Leveled Bed >> Auto-Leveling Probe

Hi,

I am Arduino Mega 2560 and Ramps 1.4 user and I use it in cartesian 3d printer type. I modified g-codes for Z-Probe with Capacitive Proximity Sensor (LJC18A3-B-Z/BX).

I measure capacitive sensor data from multimeter:

Input: 11.64 Volt
Signal: 3.80 Volt
Sensor Output: 9.72 Volt

Is there any problem?



Edited 1 time(s). Last edit at 01/27/2016 02:21PM by usen.

Quote
nebbian
NPN.

No extra components required.

When I was setting one up for a friend he was very nervous about having no extra components, so we put diode in series with the signal line of the sensor. This worked just fine.

I'd avoid using a resistor voltage divider, because unless you understand what the pullups are doing inside the arduino chip, you can stop the signal making its way into the arduino altogether.

Dooh: I just spent a day learning all about PNP vs NPN and NO vs NC sensors with the 12 volt to 5 volt issues. Got the breadboard and UNO out just to confirm and you just simplified it, the minute I read diode everything came rushing back.
On my HICTOP with a MKS Base 1.3 (the one with blue connectors not the other three MKS Base 1.3 boards LOL) the limit switch takes the S pin to ground so a LJ12A3-4-Z/BX NO NPN sensor will work for me. I checked the diode circuit out with the cathode pointing to the sensor I now have the Arduino voltage at the limit switch connector of 4.76 volts and when the sensor triggers I get 0.

@usen
Did you do a voltage divider?

Edited 1 time(s). Last edit at 08/26/2016 08:15PM by KevinA.

To come back to the original topic, I can see why ABL is a firm favourite with budget printers, it just makes using them easier, my old i3 would have been useless without it. The more you spend on a printer the more the printer frame, axes and bed get stiffer. They are less likely to move, twist or drift unless you really chuck it in th back of the car and bounce it round for a few hours. If you have an ABL sensor but it is applying no compensation, the z axis doesn't move as the head travels around in x and y, you aren't actually doing anything with it. You're just carrying extra mass on the print head, and spending an additional few seconds probing every print. I removed my ABL sensor from my corexy and now just have a z endstop.

I am going to fit one on my new delta to do auto calibration, not autolevelling.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

While I agree that a well made printer shouldn't need auto bed compensation, IMO it's still useful to have a Z probe to set an accurate Z=0 position, because changes in ambient temperature or heated bed temperature can affect the height of the bed and/or the hot end.

Edited 1 time(s). Last edit at 09/01/2016 04:47PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].