PAROL6 Desktop Robot Arm

https://github.com/PCrnjak/PAROL6-Desktop-robot-arm

by tildef • 3 years ago

163 56 3 years ago

github.com

barkingcat• 3 years ago

Cool I'll try to build one.

krasin5• 3 years ago

The video of the robot arm in action: https://www.youtube.com/watch?v=PiBCbHtvbpE

Very impressive repeatability and very smooth movement for a 3d printed arm.

Vespasian2• 3 years ago

Interesting project.

I wonder how the rigidity holds up over time. Working at a robotics company, the mechanical engineers had to overcome quite some challenges to find a compromise between, precision, speed and repeatability.

And that was with a metal frame.

sgnelson3• 3 years ago

I imagine a lot of that will have to do with the 3d printed material used. If you're talking typical FDM style PLA, ABS, the creep on these can be pretty terrible.

If you're talking something like carbon fiber reinforced nylon, it's probably a bit better. If you move to something like Markforged's fiber-strand reinforcement it'd get even better. And then there are the SLA/SLS solutions, like Formlabs "rigid" material, which I think would be a very interesting material to try for this.

I think at the end of the day, you need to keep in mind this is an educational robot, not an industrial robot. If it can maintain 0.050" of repeatability, that would probably be good enough for a lot of use cases (but of course, that depends on your use case.)

krasin5• 3 years ago

My biggest concern is that they use screws over plastic as fasteners: https://github.com/PCrnjak/PAROL6-Desktop-robot-arm/blob/mai...

Quote from the manual:

Screws are in this example M3 screws and holes are undersized to 2.7-2.8mm that means that when we screw in the screws we are tapping holes in 3D printed parts.
There are multiple benefits to this:
● Connection is strongest compared to tapping holes with a tap or using brass inserts
● It is simple and fast
● No need to prepare the hole, it can be printed undersized
Cons are that you can’t disassemble it a lot of times. In case you feel screws slipping in the hole. Put some super glue in the hole and wait for it to cure. After that re tap the hole.

invalidator• 3 years ago

I've used this technique on several of my projects. The formed threads are strong and reliable. It cuts down assembly steps and BOM. The tight fit means the screws won't back out (like locktite or nylocks). The only downside is they can only be reassembled a few times before they start getting loose, at which point you can either add material (superglue), or just reprint the part.

If you have something you want to reassemble frequently, use inserts. If you're putting it together once and intend to use it that way for a long time, threadforming works fine.

iancmceachern6• 3 years ago

If you like, you can always slightly modify the parts in CAD before printing or even after printing with a drill bit and then put one of those heat set threaded inserts in with a soldering iron. Not a big deal. Do what you want

PCrnjak6• 3 years ago

I have been abusing it for 8 months straight and too be honest I was trying to break it. Software has a lot of safety features to not hit joint limits, speed limits, ESTOP is operational... Only problem is that robot has no brakes so during power loss it falls. I thought it will be fatal for robot to fall like that but it survived it multiple times. Only parts that brake are esthetics and covers. Also i thought that repetability will suffer under such abuse but it stayed the same. The clip on youtube is after 6 months of a lot of use.

fudged71• 3 years ago

Is a possible solution to the arm “falling” to mount it upside down?

Vespasian2• 3 years ago

Sounds very interesting.

Maybe this is a project where I can put the random collection of components to use which lying around in my basement.

Not exactly to spec but that's the spirit I think.

sgnelson3• 3 years ago

I wonder how this compares to the AR4 robotic arm ( https://www.anninrobotics.com ). The AR4 isn't truly hardware open source, but my understanding is that it's software agnostic.

My biggest question is the full cost for the PAROL6. Their BOM link is 404.

I can build the AR4 completely for less than $2000, and for education, that's a very small price for a semi-useful, full 6 axis arm. (Currently, to give a comparison, one of my suppliers is offering an educational cobot solution for $40,000. Yes, it's truly "industrial," and is a complete self-contained solution, though it's only capable of 2kg if I recall correctly. This was what they were pushing for the educational market.)

As someone who is trying to implement robotic training in education, with a budget that approaches zero, I just need something cheap that students can hack/break/fix without costing a fortune in maintenance costs.

One of the cool thing about the AR4 is that it can come as a complete kit, either as 3d printable or aluminum frame. and they work with Steppers Online to provide the steppers and drivers as one package. If you work for a school system, this type of solution solves a lot of logistical issues.

That said, if this thing is truly low cost, let's say under $1000, for it's capabilities, it could be a very nice project.

nulld3v• 3 years ago

The BOM file is in the repo I think: https://github.com/PCrnjak/PAROL6-Desktop-robot-arm/blob/mai...

Looks like they forgot to update the link.

Cilvic• 3 years ago

Does someone know how much this amounts to roughly?

monkmartinez• 3 years ago

Here is the link to the most recent BOM: https://github.com/PCrnjak/PAROL6-Desktop-robot-arm/blob/mai...

RobotToaster3• 3 years ago

The AR4 isn't truly hardware open source

Being pedantic this isn't either, there's no CAD source files, only stl files. Hopefully that's just an oversight.

qingcharles• 3 years ago

For someone that hasn't used a CAD package in 30 years, can you explain the importance of this for me? Is a STL like a JPG is to a RAW in a camera?

Arcanum-XIII• 3 years ago

I’m curious, what kind of project could you do once you built it ?

My major issue is that I can easily build stuff. The puzzle keep my brain on the job - but then I don’t know what to do after I’ve checked it works :D (i.e my various RC project are there, but then what ? I’ve built a rover, can do some automated stuff, but not very useful a the end…)

wigiv• 3 years ago

Seems like an open-source/DIY or kit (requiring some assembly) for educational applications is great in the context of a class or project where building/fixing/upgrading the robot is the point, and where 3D printing is readily available.

If the main purpose is for the robot to do something - the DIY approach is more likely to suffer issues that, without support, may discourage students because they're fussing with/fixing the bot instead of doing the thing.

Out of curiosity, what's the $40k kit you mentioned?

Educational packages are all over the place (some seem to be price-gouging, frankly) but the low-end (in terms of payload + reach) of commercial/industrial cobots is getting pretty affordable.

sgnelson3• 3 years ago

You're completely right about the DIY vs. Industrial issue. And the reality is that I need both, a DIY solution to teach students "this is how they work, these are the fundamentals, this is how to fix them/change them/operate them." And I also need one that can be hooked up to other machines, and able to be a true industrial robot (not so much with weight capacity, but with reach), and be a true integrated system to show students: "That other one was a toy, now here's how to use a real one in industry."

But I basically now operate in Bureaucratic Hell, and I have to figure out a way to get the equipment to teach my students. And due to changes in how my organization operates, ironically enough, I've found that getting the "professional/educational/industrial" products is often not the right decision.

One of the worst things that can happen is that we buy a $250,000 piece of equipment. The administration will never ever budget for the cost of maintenance, consumables, tooling, training, everything else required to successfully operate it. Within a year, you're stuck with a $250,000 piece of equipment sitting in a corner collecting dust, that is always shown to VIP's on tours as the latest in greatest in what we offer. Oh, and it's so expensive, we're not going to allow students to use it anyway, because we can't let them break it.

And it's amazing, they won't have funding for that $100 tool I need to teach the students and use everyday, but every year they'll manage to find $100,000 to spend, a week before the end of the fiscal year, which we have to spend immediately, but it can only be spent on certain items, like the things that I don't actually need. Welcome to public technical education in America. (Sorry, obviously, you unintentionally touched a nerve.)

But if I can get something that costs $2000, well, I can either fix it myself, or better yet have the students do it I will take something that I know is sustainable, that students can actually put their hands on and operate over that white elephant every day of the week.

In reality, this is all moot. No matter the cost, my budget is effectively zero at the moment. But I can hope.

The $40k was a Universal Robots UR3e I believe. The vendor put it on a cart as a portable, self-contained system.

ilaksh• 3 years ago

The instructions detail everything including the exact screws/nuts needed. EXCEPT the most important parts, the actual motors! It doesn't give any specs or names or a thing for those. Incredible.

Also the BOM info is gone.

unwind• 3 years ago

Another poster mentioned the BOM link, it's 6 NEMA 17s of various torque ratings.

PCrnjak6• 3 years ago

Hi i am creator of PAROL6, the BOM link is fixed. Also about the bom it will soon be updated in more detail. My focus is now more on software and finishing touches on hardware to make it safe so some changes happen in BOM. That is why is seems "incomplete or rough"

bitwize• 3 years ago

Sweet! An Armatron for adults!

iancmceachern6• 3 years ago

I love the armatron. It was so many engineers first exposure to robotic systems, was affordable and get-able by regular people, and magically ran off on one single motor. I was just watching some YouTube videos on it and how well designed the mechanics of it are, so clever!

mohn• 3 years ago

I was researching the Armatron last weekend and was surprised to learn then about the single-motor operation. It's quite a complex system of linkages and transmissions [0] to enable the six degrees of freedom. I suppose that explains why the toy is so noisy. I had no idea that was how it worked, must not have taken mine apart when it broke or I outgrew it or whatever happened.

[0] http://www.jeff-z.com/pinball/toys/armatron/armatron.html

janci2• 3 years ago

I would love having one capable of unloading the dishwasher.

NavinF2• 3 years ago

I've thought about building a robot to do that, but I think it would be cheaper to buy 2 or 3 dishwashers and modify them for use as cupboards. One will always be open for loading dirty stuff and another will always be open for retrieving clean stuff.

btw ultrasonic cleaners are like miniature dishwashers and having one near my office room is very convenient for cleaning hardware compared to using the full-size dishwasher in the kitchen. Only disadvantage is that it needs soundproofing

BizarroLand• 3 years ago

Just put the ultrasonic actuators onto your sink basin, and have a dish rack built in to it as well.

Fill with water & soap, insert dirty dishes.

Then when you head out for work in the morning, turn it on. let it buzz for 30 minutes or so, and then have a separate actuator drain the dirty water, refill and drain a second time as a rinse, and then drain again to let dry.

That would be what, $1200 in parts and a season of testing to make work?

janci2• 3 years ago

Yeah, I came to the same conclusion: 2 dishwashers. But a robot arm would be much cooler.

hobofan2• 3 years ago

I tried to collect a rough overview of available robot arms a few years ago (with focus on low-cost/open-source ones).[0]

If anyone has some pointers on other recent projects in the space, I'd love to hear about them!

[0] https://github.com/hobofan/collected-robotic-arms

Svenstaro• 3 years ago

Are you maintaining that list?

hobofan2• 3 years ago

Depends on what you mean by that :D

As one can see the last commits are a few years old, and in the issues there are a few robot arms that I haven't worked in yet, which I want to do soon. However, I'd largely attribute the lack of activity to me not actually seeing a lot of new robot arms popping up. If there are any I'm missing or resources where one might regularly find some, I'm eager to hear about them and add them to the list!

Animats• 3 years ago

There are lots of low-end robot arms. I have a uArm, which is not very good, on my desk. Way too much slop. Repeatability maybe 2mm.

PCrnjak6• 3 years ago

Hi guys I am the creator of PAROL6 arm. I was not aware of this community so if you have any questions feel free to ask me here. Also new video is up explaining more things. https://www.youtube.com/watch?v=PiBCbHtvbpE&ab_channel=Sourc... Also anyone interested in building/buying it can sign up on these 2 forms for more updates.

You can sign up here for beta testers (there are a few spots left: https://forms.gle/sZqHVLPoMJxuVAyJ9 This is general form for people interested in control boards, kits, or whole robots: https://forms.gle/XkSvStwnQxw1f8xL8

RobotToaster3• 3 years ago

Do you plan to publish the CAD and EDA source files?

chillbill2• 3 years ago

Requiring a google account to fill in the form is annoying and weird…

iancmceachern6• 3 years ago

Welcome to the future

PCrnjak6• 3 years ago

PAROL6 creator here. I believe you dont usually need google account for forms. I messed it up when I was creating it :P

PAROL6 Desktop Robot Arm

Related Stories