3 Key Tips on 3D Robot and Toy Design from MechaZone!

3 Key Tips on 3D Robot and Toy Design from MechaZone!

This article is written by pro illustrator and toy designer David White who created the MechaZone toy robot series.  He will share some of the design tips and tricks he’s learned from his experience as both a 3D designer and maker.  Keep these pointers in mind when you design for 3D printing and you’ll be well on your way to creating great toy designs that print beautifully. 

 


3D printing has been around for a long time, but only recently has it become available to the general public. My friends and family still think of a 3D printer as some sort of miracle device that can make whatever you want at the push of a button. Of course, we as creators know that it takes a lot of work to go from an initial idea to a final 3D printed product.

There was a period of time where everyone was telling me I HAD to make prosthetic hands because I own this futuristic 3D printer and I had a social responsibility to use it for the forces of good.  I think of 3d printers like any other tool such as a table saw or lathe. Sure you can make just about anything, but what do you want to make? I’ve always loved the aesthetic of boy’s action toys so I couldn’t resist the opportunity to make my own action figures.

3d robot robot mechazone

I used to make video games so I already knew how to create low-polygon style 3d models. That set me on the right path to making my first action figure, but there was still a lot to learn about making models that print optimally on an 3D printer. I’ve made hundreds of toys since I got started a few years ago and I would like to share a few tricks I’ve learned through trial and error. If you’re wondering what software I work with, I make most of my models in a free modeling program called Blender. 

 

3 Tips on 3D Robot and Toy Design for 3D Printing

 

1)  Print pegs for joints horizontally

How the plastic of an extrusion style print is deposited in layers gives the print strengths and weaknesses just like the grain in a piece of wood. It’s very important to be aware of this as you model so you can design the parts to print at the optimal orientation for strength and durability. For me, this mostly affects the way I design the joints of my action figures. I use a lot of peg and socket joints as well as a lot of ball joints.

 

3d robot mechazone robotsThese toys all share the same basic joint structures. I used a peg for the necks and waists. Ball joints were used for the shoulders, hips, and ankles. It’s simple, but gives the figures a large range of poses.

If I design a part with a peg that prints vertically, then it’s almost guaranteed that the peg will easily snap in half.  It is always best to print any pegs or pins horizontally so the grain runs the full length of the peg. This isn’t always possible if the peg is part of a larger part so I often print the pegs separately and glue them into the larger part.

3d robot ball and peg joints

Horizontal = Strong                                       Vertical = Weak

 

In the picture below, you can clearly see the layer striations, or grain. Pay close attention to the ball pegs… the grain runs lengthwise to make the parts stronger.

3d robot angling

This same concept should also be applied to the peg receptacles to prevent the part from splitting when the peg is inserted. I know from experience that it is not always practical to print the parts at this orientation. When I can’t print parts at the optimal orientation, then I use a higher nozzle temperature for a stronger layer bond.

3d robot angling

The underside of the torso and arm ball-joint receptacle.

2) Angle to avoid supports 

I make dozens of toys at a time for online sales so it’s important for me to be able to clean off the support material as quickly and easily as possible. Less support material also means the surface of the print will be cleaner and smoother. My printer, an Afinia H-480, automatically calculates the support material based on the angle of the underside faces relative to the print platform. Sometimes you can design a part so it doesn’t need any support material, but most of the time a part will need some kind of support structure.

A lot of my parts are very angular and boxy with shapes like 90-degree stair steps. These shapes always need support material when they are on the bottom of a part. I’ve found that it’s often possible to adjust the stair step angles so the bottom surface is at a gentler angle like 30-45 degrees. This can make it easier to remove any needed support material or eliminate the need for it all together. Below is an example of a step that has two different adjustments which reduce or eliminate the need for supports: 

 

3d robot angling to avoid supports

  1. An underside angle of 90 degrees will always need support material.
  2. An underside angle of 10 degrees will still need support material, but the support material will be easier to remove.
  3. An underside angle of 30 degrees or more may not need support material at all. It will depend on your printer.

3) Add a slight concave angle to flat surfaces with rafts

Flat parts can be very difficult to remove from support material and printing rafts. I use ABS plastic because of its durability, but it is also prone to warping as it cools. Because of this, I need to use a support raft to keep the parts flat. Parts like the bottoms of feet can be time consuming to remove from the raft without a lot of effort. I’ve found that this can be remedied by adding a slight angle to the bottom faces. Another solution is to add some sort irregularity or texture to the bottoms.

3d robot parts

This action figure has large, flat feet and I found I was spending a lot of time with a craft knife removing stuck-on bits of the support raft. My solution was to add a concave area to the bottom of the foot.

3d robot concave flat surface

As you can see from this screenshot of the model, I left a flat area around the edge so the part would not dislodge from the support raft during printing. The slight concave shape made the rest of the support raft detach easily and saved me a lot of effort during part cleanup.

I hope you find these tips helpful when creating your next toy design. Keep them in mind the next time you are designing and modeling or integrate them into your existing models.

Screen Shot 2016-01-27 at 10.44.35 AM
Questions? Comments? Leave them below! 

If you want any clarifications or have any design tips to add, leave a comment below and let us know! If you’re interested in purchasing a robot that’s already 3D printed, check out David’s Mechazone website or if you want to purchase his design files, check out his Pinshape page.

 


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3d robot testimonial

 

 

 


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  • Christian Brock

    fantastic tips Dave! Definitely stuff to keep in mind. I’m curious to know how well you’re able to do the ball/post portion of the joints horizontally w/out any support material. or maybe it’s minimal? Thanks for putting this together.

  • David White

    Hi Christian. The ball joints do need supports. No getting around that, I’m afraid. here’s a photo of an Afinitron fresh off my printer. You can see the supports. And you can see the absence of supports on the sides of the feet (on the left by my thumb) because I angled the underside faces as described in this article.

  • David White

    here’s the pic

  • Håkan Sjö Ballina

    Great write up, Dave! I’m looking at your supports for the Afinitron. Do you create them by hand or in a slicer? Just curious since they don’t resemble any supports I’ve seen (though, I have to admit my experience of different slicers is quite restricted).

  • Hello. My Afinia http://afinia.com/3d-printers/h480/ printer has custom slicer software that automatically generates the supports when I send a print. It works great so I am always surprised when I hear about people frustrated with that stuff.

  • Wow, I would have written this totally differently. 1. Pegs prints sideways, but ball joints print vertically. This way with a cleverly designed ball joint no supports are necessary. Supported round bottoms work okay with PLA, sometimes, but terribly with ABS. And orientating the joints that way is just begging them to snap when they flex. I learned this when playing with disolvable supports: https://www.youtube.com/watch?v=jR9-up4HX6k Notice the feet at 6:25. Turn that thing 90 degrees in the Y so the layers go perpendicular to the flex.

    2. I’ve always found if you have to use supports that parallel to the build surface removes cleaner than slightly angles and leaves less mess. I can clean it up much more accurately since the layers define where the break occurs, but I tend to angle overhangs so no support is necessary whenever I can.

    3. Reducing the contact with the raft does help removing it, but getting rid of the raft is even better. I’m going to back and forth on this argument here, so bear with me. Designing for a raft is designing for a weakness. Then again, designing for your manufacturing process is a strength. But this is such an easy thing to fix that you really shouldn’t be designing for that. Just get rid of your raft.

    Now you’ve clearly have a body of success to go with this article. I’ve got some success myself in this. Just saying what you’ve discovered runs kinda counter to what I have. I guess there’s more than one right answer and whatever works for you is right.

  • I agree, there’s usually more than one right answer. I have a coupe of printing buddies and we sometimes disagree about the “correct” way to do something. My buddies even have the same model printer so our experiences are parallel. We occasionally have get-togethers where we try to convince each other of the best way to do things. We always learn something new. With that in mind, please understand that these are examples for the novice and are not a 3D printing manifesto by any means. user experience may vary, as they say.

    #1- I know what you mean with the support issues where the bottom of the ball can be almost conical. My printer usually doesn’t have that problem… only if the ball is very small. Sometimes I do actually print the balls with a socket on the bottom and glue them onto a peg.
    I determine print orientation on a piece by piece case and agree that the foot in your example video should have been printed in the other orientation. There wasn’t enough material around it to support the stress and it’s possible that you didn’t use a high enough nozzle temp to properly bond the layers.
    I’ve printed at least 60 of the arms from my example pic and not a single one of the shoulder sockets has ever cracked.

    #2- My experience has been as stated in my writing. Probably a difference in the way your printer or software works. Or maybe I live in a bizzaro universe, parallel to your own?

    #3- I’ve tried getting rid of the raft and it does not work. I use abs for strength and finishing reasons. The parts always warp without a raft. I also make a lot of parts all at once so that probably adds to the problem.

  • Håkan Sjö Ballina

    Ah, that explains it. I only have experience of Cura and Slic3r and I can’t get neither of them to produce good support. Though, it might be my fault as much as theirs 😉

  • Ptricks

    Some good info.
    I would add:

    Layer thickness
    Consider layer thickness you are going to use to print the part. If you model a part that is 10mm tall then slice it with a layer thickness of .3 the size of the print will be wrong because 10 does not divide by .3 evenly, so .25 would be a better choice.
    Some programs like slic3r allow you to set thickness per layer so you can get detail where you want it and print faster when you don’t need it on the same model. I usually lower layer thickness for holes and increase back to large when the hole layers are done.

    Corners
    Filleting corners can make a better print . Whenever the printer encounters a 90 corner there is a lot of inertia that the printer has to compensate for to make the change in direction.Rounding the corner in the x+y directions help to mitigate the jerking and increase print quality and lowers print time.

    Support:
    Really should not be needed, use glue or design the model to use a system like a carpenters dovetail joint. I have built water pumps out of PLA that were created with a hole and peg type joint and glued together with cyanoacrylate based glue and then tested for strength, the other parts broke before the glue joint.

    Holes
    If there are round holes in the model that will need to be really strong, don’t print the holes, instead make that area solid infill and use a drill bit after the print. It is much stronger than the perimeter layers a typical print would usre.

  • Khajanii Celestine

    That was great advice
    but im curious What 3d desgin software do you use?

  • Bruno Fernandes

    Hey sir! Can you contact me by e-mail: [email protected]. I want a lesson of building joints. I pay for it.

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