Thursday 26 February 2009

RepRap Software

Over the last couple of days, I've installed the RepRap software on my tablet PC. Last time I didn't have much luck, but this time I've sorted out the Arduino issue I had before. The /dev/ttyUSB0 port has restricted permissions - you need to run the Arduino software as root to enable the 'USB' select. I'm not sure if it's a general issue or just on my laptop.

The Skeinforge scripts are a set of Python scripts that slice a model and write G-Code (text code to control a CNC/RepRap). I got them up and running and sliced some example files.

I'm not sure if I'm doing something wrong, but when I slice the example minimug.stl, I get longtidudinal slices (C-shaped) as it tries to build the minimug on it's side. There doesn't seem to be an option to rotate the file in the scripts.

I fired up AOI (Art Of Illusion) and built myself a replacement minimug oriented differently. When I pass it through the skeinforge now, it seems to slice into better slices (circles) as I expected. Here's a few layers:

You can clearly see the raft laid down underneath the object, the base of the shot glass and the circular layers building up. It looks like the walls will be 2 layers thick.

When running the code through ReplicatorG (to pass the code to a simulator or the real RepRap) it appears to draw over the outer circle several times. I have yet to test this out for real...

At least I know the toolchain to build an object, slice it, check the G-code and then attempt to pass it on works...

I'll try to build an object soon.

Jay Leno does 3d printing!

American host Jay Leno describes a commercial 3d-scanner and Dimension 3d-printer:
Jay Leno's Garage
It shows the scan/print process for copying a rare physical part, describes how a 3d-printer works, and shows off some very cool examples of physical prints.
A good primer on what the technology is in 5 minutes

Saturday 14 February 2009

Nuggets of truth

Just found this on B3ta. Made me laugh.
NSFW (sweary) How Not to fail at life

Does seem to contain some nuggets of truth that I agree with.

Friday 13 February 2009

Digital Footprints

Everywhere you go on the web, you leave digital footprints.
Every web site you access, you send your IP address, user agent (which browser), which page you want, when you wanted it - and most of the time this gets written to a log. No-one tends to ever read it, apart from counting up a few stats, and eventually the log gets rotated to long-term storage or deleted.
It's a bit like walking on a beach with a crowd - eventually your footprints get washed away, and unless someone is trying really hard to find you, it's quite difficult to get anything useful.

That's just to start with, though.
Every time you touch the web you're adding to the information trail.
Post on a forum, post your facebook status, update your profile, edit a wiki, even shopping sites tend to track your viewed items to identify your likes and dislikes.
Every single touch adds. And it's not just the text of what you post - you can infer a lot of information from when and where posted. Even what you don't do can provide useful info. If you're running a shopping site, and one paticular item is viewed a lot but does not result in sales, this could indicate that a competitor is undercutting you, or you need to change the description.

Be careful where you step!

Tuesday 10 February 2009

Google Stalking

On the flip side of my privacy discussion, I've had reasonable success tracking people down on the net: having done it a couple of times I thought I'd share my successes.

In these few cases, I spent a half-hour or so with google: most of the time, it was pretty easy to do, keeping potential matches and scanning through a lot of chaff, and building a consistent profile of the 'target'.

Case 1:
I wondered what kind of people were in the mod team with me? Starting from their forum handles, I google'd a few. A few had pretty common handles, but one had a pretty unique username. I chucked it into google.
This produced about five or six forum profiles. Most had almost no personal info, but one had a link with a real name, also pretty rare.
Running the real name through google produced some interesting results. Several hits were from a paticular country, which I already knew matched my target's country.
Then I struck gold. Google returned the website for a band, where the keyboard player had the target's name. Even better, there was a picture of the band at a practice showing the target. Some of the info about the band indicated that they were together at college.
Combining one of the band members and the target's name returned a word document containing a college class list including the two names. The country and area matched, so I was pretty sure it was correct.
This gave me the name of the college and even the class ID. Googling again, it returned a handy timetable of the lessons for the class including the lecture theatres, dates, and subjects.
To recap, from an 'anonymous' name and hidden profile on the original site, I was able to find a picture, real name, school and timetable. In theory, I would have been able to stand outside waiting for the target.
(I later sent the photo to my friend in an online chat session - he was extremely surprised as he wasn't even aware the band had a site!)

Case 2:
I was looking for an old school friend, someone who'd been to my primary school. Starting from Friends Reunited, she had an account profile there but hadn't checked there for a while.
On her profile, she mentioned that she'd contributed some research to a paticular wiki article and she now lived in London.
Checking out the wiki page, the history gave me the list of edits. Of the article, most of the text had been added at one paticular point by one user, and all subsequent edits had been spelling mistakes, rewording and grammar correction. I had a pretty good bet that the username who added the main chunk of text was my target.
This username had also been discussing edits on another page, which I found on wiki search. This new page also had edits by the user, and one of them linked to a flickr photo.
The flickr photo gave me a flickr username (different) but checking through the other photos by this user, and reading the comments, confirmed my suspicion this was probably the target.
Google then was able to give me the other places that this flickr username had been used. I concentrated on the forum hits that included photos from the flickr account and found a regularly used forum that contained several of the flickr links. The forum poster username was different again, but shared a common topic linking it to the other usernames.
The new forum was interesting: it was a 'local' forum for a paticular area of London, and was quite happy to give me a list of posts by a paticular user.
At one point, discussion had touched on a paticular local shop, mentioned in other posts by name.
This gave me the exact local area of the poster. Combined with a couple of the flickr photos of 'my new flat' and 'the park across the road', and the googlemap ariel photos, I tracked down the exact building.

I stopped then, because it was getting creepy and felt voyueristic. Total time : 48 minutes (including half-watching Eastenders).

This was a person who did not have a big online presence, used multiple usernames, and stuck to general internet saftey rules (no addresses or real names in profiles).

This method isn't guaranteed, and does depend on building a likely profile of the target, crosschecking with what you know. You also end up wading through lots of chaff, but if your target has a relatively unique name it's a lot easier. You can also cross-ref with the location (town, country) and anything else you know, such as hobbies or interests.

Happy stalking!

Thursday 5 February 2009

Online Privacy

I'm generally a pretty cautious guy with my online life. I've read the horror stories, seen people make *huge* mistakes and generally made a prat of themselves online (e.g. posting photos of yourself drinking when 'off sick', etc). So, although I've been using the internet in various forms since the late '90s, to start with I never had a blog, didn't have any online websites, and only communicated by e-mail. I was strictly a consumer only.

My strictly regulated privacy has slowly and gradually slid away until now, I'm posting a couple of times a day to random people I don't know via twitter (dave_renoir) quite happily. How the hell did I get from there to here?

The first step was probably forums. It started with one or two cautious posts, jealously guarding my email address, to stuff I really needed. One by one this crept up from a simple question and answer until I finally realised I actually sometimes knew more than some of the other regulars and started answering questions rather than answering them. In 2001, I got into building maps for Half-Life 1 and ended up joining a 'mod' team where I was introduced to the joys of chat rooms and direct messaging. I was still pretty cautious, and only chatted to a few people, but for the first time I'd given my real email address to someone I hadn't seen! The world didn't end, I didn't get hacked, and in fact, everyone I'd met was actually pretty nice (Hi to the T:FfF team!).

A couple of years later, I took up Aikido. I'd been to a several lessons and was pretty committed, so I set up a small website for the club ( I wrote up a few articles on the basics, a bit of publicity material, and really needed to post an email address so readers could ask questions. I took a deep breath, and posted my real address, waiting for the torrent of hate mail and spam that would inevitably follow.

I was pleasantly surprised. There was no increase in spam and no bad mail. Over the last 5 years, I've had about 30 polite questions which have been easy to answer and about 3 targetted mails from chinese martial arts maufacturers. I've only had one possible 419 scam, from 'the Nigerian National Judo team' wanting to hire our hall for the 2012 olympics.

The social networking sites started the same way, thin end of the wedge. I created an account on Friends Reunited to look up some old friends. Then it became a facebook account, just used to monitor and keep up with my family, who have adopted it wholesale. Even my mum and dad (silver surfers) have an account.

About this time, I started building a RepRap, and started this blog primarily to track my progress and to help anyone else building one. After a break to have hand surgery, I've started posting again.

I sat down and thought a lot while I was off - it was pretty much all I could do without my hands. I came to some conclusions:
  1. Most people are either pretty nice and polite or just don't care. There isn't a large pool of 'stalkers' waiting to catch the unwary.
  2. The 'signal to noise' ratio is so large on the net that only interested people are likely to find your postings.
  3. Only people I know are even likely to be interested in my rantings. And they're probably just being polite.
  4. Tracking down people on google is already fairly easy, and there's already enough there for a motivated user to track me down.
I came to the conclusion that there's not really a lot extra to worry about - the genie is already out of the bottle. I don't do anything that I wouldn't chat to a stranger about, and if they want to be bored by the geekiest nerd in existence then I'm quite happy to tell them all about it.

I might as well make the most of this new technology stuff. So I'll post more.

Wednesday 4 February 2009

Added feet

To avoid the rods scratching the table, I added some feet :-). I know some have reprapped them, but I haven't quite got it adjusted yet.

I went down to Wilko's and picked up a pack of 4 rubber feet and a pack of carpet coasters. The rubber feet worked pretty well the wrong way up, the holes for the screws were a bit larger than the rods. I wrapped the ends of the feet in insulation tape and the feet wedged on nicely.
I then superglued the feet into the carpet coasters, making some nice large rounded feet.

Worked pretty well!