If you're going to have a 3D Printer, you have to be able to design things to print with it. Thingiverse can only take you so far, you know. The only problem with Makerbot/RepRap style 3D printers is that they have limitations. Some overhangs can't be printed, layer delamination can cause parts to break, etc. My goal in writing this article is to create a guide for how to design around the limitations of this type of printer to create strong, functional parts.

For the purpose of this article, I'll be using OpenSCAD, an open-source 3D CAD tool. However, most things covered here can be applied to other programs as well.

The photo is of Erik's label dispenser .

This instructable was produced for Pumping Station: One.

Step 1: A Note On Software

Software is important. Your choice of software affects your design process, and to an extent the way you think about design. For this article, I'll only use open-source cross-platform tools.

One popular option for  3D work is Blender. Blender is a very powerful modeling and animation tool. Blender is also a mesh modeler , meaning your designs are made of triangle meshes. You can then shape these meshes into your designs. A tool like blender is a good option if you like to sculpt or "feel" out designs as you work.

I use OpenSCAD. OpenSCAD is a CSG (constructive solid geometry) modeler. This means that you make your object by combining primitive forms. OpenSCAD doesn't sculpt. It uses a code-like design process, much like POV-RAY or other ray tracing programs. If you like to design mathematical forms, or really like writing code, OpenSCAD is for you (it has for loops). OpenSCAD has one especially powerful feature: variables. Being able to assign dimensions to a variable and then generate the object from those allows you to make parametric designs.

One important thing to keep in the back of your mind is making sure your designs are manifold. In the interest of time, I refer you to this excellent article on the subject. It's much easier to make non-manifold objects with a mesh modeler than with a CSG modeler.

A final note: Although I will be using OpenSCAD, this is not an OpenSCAD tutorial. There are plenty of good ones out there. I will, however, share my source files for every step. I assume that you have some ability to do basic 3D design, and am only providing tips for optimizing designs for 3D printing.
<p>Thanks I learned a lot from this. However I was looking for a more step by step guide on using this devices. Specifically the Mendel Max. Did you make a guide or know of one?</p>
I have been Using Scetchup to doodle 3D things but finding it's limited, I'm going to look into &quot;Blender&quot;, I'm not sure about the OpenSCAD thing since I'm not sure about the script based interface, it's not something I'm familiar with or comfortable with.
<p>I use Sketchup too If you get the pro version (student is about $50) and download a few key plugins its a very powerful and easy to use tool.</p>
Unfortunately I cant afford that, and the free version has been so severely cut back now that I've stopped using it. If it would actually net me real paid work it might be a different issue, It's still on my CV but I don't really have time to &quot;doodle&quot; anymore, nor complete any of my projects, or even hang out on instructables anymore.<br><br>
If I win the lottery I am going to pay you to doodle.
<p>A solution similar to the captive nut method for providing machine threads in 3D-printed plastics uses a type of threaded inserts designed for use in thermoplastics. McMaster-Carr calls these &quot;Heat Set Inserts for Plastics&quot; and they can be found at: </p><p><a href="http://www.mcmaster.com/#standard-threaded-insert-tools/=v7d39d" rel="nofollow">http://www.mcmaster.com/#standard-threaded-insert-...</a></p><p>Basically, if you 3D print or drill a small pilot hole, you can use a soldering iron to heat up these threaded inserts and push them right into the plastic. They heat quickly because they are made of brass, and set in place quickly once heat is removed. This works GREAT as it can allow a deeper thread length (than a regular nut) if you order a longer version, they stay in place once they are installed (but can be easily removed), and they can be put on the &quot;back side&quot; of an object (as a nut would be placed) or the front side (if the back side is inaccessible). I use these with M3 screws to connect my ABS and PLA parts, and they work very well. </p><p>It does help having the insert and removal soldering iron tips (if you need to remove them. Actually, just the removal tool can work for insertion and removal). You can probably use any soldering iron to heat them sufficiently, however, and avoid purchasing the insertion and removal tips.</p><p>If you get the soldering iron tips, they only fit on slightly larger diameter soldering irons (relative to those one might use for electronics assembly). The diameter of the tips is a bit larger than what your soldering iron might be.</p><p>If you have a need for lots of precise threads that are fairly strong and will hold up to multiple screw insert/removal cycles, these could be for you!</p>
<p>Good points in your Step 2. Also, there is no law that says that you must create all of your geometry with the printer. There is nothing wrong with modeling (and subsequently printing) a small divot, or other marker/placeholder for a hole, and then drilling the hole after the print operation is done.</p>
<p>I haven't heard of OpenSCAD prior to this. Trying it out for the last few days. Still much to learn but I like it so far.</p>
Cool, I just started playing around with OpenSCAD. I like it a lot and the use of variables and for loops has been hugely helpful.

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