I finally got a chance to try out the Autodesk 123D catch program and the results are fantastic. Autodesk claims that the program, “takes ordinary photos and turns them into extraordinary 3D models”, and it is true! During one of my bicycle rides I noticed a few interesting statues in a local cemetery and decided to use one as my model. The goal was to print a small version of the statue on my Reprap 3D printer. I took about 50 photographs around the statue to capture it from every angle. I forgot to take some shots from the top down and I’ll explain about that later.

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Tags: 123d catch, 3D printer
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A lifelong dream has been to have the ability to design a robot using a CAD program and then easily produce a prototype or finished product from that design right on my desktop. After a few months of tweaking my Reprap Mendel 3D printer, that dream has finally come true. I’ve always been interested in designing, modifying and refining robotic grippers. Last week I used Solidworks to create and test a new design that would lower the complexity and number of parts. The great thing about Solidworks is the motion study capability. It lets you simulate the movement or your assembly before creating a physical object. This tool saves a lot of time when figuring out if the assembly is functioning as desired. When the simulated design was working properly, I exported the parts as sterolithography files (.STL). Another program named Skeinforge was used to create g-code that the control software uses to direct the 3D printers movements. The grippers were printed using a strong biodegradable plastic called PLA. I really like the white plastic because it reminds me of  the Star Wars storm trooper body armor suits.

3D printed standard servo robot grippers

Robot gripper printed with white PLA plastic.

Karl P. Williams

Tags: 3d printed robot gripper, 3D printer, mendel, reprap, robot gripper, robotic gripper, robotics
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Okay, I’ve now read enough blog postings, etc, to come to some conclusions.
* When you build your own reprap, it’s a DIY research project.
* Part of that research project is hacking together a working software toolchain, which requires debugging and modifying software. You can’t expect to just download polished, bug free working software.

We built our reprap from a Tech Zone kit, one which includes a particular version of the Tech Zone Gen 3 Electronics Remix. Tech Zone sold HUNDREDS of these kits (possibly with several versions of the electronics) before doing a complete redesign and creating a “monolithic” single board controller. This is hardly mass production, so there are relatively few people with hardware like ours, relative to more commercial 3D printers like the MakerBot and the MakerGear Mosaic (which come closer to the ideal of ‘plug it in and it works’). MakerBot has their own software development team, and have created polished, working software that works with their hardware. Nothing like that seems to exist for Tech Zone hardware. The software is DIY.

http://adventuresin3-dprinting.blogspot.com/2010/11/what-causes-warts.html is someone else who has our kind of hardware, and who has also discovered that SkeinForge does not generate GCODE that is compatible with his firmware. In this blog post, he analyzes a particular kind of printing error (“warts”) that we are not far enough along yet to care about, explains how it is caused by bad GCODE, and how to fix it (he wrote his own GCODE postprocessor). And, of course, we’ve identified our own problems, different from “warts”. Kevin has figured out that the M108 codes generated by 3dtoolchain.com are incompatible with the FiveD firmware, and screw up our prints. And there is the still undiagnosed problem of the Y axis jumps (when printing SkeinForge generated GCODE), which is probably also a GCODE problem.

I don’t think there is any GCODE generator that works correctly with our firmware. I kind of doubt that a working firmware/GCODE generator pair exists for our hardware as packaged software that you can just download and run. Maybe there is firmware that is better than FiveD and works with our hardware, if so I’d like to know about it. I’m more certain that there is no working GCODE generator, and that hacking Skeinforge is the best way forward. [I've cc'ed Kimberly from Tech Zone. She can correct me if I'm wrong. But since Tech Zone's own 3dtoolchain.com software generates GCODE that is incompatible with our firmware and hardware, I'm not optimistic.]

I’m a software engineer. I don’t have Kevin’s hardware smarts. My plan is to hack Skeinforge (and possibly the FiveD firmware) until we can generate GCODE that is compatible with our firmware. Some of the hacking will just be Skeinforge configuration settings (the goal is to come up with a machine configuration file that works with our printer). Some of the hacking will involve adding new configuration settings to Skeinforge so that we can accurately describe our hardware and firmware. I’ll contribute the changes back to Skeinforge. Ideally, I shouldn’t modify the firmware unless necessary, I should try to make Skeinforge work with our firmware, not vice versa — that way, my changes will be useful to a larger group of people.

There are other ways forward. We could replace our electronics with something more modern, eg a single board solution that is compatible with the hottest and most capable firmware and software (eg, Sprinter firmware and the Pronterface front end). That will require time and money, and I suspect we will still need to hack software.

We could also get a new 3D printer, something that is closer to plug and play than a reprap. That requires another $1000 in funding, more or less.

The end goal is for our space to provide a 3D printer that can be used by artists and other makers, people who are not interested in reprap hacking.

Tags: 3D printer
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Tuesday night, after most of the crowd had left, I got the 3D printer to move and extrude reliably, and printed two pieces with it. The first was the same part we had printed previously, before we started having nozzle problems: it is a printer part which acts as a spring mount for the home-position optosensors. The other is a Kwartzlab logo rendered in 3D by Alex with some modifications (scaling and a base to hold all the parts as one) by myself.

Fresh output from the 3D printer

The two smaller L-shaped bits are artifacts of the GCode generation. The print head returns to the XY home at the end of each layer, and once the Z axis has moved up, the first thing done is to print another layer on this piece. I think its purpose is to snag drool that occurs during the home and Z move operations.

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Tags: 3D printer, mendel, reprap
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