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Jeremie Francois
An open-minded technophilic iconoclast driven by curiosity.
An open-minded technophilic iconoclast driven by curiosity.


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Something I always did without real explicit consideration, based on pure pragmatism. It just spares time and it reduces errors when dealing with files later on. On Linux I even programmed a shortcut (shift-win-d) to set the copy/paste buffer to the current yyymmdd formatted date so I can name my files with an appropriate prefix directly within the app that saves it in an eye blink.

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Comparing probabilities is a risky job. The explanation below is striking and requires no calculation at all. When A is more probable than B, and when B is more probable than C, then A is NOT necessarily more probable than C. This happens so many time in real life, e.g. when choosing and comparing items. So long for trying to sort the good and the bad on a single axis :)

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A straightforward little tool for embedded linux, which delays writing to the logs. Another one is which creates a RAM disk and sync it to the harddrive (or SD card) before shutdown. These are efficient strategies to reduce wear on the SD card and extend the life of your embedded linux system.
Ramdisks are also useful for any kind of temporary files (like the object files when building a project). They are super fast to access and disappear when power is lost. I usually have a dedicated partition on my linux boxes mounted in /etc/fstab, e.g.:
none /volatile tmpfs size=256M,nr_inodes=6k,mode=0777 0

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Laser cutting machines: an interesting way to find the maximum power that makes sense. Namely here running over 60% will probably shorten the life of the tube with no cutting benefit.
The video is a bit lengthy, and real testing starts at (note how he removed the focusing lens first). The depths of the conic holes in the perspex bloc match the curve he talks about on the beginning of the video, where a kind of saturation of the cutting power occurs significantly before the power supply limits.
TL/DR: no surprise: the power you are being sold is more that of the power supply than that of the useful laser capability. But it also makes sense to refrain from turning the knob to max power, at least not before checking you really get something out of it...!

BTW if you are interested in laser cutting (like I am), or if you already have one (still not my case!), +SarbarMultimedia's channel is a trove:

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Unusual real-world test of 3D printed plastics. Interestingly, the Carbon-fiber reinforced propeller got torn first (imho too stiff and cavitation could have ruined it). Surprinsingly, PLA+wood stood better! Of course, polycarbonate plain worked for the job. ABS was poor. I always disliked ABS and this test did not help change my mind :D I wish they tested PET.

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He could add servos to move the different parts automatically.... :)

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0.4mm pitch milled PCB traces with high quality gear (1500€ is still a decent price IMHO)... It gives me an upper bound to what I may eventually reach with my Chinese CNC. This is no cheap V-carve mill bit by the way, and it probably makes a difference.

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I'm working on illustrating my book, and kind of flabbergasted by the range of belt quality I found in my parts bin...

From top to bottom in the photo:
1) Geeetech "GT2" from Amazon - it's a frickin' trapezoidal profile! Oh, and the belt is 7.35mm wide, which is baffling.
2) Merlintools "GT2" from Amazon - looks like it's actually FHT or STD, not GT2
3) "Made in Japan" GT2 from SDP-SI - good tooth form, ok quality
4) Genuine Gates GT3 from SDP-SI - premium stuff :-)
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