I really like the idea I came up with for this project. It may be obvious, even passé for the experts, but when the idea hit me I had to immediately make it happen.
Don't judge by the photo; I deliberately included the very first print I ever did with this technique, warts and all, to allow others to take on this idea and run with it. I, of course, am iterating the print to improve it - but that's all part of the journey, right?
This photo includes an Australian two dollar (commemorative) coin for scale.
White, then Black
The FlashForge Finder only has one extruder, so I printed the white labels, then the black rest of it. See "My Technique" below.
Hot off the presses!
I haven't done anything to this first print, specifically to see how it went.
What I learned:
- Lower the temperature before printing the letters!
- "Groom" the result of the letter print to remove strings before printing the main body.
That last is going to be tricky! I want to remove the strings, but I don't want to disturb the placement of the text. And those indicator dots are small, so they'll be easy to disturb...
Would you believe that I hadn't even heard of parametric modelling a week ago?
And now I visualise the steps necessary to print both the positive and negative versions of the model in contrasting colours to produce this result.
See "My Technique" below.
Why I started 3D printing - this exact project!
I play around with electronics; building and populating circuit boards to experiment with different aspects of our electronic world. But after the circuit board is complete, the next step is more frustrating than the electronic design: housing the circuit board in a box, allowing access to the controls.
I usually use a range of different Jiffy™ boxes; plastic (ABS) boxes that come with slots and/or screw mounts inside to house the boards, and a lid that you can drill and cut to mount the external controls. But I've wasted more than one lid with mis-drills or off-angle cuts, and my latest project was a monster!
Not literally; but this project used an old-style analogue meter, and the hole to accommodate it needed to be 44mm. Apart from the fact that I don't have a hole cutter this size, the fact that it was inside only a 65mm wide lid, and had 4mm holes very close to it to precisely hold the meter in place, meant that I doubted I could line everything up well enough to do the job.
That's when I realised: maybe this was the perfect reason to finally get into the world of 3D printing? If I could replicate the Jiffy™ box lid first, then virtually "cut away" the holes for mounting the controls, the result would be better than me hacking away at the lid - and probably wasting a few days, and lids, in the meantime.
I was willing to consume more hours than needed on this project for three reasons:
1) I felt the results would be better;
2) If I built the starting lid first, then I could use that model in future projects;
3) An excuse to learn 3D printing - and parametric modelling.
I'm a systems programmer by profession, so I was curious to know how I would feel about "programming" the printer to produce the model I wanted - and I learned that I love parametric modelling. It "sings" to me: the idea that I can virtually define an object in exact detail - and then get a printer to produce a close facsimile thereof - satisfies something deep inside of me.
I had fun with this project. I bought the cheapest 3D printer available that would do the job I needed, foregoing many things that maybe I shouldn't have scrimped on:
- A heated bed;
- Multiple extruders;
- A larger print area.
But the result was more than good enough for this project, and probably many future ones too. However, the neatest thing I did was why I posted this project on Thingiverse: I realised that I could incorporate the labels for the controls inside the actual print itself! See the next section on how I did it.
In FreeCAD, you can use the Draft Workbench to write ShapeString text on the face of a solid. You can then Pocket that text into the solid, to make a reverse-embossed "hole" in the shape of the text.
If that text is large enough, the effect is striking. For small, shallow text however, there isn't sufficient contrast to see what the text says. You need to "fill" those holes with a contrasting colour - and then the results POP!
Steps to Reproduce
Luckily, it's easy to produce the "opposite" image for an area by using the Boolean Cut tool. I did the following:
- I produced a Body that contained the starting image that I was going to reverse-emboss with text. Let's call that the "Base" Body, at Step X.
I then kept adding to the Body, defining the necessary text strings in the correct areas, and "Pocket"ing those texts into the Base - but only for 0.2mm. Let's call that the "Final" Body, at Step Y.
Note that you can only write text on one face - and that has to be the starting, face-down face when printing. The reason why will become obvious below.
- I then selected the "Base" Body at Step X, and chose "Clone". This produces a new Body based on the Body at that point.
I then selected the "Final" Body at Step Y, and again chose "Clone". This produces yet another Body based on the final step.
Why did I use "Clone"? That makes it easier to modify the original design - and the Clones then follow along.
- I then very carefully selected the Clone of the "Base" Body. It's important to select this one first, because it has all of the material in the design.
- Holding down the
<Ctrl> key, I then very carefully selected the Clone of the "Final" Body. This is basically all of the Base Body, minus the text parts.
- I then chose the "Boolean Cut" operation in the Part Workbench. This "subtracts" the second selection from the first one - the Everything-but-the-Text Body from the Everything Body - leaving just the Text in a Body all by itself. Let's call that the "Cut" Body.
- There are now two Bodies of interest in the project: the "Final" Body, minus the letters; and the "Cut" Body, which is only the letters.
- I then used the Mesh Workbench to produce two Meshes for these two Bodies, and Exported them as STL files.
Steps to Print
To print these two STL files, you need to make sure that you specify the same locations for the two separate prints. If the default position works, then there's no problem. If you need to move one, then make sure you apply identical movements for the other - don't just drag the image into position! Use the printing software's X/Y/Z and Rotation angle input fields to type in values, rather than guessing with the mouse.
Load one colour of filament for the lettering (obviously White for this project). I personally "squish down" the starting Z layer a little for better adhesion - the whole print is only one layer after all. Make sure you print a long "snail trail" to prime the extruder, and that you set the temperature lower to avoid as much stringing as possible. Select the Lettering STL saved previously, and note that the print will be finished very quickly.
When the print finishes, you need to perform surgery on the existing print without removing the bed from the printer. Try very hard to not even touch the bed, to avoid it moving before the next print. Remove the "snail trail" to stop it interfering with the next print. If you notice any stringing, very carefully remove those too. I use a pair of tweezers, grabbing the string near the actual print section, and then carefully wiggling it back and forth until it breaks. You do not want to remove the text the string is attached to - but neither do you want the strings to remain! (Otherwise, see photos…) If you do interfere with the letters' positions, you'll need to remove everything, clean the bed, and start again.
Once you're happy with the letters, you can then change the filament and start the next print. This time select the STL Mesh for the rest of the body and simply print it - providing the same offsets (if any) from the previous print. This should start printing directly over the previous letters: the holes in the final print should match exactly with the letter fill from the first print.