Thanks to the Hong Kong Parcel Post, I got my metal-gear servomotors last week, and then thanks to work commitments, they had to sit taunting me on my workbench the whole week. Luckily, I had a chance to do some assembly work this weekend, and got a couple of the major subassemblies put together. As you could see from the earlier post, I had the base assembled, and it was short work to put the base rotation servomotor in place.
You have to make sure that when you assemble the deck, you put the servo in so that it is at the center of its rotation when the arm is facing forward. Once that was done it was short work to get the deck put on. I went ahead and clipped the little screws that hold the servo horn on short, so they won’t rub on the acrylic frame and scratch it. I also added a trio of modified furniture casters to provide a bearing surface for the rotating platform. The oomlaut guys used M8 screws with acorn nuts, but that would also scratch up my beautiful red acrylic, so I chose to go another way. If you look at the flickr set, you can see how I did it. I had to trim them a bit to allow for the small M3 nuts on the bottom of the platform to have sufficient clearance.
You can see that the first joint of the arm is supported by two servos- note that in order to make the parts fit without undue stress on the lasercut plastic, I put one servo inside and one outside the mounts. I also had to make sure that the motors were both turned to the same degree of rotation before mounting them. The way I mounted them, the first joint can swing from fully to the back of the platform all the way to fully front. This should be perfect, and maximize the reach of the arm.
Assembling the second joint turned out to be much more problematic, and necessitated several tear-downs and re-assemblies. As far as I can tell from the (albeit sparse) pictures on the oomlaut website, it appears that the motors are mounted on the outside of the arm assembly, but as far as I can tell, this will not fit without really bending the lasercut frame. I don’t want to do this as I do not want to break the plastic, but I am at a loss about what to do. I am planning on sleeping on it, and ordering a couple of the motors that the oomlaut guys suggest and see if they fit better. According to the specs posted on the motor source website, they are exactly the same size as the ones that I have now, so I am kind of puzzled.
Next up- second arms joint, gripper (which is its own puzzle, to be sure) and the control mechanism. (Yes, I am still hacking around with my old Playstation2 controller!)
This weekend I organized a few hacdc members to come help out a fellow hacker in need. Alden broke his collar bone and had many smd boards to get done for xmas presents for family and friends. He was obviously going to have a hard time making the xmas deadline. So here is the Chinese sweat shop assembly line we created in an Arlington VA basement workshop.
The “fuzzy clock” as I have named it basically tells time like so. Five after Noon. Eight past six, etc. This board will be available as a kit on the synthetos.com store around the new year and the design files will also be available. We will also offer custom laser engraving for the back side at an extra cost. Hope you guys like the work. Alden and I have put a lot of time and effort into the boards.
As you know I recently purchased a milling machined to be able to do some custom PCB stuff along with some intro level metal working. Well today I thought that I would try to create a collet holder that would have its sizes clearly visible. However being short on time and on a break from some “real” work I made an end mill holder for my 10 piece set from grizzly instead.
I am using a method that I invented I termed: Self threading square tube insert method. Whats so cool about this is it combines fairly easy cuts of aluminum that pretty much anyone can do with a band saw, hand saw or rusty pocket knife… Well not the last one and I don’t suggest you try it. But is very cool. Basically its all in the spacing of the 4 holes that were laser cut that the aluminum sits below. Its a very tight squeeze which allows the screws to “self thread” inside the square tube’s inside. Hence the name. Not super witty but it describes it nicely. Comments, questions or concerns always welcome. Next thing to make is the collet holder.
The progress of my Mini-CNC build is going along great. I finished my X Table axis this last holiday weekend. Here is a video of the newest working section of my CNC running a stepper test program from the arduino.
I placed a 35Lbs weight on the table to get a feel for how sturdy the table was. The platform is made from two 1/8th” hardboard (masonite) pieces screwed together. You can view the video below to see it moving the weight np. The stepper motor used is a NEMA 23 Alltronics stepper. I am driving the stepper from the older 1.2V Reprap driver board. I had built these boards a long time ago and have not had the chance to get the newer (cheaper / better) models. I currently am waiting for the reprap stepper driver v3 board to become a reality. This board support microstepping also! Which should make the accuracy of the Mini-CNC even more accurate while suppressing vibrations throughout.
I still need to finish the Y and Z axis. This I am hoping show go much faster not that I have the basic idea in what is required for the linear motion using steel tubes to progress. I am hoping for this week to at least finish 1 axis. In a perfect work I would get both done. However I have a work project that is going to need my attention to get together pretty quickly. So we will see. I will make updates as I make progress. Check my flickr photostream for more frequent updates.
This is my first attempt at creating a custom enclosure for the Buss Pirate V3. I think these plexi-glass cases are pretty awesome. They take very little resources to make and can be pumped out pretty quickly. On the opposite side (see below) I etched a “cheat sheet” on the bottom for quick commands.
I could not find my spray paint last night (due to re-organizing my workshop.. I guess a little too well ) so I used a magic marker. This provided ok results for the prototype but if you zoom in perhaps you can see that the letters “bled” a bit. I will fix this on the next version. I like the size of this enclosure but I am thinking that the top might benefit from 1 more 1/8 layer or possibly a 1/16 layer to cover the USB connector. I will post this on Thingiverse in the next few days.
