How to use Openscad (2): variables and modules for parametric designs

Part 2/5: Variable and parametric design

The previous part addressed the basics of Openscad. It relied mostly on "immediate values": we were providing dimensions as explicit numbers. If you want to tweak the design dimensions, then you need to parse the scad source code and fix the numbers all everywhere.

In fact "hard coded" numbers must be avoided. As opposed to "static" designs, parametric designs give the flexibility to tune the numbers very efficiently at one place only. The good point is that Openscad is one of the best tool to do so.

A larger mug by using the scale operator (from the "basic" tutorial).

This is still not parametric, as numbers are hard-coded (a bad practice).

See how the numbers in our mug design above depends on each other? If the cube is to be made taller for any reason, then the intersecting sphere and hollow cylinder must be tuned accordingly in the source code. And this is exactly something a computer can do better than us.

So let us first convert this design to a parametric version, i.e. a design that can be tweaked with a small set of parameters that all have a clear role (width, height and so).

How to use Openscad (1), tricks and tips to design a parametric 3D object

Part 1/5: Introduction to constructive solid geometry with Openscad

Some technical and non-technical people keep asking me how I create new designs. As often, after a few personal replies, I end up heading to the blog to share the answer as they keep asking for more.

Also, I long wanted to write a pragmatic and step-by-step introduction, howto and tutorial to Openscad. The idea is to help people even with no programming skills (mostly in this part) and to bring newcomers to a point that they can design their own 3D objects (part two). Interestingly, Vicariously, Openscad is very interesting to get a glimpse at what programming is because you get an immediate, visual feedback of your actions (even my mother, a former history teacher, was eventually able to get a clue at what my job was about). Once understood these concepts, it may be much easier to move to other languages.

Now, if only a few readers become "designers" by reading this I will be quite happy. If some people realize that programming is not that obscure I will be happy also. Meanwhile, I will have given a detailed answer to my friends and contacts!

A non-obvious GoPro mount of mine, that is fully customizable thanks to Openscad.
It looks complex, but it is still exclusively made of spheres, cylinders, and cubes with a few basic "joints".

A forthcoming last part will deal with the complex features of Openscad. This one is for people that either learn fast or for those that are already proficient with the usual features of Openscad.

1. Introduction to constructive solid geometry with OpenSCAD
2. Variables and modules for parametric designs
3. Iteration, extrusion and useful parametrized CSG techniques
4. Children, factorized placement and chained hulls

So first, what is Openscad? Within the CAD family, it is a 3D modeler: a software that helps you to create 3D objects. There are many such tools, but this one is used extensively in the 3D printing community, not only because it is free but because is it really efficient for some kind of objects.

It may or may not suit your mind, but with time I am able to "see" the shape I describe, not as text but directly as shapes. I guess it depends on people, but I am sure there are people that are not programmers that can think alike. And if you are already a programmer with no industrial goal then you really should give it a try. It will be a breeze to use up to a productive level, especially if you do not want to invest time in a new and hellish interactive user interface!

The official manual is OK but it does not really work as an introduction. The navigation is also sometimes difficult to the point google is more useful. There is a nice raw cheat sheet also but it has no link to the respective functions (what a pity!) (update: it does now!). In any case, these fail to help to learn Openscad quickly in my humble opinion.

Home made filament drying box

How to make a simple dehydrator (drying box) with a solar vacuum tube

A short and probably overkill post for a passive and zero carbon footprint drying box (not counting the required one to make the tube).

I use a spare, high tech and powerful vacuum solar tube, but it is easy to make something with a copper or steel tube painted in black, around which you slide larger transparent plastic bottles. Such insulation is required to avoid the ambient air temperature from cooling your own heated air.

The second required item is a brand used low-tech cardboard box.

E3D v6 hot end: ideas and assembly tricks

Assembled E3D v6 with a few particularities

You may remember that I wrote broadly about hot ends in an another post, but this short new one is specifically about the sixth revision of the E3D family (E3Dv6).

This is probably the best hot end on the market right now (in my opinion -- and I did not check them all). It is not cheap, hence expensive as all the good quality hot ends. But this is a critical part where you cannot really lose money if you value your time...

However there are still some room for some improvements. 

Materials for artists: 3D printing wood, chalk, and eventually metal with bronze

Important materials for artists

An amazing door knocker by Sonia Verdu
(rust comes from post-processed glued iron dust)

Still today, the visual quality of 3D printed objects is far from perfect. Of course, a stringy or bumpy surface does not mean the part will not work: you can get a visibly ugly part that still works well enough as a mechanical connector for example. But an artist will certainly not like it.

This post tries to list the main filaments that artists would look for first. Many other filaments are listed in a former post about materials that can be printed (without artistic consideration).

It also talks about the brand new bronzeFill filament from ColorFabb. Yes, it does contain bronze. No, we are not yet printing metal really. But certainly it is a major and very welcome addition to the list of interesting materials to 3D print.

Four in the morning. Just had a few tweaks to finish my upgrade...

Eventually "implemented" my upgrade! I certainly did not think it would take me so long, but once you start to sort the mess that's below a 3D printer you just can spend days on it! There is a brief list after the break.

I am sure a lot of 3D printer owners share the "two minutes into two hours" syndrome.

Why you should not buy Makerbot 3D printers!

Avoid Makerbot and its 3D printers, they are both wrong.

Really! And there are many reasons not to buy: cost, reliability, human values, innovation and so.

I endorse even less Makerbot business
than I already trusted their products !
But enough is enough, this time I say why.

Seriously, Makerbot Industries care more about money than 3D printers. They so badly want your money that they start using dirty business practices. As a client, their overall strategy is simple: you will increasingly pay more to get less. The quality of the product does not count as long as they keep selling it through marketing tricks.

Update (nov. 2014): eventually, well-known resellers of 3D printers like imakr even stopped selling them because of after sale burden and heavy customer negative feedback.

Update (april 2016): interestingly, this post still holds. Makerbot just moved its production to China. A few arguments may be outdated though, so read carefully.

Do not think this is a biased joke, neither only a maker's rant (as formerly). I really want to warn would-be customers that they should not buy. And I want to try and stay objective.

But beside this, Makerbot brutal business strategy makes all this clear beyond doubt. I cannot think of any other motive than greed, or may be also for the inflating ego of Bre Pettis, its director. By the way, 3D printing certainly never was invented by Makerbot -- this is pure usurpation. Please do not fall in the trap of old and dirty business practices.

The businessman and the maker

The Businessman and the Maker

Businessman v.s. Maker (although Dilbert is certainly not a maker!)

At Fabcon 2014 3D print fair (my feedback is here), I gave a speech entitled "Make it yourself: it can be better than what the industry sells you!".

It was insipred by this former post on the same vein, which rang a bell in Florian Horsh head (so much he very kindly invited me).

3D print fair at Fabcon 2014: feelings and people

Fabcon 2014 - was worth 2575 kilometers and 31 hours on a motorbike!

So I was kindly offered to give the closing talk of the 2014 edition of Fabcon 3.D in Erfurt, Germany.

My talk is now available online as slides, and also as a youtube video (for some unknown reason I cannot embed it here).

Note that I added a short separate post that resumes it, with a few new ideas: The businessman and the maker. This one is about the people and projects I met there.

My spoken English should definitely be improved (and I was half sick half exhausted), but it will spare you pushes on the space bar for the next slide, and more importantly, you still get details in the 25 minutes not-so-lively speech. My apologies, as it was the first time I spoke in public for years (back to my time at the long-gone Palm company, and more significantly during my PhD, huh, 14 year ago!). Please read ahead.

Quick comparison: pro versus low cost FDM 3D printers

Are so-called "professional" entry-level 3D FDM printers worth their price?

A LinkedIn user in my network asked for more data when I said that "low cost" FDM printers could compare favorably to "professional" (and expensive) printers. Sure, it is a bold statement, and it does not hold for every of the many "levels of quality", as there are just too numerous. But let me get into more details.

In my opinion, an Ultimaker rev. 2 (~2K€) compares very nicely to a Stratasys UPrint-Se (~23K€)

I certainly do not want to say the "pro" printers are crappy, nor that any brand is crappier than the other, but I had the chance to compare my Ultimaker prints with a "professional" Stratasys entry-level printer (i.e. 1200€ versus 23K€). The outcome is that I just would never swap the two even if I was offered the "pro" one for free! Huh.

Now I am a power tinkerer, I know how to print, I prototype the printer itself, and I cherish freedom, but I tried to keep this bias out of the following arguments.