Hi Annin Robotics community! I want to start this build log off by giving a great big thank you to @Chris Annin for designing this machine, releasing it under open source and then dealing with all of our nudgery as a result of said release. I've been following the AR2 development since may of 2017 and I really think that it is the first 6DOF arm out in the market space that addresses the "robotics for all" mantra correctly. It balances this knife edge of economy / quality through good design. I also really like this community so far.
A bit of background on where this build started .......
Several months ago a young friend of mine Julian decided to build an AR2 for his school project, and then asked me to sign off as a mentor. I had been wanting to build an AR2, and now I have my chance to live vicariously through Julian and possibly participate meaningfully in the newly forming community. Thanks to everyone who has been replying to our emails and comments lately, and a super big thanks to Julian for taking on our dream build like a champion.
Julian and I also follow the Niryo one, the "sixirobot" from marginally clever, and the Edo arm (which are also taking off). We hope one day that all of the communities will combine / cross collaborate and eventually merge their open source material in an effort to really compete with industry standard robotics such as Fanuc, Kuka and ABB. This could fundamentally change the world and bring opportunity back to working class folks who don't have millions to jump into competitive production / automation.
Here we are just a few weeks after the beginning of #JuliansAR2 build ........
Awesome, thank you for the kind words, I look forward to seeing your progres. Thank you for posting and sharing your experience and your robot build.
Really cool, did you guys 3d print the whole set yet? if so how sturdy does the part feel? and is it in PLA or ABS?
Julian has really just begun 3d printing and there's a bunch more time to go before we can have a completed set to show off. Everything is in ABS (which demands an enclosed and heated build chamber). I can't attest to the strength of the parts just yet we'll have to get back to you on that.
3/4/2019
I used to be a SW user for 12 years and I can say that I miss the work flow very much, but i am not missing the price. Over the last 2 years I’ve gotten used to Fusion 360 and although slightly feature bare I can say that the MCAD / ECAD (eagle) integration, Surfacing features and Make function / Mcmaster import are all improvements over SW. Lastly the team workflow (although tedious to merge) is amazing and makes me loathe the “Vault / PDM” experience of SW.
So Julian, his father and myself all share this model with each other in order to communicate the progress of the build, view changes together and as a bonus the make function is also producing better STL’s and therefore results on Julian's Lulzbot 3d printer.
First off you need to import the entire assembly into Fusion in one single shot. Don’t bother trying to piece together the entire model unless you are trying to do it for free by using the STL’s. I don’t recommend this approach because its an entire reverse engineering process that is not worth your time and provides no financial support for the AR2 project.
Here are some quick tutorials that are sponsored by Autodesk ………...
https://knowledge.autodesk.com/support/fusion-360/getting-started/caas/screencast/Main/Details/849e3578-f5d9-4f64-a0cf-750f9e2492f2.html
https://www.youtube.com/watch?v=l7ViMKZPGKk - Lars C
First off when importing the AR2 models one should ideally import every single part necessary in one single upload. You may have to go back an hit the “select files” button again to get the dependant components in any subfolders.
When you have everything you need in the file selection screen you’ll then need to pick the master assembly
From there I get a failed status on the main AR2 assembly and take a look at the translation report.
Regardless of this error I just hit refresh on the left side panel and then waited quite a bit of time for the assembly to appear. It shows up as one giant heap of bodies in one single assembly.
Now we’re in business ……….. More to come on conditioning the model later with joints, some minor references and possible mods if necessary.
@Julian Holcroft has been busy 3d printing components and making great progress on this build over the past 2 weeks. So far he’s generally halfway through printing as you can see from the Fusion model here.
The base of the AR2 came out very nicely. The tolerances allowed for the main J1 bearings to be pressed in lightly. The belt is definitely tight and rigidly held by the J1 gear motor.
The J2 parts are encountering a bit of sanding in order to make fit. And the J2 turret housing is on the bed now for the 3rd time as it tended to warp on the build plate
Julian took the opportunity to really tackle and complete the electrical cabinet while waiting for the printing to complete. We both thought it would be best if the aircraft cables came out of the side to reduce wire length and therefore inter cabinet EMF.
We have also been following
Here you can see that 3d printing can be tedious sometimes and you should honestly plan to reprint many times on certain parts in order to dial in the results for your machine and take precautions to improve your printer if necessary . Early on Julian had improved his Lulzbot but laser cutting an enclosure and applying temperature control so that he could deal with ABS prints effectively. Even with such a big printer mod there are still moisture conditions to combat as well as part distortions that can just wreak havoc with tolerance critical parts. Kudos to Julian for preparing, tweaking and testing his printer early on before diving in.
A couple of important observations that we had the chain gear specced for J3 does not have a tapped hole or keyway. This is a bit difficult as most of the build here is happening on a dining room table without the aid of a shop or in this case a drill press and a tap. Luckily Julian and I do have access to such things so we will get by but I think this might be a spec consideration for anyone in the community. We’ll see if we can find something helpful to add on that later.
Additionally I would recommend looking at the connection from the based plate to the J1 column. It seems to have a bit of difficulty printing when supports are combined, as well as having a very tight fit to the base to begin with which needed some hand work.
Thanks all and looking forward to the next update. So far so good and we are both very excited.
Nice work Julian!
Check out my build log photos, I redesigned the base to be printed as one piece, with the gussets built in. The only supports needed were in the middle of the turret where there’s the step for the bottom bearing. I modified it for different bearings, but can easily modify it back to the spec for Chris’s design and toss you the STLs.
I have extra PCBs for the Arduino shield, as well as some extra buck converters i think. Let me know if you want me to send one to you.
Hey
I had no trouble getting those bearings in - they required some force, but just by putting the roller side of the bearing into the outer race and pressing down by hand. I think I slightly oversized those surfaces so I didn't have an interference fit after printing.
Keep in mind, though, that I printed it in PET-G (and at 20% infill). It was certainly plenty rigid through the turret with the integrated gussets, but the base got a slight twist from the tension of the J1 belt. I figured that wouldn't be a problem once the base was clamped down to whatever surface it would "permanently" end up on.
However, I've abandoned that direction entirely, and am in the process of redesigning J1. (Chris, there's absolutely nothing wrong with your design! haha I just like to tinker). I haven't posted anything about that on my build log just yet, but hopefully soon - stay tuned.
I like the updated frame!
Me too. I'll be looking to try this single piece design out for the next upgrade.
Hi Annin Robotics community! It’s been quite a while since I’ve provided an update on @Julian Holcroft ‘s progress and successes with the project. So I am going to have to do a couple of back track posts here. Lets Just pretend for recording sake that this post covers the end of March and then into early April.
Near the end of march Julian myself and his dad all took a trip over to the Generator Maker space in an effort to drill and tap the J3 chain sprockets. This required a bit of old school machining trickery in which we clamped the sprocket into a vice and then lowered the drill bit right up to the highest point of the barrel that we could and move the vice back and forth until the tip of the drill bit scraped a line into the part indicating (very roughly) where the apex of the barrel was.
From there it was easy to use a caliper to mark the distance from the end of the barrel where the set screw should be placed. Drilling was easy tapping was a little nerve racking and deburring was a little challenging.
While we were there we also cut and drilled the tubing for the J4 axis using a pretty heavy duty metal lathe.
In Early April Julian had completed nearly all of the 3d printing and did nearly all of the wire harnessing while waiting for the last few parts. It was really impressive to see how fast everything was moving at this point, however I can’t say that we did not come up with a few major challenges.
One of the first issues that presented itself was that the rail stock for J5 did not quite fit into the mating linear guide. Upon forcing it the first time Julian's dad had accidentally destroyed one of the linear guides.
We also noticed that when putting the J3 axis together that the ABS arm at J3 tends to bend just a little bit. This did get a little straighter when mounting the chain covers. Being that the AR2 is really designed to be made in aluminum you may find that this particular arm part in 3d printing is a bit wobbly when whipping around the J1 axis.
Upon tackling the wiring harness Julian had mentioned that it was a bit difficult to solder the wire terminals to the aviation connectors. It requires a little bit of finesse in order to pull it off well. I would recommend having a decent soldering iron that has a larger tip on it to heat sync faster and hotter. Also really spend some time making good soldered joints on these aircraft connectors (watch a youtube video) as it will save you a lot of headache in the long run if they fall apart or break. I would also recommend getting a deeper (generally slightly larger) project box, rather than the hammond project box, as this was the most challenging point to squash all of the soldered wire connections into. Aside from this one thing I would say that the wiring harness documentation is really great and straight forward. Also if you have the ability to spend a little more on the limit switch wire I would suggest going with something that has shielding (especially If you plan to use the AR2 around applications that have big electromagnetics IE: welding, contactors, 35HP motors). This is my favorite shielded wire spec for limits here.
Around the beginning of May, after much toiling, continuity troubleshooting, and youtube watching, Julian had finally put the whole system together in perfect working condition. It truly is a thing of wonder to watch the AR2’s movements for the very first time in person after drooling over Chris's youtube videos for many years. Very exciting!
A few days later we all went to see Julian present the final project to his school class. I have never seen so many young kids swarm over a project quite like this. He certainly deserved every second as the center of attention for all of the hard work that he put into this project. Additionally I’d like to thank Julian’s parents for really investing in his education and for really pushing him through some of the hardest parts of the project. You guys are doing it right!
Nice job !!!
Thank you
Very nice. Would love to see a video. How loud are the steppers? How flexible is the ABS?
Can it still lift 4 lbs?