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AutoBed Leveling Guide for Marlin 1.8.1

by EE_Maker May 9, 2018
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As shown on PAGE 6 of my document, the sensor simply connects IN PLACE of the standard Z-AXIS limit switch. I installed a little 2-screw-lug terminal strip on the outside of the frame near the spot where the normal Z-axis switch mounts and ran the wires the STOCK Z-axis limit switch to the terminal strip. On MY PRINTER, there is a YELLOW and a BLACK wire going between the control board and the Z-axis limit switch. The YELLOW wire is the Z--Signal wire, and the black wire is GROUND. Yours is probably the same, but you can verify should verify the wiring before proceeding.

You can verify which wire is the GROUND WIRE using the following checks.

1) Turn the printer OFF.

2) Use an ohm meter meter between the BLACK Z-axis switch wires and the NEGATIVE post of the DC power supply. It should read 0 ohms.

3) The signal wire (YELLOW in my case) should have a high resistance to ground (>10 K ohms).

You will want to connect to the HIGH RESISTANCE wire to the ABL sensor output (through a diode!) per page 6.

To avoid conflicts between the Z-micro switch, I have completely disconnected signal wire going to the the original switch and now only drive this signal wire with the ABL sensor output.

By the way, once you have the ABL sensor powered, you can test it by moving a piece of metal (or the bed itself!) near the sensor and what the output status light go on when close to metal, and off when far away.

Hope this helps. Good luck.

Hope this helps.

Hi, do you have a picture of how this is wired to the stock board? I have tried to look all over the internet, but cant find any useful information on that part :-(

Wilsonfromdevon - Thanks for your comment.

1) With respect to the X5s 400...I have a standard X5S and am not familiar with the differences between the two. If you start with a known working CONFIG file and make the changes to the file just in the areas, a prox sensor should work. I'd recommend that you do some more research to be sure you have a working set of code and config before you add the ABL changes.

2) I've looked at the link for the sensor you found. I would NOT recommend that sensor as it claims to have a sensing distance of only 2 mm. This means that the sensor must get within 2 mm of the surface before it will detect it. That is not very much range as the sensor detects the METAL SURFACE, not glass or other non-metallic surfaces that you may have ON TOP of the metal build plate. Also, these prox sensors seem to have max range detecting steel, not aluminum. So this means that range will be further reduced.

The sensor I am using has a 4 mm range and that works well HOWEVER, I only have the TRONXY sticker on my aluminum build plate (very thin!). I am not certain my sensing distance is great enough to put a glass plate on, for example.

The PROX sense distance and variables added when you put additional layers onto the build plate I think is a major reason many folks use a TOUCH-style sensor.

3) PEI surface - See comments above, particularly with respect to layer THICKNESS.

Best of luck!

I am going to do this to my x5s 400 will this firmware work?
I am a beginner to the mods so will this bed level sensor work? https://goo.gl/cEQTUn
Will this work on the standard thick PEI surface?

I'm trying to do the same on a CR-10S at the moment. What print surface are you using? I tried changing to a metal sheet with pei on it to provide the sensor steel to detect, but I think the bed was too out of level.

I am using the standard X5S aluminum bed plate (~ 3mm / ~.125 in thick) with the pei material stuck on. My sensor does a good job with aluminum and has a sensing distance of about 4mm (as noted on page 11 of my document). From what I gather, some prox sensors can provide more sensing range than others, and all perform better with steel as opposed to aluminum. Never the less, I'm okay with alum. I might get more repeatable performance if I select a 3 or 4-pass measurement scheme - - I haven't yet tried that. (See pg 16 of my guide).

My bed plate is also warped but by using the 16 point bi-linear ABL selection (as set within the Config.h file) I am getting good results and the printing seems to be compensating for bed warp pretty well. First layer adheasion is good and uniform. HOWEVER, remember that you must make the ABL sensor run when the Hot end and Bed are up to temperature.