Project help, printing a Neopixel enclosure to secure to a car rear windscreen

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I haven't purchased a 3D printer yet, I've been working on the software and electronics for my project and now I'm about ready to get a printer, haven't decide on which yet.

Recommendations welcome.

My project will put 3 rows of Neopixels on the windscreen of my car, attached to the top inside. I intend to print the container in sections that will slow together.

I want to allow for the curvature of the windscreen in the design of the container and this is my question, I want to design a container that will hold 3 rows of Neopixel strips, thats the easy part, I want the container to fit neatly against the windscreen with no gaps, how do I work out the curve of the windscreen so I can put this onto the enclosure ready for printing?

The enclose will be as wide as the read windscreen and split into printable sections that will slot together for installation.

The car this is going into is an Audi A5 2012.

SPlatten

Posted 2017-11-26T18:29:55.927

Reputation: 227

I know this is an old post, however since creating the post I've progressed a lot and in the end the solution was quite simple....Using a peace of wood which I position across the back of the windscreen, I measured at regular intervals the distance from the wood to the screen. I then plotted this in Autodesk Fusion 360 and produced an accurate curve of the windscreen, then then split this into printable sections and it fits perfectly. – SPlatten – 2018-08-22T06:20:12.140

I'm not entirely sure what your question is. How big are the pieces that you want to print? – Mick – 2017-11-26T20:05:26.070

There are 3 rows of NeoPixel strips arranged one over the other with a gap between each row of approximaltely 2 mm. Each row contains 62 pixels. The entire strip will be large enough to span the rear windscreen, I plan to print segments of the entire enclose the size of each will depend on the printer chosen and what size it supports. – SPlatten – 2017-11-26T22:07:38.707

Answers

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There's a handy tool for replicating curves that use a series of plastic or metal fingers in a sliding mount. One presses all the fingers to one side, then presses the bracket to the desired surface until all fingers are in contact. The opposite side now represents the measured curve and can be traced into a modeling program.

For your purposes, that is unlikely to work, as the tool is perhaps six inches long, far too short to span your windscreen.

Consider the following:

Attach a string to each edge of the windscreen or wedge a thin rod from one side to the other. This provides you with a straight line reference. Measure as nearly as possible to perpendicular from the reference string to the windscreen surface. I have a laser measuring device that has 1/16" or 1 mm accuracy above certain distance, which would not work well in this case as you approach zero at the edges.

Start in the center, record your measurement, and move an appropriate distance outward. I suggest you need only approximately 20-30 mm spacing as you are collecting points on a curve, which are likely to be relatively uniform and easily reproduced in software.

Your graph now has zero, zero on the left, and say 750 mm, 40 mm on the right, with matching numbers in the middle. On real paper, turn it into a graph, or use a suitable vector editing software such as Inkscape and duplicate it there.

Depending on the shape of your window, you may have to replicate the process at different heights in order to get a proper representation of the curve of the glass.

Once you have the dots, run a Bezier curve through the dots. The resulting like can be extruded or otherwise converted into the segments necessary for your 3D printing project.

fred_dot_u

Posted 2017-11-26T18:29:55.927

Reputation: 8 399

Thank you, was you laser measurement tool expensive? Sounds like a good plan. – SPlatten – 2017-11-27T06:48:52.050

I found lots of laser measurement devices on Amazon, thanks. – SPlatten – 2017-11-27T06:55:40.157

Be sure to check the specifications for minimum distance with the laser. I don't recall what limits are on my Bosch version, but it's not practical to measure near zero. For your requirements, a mechanical device like calipers may be better suited. The depth measurement feature of an inexpensive set of Harbor Freight calipers would give you suitable accuracy as well. – fred_dot_u – 2017-11-27T10:06:53.680

I was thinking of making up something simple using one of these: HC-SR04 as it will be very short range, 30mm max. I could rig up a bar with the range finder taped to a bit of tube that slides along in front of the rear windscreen. – SPlatten – 2017-11-27T10:25:49.313

Just ordered this: https://www.amazon.co.uk/gp/product/B01CU2MCM4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

– SPlatten – 2017-11-29T12:26:38.490

1I don't think that will help with taking the measurements, but it certainly will help with producing the parts. Your choices for software are many. You'll be able to use (free) Fusion 360 or similar. I'm fond of OpenSCAD, but with the complexity of the shape you'll have, any program may be a challenge. Aim for a parametric software, as you'll want to be able to enter your data, not drag and draw, so to speak. – fred_dot_u – 2017-11-29T15:59:28.820

I'm quite familiar with Autodesk 123D, lots to lean now, will use the printer to make up a tool to help me mount the HC-SR04 on a rail and slide across to take measurements. The tool will create an ASCII file of measurements which I will import into 123D to make a polyline. – SPlatten – 2017-11-29T16:01:09.913

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I've not used Autodesk 123D and from this link https://www.autodesk.com/solutions/123d-apps, I understand why not. "Autodesk is no longer offering Autodesk 123D" and the first suggested replacement if Fusion 360! I expect you'll find Fusion 360 to be similar in many ways, reducing the workload of your learning curve. Tutorial videos abound.

– fred_dot_u – 2017-11-29T17:40:47.673