Filament recommendations for a Ball Droid

[Harblar]

Hey everyone!

I'm currently working on a design for a (near) full scale replica of the BB-8 Ball Droid from the upcoming Star Wars Episode VII. I plan on making it a fully functional replica (just like what was seen on stage during the reveal of the last trailer). Inner workings not withstanding, the main ball can be assembled from 14 separate prints (not including details and inner support brackets) with no splitting of the parts prior to slicing. Gotta love the print volume on the Max!

Since the main ball will be rolling all over the place, I'm thinking it would be a good idea to print it from something tougher/more flexible than ABS. So what should I be looking at? I've got an E3D V6, so there isn't much I shouldn't be able to handle in terms of filament temps, etc...

What about some post print coatings? I'm going to have to paint it once the supports are removed and surface cleaned/smoothed. Does anyone know of any good spray-on rubber like coatings or sealers that would stand up to the wear of constantly rolling around?

Thanks for any suggestions. This should be a really cool project. Over 90% of the entire droid (except the electronics) can be printed. It might take several weeks of round the clock printing to get it done, but it should still be cool, none the less!

[teoman]

Looks pretty cool.

BB-8 on the stage at Star Wars Celebration 2015: http://youtu.be/ABzjUf3E_0c" onclick="window.open(this.href);return false;


Do you know how they have done the animatronics?

it looks to me as if they have an omnidirectional truck type of robot that is bottom heavy in the ball that just spinns the ball around itself. And a magnetic coupling to the head of the robot)

You may be better off finding a solid ball and chopping that in to two.

Or one of those ball shaped street lights.


Awesome project.

[BenTheRighteous]

You might want to look into nylon filament. Many people, myself included, have had success with printing from trimmer line that can be bought cheaper than most traditional filament from Amazon.

[geneb]

As for the coating...how about some of that spray on truck bed liner? I think you can get that stuff in rattle cans these days.

g.

[teoman]

Bed liner may ruin the concept visually.

If you need traction and have a double extruder setup you could prolint the outside in ninjaflex.

[Harblar]

Looks pretty cool.

BB-8 on the stage at Star Wars Celebration 2015: http://youtu.be/ABzjUf3E_0c" onclick="window.open(this.href);return false;


Do you know how they have done the animatronics?

it looks to me as if they have an omnidirectional truck type of robot that is bottom heavy in the ball that just spinns the ball around itself. And a magnetic coupling to the head of the robot)

You may be better off finding a solid ball and chopping that in to two.

Or one of those ball shaped street lights.


Awesome project.

I was there! Blew my mind!

After getting back and doing a lot of looking, as well as tying in with the guys over at the R2-D2 Builders club, I've got a pretty good idea of how to make the internals work (from a structural aspect, anyway... the electronics, programming, remote control, etc... I'm definitely going to need some help on! hahaha)


A lot of the guys over at the builders club are using (planning on using) everything from Styrofoam balls to acrylic hemispheres and the street light shells you mentioned. While those would all work, they all present their own unique challenges and drawbacks. Most of the street light balls have been arriving broken, hemispheres are deformed, and Styrofoam... well... it's styrofoam. After looking at the shots of the working Celebration model and the static display they had there, it looks like it was built from a multi-piece shell.

[img]https://lh3.googleusercontent.com/Otgi6 ... L8=s935-no[/img]
[img]https://lh3.googleusercontent.com/CmVzC ... 80-h720-no[/img]

As you can see, there are panel lines, indentations, etc... Not to mention LED's, which would be difficult (or Impossible) to install in the one or two piece solutions. However, 3D printing the individual sections should be a slam dunk... almost. The general consensus is that the lower ball has a diameter of 500mm. In order for the individual pieces to fit the Rostock's print bed, mine will have a diameter of 472mm. Not bad, considering most other guys are using 18" or 20" acrylic spheres, lights, etc. I'll be right in between.

Anyway, The outer shell is made up of 8 triangular shaped pieces and 6 spherical pieces. I've designed those 14 pieces to be joined together by 12 brackets internally. The shell will be 1 inch thick and completely smooth on the inner surface when screwed together (minus the indents for all the Tee Nuts used to screw it together).

Here's what I have so far:

[img]https://lh3.googleusercontent.com/WnUbj ... 20-h833-no[/img]

Here's just the internal brakcets:

[img]https://lh3.googleusercontent.com/vdQFg ... 20-h833-no[/img]

And the outer Triangular pieces:

[img]https://lh3.googleusercontent.com/JMXV- ... 20-h833-no[/img]

You might want to look into nylon filament. Many people, myself included, have had success with printing from trimmer line that can be bought cheaper than most traditional filament from Amazon.

I was definitely thinking Nylon would be a good way to go. Fairly strong, but flexible enough to absorb a little shock without breaking. I'll keep the trimming line in mind (for just the cost if nothing else). Assume for the moment, that filament cost isn't a factor. What would be the suggestion then?

As for the coating...how about some of that spray on truck bed liner? I think you can get that stuff in rattle cans these days.

g.

Thought about the spray on bed coating. It would be durable, but I wonder how easy it would be to get in the right colors. More importantly, truck bed liner is usually a very rough texture, which wouldn't work very good on this build. Plastidip crossed my mind, but again... getting the right color might be difficult and it tends to peel off fairly easily once it's ripped or worn. Also, to get a thick enough coat might cost me a small fortune in rattle cans. What I really need is something that sprays on thick and smooth. If it sprays on clear, all the better. Worst case scenario, I just need something that would spray on clear and protect the finish on the parts. Maybe a clear epoxy of some sort? This isn't overly critical at the moment. just something I've been thinking about as potential issue down the road.

[mvansomeren]

I recommend printing it in PETG. It is strong, and many of the qualities of ABS except that it doesn't warp or shrink like ABS.

[BenTheRighteous]

Honestly I've only ever printed the trimmer line nylon so I can't recommend any other kind. I can only point you in a vague direction toward Taulman's products, but I don't know the difference between those varieties of nylons. I'm sure you can find something that suits your needs though!

[geneb]

The plastidip might work if you thin it and use a HVLP gun with it.

g.

[teoman]

Print the parts in their own colors.

Then little dents etc will just look like wear and tear on the robot. On those parts add a bit of silver paint so that it looks like the paint was stripped off.

[teoman]

How durable do you need it to be??

You will not be racing these offroad will you?

[Harblar]

How durable do you need it to be??

You will not be racing these offroad will you?

I live in rural South Dakota, so it's a distinct possibility! hahaha

The more I get to looking about it the more I'm thinking the best route might be to just print a few of the base parts, and then do some casting and duplicating for the final product. If I were to print each piece individually that would be a total of 26 large diameter pieces, each of which would then need to be sanded, filled, smoothed, primed, and painted. Other than the 6 circular orange ring sections (which all have unique details and would need to be printed individually), everything else breaks down to 5 distinct pieces. Casting these pieces and duplicating them as needed would save a lot of time and work. In addition, depending on the casting compound I went with, they would be much stronger and more durable.

The problem is I know next to nothing about casting and making molds beyond the basics. The parts themselves aren't overly complex, but the mold would need to be done in a way as to get details from all sides. Aside from that what resin, poly urethane, rubber, etc... would be best to use? If I cast the parts, is it likely that'll i'll be able to apply a dye to the resin to cast the parts in their proper colors (eliminating the need to paint them)?

Any good suggestions/links to tutorials/recommended matierials, etc...?

[KAS]

I've been following this channel for a while. Maybe it will help getting an idea.


https://www.youtube.com/watch?v=RbesCNvae1M" onclick="window.open(this.href);return false;

[Harblar]

I've been following this channel for a while. Maybe it will help getting an idea.


https://www.youtube.com/watch?v=RbesCNvae1M" onclick="window.open(this.href);return false;

That's really cool, but not practical for an actual remote operated droid. One good bump and Ol' BB's head would go flying.

For the inner mechanism I was going to go with something more like what these guys came up with. http://www.howbb8works.com/#3d

I'll be trying to do something similar to Mechanism style 2.

[teoman]

Not sure if 3d printing is ideal if you will be going that route. The internals of the ball will have to be smooth if you want it omnidirectional.


Hnmm...

If you had a pilates ball, you could semi fill it with epoxy and then rotate it around untill the epoxy dried effectively using the ball as a rotor mold.

This would give you a very hard and durable sphere. That has a smooth inside aswell.

As for the controllers you could/should use a faster controller than that guy. (And that guy should have used an ardupilot, an arduino board with a built in accelerometer).

[teoman]

Then what you would have to do would be to stuff this:
4WD 100mm Mecanum Wheel Learning Arduino Kit C009: http://youtu.be/TXTo16KKm8Q" onclick="window.open(this.href);return false;

with a lead weight strapped to the bottom inside the ball.

[KAS]

I've been following this channel for a while. Maybe it will help getting an idea.


https://www.youtube.com/watch?v=RbesCNvae1M" onclick="window.open(this.href);return false;

That's really cool, but not practical for an actual remote operated droid. One good bump and Ol' BB's head would go flying.

For the inner mechanism I was going to go with something more like what these guys came up with. http://www.howbb8works.com/#3d

I'll be trying to do something similar to Mechanism style 2.

I understand. Maybe this patent will help? seems a bit different from the one found on that link you provided.

http://www.faqs.org/patents/app/20140345957" onclick="window.open(this.href);return false;

[Harblar]

Then what you would have to do would be to stuff this:
4WD 100mm Mecanum Wheel Learning Arduino Kit C009: http://youtu.be/TXTo16KKm8Q" onclick="window.open(this.href);return false;

with a lead weight strapped to the bottom inside the ball.

Hard to see in my pics, but the inside of my design is a smooth spherical surface. The brackets are inset into the panels and share the same inner diameter as the panels. When it's all assembled and screwed together, the inside will be a perfectly smooth (not counting the numerous seams, which will be sanded for a nice smooth join) sphere.

That robot is certainly one way to go, but I'm leaning towards a faster, heavier duty version of this: https://m.youtube.com/watch?v=5vJCucpVdX0

I think using 4 Omni wheels would give it a little better grip on the interior surface and allow for mounting with a lower center of gravity.

I understand. Maybe this patent will help? seems a bit different from the one found on that link you provided.

http://www.faqs.org/patents/app/20140345957" onclick="window.open(this.href);return false;

I've looked at that patent before. (Within the last week) if you read through the entire page in my link, I think they even reference it. Either way, they're all using a similar concept. Before I saw it on stage at celebration, I would have bet a million bucks it was all cg. After seeing it, I figured it had to be some kind of super complicated feat of electronics and engineering. After thinking on it for awhile and reading up on similar devices, I'm starting to realize that there are a number of ways to approach this, most of which aren't overly complicated.

I've already got a pretty good idea in my head of how it's all going to go together... Mechanically. The "complicated" part for me is going to be putting together a part list of all the electronics, servos, and motors and then figuring out how to program them and tie them together with some kind of wireless controller. Given a list of parts and a set of instructions, I'm pretty capable, but when it comes to sourcing my own electronics and/or building my own custom circuit boards, etc... I'm near clueless. Same thing with programming.

The other hard part is deciding what to make the parts out of. Right now I'm leaning towards making the initial pieces on the printer out of abs or pla... Whatever gives me the least shrink/warp and most easy smoothing/finishing. And then using those parts to cast finished pieces in a fairly tough and durable Poly Urethane. I think I could do this easy enough, but pointing me in the direction of a few helpful tutorials on the subject of mold making and casting wouldn't hurt.

[barry99705]

I thought it was just a giant sphero?
[img]http://www.geek.com/wp-content/uploads/ ... CN4831.jpg[/img]

The head portion is on a modified positioning arm like the sphero itself. The full sized BB8 doesn't really have to worry about getting thrown about by children, so it doesn't need the arm, so the arm can move about inside the ball. The head is magnetically coupled to the top of the arm so it can move about the top of the sphere independently. Throw four or five large N48 magnets on top of the arm with the ability to rotate and you can turn the head.

[Harblar]

That's what everyone thought initially, but the sphero only utilizes two wheels. This means it can only go forwards/backwards and rotate left/right. Also, since it only has two wheels to balance on, it would need something to keep the robot chassis from resting/rubbing on the inner surface of the sphere. Either a a set of Segway like sensors to actively keep the bot balanced on two wheels, a third support point (the upper arm as seen in your pic), or a combination thereof. The one at celebration could also move laterally left/right. To do this you would need to use at least 3 Omni wheels. With three or four wheels you eliminate the need for electronic balancing and/or the support arm and allow gravity to provide the stability.

I'm not saying the company, Sphero, didn't have anything to do with making BB-8, but whatever they did is more than just a scaled up version of their current products.

[geneb]

What if they're using these: https://www.sparkfun.com/products/11578" onclick="window.open(this.href);return false; or something similar?

g.

[Tonkabot]

They way it was moving indicates to me that the main stuff is in the lower ball. and while it could have the head 'independant' and balancing on top, I suspect that it may be just running on castors (omni-wheel castors) and is magnetically coupled to the interior stuff. Although it probably would spin the head easier with an actuator in the head.

I have some experience here, my robot could be adapted to balance on a ball
HEY! youtube took down my robot video that has been there for years. Now I have to go dig it up somewhere.

Oh, hey look there is a picture of it as my avatar... but I have video of it somewhere too (just not on youtube anymore apparently)

[DadFrankie]

Thanks so awesome! I am actually looking for one for my son's birthday, cant seem to find it anywhere, its sold out! http://store.sphero.com/products/bb-8-by-sphero" onclick="window.open(this.href);return false; and http://www.buybb8droid.com/" onclick="window.open(this.href);return false;, does anyone have an idea where I could find it?