On Wednesday 26 September 2018 17:22:01 Chris Albertson wrote: > ---------- Forwarded message --------- > From: Gene Heskett <ghesk...@shentel.net> > Date: Wed, Sep 26, 2018 at 12:08 AM > Subject: Re: [Emc-users] More on bed wear fix > To: <emc-users@lists.sourceforge.net> > > > But finding a camera chip big enough to shine these laser's on so that > > > the laser stays on the imaging chip cannot be found in an integrated > > package that will plug into the 15 pin connector on a pi. The laser > > beams are 10x the size of the imaging chips even if they're > > perfectly aligned. > > What? If I buy a normal green laser pointer the green spot is about > 1mm in dimmer. If I place a 0.01 pinhole in the path of the laser > the spot is pretty close to 0.01. As for a camera that plugs into a > Raspberry Pi, any USB web cam will do. But I'd use a notebook PC > rather then the Pi. What you probably want is not to shine the beam > on the sensor but have a glass or plastic target and use a $20 USB > microscope to focus on the target. Glass is good because it will > reflect 99% of the laser light away and not blind the camera. > > As you move the carriage the laser spot should move on the target and > the USB microscope will image the back side of the target and you can > measure the movement by counting pixels, Software can do better by > doing some curve fitting. Even if the bed is very bad I doubt the > laser spot move even 0.5mm > > If the laser spot looks huge, perhaps what you have is a small spot > that overloads the sensor.
I am looking at the spot with my eyes. I can see the individual dots, probably 40 of them. If I could restrict it with a pinhole on the laser to block most of the dots, that would be great, but even with edm I don't think I could make a pinhole that small. > The target may need to do some serious > amount of attenuation. I have a polarizing variable filter with a range from ND-2 to ND-400 coming. > And while I said "USB "microscope" I bet a > magnifier hot glued to a web cam works. But I did buy a $10 > microscope and the image is poor but I can inspect the solder joints > on SMT parts, A medium size SMT resister pretty much fills frame, > these things are on eBay for $9 to $35 and they all appear to the the > same. Humm, more experimentation seems in order. I have drills down to #80, and yards of Reynolds wrap, which might get me down to a usable spot size. > Pretty much everyone who wants to measure displacement from a line > uses a laser. It is hard to find a better reference line > > If your bed where really bad Just put a steel rule in the tool holder > and eye-ball the laser spot in the rule, maybe use a loupe to read it. > > Something is wrong if the laser spot is large. Its way too big at the source, and 2 of them (different brands) are doing it. The pinhole at the src seems like a good starting point. [...] -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
