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Building an open source robot arm for makers and small businesses
Like what you see? Support me on Patreon.
I was up until 4:30am last night working on the fifth attempt to design the arm. Previous post on HAD.io were of (at best) study 4. I reached a point in the design where I'd found enough mistakes that it was easier to restart and use the existing design files as a reference to do a better job. I believe that - after three days of work - I've got something that solves all my previous issues and has fewer prints.
With lessons from the previous attempts, this time I built things in large passes:
place all the things that can't be negotiated (bearings, motors, screws in motor faces)
Speaking of BOM, here are some stats:
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Bicep parts are all printed. I have to collect a number of missing fasteners and wait for bearings to be delivered. In the meantime I'm going to assemble the circuitry for the controller and run some tests on a rotation sensor idea that's staying under wraps for now.
Here are some pics from the 6 axis model I'm currently working on.
As I print and assemble each part I check it against the model. More efficient than building an entire model in a vacuum and finding I made mistakes. Maybe it couldn't be done without an existing, purely-vacuum model as a reference. Hard to say from the other side!
The design files for this version are on Patreon. https://www.patreon.com/imakerobots
You can wait until it's for sale or chip in a little now, get the files early, and support development. Your call.
I'm always thinking about building the arm and life laughs at my plans.
I'm currently building several robots as commissions; running Marginally Clever.com; and spending a lot of coding time on Robot Overlord. I've got newly designed AS5045 sensors that work well, they now need to be integrated into an updated arm design. I may actually repurpose those sensors in another project first: A new Stewart Platform being built for a local science museum.
The biggest problems with the last arm design all stemmed from poor sensor construction.
- the wires were exposed to users where they could catch, fall off, etc.
- the sensor and magnet have to be held in perfect alignment or the arm loses sensation and goes nuts.
To fix that I'm working on a single sensor unit that I can test independently and use as needed in my next arm.
I'm deep into preparing for a new product launch, and then finishing the Jigsolve. My winter project is to make a new arm and integrate it with Robot Overlord, which still needs a way to record/play back every robot it supports. I'm also putting together a team to build a new game based on my design doc, which should eat ~6 months and cost ~100k.
All of which is to say I'm really busy and I need all the help I can get. I'm looking for talent everywhere.
There is a growing number of open source robot arms, which is super. I only build one because I can't get one at an affordable price. So if you're making an arm, please let me add Robot Overlord support and together I hope we can achieve greater things.
@Andreas Hoelldorfer has been building a 3D printable robot arm. It's making progress faster than mine.
His forte is hardware and mine is software. It seemed only reasonable to combine forces. So I asked him to share his Inventor model files with me, and then I imported them to Robot Overlord.
Here's a quick video of forward kinematics in action.
Inverse kinematics shouldn't be too hard. Java support for joysticks is shamefully bad. Firmware to connect RO and AHRobot together is definiitely possible.
Meanwhile I've been spending a lot of my free time working on my own design. It's very slow going. I have the wrist designed to satisfaction and the elbow is working-but-ugly. The shoulder and the pistons to drive the arm backhoe-style is where I'm currently struggling. I wish I had more time!
instagram doesn't embed, boo hiss. https://www.instagram.com/p/BDoEmVzIfO7
Yesterday I moved the software for controlling the arm from http://github.com/i-make-robots/Evil-Overlord to https://github.com/marginallyclever/Robot-Overlord. I, for one, welcome this move.
I also completed the merge of the older Arm3 into Robot Overlord, along side the Evil Minion (5 axis), the Delta Robot, the Stewart Platform, and Spidee (crab robot). The only robot that isn't merged is the Makelangelo, which has been eating all my time by being very very popular.
Also last week I was looking at https://hackaday.io/project/3800-3d-printable-robot-arm and I see @Andreas Hoelldorfer has used a camera quick-connect for his tool changer. Great minds think alike!
Going from zero to one of something is challenging.
Going from 1 to 2 is still challenging, even if you're planning ahead for it. The bill of materials was wrong, the assembly instructions weren't written down, and there were design choices that didn't matter for "just getting it done" that made doing it again a pain in the ass. Already I'm thinking "all this here, this over here, and those bits should be changed for easier manufacturing".
I've ordered enough parts for five machines, and I've begun assembling them. The documentation will be smoothed out by then.
Because of the high difficulty assembling the machine I'm only offering to ship fully assembled arms: http://www.marginallyclever.com/product/evil-minion-5-axis-arm/
I've only had one robot go to >1000 units. I look forward to having an arm do the same.