Leveled Bed >> Auto-Leveling Probe Anyone else agree? Recent put together a PrintrBot Simple Maker Edition kit that didn't come with a bed leveling probe, then purchased the upgrade kit for it and put a bed leveling probe in. Few days later, ditched the probe. Nothing beats a leveled bed :) thoughts? Is this a universal opinion or am is the inverse popularly agreed upon? I see a bunch of printers coming out now with bed leveling probes, which I guess makes it easy for the end user, but I think a leveled bed is some secret sauce https://reprap.org/forum/read.php?1,430371,430371#msg-430371 Tue, 09 Jun 2026 08:10:39 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,430371,704566#msg-704566 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,704566#msg-704566 dc42 General Thu, 01 Sep 2016 16:47:19 -0400 https://reprap.org/forum/read.php?1,430371,704494#msg-704494 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,704494#msg-704494
I am going to fit one on my new delta to do auto calibration, not autolevelling.]]> DjDemonD General Thu, 01 Sep 2016 10:47:57 -0400 https://reprap.org/forum/read.php?1,430371,703364#msg-703364 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,703364#msg-703364 Did you do a voltage divider?]]> KevinA General Fri, 26 Aug 2016 20:13:18 -0400 https://reprap.org/forum/read.php?1,430371,703363#msg-703363 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,703363#msg-703363
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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.]]> KevinA General Fri, 26 Aug 2016 20:10:09 -0400 https://reprap.org/forum/read.php?1,430371,616542#msg-616542 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,616542#msg-616542
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?


]]> usen General Wed, 27 Jan 2016 13:06:05 -0500 https://reprap.org/forum/read.php?1,430371,599113#msg-599113 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,599113#msg-599113 JuliaV General Sun, 20 Dec 2015 19:27:56 -0500 https://reprap.org/forum/read.php?1,430371,598904#msg-598904 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,598904#msg-598904
I have not had to level my bed in over a year. I have my printer tuned in to the point I can power on and print.

And on the flip side, this same printer has a 0.3mm backlash on the Z axis. It is repeatable and only occurs when reversing direction. Since my slicer setting is to raise 0.3mm at the very beginning of a print, it compensates that backlash and it does not effect the print. But when I installed auto-leveling and purposely tilted the bed, it was a mess.

I guess what I am saying is that auto-level really depends on the printer itself, not a generic 'this is better than that'. And I am glad there is a solution for those that have beds that keep moving out of level.]]> Hazer General Sun, 20 Dec 2015 10:40:20 -0500 https://reprap.org/forum/read.php?1,430371,598329#msg-598329 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,598329#msg-598329
With pnp the standard open voltage once regulated (see below) is 5v and it switches to 0v when triggered. So if the sensor fails the printer reads triggered and the z motor/s stop. So no head crashes.

Avoid voltage dividers use a voltage regulator for the signal pin. It costs very little and its very easy to wire and reliable.]]> DjDemonD General Fri, 18 Dec 2015 15:51:36 -0500 https://reprap.org/forum/read.php?1,430371,596450#msg-596450 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,596450#msg-596450
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.]]> nebbian General Mon, 14 Dec 2015 03:49:31 -0500 https://reprap.org/forum/read.php?1,430371,596018#msg-596018 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,596018#msg-596018 Jotirling General Sun, 13 Dec 2015 01:32:15 -0500 https://reprap.org/forum/read.php?1,430371,596016#msg-596016 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,596016#msg-596016 please help
thanks in advance]]> Jotirling General Sun, 13 Dec 2015 01:30:38 -0500 https://reprap.org/forum/read.php?1,430371,587547#msg-587547 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,587547#msg-587547 eviltoy General Sun, 22 Nov 2015 12:18:18 -0500 https://reprap.org/forum/read.php?1,430371,432271#msg-432271 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,432271#msg-432271
Quote
Easy
There is probably a good reason why a PNP device is being used. I guess I may find out why.
It's just a personal decision when designing a circuit. Are you sinking or sourcing the signal? It's not that one is better or worse than the other, it's usually where is the transistor places in relationship to the load, supply, and ground.]]> cdru General Fri, 14 Nov 2014 13:19:06 -0500 https://reprap.org/forum/read.php?1,430371,432217#msg-432217 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,432217#msg-432217
Quote
cdru
Quote

So using a built-in pull-up resistor, I do not understand why a voltage divider is needed on the output of the sensor.
The diagram in the thingiverse page is a PNP. It outputs 12V so a voltage dividier is necessary to drop it to a safer 5V level for the microcontroller to use. If you use a NPN sensor with a pull up resistor, that should work, you'll just need to supply more supply voltage to the sensor unless it's able to work at only 5V. The sensor specified appears to need 6V at minimum so it wouldn't be directly compatible with most boards that only have 5V with the endstop headers.

I guess I am really showing my age by how confused I got with this whole thing. Somehow I got the impression an NPN device was being used, then I got confused on the output of NPN and PNP devices.
Anyway, I am going to try to use an NPN device, since it should not need any signal conditioning (just the pull-up enabled), NPN is safer (shorting signal to ground does not hurt it), and you can safely tie multiple NPN outputs together.
There is probably a good reason why a PNP device is being used. I guess I may find out why.
You should be able to operate an NPN device at its maximum operating voltage without regard to the signal voltage because it only switches from ground to an open circuit. There is no voltage output, the pull-up resistor on the input device sets the high signal voltage.]]> Easy General Fri, 14 Nov 2014 11:20:18 -0500 https://reprap.org/forum/read.php?1,430371,432190#msg-432190 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,432190#msg-432190
Quote

So using a built-in pull-up resistor, I do not understand why a voltage divider is needed on the output of the sensor.
The diagram in the thingiverse page is a PNP. It outputs 12V so a voltage dividier is necessary to drop it to a safer 5V level for the microcontroller to use. If you use a NPN sensor with a pull up resistor, that should work, you'll just need to supply more supply voltage to the sensor unless it's able to work at only 5V. The sensor specified appears to need 6V at minimum so it wouldn't be directly compatible with most boards that only have 5V with the endstop headers.]]> cdru General Fri, 14 Nov 2014 09:36:41 -0500 https://reprap.org/forum/read.php?1,430371,432016#msg-432016 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,432016#msg-432016 I have some NPN and PNP proximity sensors on the way so I will find out what is happening when I get them.]]> Easy General Thu, 13 Nov 2014 22:22:00 -0500 https://reprap.org/forum/read.php?1,430371,431596#msg-431596 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,431596#msg-431596 GITRDUN General Wed, 12 Nov 2014 22:18:13 -0500 https://reprap.org/forum/read.php?1,430371,431320#msg-431320 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,431320#msg-431320
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ggherbaz
cdru,

Then i'm sorry for the misunderstanding, my thoughts were that without the pull up resistor the mega will throw the 5 volts straight to ground.

It will if the port is configured as an output, which can happen with run-away code. But as an input, the pull-up only connects the pin to the supply voltage though the resistor. This pulls the high signal up when the input is not ground, or low.]]> Easy General Wed, 12 Nov 2014 11:46:06 -0500 https://reprap.org/forum/read.php?1,430371,431279#msg-431279 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,431279#msg-431279
Then i'm sorry for the misunderstanding, my thoughts were that without the pull up resistor the mega will throw the 5 volts straight to ground.]]> ggherbaz General Wed, 12 Nov 2014 09:43:45 -0500 https://reprap.org/forum/read.php?1,430371,430933#msg-430933 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430933#msg-430933
[www.thingiverse.com]

But I think selecting a PNP device would be better than the NPN device, as used in the above link. That way all you need to do is connect the output of device, select pull-up enabled, and then select normally open or normally closed. I think!]]> Easy General Tue, 11 Nov 2014 15:45:44 -0500 https://reprap.org/forum/read.php?1,430371,430878#msg-430878 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430878#msg-430878
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ggherbaz
"Care to explain how not enabling the pull up resistor is going to fry the board?"

If you don't set your resistors in marlin, you will pass straight to ground 5 volts. Will this explanation makes more sense to you? . Do you know what happens when you connect together both terminals of a battery?
I'm no EE, but you might want to double check what the purpose of a pull up resistor is.

The pull up resistor is between Vcc and the pin, not between the IO header and the pin. The pull up resistor, if enabled, holds the pin input high (reading 5V) until the circuit is grounded via a switch which causes the pin to read low (0V). If you don't enable the pin high, there is no 5V at the pin and the pin floats at an indeterminate state. You can supply 5V to the pin, or you can ground it and it's not going to make a bit of difference from a frying the board perspective.

Now if the pin was configured as an output pin, then yeah, you won't want to ground it directly without a load, but that would have absolutely nothing to do with the pull up resistor which only applies for an input pin scenario.]]> cdru General Tue, 11 Nov 2014 14:05:27 -0500 https://reprap.org/forum/read.php?1,430371,430825#msg-430825 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430825#msg-430825
Edit... I just found some diagrams on eBay from a vendor. It shows that a PNP device would switch from ground to open. It shows the NPN device as switching from open to Vcc.
I would think the PNP device would be preferred if the input board has a built-in pull-up resistor.]]> Easy General Tue, 11 Nov 2014 12:21:02 -0500 https://reprap.org/forum/read.php?1,430371,430814#msg-430814 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430814#msg-430814
If you don't set your resistors in marlin, you will pass straight to ground 5 volts. Will this explanation makes more sense to you? . Do you know what happens when you connect together both terminals of a battery?]]> ggherbaz General Tue, 11 Nov 2014 11:54:02 -0500 https://reprap.org/forum/read.php?1,430371,430805#msg-430805 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430805#msg-430805
Quote
isonoob
doh! guess my views on bed leveling probe aren't so popular! probably why the shift towards manufacturers including them is happnening... Maybe ill dust off the ole induction probe and give it another chance

You just haven't had a sentient printer which can change it's own leveling on a whim. ;)

When I started researching to build/buy a printer I saw the self leveling systems and had the same thought you did, why should the bed have to be re-leveled after the initial build especially if I take great care and get it as close to perfect as possible. After a couple of weeks where I have had to re-level after every time I let it sit for several days or if I lift it up on one side to work on something easier, I've come to the conclusion that my printer is ether alive or possessed and that it's female. So if I don't pay attention to her or force her to do something she doesn't like, i.e. standing on one of her sides, she changes the bed settings to annoy me. 8-) So now I'm planning on setting up a bed leveling system soon.

Now if you don't mind the voices in my head want lunch (:P)]]> Wpflum General Tue, 11 Nov 2014 11:31:30 -0500 https://reprap.org/forum/read.php?1,430371,430804#msg-430804 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430804#msg-430804
It simple and just take few minutes to get it done and working.

Yes use the 10mm one, powered with your 12 volts, and it has 3 wires, Vcc, ground and signal. Vcc to 12 volts supply, ground to ground in ramps and signal to pin 1 of the LM7805 pin 2 to ground and pin 3 to signal on ramps,that's it, plain simple.

The LM7805 will not need a heatsink, and you can either bolted somewhere in the frame or use shrink tubing. And fix it to your sensor wiring.

My sensor: LJC18A3-R-Z/AX]]> ggherbaz General Tue, 11 Nov 2014 11:30:36 -0500 https://reprap.org/forum/read.php?1,430371,430788#msg-430788 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430788#msg-430788 Where would I find information on connecting, setup and calibration?
Would you use a 10mm if you were to do it over again.]]> Easy General Tue, 11 Nov 2014 10:54:51 -0500 https://reprap.org/forum/read.php?1,430371,430741#msg-430741 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430741#msg-430741
Quote
ggherbaz
Don't forget to set your pull up resistors in marlin or you will fry Your board.
Care to explain how not enabling the pull up resistor is going to fry the board?]]> cdru General Tue, 11 Nov 2014 08:56:23 -0500 https://reprap.org/forum/read.php?1,430371,430691#msg-430691 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430691#msg-430691
Don't forget to set your pull up resistors in marlin or you will fry Your board.]]> ggherbaz General Tue, 11 Nov 2014 06:53:28 -0500 https://reprap.org/forum/read.php?1,430371,430587#msg-430587 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430587#msg-430587 Something like this.
[attachment 43485 sensor.png]]]> Wurstnase General Tue, 11 Nov 2014 02:35:47 -0500 https://reprap.org/forum/read.php?1,430371,430571#msg-430571 Re: Leveled Bed >> Auto-Leveling Probe https://reprap.org/forum/read.php?1,430371,430571#msg-430571 Easy General Tue, 11 Nov 2014 00:35:22 -0500