After watching Thomas Sanladerer’s Sensor showdown, it make me wondering since inductive sensor will sense ferrous metal at greater distance than aluminium.(Almost 2 times as much)
So can we use flat bottom drill bit, make a 1-2mm deep holes on the aluminium bed and insert some 1mm steel round plate at nine point on the aluminium plate and make sure it set flat on the surface, set the inductive sensor at height that will detect steel plate before aluminium. Make it poor man MK42 heated bed which support auto skew calibration from Prusa i3 MK2 firmware.
I don’t have cartesian style printer or the right tools to test this out so are there anyone want to test this idea?
It’s the “making sure it sets flat on the plate” part that will cause trouble. The correct way to achieve this is to press fit the ferrous plugs into the aluminum plate and then grind the entire surface flat. Seems very expensive to do it right.
I might going to find some really thin steel sheet(maybe 0.05mm or less) and check if the sensing distance still greater than aluminium plate, if this work we might just tape it under glass or PEI sheet.
@Pieter_Koorts If I understand it right copper should giving the same sensing distance as aluminium, What we want is 9 small circles on the bed that inductive sensor can detect not the whole bed which aluminium already did that.
If the bed isn’t metal then this would be easier but many people might want to use aluminium bed for more even heat distribution.
A simple and inexpensive way is to use M8 threaded rod plugs. Drill a hole in the aluminium bed at proper locations, then tap it and screw the steel plugs in place with a drop of thread locker. Alternatively, saw smooth rod plugs and use epoxy to fix the plugs in place (I have no idea of how long that might last due to the termal expansion of heated bed).
@Dont_Miyashita the metal needs to be thin so its not lift the glas away from the heater-element. A razor-blade is a good size and easy the set in focus for the sensor.
The shape could be any shape at all. There is no parameter in the Firmware that needs to be adjusted. The sensor actually is a “dumb” on/off switch. It only need a distinct face in focus to change status.
I really think the 3d printing community needs to get over the whole inductive sensor obsession. There are much simpler methods of bed leveling. I print directly to mic6 with only hairspray for adhesion. I have never had any issues with prints not sticking PLA, PETG, ABS, and various Taulamn Nylons. I always have to pry my prints off the bed. Aquanet Strong Hold works great on MIC6.
My bed leveling senor is my nozzle.
The Zprobe signal wire to the mic6 bed.
The Z probe ground wire to my hot end.
The zprobe ground wire is attached to my e3d hot end mount which is aluminum, and since the e3d is all metal this ensures continuity to the nozzle.
My heat bed is isolated from the rest of the printer with nylon bushings.
My procedure is to clean the bed with a damp cloth. This easily removes the hairspray. I then wipe the bed with alcohol. I heat the nozzle to 150C and wipe it with fine steel wool. Now my bed is ready to be leveled.
I only have to level the bed once, but I like to re-level once a month. Zgrid leveling 15x15 grid.
My first layers are always perfect.
To set the Z height all I have to do is home Z to max and tell Smoothieware to find the bed with a G30. Smoothie then reports the distance traveled from my Z home(max) to the nozzle (Z0). I update the config with the value reported and I’m good to go. I don’t have to probe the bed every time and my Z height is dead on.
I have had nothing but stellar performance from this method. Inductive probes are cool and all but there are much better ways to get accurate results without going through the hassles and limitations of inductive bed probes. IF you are using a mic6 bed I would definitely suggest setting up your printer’s nozzle as the zprobe. Only a two wire hook up and no extra parts to buy, you already have everything you need for the bed probe which is the nozzle and the print bed. And best of all no probe offsets to worry about!!!
