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Support for $3 chinese webcams #42
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I've tested out one of these - it works OK, and the lens was mounted in an M12 thread so I could actually use the same optics module as I use for the WaterScope chinese webcam. I de-soldered the LEDs from the board, and had intended to use one of them for illumination - but they all seem to have stopped working... The main issue is that, with the ~50mm tube length of the M12 optics module, the image is massively too zoomed-in. What would be ideal is to come up with a module that places the sensor right next to the lens, which would get a zoomed-out image with similar resolution. That would not only look better, it would also be more useful for education, where a slightly lower magnification is often desirable. This might require making the stage a bit bigger to fit the board inside the stage rather than underneath the microscope, as it is currently. I'm imagining a dummy optics module that finishes in a platform, the board sitting on that platform, and the lens mounted directly on top of the camera PCB. |
@Maaphoo do yell as and when you might be interested in this. |
I've made a start on this in the 6led_webcam branch. It's just a flat platform and needs blu tac/other mounting technology - something that clips or screws onto the camera board would be much better! |
Nice work @Maaphoo! I would love to see your CAD files, I guess you can upload them to this issue or point me to a github repo somewhere. Sounds like you've done a power of work and your images look fab. STLs and Solidworks would be great, I don't have Solidworks but I'll see if I can get an educational license from somewhere. I'm curious how well the actuators work without the extra tension from the bands; is there a "dead zone" in the middle of the stage's travel where the actuator swaps from "pushing" to "pulling", or are you able to get everything tight enough that it's not a problem? I will look at your actuator column design with lots of interest! Also, is there a reason you were keen to use the 40mm version of the stage - the 65mm version has longer travel and less mechanical reduction, so might be nicer to use with the slightly lower-magnification optics of the 6-LED webcam. I have had also some issues with the optics not being perfectly vertical as well, and tracked it back to the objective clip being knocked over during printing. The tell-tale sign was that the dovetail clip has a kink in it at the same layer where the higher set of struts attach it to the microscope frame. I added some thin links to tie it down during printing, which helped a lot - but these may have been lost at some point. I found the LS65 version of the microscope was big enough to fit my 6-LED webcam, though it may have been smaller than yours... |
By the way, Nichia NSPL500DS are a nice colour of white :) The bigger problem is controlling the white balance of the camera, which I've now got a handle on with the Raspberry Pi webcam, but might be tougher with the $3 ones, as the software drivers aren't so good... |
Just set it up so that all of the files can now be be accessed at our Grabcad Partner Space. Each of the main bodies is in its own folder (same design just different equations). Some of the other stuff we are using is on the partner space as well. Mainly, the box. As for the actuators, there is a slight bit of lash when reversing direction. Maybe 15 degrees of revolution? Not too much. I tried scanning past the change from push to pull a number of times and didn't notice a dead spot. If it is there, it seems small. My guess is that if it is an issue, it would be an issue for the motorized version during automated operation. It would be much easier to evaluate the performance of this setup with a motorized microscope. As for the stage height, I did it justto reduce the number of layers and print time. In retrospect, the ability to use the normal objective clip would be much better as the small version that I'm using doesn't have much flex and requires post processing to get everything to fit together. I'll play around with the LS65 and see if I can come up with a better solution that what I have now. Thanks for the tip on the LEDs and the objective clip angle. |
Oops forgot to mention that if you just want to view Solidworks files you can do that in Grabcad. You can also use eDrawings. |
Thanks for that - it looks really nice. 15 degrees is a fair bit of backlash, so might not be an option for the motorised version, but if it makes the assembly less painful and avoids needing a bunch of parts, it might be a good trade-off for the manual ones. I've not measured; would your optics adapter fit the LS65 stage, or would it need to be wider than that? I think your clip is 20mm from the centre, so I'm guessing not! Also, how do you fit the lens into the model - does it just push-fit, or do you screw it in from underneath? |
STICLab have put together an OpenSCAD version here: https://github.com/sticGit/cheap_webcam |
Also, @Maaphoo if it's useful to you, I do have a version of the optics module that has a slightly flexible push-fit for the M12 camera lenses. If you're having quality control issues with them not fitting, this might be of some help: https://github.com/rwb27/openflexure_microscope/blob/master/builds/optics_m12_m12_lens_LS65.stl (from optics.scad with the camera and lens set accordingly). |
Thanks Richard. Do you or Grace have an image of how it all goes together? I've just changed the way I'm installing the optics on the 6 LED version. I've made the stage removable and install the electronics from above. This has also allowed me to make a larger stage and sample clips. It is working fairly well. Just tweaking a few details. Files are located at our GrabCAD partner space in the folder "Microscope 6 LEDs-2". |
hey, that looks really nice. I'd love to see one - any chance there might be a microscope (or even better, yourself) in Nairobi in mid-June? I've sent an email about dates. In terms of the push-fit, I don't have photos but I'll pop to the lab now and see if I've got the bits to take one! |
Thanks for the clarification. I was having trouble seeing how it fit with the microscope I think because I was confused about the length. Unfortunately I won't be in Nairobi, but Solomon should have a number of the new design printed by the time you arrive. We are planning on making 10 next week. |
Some possibly-useful updates:
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As of now, the latest release can be built using a camera platform that fits the 6-LED webcam. Currently it's just a bit of tape that holds the lens onto the webcam, I think this can be replaced in due course with a nicer adapter (e.g. STICLab's one, or Matt's one). However, as there is now support for this on the master branch, I'm going to close this issue :) |
The part was added in a7df420, it's possibly missing from the builds directory but will build with the build script - so it will make it into the next bugfix release. |
The cheap webcams used by e.g. hackteria would be a nice alternative for educational stuff, particularly when working in areas of the world where the £25 price tag of a Raspberry Pi camera or Logitech C270 is a problem. By "cheap webcams" I mean the ones with 6 LEDs, available usually for around $3 on AliExpress.
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