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

ReprapSimpson

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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Rubicon gives the Makerbot Digitizer a run for its money

rubicon

Look out MakerBot, there’s a new 3D scanner on the block and it’s about 10% of the cost of the Digitizer. Enter the Rubicon 3D Scanner which just hit Indiegogo, a device much closer to being worth its price $199.

Just like the pricey Makerbot Digitizer it’s a very simple design made up of a webcam, two laser lines, and a stepper motor controlled turn table. Still very easy to make yourself, but at $199, it’s not a bad price for an all-in-one kit, especially compared to the Digitizer. The newcomer claims a much faster scan time (3 minutes versus 12), and the same stepper rotation (800 steps or 0.45 degrees per step). There are no details about making the design open source, but after some digging in the RepRap forums we found some discussion on that topic from designer [Robert].

It scans objects up to 160mm in diameter and 250mm tall, however it has the ability to scan marginally larger objects if the camera is moved farther back. The funding for the Indiegogo campaign will go towards a custom arduino-esq PCB with a motor driver built in – personally we would be interested in just getting the PCB and 3D printing the rest of the scanner ourselves!

More information is found in the video after the break. [Read more...]

A deck screw extruder

deck

A lot of great ideas happen in the middle of the night, and for [Werner] it’s no different. One night he came up with an idea for a new 3D printer extruder, and after a very basic prototype, we’d have to say he might be on to something. It’s basically a deck screw acting as a worm gear to drive filament, but this simple idea has a lot of really cool advantages.

There are two really interesting features of this extruder, should [Werner] ever decide to flesh out his idea into a real prototype. First, the stepper motor for this extruder can be extremely small and mounted directly above the extruder. This opens up the doors to easily creating multi-extrusion printers that can handle more than one filament. Secondly, using a deck screw as a worm gear means there is a huge area of contact between the plastic filament and the driver gear.

Whereas the usual extruder setup only makes contact with the plastic filament along one or two splines of a hobbed bolt, [Werner]‘s design drives the filament along the entire length of the deck screw worm gear. This could easily translate into much more accurate extrusion without all the fiddling around with springs and hobbed bolts today’s extruders have.

In any event, it’s a very interesting idea, and we’d love to see [Werner] or someone else make a functioning extruder with this design.

Dual extruders in the space of one stepper motor

dual

The new hotness in 3D printers is – and has been for a while – dual extrusion. With two extruders and the requisite filament supply, it’s possible to print objects in two colors or two different materials. There’s a problem with this setup, though: each extruder requires a separate motor, greatly reducing the print area should you want to print in two or more colors. [Carl] and [Brian] think they have the solution to this with their dual extruder that is powered by one stepper motor.

As you can see from the pic above, the idea is relatively simple. Two strands of filament are fed past one gear attached to a stepper motor. Each strand is moved into the hot end through two idler gears and side of the extruder feeds into the hot end is determined by the rotation of the motor. It’s really one of those, “why didn’t I think of that” ideas.

[Carl] and [Brian] are also offering a quad extruder, a dual-sized extruder able to pump four different filaments onto a printer bed. With this, we expect some people to experiment with CMYK (or CMYW) prints, truly turning any 3D printer into a machine that prints full color parts.

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DEF CON: Hacking Hardware and Cars

DEF CON Hardware Hacking Village

The first full day of DEF CON was packed with hacking hardware and cars. I got to learn about why your car is less secure than you might think, pick some locks, and found out that there are electronic DEF CON badges after all. Keep reading for all the detail.

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