͫrrupt entities (like SGML entities, but more corrupt) a mere glimpse of the world of reg​ex parsers for HTML will ins​tantly transport a programmer’s consciousness into a world of ceaseless screaming, he comes, the pestilent slithy regex-infection wil​l devour your HT​ML parser, application and existence for all time like Visual Basic only worse[…]

The whole StackOverflow answer makes a very sane and reasonable argument for not using regexes to try and parse HTML, so I’d recommend taking a look. However, if you’re not totally convinced, perhaps you’d prefer Bring Me Your Regexes! I Will Create HTML To Break Them!. That did convince me.

PHP does have a DOM extension, so it’s possible to use that to operate on XML elements, but it all looked to complex and involved for me to find a way in, but S.C. Chen’s PHP Simple HTML DOM Parser made the whole thing fairly straight forward.

The whole, commented, revised code is up at Github, but while I have a few regular expression match calls, they’re all operating now on the returned HTML attributes from the DOM parser, instead of trying to pull put the details from raw HTML.

After including the Simple HTML DOM library, the script:

  • Finds any link wrapped images.
  • Checks that the link points to an image file and doesn’t have a “lightbox” relation proterty applied. (as a side effect, any link with rel=”nolightbox” will also be overlooked)
  • Adds the popup caption from the database if it’s a single hosted image, or part of a gallery.
  • And finally, adds “lightbox[post-(post_id)]” to the rel attribute of the link

This should be more robust than version 0.3, although I haven’t seen any problems with that version in practice. However it does also make the code much easier to extend or expand in the future.

While I’ve been meaning to do this for a while, I’ve only just got round to coding it up. Everything in the “DOMcontrolled” branch looks good in the initial testing, so the version is currently set at 0.4.RC1, which I’ll roll out after it’s survived more prodding.

See also: Coding Horror > Parsing HTML the Cthulhu Way

Posted in add-rel-lightbox | Tagged , , | Leave a comment | Short URL: http://def-proc.co.uk/b/uqfrw

Kingsbury K-Drive

By Patrick Fenner | Published 6th April 2012

The video below of the Human Power Team‘s elliptical drive system is the first time I’ve seen a non-circular power system in motion.

Functionally identical to the “K-Drive” of the Kingsbury Kingcycle, the mechanism is first described in 1890, so it might be more correct to call it a “Vietor Elliptical Drive”, it’s best known as the “Kingsbury K-Drive” from Kingcycle’s successful use of it the early 1990s. Continue reading »

Posted in Atomic Duck, Open Source Engineering | Tagged , | 2 Comments | Short URL: http://def-proc.co.uk/b/oxgzp

Making it Better—Open Source CNC

By Patrick Fenner | Published 30th March 2012

CNC routers and laser cutters are now common machines. Not ubiquitous, like a hammer, but they are common enough that I can send a pattern for cutting, or visit a lab and operate one myself. However, they still remain expensive, industrial machines.

Makerslide took the idea of a standard aluminium extrusion frame system, used for building custom frame structures, and added a v-profile to make it usable as an accurate linear bearing system. And created the necessary combining hardware, v-pulley wheels, mounting plates, eccentric adjusters for the pulleys and belt drive attachments to create a linear bearing system that can easily be used for motor control.

Makerslide is intended to be a standardised solution to linear drive systems for the home builder. Aluminium extrusions need a certain amount of capital to produce, and since Makerslide successfully raised five times it’s goal, is now manufacturing and shipping rails and the other associated parts.

Then, a month after Makerslide’s Kickstarter success, the Project Shapeoko’s $300 CNC machine was funded. And a low-cost CNC machine that is now available as a kit. It uses the Makerslide system as it’s major structral components to keep costs low, while allowing good accuracy; and this means that it’s now possible to own a desktop CNC machine for as low as $338 (as of time of writing).

So with aluminium extrusions extended to create linear bearings; in turn extended to a complete CNC platform; run with open source motor controllers, built upon the open source Arduino board and powered by open source CNC controller software: the cost of a CNC machine is falling steadily into the realm of the hobbyist.

Posted in Deferred Procrastination | Leave a comment | Short URL: http://def-proc.co.uk/b/aoonj

LaTeX-SVG-to-PDF as git submodule

By Patrick Fenner | Published 23rd March 2012


I’ve mentioned previously that I’ve got a large project in \(\LaTeX\) and while I was using Dropbox as a pseudo revision control and external backup. However, I’ve since been persuaded that a proper revision control system with meaningful commit message is a better way of tracking progress and changes.

So I’ve moved the project to git, set up a remote repository for synchronisation and backup and started making commits. Then I realised that my symlinked makefile was only included as a link in the git repository. This is different to Dropbox, which would synchronise the contents of the linked file.

Instead of just having a symbolic link to a file that might not exist on another computer, I needed another way of including the file properly. I could just drop the file into the git repository, but then it won’t update if I make any changes to the main project files. If I make use a hard link then git will include the file contents, but then it’s possible to make tracked changes in the \(\LaTeX\) project repository by changing the file in its original repository — and that is just a recipe for confusion.

Instead, it’s probably better to include the makefile repository as a git submodule and then symlink into the sub-repository’s makefile. That way, the exact commit information is included in the parent-repo, but the sub-repo can be updated, changed and branched as needed.

To do this:

cd ~/LaTeX/project/folder
git submodule add git://github.com/DefProc/LaTeX-SVG-to-PDF.git
rm makefile # if you already have a makefile in the directory
ln -s LaTeX-SVG-to-PDF/makefile makefile
git add .
git commit -m "added LaTeX-SVG-to-PDF as submodule and linked to makefile"

There are a couple of complications to this method:

If you clone a new local repository of the parent project then you also have to initiate and update the submodules to add their contents.

git clone my@server:git/project.git
cd project
git submodule update --init

And you also need to be careful of including changes to the sub-repos. If you git add . && git commit to the parent-repo with uncommitted changes to the sub-repo, then you’ll be telling the parent-repo to use that dirty head on every clone — not good.

If you’ve made changes to the sub-repo, make sure that these are committed (and pushed) before commiting on the parent-repo.

LaTeX-SVG-to-PDF makefile project source and download.

Posted in LaTeX-SVG-to-PDF makefile | Tagged , , | Leave a comment | Short URL: http://def-proc.co.uk/b/ejfue

Print your own John Carter

By Patrick Fenner | Published 16th March 2012

I’ve been coming across quite a few references to Edgar Rice Burroughs’ book “A Princess of Mars” over the past couple of months, from being the story behind Disney’s upcoming film “John Carter of Mars”, to being a classic science fiction text that has inspired many creators.

So when it appeared again, as I was looking at buying Peter Cline’s book “Ex-Heroes” and reading the authors “ranty blog” that became enough repetition for me to bite. And as I was already buying one book on Amazon, I took a look at what dead tree versions were available for “A Princess of Mars”.

A few, it turns out. There’s a Disney Books edition with all the nice typesetting, a Simon and Schuster published collection which makes very clear that it’s not endorsed by the Edgar Rice Burrows estate, an edition with a Frank Frazzetta cover and more.

And then I realised that the book was written long enough ago that is fallen into the public domain. And that I already had an ebook version from the Gutenberg Project that I hadn’t read. This means I didn’t even have to wait for delivery, as I already had paper, ink and a printer sitting right next to my desk…

So after converting from ePuB to HTMLZ with Calibre and running the resulting index.html file through pandoc; I ended up with a remarkably clean \(\LaTeX\) file ready for formatting.

Even better, by the power of public domain and a competition based market place, I can offer the resulting, print ready, pdf for you to download and print off at home in a variety of page formats, free of charge.

Or just buy a pre-printed copy from a bookstore.

Or get a copy of the free ebook.

For single sided printing on A4 or letter paper:

A Princess of Mars (A4 Single Sided)

A Princess of Mars (letter, single sided)

Or double sided if you have a fancier printer:

A Princess of Mars (A4 Double Sided)

A Princess of Mars (letter, double sided)

It’s a big print, ≈165 pages (85 sheets double sided) so I’ve bound my copy with binder clips with the levers removed to make a book-like document.


I’ve left the Gutenberg Project Licence text attached. I could remove it, but it seems a little churlish — after all they did all the hard work, I just formatted it. One of their licence requirements is to give a link to a plain text copy for any compiled formats, so here is the download link for the single \(\LaTeX\) file and cover image.

It might be worth reiterating that the copyright on “A Princess of Mars” has now expired, and the work is in the public domain. This means you, I, and Disney can copy, transform and combine to our heart’s content.

Posted in Other Topics | Tagged , , , | Leave a comment | Short URL: http://def-proc.co.uk/b/eknhl

Putting Dotfiles in Git

By Patrick Fenner | Published 9th March 2012

If you’re a Windows user, then you probably won’t have come across dotfiles before. For Mac (a form of Unix) and Linux users, dotfiles hold certain environmental settings and customisations, so if you work on more than one computer, you might like a way of sharing your preferences between them.

And they’re called “dotfiles” because any filename that begins with a full stop (period) is a hidden file in Unix, Linux, etc.

Since I started using vim for text editing and made some tweaks to my .vimrc file and added some plugins (pathogen, vim-fugitive and vim-latex), I quickly realised that I’d like to be able to take these settings with me, so I started looking at keeping the configuration files in version control.

Now there are any number of dotfile repositories on github and many, many guides on setting up your dotfiles with git, but I noticed that there were two main arrangements, but the pros and cons of each arrangement seemed to be spread out around the web.

  1. Put your whole home directory into revision control and track only a few files.
  2. Add a dotfiles subfolder in your home directory that is under version control, move in the files that you want to track and symlink them back to the original location.

Which one to choose? I tried both, but I like the second best.

Why? See below: Continue reading »

Posted in Computing | Tagged , , | Leave a comment | Short URL: http://def-proc.co.uk/b/mgspv