A this week’s CNC Build Club Thursday, 8/29/2013 @ 7:00pm, we are going to have a 3D printer demo from a new Chicago hardware startup called Isis3D. They are going to demo their new Isis One 3D printer. The printer has a large 300mm x 300mm build area and is producing some awesome prints.
After the demo we will go back to our regular activities of discussing, building and using CNC equipment. Next week we will gathering a huge collection of CNC controller boards including some cool new things like the BeagleBone Black running LinuxCNC and the Simple Cortex runnnig Smoothie.
We have a very special event planned for the next CNC Build Club meeting on Thursday, July 18th. We are going to do a Gonzo Build with the Make With Moto crew. Make With Moto is a Velcro covered Sprinter van filled with making equipment that is touring the country. In addition to the making equipment they have a bunch of unlocked and hacked Android smartphones. They have been doing hack-a-thons around the country.
We thought it would be awesome to do something that combines our CNC hacking skills with their phone hacking skills. We would temporarily remove the “a-thon” and do a one night Gonzo build.
The plan is to do a digitally controlled camera slider. The phone would replace the camera and control the motion. We are still seeing what is feasible on the phone control options, but ideally you could control the phone from a second phone and view live video or snap shots from the slider phone.
It will probably look similar to this camera slider that was done in the past, but it will have a mount for a camera and have all the drivers on the slider.
Inventables will be supplying all the CNC materials. As the details get more firmed up, I will edit this post so check back later. If you have any other ideas, let me (Bart) know. We may be able to get materials for multiple versions.
The project was to build a “single axis” drawing machine in one night. This machine uses two independently controlled carriages on a single piece of MakerSlide rail to control a pen at the tip of two linkages. The primary purpose of the project was a fun group build and a learning exercise in setting up a non-Cartesian machine using inverse kinematics. Kinematics in this case means mathematically describing the machine to the CAM controller. The One Axis DrawBot is a very simple non Cartesian machine.
The equations used are shown above. The ends of the linkages on the carriages end are at joint and joint. The pen is at pos->tran.x and pos->tran.y. The first two equations convert the desired pen location back to actual machine locations. They were plugged into the CAM program. The last two equations do the opposite and convert machine locations to the pen location.
We had one team assemble the machine, one team wire the electronics and one team setup the controller. It took about two hours to complete that phase. We try to use newbies wherever possible, so adding solder training into the mix usually adds a little time. The next step was to setup the CAM controller.
We borrowed the CNC router computer and control box to run the machine. This has Mach3 CAM controller software on it. Mach3 has a “formulas” feature that we used to enter the kinematics. We quickly had the machine running, but it was soon clear that Mach3 was not completely up to the task. In the formulas mode, it appears to disable the DROs (digital read outs) which tell you exactly where the machine is. It was also difficult to home or tell the machine the current location. Moves in the Y axis are non linear and need to know the current location. This resulted in Y axis moves that were not 100% accurate.
The other problem was coordination. If you tell a CNC machine to move from X0, Y0 to X1, Y0, it accelerates up to the desired speed then decelerates to the end point. If you tell it to move from X0,Y0 to X1 Y10, the two axes are moving different distances, so it needs to coordinate the different axes speeds and accelerations. The X axis would move quite a bit slower to coordinate with the longer Y distance to get a straight line. Mach3 was coordinating the two machine axes, but it was not coordinating the pen axes. Moves in only X or only in Y were nice and straight, but moves in both X and Y had a bit of a curve to them, but they did accurately arrive at the end point. A graphic with a lot of short moves would not show any on the problems above so we ran a quick “PS1” graphic. Watch the video and be sure to wait for the applause.
We will switch to using EMC2 (LinuxCNC). This has a true inverse kinematics feature that should fix the problems.
There is some discussion on the EMC user mail list to help us with this project.
Update 6/23/2013: Here is the latest (untested) version of our LinuxCNC kinematics file mykins.c
This week the CNC Build Club is going to attempt Gonzo Build #2. A gonzo build is where we try to knock out a complete CNC project in one night. Gonzo build #1 was the Quantum Delta 3D printer.
This week we are going to build a one axis 2D drawing machine. This uses two independently controlled carriages on the same axis to get 2D motion at the ends of the linkages. The purpose is only to have a little fun and to cut our teeth on a simple inverse kinematics machine before moving onto a much more complex 6 axis machine.
If you want to help, please join us. The meeting is open to non members. Please RSVP via meetup.
About 4 people certified on the vinyl cutter by me. I started adding tips to the wiki page for the vinyl cutter because there was a little struggling to get good results. I think it was due to not setting the orientation of the plot (worked for me)
I saw some certification on the LulzBot. We need the linux computer for that fixed or replaced!
Ryan and Liz Certified on the CNC router and they cut a complete project on their own (cool little circle/star thing)
Acetone Smoothing….So it appears to make good prints look great and bad prints to worse. You can’t polish a turd.
The Quantum Delta was slowly cranking out angry ducks and squirrels all night.
We did some experimenting with ABS Smoothing. Donald J brought in most of the equipment which consisted of a heating pad, glass cookie jar and a little stand to put the parts on. We put a small amount of acetone in the jar, then put 3D printed ABS parts on the stand. When the acetone heats up it forms a cloud in the bottom of the jar, enveloping the ABS part. Most of the acetone condenses back near the top of the jar.
It worked pretty well on finely layered parts. It made some parts actually look little worse by highlighting flaws. It took quite a while to heat up and could be optimized. Donald is looking for volunteer ABS parts to practice with.
We have a temperature controller for it we can wire up. It can only drive about 3amp @ 110V. Does anyone have an SSR? The mechanical relay probably won’t last long in this application. The heater is probably 5-7 amps (guess)
There is no special topic or speaker for this week’s meeting, but here are a few things we will be doing.
Member Certifications: Colin, Steve and I can certify on various pieces of CNC equipment including the Laser Cutter, Vinyl Cutter, 3D printers and CNC Router.
ABS Smoothing: Donald J is hopefully going to bring in his acetone vapor chamber for ABS print smoothing. Bring your ABS parts and a any spare fire extinguishers you have.
DSP Stepper driver tuning. I now have a programming cable for the drivers. We play with and learn about the benefits of stepper driver tuning.
Another group, gonzo CNC build? It might be fun to plan another gonzo build. We could kick around some ideas to try to build in one night again. I think a simple inverse kinematic (oxymoron?) project might be fun. Eventually I want to do a six axis machine, but it might be good to get our feet wet with a non Cartesian 2 axis draw bot. If you have other ideas, please suggest them.
I can bring in a few sample of V carving. We might do that the following week.
This Thursday at 7:00pm Edward Ford will be hosting a ShapeOko night. Edward can help you build, complete, setup and use the ShapeOko router.
He will also give a quick overview of the web based MakerCAM program. MakerCAM can be used to create toolpaths for CNC routers. Edward and Inventables are working to develop this program into a full featured CAM program.
For those without ShapeOkos, we can talk about your CNC project or work with some of the digital fabrication equipment at PS:One like the laser cutter, CNC router or 3D printers.
This week we have a presentation by Jason Huggins (@hugs) on Bitbeam and the Tapster robot he built with it.
Thursday, May 9th @ 7:00pm, upstairs in the electronics area
Jason will give an overview of Tapster, his open source, 3D printable, mobile app testing robot. In addition to explaining why creating a mobile testing robot is not the worst idea you’ve ever heard of, Jason will give an overview of Bitbeam, the open source building toy that he developed, which Tapster’s made out of. He’ll cover his making journey as he’s experimented with laser cutters, CNC mills, and 3D printers to make Bitbeam. For fun, the talk will also include live demos of Tapster playing Angry Birds.
Jason Huggins is CTO and co-founder of Sauce Labs, a software test infrastructure company, and is the original creator of Selenium, a popular open source web testing tool. In 2011, for an art project he was working on, Jason created Bitbeam – a 3D printable LEGO-Technic-compatible construction toy. Jason lives in Oak Park, Illinois.
Following the presentation we will break away to work on various CNC projects. The ongoing group project continues to be the mid-sized CNC Router. The machine is now fully functional under Mach3 control. We can talk about the Mach3 setup and cut a few things.
We had a great presentation by Jarvis Schultz on the Microsoft Kinect last night as part of the CNC Build Club. Jarvis works with the Kinect as part of his PhD research in robotics at Northwestern University. We had an overflow crowd of close to 30 participants.
The presentation was an introduction on how to get started with hacking the Kinect. He described what is known about the internals and the data you can get out of it. He talked about the preferred open source software tools and libraries.
He gave several live demos. The pictures you see above are shots of how the Kinect saw the crowd at PS:One. The still shots don’t do justice to the coolness of watching it live. His presentation is in PDF format here.
This week we have a presentation from Jarvis Schultz on using the Microsoft Kinect motion sensor input device and other related devices. He is going to give an overview on how they work, what kind of data they can produce, what software is needed to interact with them, and what you can do with the data once you have it. He will include some live demos of what the data looks like, and what you can do with it.
Jarvis is a fourth-year PhD student in Mechanical Engineering working on robotics at Northwestern University. He is part of the Neuroscience and Robotics Laboratory, and he has been working with the Kinect since it was first available, and it has become an integral part of his PhD research. Further information is on his research webpage in case you are interested http://nxr.northwestern.edu/people/jarvis-schultz.
Thanks to Steve Finkelman for arranging this.
Following the presentation and discussion we are going to continue with the CNC Router project. We are going to add the limit switches for the X,Y and Z axes. Limit switches can protect your machine from over travel, but also provide an accurate and repeatable home position.
We are also going to setup Mach3 as the machine controller. We will try to do this while hooked up to the projector, so everyone can participate in the process and learn how to do it. Mach3 is a professional level commercial controller and is a huge step up from the typical DIY solutions, like GRBL.
After a few projects with Mach3 we will probably also install EMC2 which is an open source, Linux based alternative to Mach3.