Accurate Temperature Control Of Your 3D Printer Extruder

September 19, 2013 by Mathieu Stephan 16 Comments

[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

September 18, 2013 by Adam Fabio 23 Comments

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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3D Printering: Alternative Filaments

September 18, 2013 by Brian Benchoff 15 Comments

ABS and PLA are the backbones of the 3D printing world. They’re both easy to obtain and are good enough for most applications. They are not, however, the be-all, end-all filaments for all your 3D printing needs. Depending on your design, you may need something that is much tougher, much more flexible, or simply has a different appearance or texture. Here are a few alternative plastics for your RepRap, Makerbot, or other 3D printer:

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Automatic Tool Changing On A 3D Printer

September 17, 2013 by Brian Benchoff 9 Comments

tool

[Luis] has a pretty interesting project on his hands. He’s using a delta 3D printer to plate a few edibles – yogurt, chocolate, and other thick liquids. Because he intends to use actual plates as the build surface, calibration is key. One solution to this problem would be to use identical, pre-measured plates for everything this printer makes. [Luis]’ solution is much more ingenious than that, however. He’s programmed his printer to automatically swap out two tools – one for probing the build surface, and another to extrude liquids.

The two tools are suspended from the body of the printer, and with a little bit of software it’s possible for them to be picked up by the head of the printer and held in place with a few magnets. After auto leveling the build surface in software, a G Code command switches the tools over to a paste extruder for all those delicious edibles.

If an automated tool changer isn’t enough, [Luis] has also completed a very nice 3D printed peristaltic pump to squirt out foodstuffs. You can check out a video of this printer in action below.

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3D Printed Injection Molds

September 15, 2013 by James Hobson 28 Comments

A team at Budapest University has successfully created a functional injection mold for prototyping by using a Stratasys 3D printer.

Prototype injection molds are expensive. They are typically machined out of steel or aluminum which is both costly and time consuming, due to the complex geometries of most molds. [Dr. Jozsef Gabor Kovacs] works in the Department of Polymer Engineering at Budapest University, which is where he came up with the innovative approach of using 3D printing to produce a prototype mold.

The mold was printed in Digital ABS PolyJet Photopolymer plastic using a Objet Connex 3D printer. The injection material used was polyacetal; which has a fairly low melting point of 175°C. By using this method they were able to go from a prototype mold to a test part in less than 24 hours. We don’t even want to think about how expensive that would be to expedite from a machine shop.

After the break you can watch the entire production process from printing to molding.

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Students Build A 3D Printed Plane

September 13, 2013 by James Hobson 33 Comments

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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DesignSpark Mechanical – The Gift Of Invention

September 13, 2013 by James Hobson 58 Comments

Ever heard of DesignSpark? They are releasing a powerful CAD package on September 16th — for free!

The company is owned by RS Components, a distributor of electronics and maintenance products. They offer a large library of 3D models of parts that they sell, dubbed the ModelSource. So if you are wondering how they are giving out software for free, that’s how. They also have free PCB designing software, and something called DesignShare which hosts open-source project collaboration, sharing and discussions.

By the looks of the demo video, DesignSpark Mechanical is a well laid out CAD package that is rich in features. The software allows for the import and export of several file types, and it looks like ECAD, OBJ, Sketchup, STEP, DXF and STL are all there, as well as the native file types. While it looks like you can import any files, we are willing to bet adding ModelSource files are by far the easiest and most convenient because of the integrated ModelSource library. But we think that’s a small price to pay for an alternative to SketchUp. After all, the component models will be useful for assemblies, even if you don’t order through them. Oh, and it’s perfect for making free models for 3D printing as it includes the ability to export STL files.

Watch the software demo after the break.

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