First 3D Print and Bezel

I need to design some parts to be 3D printed or CNC machined. I have no CAD skills and although I bought a 3D printer, a MakerBot 2x, a couple of years ago, I never fired it up. So it makes sense to do something simple first...

The removable side-impact bars utilize interlocking couplers. When they're removed the exposed couplers don't look good, so I'm going to make an end cap. I spent an entire day designing the part below. That includes sorting out the printer, installing and learning the CAD software basics and printing the part out. While one day seems like a long time for a simple part like the one the right, it would have been much longer without YouTube! Now that I know the dimensions of the part and the basics I can redraw the part in a few minutes.

I chose Autodesk 123D because it's free, it's approachable by beginners and it has pretty good reviews. In terms of researching packages I found this decision graph and this summary list very useful.

After designing the part, I decided that I wanted to go back and change the fillet on an edge... well the only way to do that is by clicking undo until you get to that step (assuming that the steps are still in the buffer) and then manually redoing all of the subsequent steps. The reason for this is that it's using a 'direct modeling' approach. When you make a change to a solid, such as cutting off a piece or applying a fillet, it's gone. There is no way to get it back other than undo. Parametric-based CAD stores all of the steps and you can go back to any step, change it, and then have that change automatically rippled forward. These packages are usually more expensive and more complicated to use, but that's the direction I'm going. I'm thinking about SolidWorks which is both expensive and overkill for what I'm doing.

I did a test print using the 3D slicer that came with the MakerBot. I would show you a picture of it but my wife threw it out thinking it was some 'Lego junk' -- apparently my kids shouldn't leave their Lego stuff anywhere near the kitchen. In any event, I wasn't crazy about the quality of the print so I bought and installed Simplify3D, a pro-level slicer (please don't tell Esmeralda that because I'd like to bank that mistake -- I'll need it for something I'm sure). However, I couldn't get it to communicate to the printer via USB and the SD card on the printer wasn't working. Frustrated, I searched for a local 3D print shop. I found 3D Hubs which enables you to upload a design and get instantaneous printing quotes from nearby shops. I picked Charles River Maker which is all of 3.4 miles away and had my part printed (they use Simplify3D as well). In the picture below you can see the white, 3D-printed part on the top coupler compared to the bottom coupler which doesn't have the part.

Jeremy was very helpful and he has a bunch of 3D printers (one large enough to print at least a prototype of my tail light bezel) as well as a laser cutter and other cool equipment.


I spent several more hours cutting and filing the bezels and almost all of the extraneous pieces have been removed. The picture below is a scan of the passenger side bezel.

There are three primary issues that I'd like to deal with:

  • The right side of the bezel is on a 45-degree angle which hides part of the light and will look weird on a flat-tail car like the SL-C.
  • The right side of the bezel is curved on the top and bottom. The curve on the top should look good because the tail already has a similar curve there, but the bottom curve would look much better if it were straight.
  • The left side of the light is an inch and half or so shorter than the right side. It would look much better if they were the same height (i.e., the top and bottom were parallel).

I think that I can solve all of this by cutting the right side of the bezel off and 3D printing a bezel that surrounds the entire outside edge of the existing bezel (reproducing the interior bezel would be a massive amount of work) and extending the exiting bezel it in the desired places. 

I'm not sure how to import an image into a CAD package yet, so I just did the above in a paint program. It outlines the general direction that I'm thinking:

  • Blue Lines: ~7mm thick border
  • Red Line:  ~3.5mm thick border
  • Green Line: sits on lens and slopes back at what looks 45 degrees per existing piece
  • Yellow Triangle: fill between the blue lines at top surface
  • Orange Triangle: 8mm recess to glue custom-cut reflector on