FreeCAD WebGL Export.
This is still early but it's too cool not to share. Yorik has added a WebGL exporter to the FreeCAD arch module (but it seems to work everywhere in FreeCAD)
Open a model in FreeCAD and select the objects in the tree
Select objects in the tree
Export the objcts (File -> Export) and select WebGL
Save the file and open it in a browser: WebGL export (will open in a new window)
(The default view is zoomed up close but clicking and dragging with the mouse buttons will zoom/pan/rotate the object. There's still plenty to be done with materials and lighting but being able to share FreeCAD models through a browser is very cool.)
Fun in the shop
I spent the Thanksgiving holiday at my brother's place. It was a very relaxing weekend spent eating too much and shooting stuff. (I'm not very into guns but this stuff is fun!)
My brother recently bought a jealousy inducing lathe like this:
This thing was barely out of the crate. The DRO hadn't even been installed yet and and he was just getting familiar with it. So, of course, we decided we needed to make something -- preferably a piece of high-precision technology.
Armed with a healthy disregard for prior planning, a can-do attitude, and the proper fluids:
we started making chips.
Two days (and late nights) later, the world's first tactical yo-yo. Heavy enough to take your head clean off.
The first field test was less than impressive
So, back to the drawing board:
In the end, the device functioned within specification. It's a bit heavy for normal use but there's plenty of material that can still be removed to improve it.
All joking aside, I really enjoyed this project. Too often we think through a project and, figuring that we could do it, we declare it done. Actually DOING it unearths all kinds of tricky problems but that's where real experience is developed. I know my meager skills on the lathe were improved greatly. And I had a blast.
Keeping Good Company.
A reader on my Magic Clock site made me aware of this TED talk by Massimo Banzi, Co-inventor of the Arduino. He lists some really cool projects ranging from the important to the silly. I might be closer to the Farting Chair end of the scale, but hey, I made the list. Fast forward to 10:25 to skip all that nonsense about 14 year old kids changing the world by detecting earthquakes.
Understanding Tool Path Generation in HeeksCNC
When I first started using HeeksCNC I was totally confused. It seemed overly complex. When I finally understood it, I realized what a great model it is. I still won't claim to be an expert but from my perspective it meets three really big objectives. One of these is compromised in every other solution I've seen:
1) It keeps the computationally intensive algorithms in C++ where they run fast. Other systems that are flexible and customizable are written in interpreted languages and that means they're slow for computationally intensive tasks. Generating a complex path can tax a processor and really needs to be fast.
2) It provides a scriptable interface in a friendly language (Python). No matter how good the developer was, there's no way he can anticipate every need. That's why we like applications like blender, inkscape, gimp, and FreeCAD. These apps assume that the user may want to extend the application. Making the tool path generation accessible through a scripting language unleashes a lot of power.
3) It allows customization for the machine specific output without recompiling. This is the Post-processor. Not all machines are created equal. Different capabilities and different controllers mean the final output must be tailored.
Dan Falck did a great write-up of how Python is used in HeeksCNC to generate tool paths using the C++ libraries. I hope a future CAM workbench for FreeCAD has a structure like this.
Cutting Plastic
I finally started laser cutting the plastic pieces for the chassis.
I happened to have some orange 3mm acrylic and thought it would make a nice accent color.
Unlike the standard shell, mine is cut in three pieces and glued together. I had some worries that this wouldn't be very strong but it turns out that the glued joint is extremely tough. With acrylic, we're basically welding the pieces together. The solvent cement softens the plastic and the fused joint is incredibly tough. Even so, I reinforced it with a couple pieces I'd cut to calibrate the laser. These are just glued in underneath to add some thickness to the glued surface. I don't know how durable it will be over time, especially flexing it from time to time to assemble, but so far, so good.
Launcing a new project – My OpenROV build
Anyone who knows me knows that I totally dig submarines and sub movies. Whether it's a great one like Crimson Tide or a total pooch like Down Periscope, I gotta watch it. Submarines are the ultimate toy and the closest thing to real spaceships we're likely to see for a long time. When I first stumbled across the OpenROV project, I was hooked at once
Obviously an ROV isn't the same as a submarine, but it offers many of the same benefits and even a few advantages -- like the ability to actually see while remaining well above crush depth. In the past, ROVs have been expensive so the design and testing cycle is long and they're reserved for high-value missions.
The OpenROV project is very young and they're still getting their legs under them but it has some really cool things going for it. It's designed to be inexpensive, flexible, and require few specialized tools. The physical structure is almost all laser-cut acrylic. The bottom side electronics are meant to be open hardware like a Beagle board or Raspberry Pi. That means the ROV can be cheap enough that innovations and improvements can be tried out quickly even if they risk the ROV. It doesn't have anywhere near the depth capability of a 'real' ROV but at theoretical depth of 100 meters it could reach most of the continental shelf. That's a lot of room to play. My goals are a bit more conservative. A 5 acre pond in my Missouri back yard that I'm certain is, like McElligot's Pool, connected to the deep ocean. There's no telling what I'll find down there.
OpenROV recently started a Github repo to host hardware design files and software. They seem to be working in Autodesk Inventor which is, unfortunately, a closed format. A friend converted the files to both STEP and IGES for me and I was easily able to import them into FreeCAD. From there I was able to assemble it in the computer to produce this:
I've forked the OpenROV repo and added my converted files and FreeCAD file. FreeCAD doesn't support any bending of solids which is necessary to model the outside shell. The friend who converted the files made both a folded and unfolded version of the shell for me.
Sliptonic has a (frickin) laser!
Well, not quite....yet.
I found an old Universal Laser Systems model 25A for sale at a surplus auction. It looked to be in good shape and went cheap. After I got it home and cleaned up, I found that I couldn't get the laser head to fire. I called in some expert assistance from Columbia Gadget Works, but no luck was to be had. I've since learned that RF laser tubes have a life expectancy of about 10 years before they need to be re-gassed. Re-gassing this one is prohibitively expensive and would *only* get it back to 25W. Instead, I'm looking at replacing the RF laser with a chinese glass tube. This should take it to 40W.
Either way, this looks to be a fun project. Here's a picture.
Scout: A printable tribot
Here's the first iteration of 'Scout'. A simple printable frame for a robot based on two continuous rotation servos and an Arduino.
The idea was to limit the number of printable parts and 'vitamins' to the bare minimum and keep the total cost for the bot below $50. I'll use this to teach the robotics merit badge in December. Here's how the costs breaks down:
- 2 Futaba S3003 servos or equivalent (modified for continuous rotation). $4.50 each. I found deals on ebay to buy sets of 4 for $16 with no shipping.
- 1 arduino diecimila. $20 - 25. Also an ebay deal. A nano may work better. I'm still looking into this.
- 3 o-rings for tires. $3.00. Might be possible to replace these with rubber bands.
- 9V battery
- adapter
I’m now, officially, “Hard To Live With”
The September 2011 issue of Popular Mechanics has their annual "Backyard Genius" feature. This year, my Bad Idea Pinewood Derby Car made the cut. Although I've been telling my wife for years that I'm a genius, she's still not buying it. Now, at last, we have proof. I'm sure that my days of emptying the trash, doing the dishes, and other un-genius tasks are behind me.
Test Cubes
The reports of the demise of the test cube are, perhaps, premature. I've read people saying that new firmwares and versions of Skeinforge make test cubes unnecessary, but I'm not buying it just yet. To be sure, one can get a lot closer to a usable print quickly, but there's still plenty of room to screw things up.
I don't know why I keep all the old junk. Maybe to keep my humble. Maybe I hope for a recycling option in the future. Still, in a weird way, I like to see how far I've come and what I've learned from all this fail.
Recent Posts
- FreeCAD WebGL Export.
- Vendor provided CAD data.
- Fun in the shop
- Keeping Good Company.
- Understanding My Enemy
Stuff I’ve Made
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