# Specific 3D Printers, Scanners, & Hardware > RepRap Format Printer Forum >  Need Recommendations for a simple non-contact Z-Axis probe

## Roxy

I'm looking for a simple, accurate and preferably low cost inductive probe that can plug into a RAMPS board.   Does anybody have a good experience to relate?   I'm hoping it won't require any extra electronics and be able to work mounted a 1mm or 2mm higher than the nozzle.   It would be really nice if I could just order it off of eBay.  It would be helpful if you can quote your M48 repeat-ability numbers too!

Any suggestions and comments are welcome!

Thanks!

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## bzmotoninja83

The sensor, i am actually working on ordering myself. Its going to have to be one thats 12mm for me since it will sense as far away as 4mm and i have a glass bed with aluminum under it ontop of a heated bed. 

UNLESS you use a capacitive sensor that senses anything, not just metal.

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## bzmotoninja83

I ordered 2 of the LJC18A3-B-Z / AY sensors off of ebay. They are adjustable coarsely on the mounting and iirc there is a fine tune screw on the top of the sensor. 

I will report back in a few weeks when it gets here from China

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## Roxy

I looked at the sn04 inductive probe that somebody (over on RepRap.org I think) recommended.  It is on eBay at a good price.   But I didn't order it because it required 10v to 12v.   Giving it power isn't the problem, but I was worried I would need level converter logic so I didn't fry the Arduino processor.   I also started to get concerned that I really don't want inductive anyway.  Capacitive might see the glass better.   (And as a result of that realization, I changed the title on this thread too!)

I wonder how good the 'Repeatability' is on this sensor?   Please come back after you get it working (of if you don't get it working!!!) and give us M48 numbers!   

THANKS!

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## bzmotoninja83

> I looked ........  and give us M48 numbers!   
> 
> THANKS!



The exact sensor I ordered. As for making it safe for th earduino to be able to use, a voltage divider with 10k and 15k resistors. Toms Guides has an example.

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## Roxy

Can you provide links to everything you found?   That would help others!   And when you get it connected and working, please post pictures and the results of M48.

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## stephen6309

Get the mini differential ir sensor. http://www.filastruder.com/collectio...-height-sensor

It works great on my printer with a MIC-6 AL plate for the bed using purple glue stick to get the abs & pla to stick.

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## Roxy

That looks interesting!   I wish it was a little bit cheaper.

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## bzmotoninja83

Sensor is here, resistors are wired, 15k and 10k as denoted on many videos, Brown is wired to the 12v power and the resistors are a voltage divider. The black and blue wires are wired accordingly, using the enstop plug on the Ramps 1.4 where its supposed to be. The snesor trips when it senses the bed however, the Z axis does not stop. I tried inverting the enstop info in Marlin but, still doesnt seem to see the endstop being triggered.

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## bzmotoninja83

> I finally got it working. Black wire from probe goes to the first pin on the plug. Now, i need to find out how to disable the probe after leveling...... Other wise, the print will not start at the desired height.
> 
> Perhaps Roxy you could assist with that?




Decided to just adjust the sensor to where zero is right where the print height starts.

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## zx81

I've only just read this post thought I'd share a distance sensor I was planing on using its an omron ee-spy302 it is a phototransistor senses up to 4mm and has a very wide input voltage range (5v to 24v) they are quite expensive if you get them from mouser, farnell, RS etc. however you can find them for a couple of quid on ebay if you get them shipped from china, I have a couple but haven't got round to using them yet.. I'm not a fan of the resistor divider I think I'll use a relay and optocoupler to interface with my control board!

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## Roxy

> Sensor is here, resistors are wired, 15k and 10k as denoted on many videos, Brown is wired to the 12v power and the resistors are a voltage divider. The black and blue wires are wired accordingly, using the enstop plug on the Ramps 1.4 where its supposed to be. The sensor trips when it senses the bed however, the Z axis does not stop. I tried inverting the enstop info in Marlin but, still doesnt seem to see the endstop being triggered.


This is a common issue.  And we need to clean up how this is configured.   (But that won't happen until after the Release Candidate goes Golden.)   

It is being caused by a mis-understanding on your part how to configure the Z-Probe.    The firmware doesn't know to be watching where ever you have the probe plugged in.

Do you have a Z-Min endstop?   If so this complicates things (but it still can be configured).    If you are just using the Z-Probe then the easiest way to get running is to enable:



```
#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
```

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## bzmotoninja83

I only have the one capacitive sensor. i had before, the servo and microswitch. Its working in the sense that I have the sensor basically zeroed at the print height. had to adjust and raise and drop many times but, its there. 

Will there be a way in the future to use the sensor in the endstop format but, disable its use after homing or running a G29?

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## Roxy

Typically, the inductive and capacitive sensors are mounted above the nozzle.  But they trigger before the nozzle touches the bed.   

Do you realize this?   Is this what your sensor is doing?   Because if it isn't doing this, you probably want to change its height.

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## bzmotoninja83

i just adjusted the sensor to be at the right height.

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## bzmotoninja83

Following up, I know its been quite a while. The sensor I bought, has proven, at least im my usage, to be garbage. Tonight, I was trying to print somehting in PLA. Nothing would stick, the bed didnt seem level. Fixed that, the nozzle height seemed to change from one print to the next although the print is starting int he same position. I think I am going back to a servo and micro switch. The sensor, during a heating cycle of the bed, would light up and go out, telling me that the probe was not close enough, level, etc. It was right in sync with the bed relay turning on and off. 

I cant wait for the wife to approve a complete rebuild. Friend of mine is goiing to help me make a TAZ clone. The current printer is a Makerfarm 12" i3v. Wood sucks mmmkay?

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## Roberts_Clif

I went with a TL-W3M and mounted under the Bearing Mount. 

This is a low profile proximity sensor that I have wired to my ramps 1.4 - 5volt power source. This configuration has been working correctly for nearly 2 years without any problems, having the ability to mount the sensor withing 15mm of the nozzle to achieve the most accurate bed leveling. I on the other hand choose to mount the sensor 25mm directly behind the nozzle.

TL-W3M 3.jpg


The mount has a adjustable thumb screw to adjust the height easily and quickly with a 3 Position bottom mount screw holes Left, center and Right.

TL-W3M 1jpg.jpg
https://media.digikey.com/pdf/Data%2...x%20Sensor.pdf

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