On Tuesday, 8 March 2022 04:09:35 EST gene heskett wrote: > On Tuesday, 8 March 2022 02:16:38 EST jeanfrancois wrote: > > Hi, goog day > > > > Interesting, we areworking on the development of 3D printer, although > > it's using an uncalibrated magnetic sensor, I haven't yet tested its > > accuracy. It was said .1 is difficult to reach with this, and instead > > some use a contact probe for the Z homing purpose. In that case, you don't care about its accuracy. Period, end of discussion.
What you do care about, is its repeatability, and that has been more than adequately proved by the near take-over of inductive means in those printers NOT useing thick borosilicate glass beds, something I've personally found not worth the hassle. I'd druther have the coated steel sheet held down by strong magnets. I can take it off and take it to the kitchen sink for a coating cleanup, followed by a few swipes with alky to remove any handling finger oils and then a fresh smooth coat of your fav bed adhesive. > I find it surprising that you make such a statement. My Prusa MK3S+ has > no home switches on the twin z screws, using an inductive prox sensor > on the head assembly for everything. The bed does not even have > leveling screws. Any unflat error is mapped by measuring the bed at 49 > places on a grid before every print, including z screw sync and > compensating by useing that measured map as the zero reference as it > moves during a print. > > > Regards > > > > Jean-François > > > > Le 08/03/2022 à 02:12, gene heskett a écrit : > > > On Monday, 7 March 2022 15:32:57 EST jeanfrancois wrote: > > >> Are ultrasonic sensors doing the job in that tolerance ? > > > > > > Some are. but there is a problem in the focusing the sound into a > > > tight enough beam to only measure the target, is actually a > > > physically large problem. So a real tight beam, similar to a red > > > laser pointer, takes a rather large apparatus. Impractical in the > > > average machine shop. Much better to use a little one for under a > > > couple inches as a limit switch, but inductive switches are much > > > better suited for that job. And in the current tech as an example, > > > I > > > have a BIQU BX printer that reads the flatness of its steel build > > > plate before starting each print, records the differences in it > > > height at 25 locations on the bed, and then uses that error mapping > > > to naintain a nozzle to bed spacing of .12mm plus or minus .01 mm > > > anyplace on the bed with the same sensor used on the prusa. I have > > > a Prusa MK3S+ that measures 49 places on a similar sized bed. The > > > BIQU BX at $550, beats the pants off the $800 Prusa for quality of > > > output. The Prusa fills the vacant inside of a cylinder with hair, > > > the BIQU is clean and smooth. Could be a cura setting difference, > > > or even the precursor to a thermocouple failure that currently has > > > my Prusa on the injured list. Worse, Prusa does not have the part > > > and hasn't had it in several months. And does not appear to care, > > > and that does upset me. > > > > > > Take care and stay well. > > > > > >> Jean-François > > >> > > >> Le 07/03/2022 à 21:01, gene heskett a écrit : > > >>> On Monday, 7 March 2022 12:44:21 EST Thaddeus Waldner wrote: > > >>>> Hi, > > >>>> > > >>>> I’m looking for a laser distance sensor with about 1-3 > > >>>> thousandths > > >>>> resolution and about a 5-10” working range. I wouldn’t mind > > >>>> buying > > >>>> a > > >>>> used unit. > > >>> > > >>> 1. I didn't know they came in that high a resolution w/o needing > > >>> a > > >>> quorum of the US Senate to authorize the payment, then signed by > > >>> the > > >>> President. > > >>> > > >>> If you want to know why, calculate the time difference of that 3 > > >>> thousandths of an inch increment, remembering that it has to > > >>> travel > > >>> out, and back to the measuring device, equal to C/2 in speed. You > > >>> will I suspect will come up with a very small fraction of a > > >>> picosecond. > > >>> > > >>> Interferometry can measure that change, but the mod function to > > >>> detect > > >>> the individual null and count it has to start at zero, or a known > > >>> micron sized distance before it can count the nulls passing by as > > >>> it > > >>> moves from zip distance, back to your point of interest at a 12" > > >>> max > > >>> range. Moving slow enough to count, will take a 2048 bit counter > > >>> and > > >>> several days. > > >>> > > >>> Technically, we can do it but you'll need a couple of dump trucks > > >>> full of gold to finance one neasurement. We can't yet buy a > > >>> calibrated answer in 10 milliseconds for a $500 bill. Someday? > > >>> Maybe, but it may take a new method to be invented. > > >>> > > >>>> Does anyone here know of some brands/ models to check out? > > >>>> > > >>>> Google has pointed me at some Acuity products but I wondered if > > >>>> there > > >>>> were other options besides that. > > >>>> > > >>>> _______________________________________________ > > >>>> Emc-users mailing list > > >>>> Emc-users@lists.sourceforge.net > > >>>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >>> > > >>> Cheers, Gene Heskett. > > >> > > >> _______________________________________________ > > >> Emc-users mailing list > > >> Emc-users@lists.sourceforge.net > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > Cheers, Gene Heskett. > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > 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, 1940) > If we desire respect for the law, we must first make the law > respectable. - Louis D. Brandeis > > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
