3D Printering: Making A Thing In Blender, Part I


In case you weren’t aware, having a 3D printer is nothing like owning a real-life Star Trek replicator. For one, replicators are usually found on Federation starships and not hype trains. Secondly, the details of how replicated objects are designed in the 24th century is an issue completely left unexplored by TNG, and DS9, and only a minor plot point in a few Voyager episodes. Of the most likely possibilities, though, it appears replicated objects are either initially created by ‘scanning’ them with a teleporter, or commanding the ship’s computer to conjure something out of the hologrid.

No, with your own 3D printer, if you want a unique object you actually have to design it yourself. Without a holodeck. Using your hands to move a mouse and keyboard. Savages.

This series of ‘Making a Thing’ tutorials aims to fix that. With this post, we’re taking a look at Blender, an amazing 3D modeling and animation package.

Because we still haven’t figured out the best way to combine multiple blog posts together as a single resource − we’re working on that, though − here’s the links to the previous “Making a Thing” posts:

This list is sure to grow thanks to your suggestions on what 3D modeling software to feature, but for now let’s make a thing in Blender.

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Jello Shot Printer

While inspecting some jello shots for a friend’s upcoming 25th birthday, [Sprite_tm] had an epiphany. What if you could print designs inside the jello shots? He quickly grabbed a syringe and proceeded to inject food dye into one of the jello shots — it worked. Unfortunately, his friend pointed out that it would take far too long to do each jello shot by hand, to which [Sprite] responded:

Never mind that, I’ll just whip up  a 3D printer that can make nice figures in the jelly for you.

Classic. The great thing about the hacker-mindset is that you never say no when confronted with a problem!

To achieve this printer, [Sprite_tm] has taken a handful of old CD-ROM drives to create a three axis moving platform. He’s using a forth drive’s ejector assembly to depress a syringe which pushes a concoction of banana liquor, green food colouring and cornstarch through medical tubing to the ink-head. To control it, he’s just using an ATTiny2313 with a mere 2K of memory. It took a bit of fiddling with to find the right flow, but works surprisingly well. Stick around after the break to see its printing capabilities.

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Compliant Robot Gripper Won’t Scramble Your Eggs


[Chiprobot] has created an amazing compliant gripper.  Designing robot hands (or end effectors) can be a perilous task. It is easy to give robots big, good, strong hands. Strong grippers have to be controlled by sensors. However, sensors can’t always be relied upon to ensure those hands don’t crush anything they touch. Hardware fails, software has bugs. Sometimes the best solution is a clever mechanical design, one which ensures a gripper will conform to the object it is gripping. We’ve seen “jamming” grippers before. (so named for their use of a granular substance which jams around the object being gripped).

[Chiprobot’s] gripper is something entirely different. He designed his gripper in blender, and printed it out with his Ultimaker 3D printer. The material is flexible PLA. Three plastic “fingers” wrap around the object being gripped. The fingers are made up of two strips of printed plastic connected by wire linkages. The flexible plastic of the fingers create a leaf spring design. The fingers are attached to a linear actuator at the center point of the gripper. The linear actuator itself is another great hack. [Chiprobot] created it from a servo and an empty glue stick.  As the linear actuator is pulled in, the fingers pull around  any object in their grip. The end result is a grip strong enough to hold an egg while shaking it, but not strong enough to break the egg.

We would like to see the gripper gripping other objects, as eggs can be surprisingly strong. We’ve all seen the physics trick where squeezing an egg with bare hands doesn’t break it, yet squeezing an egg while wearing a ring causes it to crack much… like an egg.

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RepRap Wally Can Print Larger Versions of Itself

SCARA based 3D printers seem to be all the rage these days, and with good reason. This RepRap Wally doesn’t use any linear rods or timing belts — in fact, it can even print larger versions of itself with each iteration! Well, minus the electronics of course.

It was first spotted out in the wild at the NYC Makerfaire, and looks to be a pretty slick design. Using fully 3D printed limbs, the steppers move the arms using a fishing line. To reduce the load on the joints, a bowden extruder is also used. The really cool part of this is the z-axis, it uses a 4-bar linkage to stay level, but because of this, it also moves along an arc in the y-axis as it raises or lowers. This is accounted for in the firmware — otherwise you’d have some rather interesting curved prints!

Stick around after the break to see it in action, it’s a nice change to watch from the standard gantry style printers.

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Accurate temperature control of your 3D printer extruder

[Tim] is working on building a 3D printer and using it as an excuse to learn as much as he can. The first big issue he tackled was accurate temperature control, so he made an interesting write-up on how to characterize the thermal properties of an QU-BD extruder’s hot end and use that information to create a control algorithm for the heater.

The article starts with a basic thermal model and its corresponding formula. [Tim] then runs several tests where he measures the heater and extruder tip temperatures while switching on and off the heater. This allows him to figure out the several model parameters required to design his control algorithm. Finally, he tweaked his formula in order to predict the short term future so he can know when he should activate the heating element. As a result, his temperature is now accurately controlled in the 200°c +/-1°c window that he was shooting for.

RepRap Simpson puts a new spin on delta RepRaps

Just when you think you’ve seen it all in the 3D printer world, something new pops up! [Nicholas Seward] posted a video of RepRap Simpson, his latest project.  Simpson is a delta robot – but unlike any delta we’ve seen before. Previous offerings vertical rails on which the arms travel. As you can see, this design mounts three articulated arms directly to the base of the printer, using steel cables as part of the joint mechanism.

Judging by [Nicholas’] posts on the RepRap forums, Simpson’s grounded delta design has already gone through a few revisions. The basic geometry though, has remained the same. [Nicholas] calls this edition a “Proportional Gear Drive Joint Simpson”. The name may not roll off the tongue, but the movements are incredibly smooth, organic, and fast.

As with any delta design inverse kinematics play a huge role in the software. [Nicholas] is trying to simplify this with an optical calibration system. For the adventurous, the equations are posted on the forums, and a python Gcode preprocessor is posted on Thingiverse.

Even Simpson’s base received special attention.  It’s built from a water jet cut piece of basalt.  We like the use of opposed helical gears on the large joints, as well as the guitar machine heads used to tension the cable drive. One thing we are not sure of is the longevity of system – will cable stretch play an issue? Will the printed parts suffer wear from the cables? Only time will tell.

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Students build a 3D printed plane

3d printed plane

A student team has successfully designed, built, and flown a 3D printed RC plane using only $16 of plastic with a consumer-grade 3D printer (Makerbot), plus the necessary electronics and motor.

The folks over at the Wright Brothers Institute (WBI) have a great program called the AFRL Discovery Lab which brings teams of students, businesses, researchers, and government together to work on a specific challenge or opportunity.

One of the programs this year was the Disposable Miniature Air Vehicle, or DMAV for short. The student interns [Nathan, Ben, and Brian] spent the first 5 weeks at Tec^Edge designing the plane. The team went through 5 revisions before they settled on a design they believed could fly. The final plane weighed 1.5 pounds, and on its first flight… plummeted into the ground. Good thing they printed a second copy! After some more practice [Stephen] got the hang of it and was able to fly and land the plane successfully.

According to the WBI, this is the first functional aircraft that has been fully 3D printed (sans electronics) using FDM technology, and the first low wing 3D printed plane to be flown. Hate to burst their bubble, but 3D printed quadcopters have been around for quite a while!

Test flight video is after the break.

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