Does anyone know where to source the 5volt inductive probe used on the Prusa i3 MK2 or is this something they have manufactured in house? (P.I.N.D.A probe)
I am looking to keep a contactless probe on my one of my printers but want to get rid of the huge fat 12 volt probe in exchange for something with less mass.
Although they look like decent probes, the voltage divider hackery is still needed with those (10 to 30 volts). If I was going to replace the probe I wanted to get something small but at the same time try and source one that is rated from a lower voltage (e.g. 5 volts) so I can attach it directly to the printer board.
@Pieter_Koorts Rather than using a voltage divider, you can also just use a diode and the board’s pullup (this is easier since the diode can be inline between the sensor’s output and the board’s input, and doesn’t need an additional connection to ground). While the sensor output is high, the diode prevents the higher voltage from flowing into your board (and the pullup keeps the board’s input high) but when the sensor goes low the diode starts conducting and pulls the board’s input low.
I wonder if these 5 volt versions will have enough sensing distance for aluminium. Not a bad price at around $36. Sensing distance is about 2.5mm for steel/iron.
@Pieter_Koorts 2.5mm is very slim and might not be usable with aluminum. Regular inductive sensors are 4mm and at least one 3D printer brand tries to go with 8mm.
@Pieter_Koorts how about the Mini IR (infrared) Differential Sensor created by dc42? Can’t get much lighter than this sensor for effector based sensing (vs FSR). It works well.
Sensing distance is around 1.6mm, just enough the sensor clears bed clips etc. Sensing the top surface not the heat bed it is more accurate. The sensing distance is enough, but there are constraints on build surfaces and zprobe height needs to be adjusted occasionally as a surface discolors from use. I.E. the blue painters tape that I use must be placed so a seam is not at a probe point, and when it starts to lighten and become more textured from use calibration zprobe height can slightly change from the change in the reflected IR wavelength. Still getting it figured out as far as function so that is all how it seems to work and what I understand of the documentation. I am not totally sure of it all, but it seems this way so far. I have no complaints about it, functions as advertised, has almost no weight and no inertia on the effector.
I may investigate the IR probe more but the thing that has bugged me a little about it is the varying nature of it. As you say, colour changes over time need adjusting for.
One of the reasons I like inductive probes, is if you probe at the same bed temperature each time the results are pretty much repeatable making it a completely automated process.
I may look into alternatives like the IR probe if I can’t find anything small but for now, the hunt continues. I am sure there will be a manufacturer of said probe somewhere.
@Pieter_Koorts its automatic and simple as long as the print surface is new and clean or tough enough it doesn’t require adjusting. I may set mine up to auto calibrate a few times as a set of readings once and then not allow it to recalibrate unless I change the print surface, or need to calibrate which will require a new clean surface or a tough surface. that issue of tape changing color or getting bubbles and rips in it is limited to certain kinds of tape. dc42 has better advice on this on his blog entry about the unit. https://miscsolutions.wordpress.com/mini-height-sensor-board/