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.
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.
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:
Now that we have covered the somewhat tricky route of tracing gear curves from images (which, by the way, you can use to create meshes out of any image) in part I, let’s have a look at the eMachineShop way. eMachineShop is a free gear designing software from the firm by the same name. They allow you to use their proprietary software for free in personal use, and then you can order the final product from them in a variety of machining finishes. I commend such an approach, especially since the software exports pure STL for our needs.
You can download the software package from eMachineShop.com and install it. When you start it the first time, you see a tutorial screen, but you can turn it off once you have the hang of the software. As it happens, it is very powerful, but a little quirky.
Gears are an interesting set of things to print. With gears you can make all kinds of things, and if you run an Arduino or a Raspberry Pi, you can significantly extend the toolbox when you can design custom gears. Of course, on Thingiverse, you have literally thousands of gears to pick and print from, but surely you want to make your own?
Blender itself has a Gears add-on, which you can install merely by downloading it and using the Install Add-on feature in the User Preferences. It adds a new type of meshes to the Add Mesh menu, namely Gears. In it you have Gear and Worm Gear, of which I will leave the Worm Gear for later.
Having had the MiniFactory 3D printer for a little over a year now, I have been very satisfied with it. It has lots of power, it can build quality prints, and it has just the right amount of the frontier spirit, that hack lab feeling to it. I have been able to produce just about every piece I have come to think about, and having stripped the machine a couple of times to the frame, I feel confident with it and can maintain it well enough. Now, Haaga-Helia bought two more, and here’s a video of one of them in operation.
I don’t know about you, but I am one to get irritated with stuff that hangs out in the wrong places. A good example is the chest strap of the computer backpack: I never use it, but I don’t want to cut it off either and harm company property. Instead, I made a quick mesh in Blender and printed it out on the Minifactory, with the net result of straps no longer hanging around causing me to lose hair even further.
It’s been a nice summer indeed, with scarcely a thought given to 3D or 3D printing at all. But now it is Autumn, school has started, and the heat on the trusty Minifactory has been set on again. The first thing I printed this fall was an unusual little device, a pie stamp, for my friend Keefie Williamson. Continue reading Back after the Summer with a Stamp→
Recently, I was asked to design and print a set of miniature tables and chairs, as well as the layout of the room these items of furniture reside in. This is to enable meeting planners to move these little printed chairs and tables and whatnot around, and then re-set the meeting room layout to suit the next meeting.
The tables and chairs need not be detailed, as long as the relative measurements of the items are correct. That’s fine, because that way I can work in Blender and scale everything relative to a table for example, and then just print sets of these at one go. The room furniture comes from Kinnarps, a leading manufacturer of such items. The dominant piece is the Trixagon table, and the cabinets in the room are hexagonal too.
So, off to Blender then. When you need a hexagon, it is actually a circle of only 6 vertices, and when you insert a circle, you can then reset the number of vertices to 6 before hitting Enter. Continue reading Quick ‘n’ dirty 3D printing→