What would it take to make a hobby version of Lockheed Martin's robot arm

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discussion
(Samer Najia) #1

What would it take to make a hobby version of Lockheed Martin’s robot arm 3D printer? New firmware? What about making a hobby version milling.machine that works with a moving 5 or 6 axis arm?

(Dale Dunn) #2

I’m not sure about programming for an arm, but rigidity is going to be a problem for milling. Unless you have a very robust arm, you will probably be limited to cutting foam and soft woods or using tiny cutters. To be sure, you’d need to investigate the arm’s rigidity specs and compare them to cutting forces expected for cutters in each material using each tool.

(Samer Najia) #3

That’s true. Ok let’s say it’s for large format 3d printing… .large enough, say, to print parts for a full sized car. What sort of firmware changes would be needed?

(Brook Drumm) #4

I think it’s possible to make a small robot arm suitable for 3D printing but it would be very expensive. Closed loop (basically unheard of in open source 3D printing) is necessary and very high quality bearings and gearing are a must. I’ve heard you can get harmonic drives “cheap” but I have not sourced them yet.
Brook

(Dale Dunn) #5

Firmware changes? This is beyond just firmware. Normal 3D printer controllers like RAMPS don’t have enough stepper outputs, and even if you hacked some more onto the unused IO pins, you’d need to add those axes to the software, then you’d need to translate the slicer’s G code through some kinematic calculations to move the joints correctly. If you went through all that, you’d probably find you don’t have enough processing speed. Maybe you could do the kinematic work as a post process on the G code.

Really, this isn’t a question for a 3D printing community. This is a robotics problem. Someone here might happen to have the know-how. Me, I’m not even sure which community to talk to. Somebody working on open robotics. I know there is such a project, but I don’t know what they call themselves or what their status is.

(Brook Drumm) #6

Robotarm.org is a fun place to start. These folks are active and well aware of the problem at hand. I think Autodesk has their sites on multiple. Axis post processors for Fusion to allow this- maybe a gcode output would work as long as the closed loop issue is solved with cheaper electronics hardware

(Ray Kholodovsky) #7

Check out Makerarm. That’s a SCARA type robotic arm. Marlin has support for SCARA. That’s probably the best “supported” type of articulation available to us right now unless you want to do everything from scratch.

(Ray Kholodovsky) #8

Arduino Due should have the necessary processing power for all the overhead calculations if the Mega doesn’t suffice, and there are boards out there that can break out up to 8 individual driven stepper motors, so that’s not the difficult part.

(Samer Najia) #9

MakerArm sure sounds like the way to go in terms of concept. By the time I pick up all the goodies I’ve spent $3K. But what I am after is scaling that up so that I can print really big things. Clearly there’s much work to be done, and I would suggest it to the team of college kids I am mentoring. If only some corporate benefactor would sponsor the research :-), not that all this hasn’t been done by the big companies…

(Dale Dunn) #10

Hmmm… If the coursework calls for the arm and necessary development, that’s one thing. But just to make a large printer, the more direct path seems to me to be to start with a large router table. Replace the router head with an extruder (swappable?) and replace the base and table with a frame containing a print surface that can move in Z. I’m giving myself ideas here…

On the 3rd hand, a fixed rectangular space may not be suitable for your needs. Just be aware up front that the angular axes of a robot arm will have speed and resolution characteristics that a rectilinear system won’t have.

Fun project.

(Samer Najia) #11

It is, isn’t it? And the end objective is to actually print an EV…

(Brook Drumm) #12

An EV? As in electric vehicle?

I’m working on a very large printer right now that I’m going to scale up for a car eventually. It might be a good fit. I expect large extrusion and moderately fast print speeds compared to desktop machines. The trade off will be resolution at first.

Details in a week or so

Brook

(Ray Kholodovsky) #13

I’ve built a 24x48 Cartesian printer before. What I’ve learned is that the mechanics need to be rock solid. And prints take a very long time, in the realm of days. The nozzle would have to be much larger than volcano sizes to be productive. The extremely large nozzle that SeeMeCNC uses on their 15’ delta along with their custom machined direct pellet extruder is probably the bare minimum you’d need to make a machine with meaningful output.

(Samer Najia) #14

@Brook_Drumm Yes. I have rebuilt cars and airplanes is my thing. I would love to learn more and lend a hand.

(Samer Najia) #15

@Brook_Drumm ​, I have dreams of a custom body on a Tabby EVO, something futuristic like a Lambo and then to use the same tech to print a Surface Effect Machine like a Yellow Jacket…an homage to a Star Wars Landspeeder.

(Samer Najia) #16

@raykholo ​ if I could slap something together at the hobby level like the SeeMeCNC I am all for it.

(Ryan Carlyle) #17

Oak Ridge National Laboratories (US Department of Energy) originally tried to use 6-axis robot arms to print car-sized objects as an earlier phase of the BAAM project, built prototypes, and eventually gave up and switched to a big cartesian gantry. That cartesian printer (the BAAMCI) is printing actual car bodies now. http://www.e-ci.com/baam/

If ORNL gave up on 6-axis robot arms, with all their insanely massive technical know-how and government funding, that tells you something about how practical it is.

(Brook Drumm) #18

Funny. I think I agree. Cartesian is so much easier!

I gotta get to work on that pellet extruder. I have the parts, just gotta do it!

Brook

(Samer Najia) #19

A huge Cartesian printer on my floor would be interesting. And huge. I wonder if a 4’x4’ one would do.

(Ryan Carlyle) #20

@Brook_Drumm Pellet extruders are an entire technical field of their own, with way more engineering required to get good results than is reasonable to pursue as a side-project… I personally think it’s a giant rabbit hole to try to design your own. The BAAM printers use industrial plastic welders with some modifications for remote continuous pellet feed via vacuum delivery system. Here’s the OEM for the extruder on the BAAMCI that printed the Strati car chassis: http://www.dohle-extruder.de/en/products/welding_machines.html

Nothing wrong with buying an off-the-shelf solution for the really complicated parts… you wouldn’t make your own stepper motors, would you? To my mind, injection screws and multi-zone heater barrels are in that same category. Would love to see what you come up with though :slight_smile: