PAROL6 Desktop Robot Arm(github.com)
github.com
PAROL6 Desktop Robot Arm
https://github.com/PCrnjak/PAROL6-Desktop-robot-arm
57 comments
Do you plan to publish the CAD and EDA source files?
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.
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.
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.
Looks like they forgot to update the link.
>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.
Being pedantic this isn't either, there's no CAD source files, only stl files. Hopefully that's just an oversight.
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?
An STL is just a mesh, a collection of joined up points. It's like exporting a JPEG of a word document, you can print it but editing is a huge pain. For instance STLs don't support curves, so they're approximated with lots of short lines.
Usually CAD interchange is either in STEP or the program's proprietary format.
Usually CAD interchange is either in STEP or the program's proprietary format.
You would expect STEP files in an open source project. This allows you to change the motor interface to use locally available stepper motors, adapters, or other modifications. STL is an intermediary, "rendered" 3D STEP file, ready for conversion into final custom gcode assembled specifically for your machine and any accessories/user specific procedural steps/initiation procedure etc.
STEP is the sheet music, MP3 is the STL and the waveform is the gcode.
STEP is the sheet music, MP3 is the STL and the waveform is the gcode.
STL is to CAD as JPG is to SVG basically.
More like source code vs object code in a compiled computer program.
The STL is a mesh file that is used to generate g-code that a 3d printer or CNC machine understands.
The CAD file, whichever format its in, is going to have all the solid modelling information and be much more useful if you want to make changes.
The CAD file, whichever format its in, is going to have all the solid modelling information and be much more useful if you want to make changes.
Freeware vs. Open-Source.
PNG vs. SVG.
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…)
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…)
Here is the link to the most recent BOM: https://github.com/PCrnjak/PAROL6-Desktop-robot-arm/blob/mai...
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.
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.
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.
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.
That is basically why made this robot. During my high school days we were 30 students on ONE old mitsubishi robot that was pain to program and was dangerous. On collages it was "oh we have 2 40000 euro robots but they are too expensive for students". So in both world we were mostly on simulators and simulators suck. I started with faze4 robot that was financed by my college but it was too large robot and i did not write any good software for it. More impressive thing than mechanical part or PAROL6 is its software and GUI. It is made for easy programming, has build in scripting language, jog control, error logging... Also i plan to port all my robots to that software and in the future make it universal for any robot. So you get a PCB that can communicate with the PAROL6 software, configure your robot kinematics and you are up and running.
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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
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
Are you maintaining that list?
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!
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!
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.
Also the BOM info is gone.
Another poster mentioned the BOM link, it's 6 NEMA 17s of various torque ratings.
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"
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.
Very impressive repeatability and very smooth movement for a 3d printed arm.
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.
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.
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.)
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.)
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.
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.
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.
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.
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.
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.
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.
> I've used this technique on several of my projects.
Did they have any moving parts? Did they experience continuous vibrations and frequent mechanical shocks? For DIY robot arms, fasteners are very often the issue #1, if arms operated more than just for demo purposes.
Did they have any moving parts? Did they experience continuous vibrations and frequent mechanical shocks? For DIY robot arms, fasteners are very often the issue #1, if arms operated more than just for demo purposes.
Just print it and find out. If there is a problem put in heat set threaded inserts. I don't think it'll be a problem though
> If there is a problem put in heat set threaded inserts
You would be surprised how many screws will go lose after a a thousand of hours of operation, even in this case.
You would be surprised how many screws will go lose after a a thousand of hours of operation, even in this case.
I'm a mechanical engineer, product designer and technical leader that has designed many products, some of which have been implanted in people and are in the Smithsonian, etc. I know screws can come out, that's why they make loctite.
What I'm saying to you is to make sure something is an actual problem before saying it is. In this case, the fact that the screws are used as self tapping, the screws themselves create the threads, likely combats this. Like a nylock nut.
This isn't what I would do for say, a surgical robotics system, but that's not what this is.
If given the choice of having the design as is, or making it more expensive, more difficult to assemble, and less accessible. I'd choose it as it is.
There are always tradeoffs. I believe the designer made the right ones here.
Before saying they didn't, maybe build one.
What I'm saying to you is to make sure something is an actual problem before saying it is. In this case, the fact that the screws are used as self tapping, the screws themselves create the threads, likely combats this. Like a nylock nut.
This isn't what I would do for say, a surgical robotics system, but that's not what this is.
If given the choice of having the design as is, or making it more expensive, more difficult to assemble, and less accessible. I'd choose it as it is.
There are always tradeoffs. I believe the designer made the right ones here.
Before saying they didn't, maybe build one.
This is a case, where appeal to authority actually makes sense. Thanks, I accept your point.
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
Cool I'll try to build one.
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.
Sweet! An Armatron for adults!
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!
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
[0] http://www.jeff-z.com/pinball/toys/armatron/armatron.html
Totally.
It also highlights an interesting change in engineering and product development that has happoned in my lifetime.
It used to be, when this Armatron was made, electronics and computers were magic and mechanical engineering, real complicated kind of mechanical stuff, was common and the slillset to do it was similarly common. In that world it makes sense to have the whole robot arm powered by one motor that constantly spins, with mechanical clutches and linkages deciding what moves when. That's because electronics and mechatronics like motors and encoders were still expensive and new.
Now its the opposite. In general, if given the choice between a complicated mechanical solution and a "simple" electronic/computer solution we choose that. Simple is in quoted because modern electronics and computers are far from simple. The manufacturing of a modern semiconductor rivals the Manhattan project. But is seems simple because we can just buy it at best buy and program it to do things. You can easily find lots of engineers to do something with code or an arduino, but finding someone who can design a fly ball governer, or even know what that is and why it matters, is rare.
Now days there are tons of cheap robot arms that have a servo motor for each joint, because servos are cheap and complex mechanics are not.
It also highlights an interesting change in engineering and product development that has happoned in my lifetime.
It used to be, when this Armatron was made, electronics and computers were magic and mechanical engineering, real complicated kind of mechanical stuff, was common and the slillset to do it was similarly common. In that world it makes sense to have the whole robot arm powered by one motor that constantly spins, with mechanical clutches and linkages deciding what moves when. That's because electronics and mechatronics like motors and encoders were still expensive and new.
Now its the opposite. In general, if given the choice between a complicated mechanical solution and a "simple" electronic/computer solution we choose that. Simple is in quoted because modern electronics and computers are far from simple. The manufacturing of a modern semiconductor rivals the Manhattan project. But is seems simple because we can just buy it at best buy and program it to do things. You can easily find lots of engineers to do something with code or an arduino, but finding someone who can design a fly ball governer, or even know what that is and why it matters, is rare.
Now days there are tons of cheap robot arms that have a servo motor for each joint, because servos are cheap and complex mechanics are not.
>Now days there are tons of cheap robot arms that have a servo motor for each joint, because servos are cheap and complex mechanics are not.
Servo motors aren't cheap at all. Encoders aren't cheap either, in what universe do you live? The RC toys don't count by the way, because the cheap RC servos are terrible.
A fly ball governer? Is this some kind of joke? How are you going to operate it in any orientation other than upright? Why would you even want to?
There are probably ways to build a control loop with discrete electronics components that is cheaper than a mechanical system like that. Heck, it is probably cheaper to build an entire CPU with discrete components and then program that.
The reason nobody knows this crap is because it is useless. Your pseudo nostalgia for an age that existed before your time is ridiculous.
Servo motors aren't cheap at all. Encoders aren't cheap either, in what universe do you live? The RC toys don't count by the way, because the cheap RC servos are terrible.
A fly ball governer? Is this some kind of joke? How are you going to operate it in any orientation other than upright? Why would you even want to?
There are probably ways to build a control loop with discrete electronics components that is cheaper than a mechanical system like that. Heck, it is probably cheaper to build an entire CPU with discrete components and then program that.
The reason nobody knows this crap is because it is useless. Your pseudo nostalgia for an age that existed before your time is ridiculous.
I would love having one capable of unloading the dishwasher.
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
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
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?
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?
Hmm some potential problems:
I don't like the idea of having the dirty dishes right next to the clean ones so this would require at least 2 sinks so one can be loaded throughout the day
My desktop ultrasonic cleaner is so loud that I can't work in the same room. Transducers that can clean an entire sink (>10x volume) will likely be so loud that I can't work in the same building when it's running
If anyone in the building works from home, the unit will have to be soundproofed on all sides. That's way harder for a sink that's built into the countertop
I don't like the idea of having the dirty dishes right next to the clean ones so this would require at least 2 sinks so one can be loaded throughout the day
My desktop ultrasonic cleaner is so loud that I can't work in the same room. Transducers that can clean an entire sink (>10x volume) will likely be so loud that I can't work in the same building when it's running
If anyone in the building works from home, the unit will have to be soundproofed on all sides. That's way harder for a sink that's built into the countertop
Yeah, I came to the same conclusion: 2 dishwashers. But a robot arm would be much cooler.
Requiring a google account to fill in the form is annoying and weird…
Welcome to the future
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