Trebuchet, part III – moving parts

Now that the frame is complete and ready to print, as seen in Part 2, it’s time to do the moving parts. This is a very good place to show you the Blender 3D Cursor in operation, because I will not be designing with exact dimensions, but rather with exact locations and approximate dimensions.

The 3D cursor is the thing that moves around the screen, when you click the left mouse button. You can place it with nice precision, when you use the views that are flat, ie. Top, Left, or Right, because then the cursor moves in only two dimensions. Placing the cursor in the User Perspective view is really hard, unless you snap the cursor onto something – most of the time it is not even possible. I’ll show you what I mean.


Trebuchet, or counterweight catapult, part II

I will now try to take you through the design of the trebuchet which has been shown in Part I of this post. This description that follows is actually aimed at showing you how in Blender all design is based on very simple starting points. The trebuchet frame is based on a single circle, the hole in which the main axis will eventually be placed, with a diameter of one Blender unit. Around this circle I based an octagon with the same center, but with a diameter of three.

The first circle

The first circle

The octagon is an arbitrary decision. I could have taken a septagon or a nonagon, but decided to go with eight vertices. It looks like this when appended to the circle above: (more…)

Greetings from Denmark

This blog entry comes from Copenhagen. Our university, Haaga-Helia, has for ten years been involved in an international IT seminar for students, and this year’s seminar is #9 in the series (2013 was such a messy year for all participating universities that we decided to skip it that year). The other schools are Cphbusiness in Copenhagen, Universidad Europea de Madrid from Spain, and a new entry this year, HES-SO from Switzerland.

The structure of the seminar is always the same, as is the theme, “How to be an IT professional”. The seminar runs for a week, with every school hosting a day. Usually there is a lecture in the morning, and then a workshop before lunch to be continued into the afternoon. Many times we have had social events and a business visit, for example last year in Helsinki we took the Spårakoff beer tram and went to Remedy Entertainment to see how games are made. (more…)

CeBIT Trade Fair 2015, Day 4 and closing notes


The weather kept up but there was a brisk breeze as we headed out to the Messe for the final visit. By now we had been to all the halls and seen all that was available, and the purpose of this day was to go and check out some things again.

I spent two hours checking the multitude of Chinese thingamajigs and whatchamacallits, most with Bluetooth if not gigabit LAN. It’s amazing what they have come up with, and were I in the market for importing USB connectors or cabling or selfie sticks, I’d have been in heaven. It was interesting as it was, don’t get me wrong. Like this Taiwanese window washing robot.


CeBIT Trade Fair 2015, Day 3

On Wednesday we hopped on the commuter train 8 again in the direction of Messe Nord. It’s very handy to have the hotel right by the railway station from which the trains leave for CeBIT and also for Hamburg tomorrow.

When I see men in lederhosen with traditional musical instruments, I can’t resist the urge to start this day’s blog with a video.


CeBIT Trade Fair 2015, Day 2

Another sunny day here in Hannover.

Sunny morning

Sunny morning

We went to the fair around ten this morning, and I started from halls 1 and 2. Mostly filled with IBM and other very large companies, but it was interesting nevertheless. IBM was trying to get back into academic co-operation (apparently Microsoft has ousted them from the close relationship they had previously, so my business card was hot stuff). (more…)

CeBIT Trade Fair 2015, Day 1

Haaga-Helia sees it fit to send teachers to trade fairs to sniff out the latest trends in IT. This year it was my turn to join the team and fly out to Hamburg, then take the train to Hannover where the gigantic expo is held every year. Together with two colleagues I signed in at the fair around noon today and will spend four days walking around. This is what I found today.

Quadcopter with ordinary iPhone or Android phone as control

Quadcopter with ordinary iPhone or Android phone as control

The first thing that got my eye was this very light quad. It has a HD 1080 camera, a 9 volt battery driving the four tiny motors, and an endurance of 10 minutes. (more…)

Finished print assembled and loaded

Trebuchet, or counterweight catapult, part I

For some time now, I have been thinking of printing a trebuchet. On Youtube you see massive trebuchets capable of hurling a flaming piano (!) to a distance of 200 meters, or trailer-based versions used in pumpkin-throwing contests. This sort of machinery is clearly beyond my MiniFactories and even the Print-Rite model I was handed the other week, but a small one should be within reason.

As always I first tried an unstable one before hitting on the right design. The first version seemed fine in Blender, and I was thinking of creating a system with many separate parts to maximize size. The first version looks like this in Blender:

V1.0 in Blender

V1.0 in Blender


Quick but not dirty printing

So, my son scavenged two 320GB drives from two laptops that were not very functional. He had space inside his own cavernous computer for them, and even a drive cage where he could fix the 2.5″ drives side by side. He screwed the drives onto the cage and it looked solid enough, but surely it’d look even better if there was something holding the tops of the drives. It was also a question of having space for the connectors, because this is not a standard layout, but would enable him to install both at one go. (more…)