3D Printed Toy Car With a Cut Out Name

My first 3D print ever, and no margin of error. 

I designed a basic car that has a name cut out from the top prifile.  The name, you ask?  It's my niece's (Sunny).  The car, you wonder?  It's roughly based on a 1967 Porsche 912. Very roughly based.  The occasion, you question?  Sunny's birthday tomorrow. The margin of error?  If I screw this up, I'll look like an idiot- being her only uncle and having nothing to give Sunny at her birthday party.** To add even more difficulty to the issue, this is my first 3D print, ever;  I'm flying in blind and hoping for a perfect strike.

I think it's important to note - as I'm writing this right now I'm watching the 3D printer do its thing; the feeling is difficult to describe.  I've spent hours and hours making something [virtually], and to see the embodiment of the item that I've created is beyond thrilling.  It's almost magic - I started with nothing, before my eyes a translucent green form that I conceived and designed is taking shape. It's really cool.  Really cool.

At this juncture I want to note that I can expand on any one of these steps.  Each of the steps in this instructable could be turned into an essay in and of itself; but I'm not going to write a whole bunch of stuff not knowing if anyone even wants all of the fine details.  If there are questions, don't hesitate to ask, I'm happy to be more descriptive if there are wondering minds out there!

**Both Sunny and her parents/my siblings are awesome - it wouldn't be much of a deal if I don't bring anything, I guess the stress/low margin of error is self imposed!

Step 1: Design the Car

Designing the car took me 3 days, almost non-stop.  I was using SolidWorks, which is both sophisticated and intuitive (and I've modeled other things in), but I based the model on a feature that I've never used before (surface loft).  I kid you not, I "built" between 5 and 10 Porsche 912s before getting it right, with each model taking me between 2 and 5 hours.  Pictured are a few of my attempts.  

Some hints that I learned the hard way:

Most important:  start with a basic shape, then add more features!  3 or 4 times I spent hours on a design, but then the surfaces failed to render, for various (still unknown) reasons.  It was MUCH easier to start with a very basic shape, make sure that the surface loft worked, and then add detail (via adding additional cross sectional sketches).  It's MUCH easier to add more detail to a surface loft than to have all kinds of details [cross sections], only to find out that SolidWorks can't render those details.

Use control polygons for splined curves.  This'll make your life much easier when you're trying to edit/modify a complex curve.

Make sure that all of the points are BOTH coincident AND pierced when you are intersecting a cross sectional line with a longininudal curve. Especially if you mirror points over a line, those mirrored points WILL NOT pierce the mirrored line if you use the middle of the  cross section as the mirroring entity.

The less cross sectional guide curves the better.  In some of the early models, I had around 10 cross sections, but the model/surface loft didn't work out or looked stupid.  I won't tolerate a stupid looking model for my only niece.  Rather than trying to modify each  model so that it was sufficient, I just started over, which I think was the right decision (it's more difficult to fix faulty things than to start from scratch). With more cross-sectional sketches that SolidWorks tries to knit together, the more the program can get confused.  I ended up using 4 cross sectional sketches, the outline of the car, and the longitudinal middle cross section of the car (running bumper to bumper).  The fewer the lines/splines that Solidworks has to combine to make a surface, the cleaner the surfce (in my limited experience).

For whatever reason, it DIDN'T work for me to sketch the front and rear face of the car.  I ended up just lofting the appropriate curves to the appropriate planes. This fact frustrated me to no end, and I probably spent the better part of 4 hours trying to remedy this, but for whatever reason SolidWorks liked it when I drew the centerline of the car, then drew ONE outside line (the bottom of the passengers side, or the bottom of the driver's side) and mirrored it over the drawn centerline, along with half of each of the 4 cross sections.

NOTE: I am far from a Solidworks pro - I'm sure that there are people who will tell you something different than what I did, and they could probably do it better.  Good for them.  I'm just saying what worked for me.

Step 2: Final Design of the Car

Here is the final design of the car (without the name cut extruded cut from the middle). I made sure to fillet all of the edges - we don't want a 2 year old playing with a car that has sharp edges!

I like big, bold, and brash things.  This final design is 7 inches long and 4 inches wide (but it ended up being 1/2 the size, I scaled it so it wouldn't take inordinately long to print).

Step 3: Car With Name Extruded Cut

After the car was designed, I just did a sketch of Sunshine (Sunny) on the bottom plane of the car and made an extruded cut through the car, which is extremely easy in Solidworks. I also made sure to fillet all of the edges where the letters meet the top face, just to make the car pleasurable to touch and interact with.

Here are a few pics of the final design.

Step 4: Steps After Design

I'm a member of TechShop in SF (TechShop is f**kn' awesome, it's a badass place with badass tools that you can use and badass empolyees who teach badass classes on how to use said badass machines) and I took a class on how to use a 3D printer.  Here's the protocol, after the part is designed:

3D design (Solidworks, in my case) -> export as *.STL -> open in rendering software (KISslicer is what I learned at Techshop, which is easy and open-source [read: free]) that outputs in G-code, which is what actually runs a 3D printer -> open the G-code in the 3D printer's software and print.

Here is a picture of the car in Kisslicer (with the printer running in the background).

Note:  KissSlicer uses whatever coordinates are innate to the imported file.  In my case, the z-axis was in the wrong direction (it was in the direction that the passenger side door opened, not the direction of the floor of the car to the roof, as one would desire).  This would result in the 3D printer trying to print  the car with the passenger side door on the ground, and print up to the driver's side rather than the floor of the car up to the roof (which is what we want). To remedy this, I inserted a new coordinate system into the model, then when you save the file as a *.STL, hit the 'options' button, then there's a 'coordinate system' dialog box where you can select the coordinate system that you've made.

I wanted high print quality, so (in Kisslicer) I chose a layer thickness of .15mm with an extrusion width of .45mm.  Because this would've taken about 6 hours to make, I scaled the car down to 1/2 size.

Step 5: Into 'Pronterface'

After adjusting the features in Kisslicer, I saved the car as a *.gcode file.  Then I opened that file up in the software 'Pronterface,' (pictured) which is what actually runs the 3D printer (it's a 'Type A Machines' brand 3D printer, and I don't know if Pronterface is OpenSource software that is used to run the printer along with other machines, or perhaps Pronterface is proprietary and only used on Type A Machines).

Being my first time using the machine and Pronterface, it took me a while to get the Z-home fine-tuned, and it also took me a while to figure out how to get the printer to warm up.  These are steps that seemed straight forward in the TechShop class that I took, but in the few days since the class I evidently forgot.

Then I hit the 'PRINT' button in Pronterface, and the printer started!

Step 6: Print!

Now just sit back and watch the 3D printer do its thing!

Step 7: The Finished Product

Holy crap - I just pulled a pizza out of the oven that I improvised - butternut squash, red onion, and a a white sauce with sage and thyme.  It's ridiculous; next time I have company over I know what I'll cook. If anyone wants to know how I made it I'll post in an update.

Meanwhile, back at the batcave......

So here are some pics of the finished product.  I'm happy with it, especially in light of the fact that this is my first 3D print..

Step 8: Improvements

Were I to do this a second time, there are a few things I'd do differently:

Make the layer thickness thicker (try going from .15 to .3 mm).  Although this would make the model rougher it would print faster and thus I could make a bigger car.  Like I said a few steps ago - I like big things.  I'd rather decrease print quality and increase quantity.

I'd add wheel wells and wooden wheels.  I was thinking of doing this, but I decided against it.  I think it would increase the 'cool' factor of the model if it had wheels (even if they didn't work).  Certainly I coul've printed wheels on, but then you've got a bunch of empty space between the ground and the undercarriage of the car, which is doable but would add a level of difficulty.

I'd decrease the detail of the initial car model even further.  I spent a lot of time making the line the runs the length of the car (most visible in the pics in step 2).  I think it's a really sexy line, but with the name cut out of the car, this line isn't really distinguishable.  As a whole, I think the model would be better served with a car design that is even more basic than the one I made.

I made it at TechShop!  Check 'em out:  www.techshop.ws