Custom phone stand 3D printed

This project is here just to test idea how easy it would be to match complex real world objects without technical drawings. Sometimes I just want to make small improvement in my office or home space, that is not necessarily useful, but it's fun and learning experience.

Design

I wanted to have a stand for my HTC Desire 620. It is equipped with special "dot view" sleeve that should be included. Top buttons should be available, and front camera and microphone shouldn't be obstructed.
I envisioned two custom pockets on both phone sides joined together with aluminium bar or pipe or angle, whatever is on hand. After looking through my scrap bin I found suitable aluminium angle.

Drawings

I started with profile picture of phone with cover open - the way it would be inserted in a stand. Try to go as perpendicular as possible. Start from upper side, and lower camera until front screen panel disappears.

Then I cropped image along one critical dimension (thickness of the phone and cover in this case), and imported image to QCAD setting image height to measured value.
Then phone outline was traced with polyline tool.

Now picture can be deleted and outline should be exported as SVG

3D model

I pondered of choice between OpenSCAD and Autodesk 123D Design for 3D modelling. Ultimately I chose 123D Design because I didn't need any parametrization, and I wanted to get it done quickly.
That happened to be problematic, because 123D was notoriously crashing silently when trying to import SVG exported from QCAD. I finally managed to make it work going through Inkscape as intermediate process.

Make sure that dimensions are correct after import. This is inside profile, so it needs to be extruded, then outside shell of 2mm thickness is created. Now there is time to remove some external walls, add few bevels, and cutouts for camera.

Then I added bottom tilted stand part. with cutout for aluminium angle that will be glued in to hold both stand parts together.

Test print

Before going with full print I cut small slice from object to test fit. It was really quick couple minutes print, and this is the part where 123D shines. It's extremely easy to cut 3D object into smaller pieces.

Full print

After I was happy with test print fit I exported combined objects to STL, and loaded one side of holder to RepetierHost. Then I added another mirrored copy for right side.
Object was printed in ABS. I had one failed print when I forgot to slow down travel speed. If travel speed is set too high I experienced print head hitting objects while passing over edges, and then x-y stage is loosing steps messing print out. When I print multiple objects I usually lower travel speed to 40mm/s, single object can go with travel speed over 100mm/s. There is an option in slic3r to avoid crossing perimeters, but it seems to work incorrectly when there are multiple objects placed on the stage.

Test fit with aluminium angle

 Final version glued with epoxy

 Lessons learned

This technique can be used for close wrap around any object that has extractable 2D profile. It allows for close fit around complex profiles.
123D design has some bugs in SVG import, so next time I'll give OpenSCAD a try.

Attachments

• 123D Design project
• SVG contour
• STL file for 3D printer