It’s been a nice summer indeed, with scarcely a thought given to 3D or 3D printing at all. But now it is Autumn, school has started, and the heat on the trusty Minifactory has been set on again. The first thing I printed this fall was an unusual little device, a pie stamp, for my friend Keefie Williamson.
Keefie sent me this text, when I asked him about how he got involved with 3D printing:
“Before I became a web designer, I was an Interior Designer. I became quite proficient with 3DS Max, and used it to model architectural interiors. About 6 years ago, I moved from PC to Mac, so I longer had any 3D software. A few years ago, I heard about Blender and downloaded it. I never really had time to get to grips with it, but recently I needed to make some 3D logos and so I learnt the basics. Once I could navigate the software, I could see how easy some of the features are to operate.
Recently I decided to make a model of my Pi logo stamp (I make British pies and they all have this logo stamped on them). My plan was to send the file to a 3D printing bureau in London, but when Heikki saw the image of the stamp I posted on Facebook, he very kindly offered to have a go at printing it himself. Making the model in Blender took me a day or two. I stuggled a bit with bevelling and extrusion, but soon got the hang of it.
The only thing that was really difficult was creating the fillet between the top part (the ‘handle’) and the base – the stamp itself. In the end I did it manually by scaling and positioning individual vertices. I think Blender is truly amazing software, considering it is Open Source and free, and I certainly hope to do more with it in the future.”
By the way, Keefie has his own Youtube channel for showing us how he cooks, and he is the author of a delightful book, “Tybalt & Theo“, which is a time traveling lark – well worth the time and money.
But back to Blender. Keefie sent me the file after I saw his rendered image of the pie stamp on his facebook page:
Of course this was something that just asked to be printed. The Blender file of the stamp looked like this:
On closer examination it was seen to be in two parts still, which is a good idea, since the handle part is quite simple in design, whereas the PI part had to be hand-crafted from a pi symbol converted into a mesh, and then joined with a circle:
So, the first thing is to join the two meshes, by selecting them both and pressing J to join. With this single mesh, we can see that the depth of the Pi on the bottom is actually quite shallow (you can see it from that first render too). Therefore I grabbed the lowest set of vertices and dragged them down arbitrarily to have a little more depth in the groove:
And this is all we have to do to get it into printable condition. The one last step is to check the design for being manifold; this can be done in Blender already, using the 3D Print tools, but I always use the free netFabb service to double-check.
Oh, one more thing – sizing. Keefie designed this in Blender without any units, but he wanted it to be something like 40 mm across the base of the stamp. There now exists the chance of setting the scale as Metric; I usually do this by saving the file first, then getting a blank Blender file and appending the object there with the scale already on. Doing this, I get to see that Blender thinks the object is 9.4 meters wide.
This is the result of arbirary units, but it’s nothing to worry about. Actually the only true way of finding out sizes is to place the object in Repetier Host, which is the driver for the 3D printer. In there, you can see that the object, despite Blender’s grandiose sizing, is actually 9.49 mm wide.
So, you can either scale your object up by 100 already in Blender before exporting, or, you can use the Scale factor directly in Repetier Host. Since I want this object to be 45 mm across, I will do some math, and find that 45/9.49 gives me a scale factor of 4.78. With that added to Repetier Host, I get this:
And the size is indeed 45 mm across. An hour and 6 minutes later, I had the first version:
As you can see, there is some blackening on the handle part. I am not sure why this happens, but the nozzle sometimes leaks some material, and when it sits on the 240 degree nozzle, it gets blackened and then deposited on random parts of the object being printed. I believe this has been addressed in newer versions of the Minifactory (they are rolling out a dual color printer soon), but this rarely causes more than a little visual discomfort.
So now I am waiting for Keefie to receive his stamp via mail, and then show me how he puts it into good use. To cap this presentation, here’s a short video of Minifactory printing the first layers of the stamp.