3D Printed Spectrometer, Using Public Lab DIY Kit.

This Instructable shows how to improve on the standard Public Lab DIY Spectrometry Kit, by using a 3D Printed main body. One main improvement of the new design, is a robust provision for securing the USB cable.

The current device can easily be carried around and used in conjuction with a netbook/laptop. The body features some hole patterns for connecting it to a separate stand with integrated light source. When the design for this will be finished, it should be possible to use the spectrometer for analysing samples in standard cuvettes (square 10x10x45mm).

Enjoy,
Richard Tegelbeckers

Step 1: Existing Kit

The existing Public Lab kit provides all the parts to build a functional spectrometer The kit includes:

• a DVD-R, from which a piece is to be cut as diffraction grating
• a piece of black card paper from which to cut an aperture slit
• a small HD webcam and USB cable
• an aluminum Type LB conduit enclosure
• double-sided foam adhesive
• instructions and a copy of the CERN Open Hardware License

This Instructable is based on the "gum stick" 2.5 version of the kit. Perform step 1 of the Public Lab instructions in order to end up with a folded insert. I actually glued the insert together.

Step 2: New Design

The new design was done in 3D, using an old version of AutoCAD. Features of the new design:

• The 3D printed body contains an integrated, flexible clamp for securing the USB cable
• The camera strip alligns in a slot and attaches with three very small, self tapping screws
• The card insert fits into the printed body, without gaps
• Several holes are present in the main body, for future use. They can be tapped to M4 size, using a manual tap. I am planning to design a separate stand, for using the spectrometer to analyse samples in standard cuvettes (square 10x10x45mm)

Attached to this step are an Acis file (Zipped) and an STL file. The Acis file can be opened by several CAD packages for editing. An example is 123D Design, which can be downloaded for free. The STL file is to be used for printing on a 3D printer.

Step 3: 3D Printed Part

I printed the new main body in black PLA, using a 0.5mm nozzle and 0.2mm layer thickness. As infill I used 30% honey combe. The printer used, is the DeltaTrix 3D Printer I designed myself. See the previous step for the STL file.

Use an M4 tap to create the required threads. The flexible tab for securing the USB cable, can be held in place by temporarily inserting a 1.5mm drill bit (see last photo).

Step 4: Assembly

For the assembly, see the photos and take note of the instructions for the original kit. The DVD-R fragment can be a bit larger (27x19mm), making it easier to handle.The required screws are 4 off M4x12 for attaching the lid and securing the USB cable, and 3 off self tapping screws to fit in the 2mm holes of the camera PCB. I ended up using two layers of double sided adhesive foam for sticking in the DVD fragment.

Step 5: Conclusion

The new design allows the replacement of the conduit box and wooden block by a purpose designed part. The resulting spectrometer provides a better fit for the camera and the card insert. It is also a bit more robust due to the provision of an integrated clamp for the USB cable, making it more suitable for carrying around.

Comments

[vribeiro1]

I have a question... I've been searching for ir for a while now. I am trying to make a fixed wavelength spectrometer with a LED and a LDR. The simplest way to do so may be using a multimeter to read the LDR, for example, although I use an Arduíno interfaced with a software I made so I don't have to register all the values and make thousands of calculations... I can use it to calculate concentrations when comparing the absorbances of my samples with standards, of known concentrations. But, the molar extinction coefficients of the compounds I'm studying are not the same as I would get in a normal laboratory spectrometer (I have access to them, so I can even compare results with the same standards in the two equipments).

I'm happy with the results but quite distressed about this molar extinction diferences. Can anyone help me or have any idea why this happens?

Thank you! ;)

[nuelma]

is so simple but can do amazing things

[McLovinGyver]

Awesome! Thanks! That is a great solution. I work at the optical R&D dept. of a sensor company as algorithm system developer and this is the opportunity to get a own spectrometer. We do only a few tests and therefore had to source all tests out and need to wait for the results too long only for little questions. But this is so smooth, professional and breaks the price-barrier that I think i will do it when there is some spare-time. Haven't thought yet about such a tricky way. Any experience of calibration, stability, linear behaviour, range or so?

Thanks a lot.

[RTegelbeckers]

Thanks for your remarks!

If you are interested in making the spectrometer, head over to publiclab.org for all the details in terms of software, calibration, etc. They sell the original kit at $40, which will work as-is. Add the 3D printed body I designed (£2 in material), some screws, and you can assemble the spectrometer in a few minutes. At this moment I actually have no real need for a spectrometer, so I have not used it as such. I received the kit as a price and just fancied improving on it...

[jeferonix]

Wow, amazing! A laser fluorescence chamber was just uploaded on PublicLab.org: http://publiclab.org/notes/cfastie/02-25-2014/mobi...

Would you post a link/photo to this on PublicLab.org so our open source community can find your instructable? It's also a great way to add to our growing open hardware wiki/repository. Fantastic work!

[RTegelbeckers]

Many thanks for your comment! I just posted a note on publiclab.org, referring to this Instructable.