N2 Z-axis adjustment

dmtulsa
Posts: 18
Joined: Wed Jun 13, 2018 6:14 pm

N2 Z-axis adjustment

Postby dmtulsa » Wed Dec 05, 2018 6:48 pm

I was having a lot of problems on my N2 with the Z-axis end stop. I would adjust it for the proper bed to nozzle clearance and by the next print it could be off be a few millimeters. It seems after time the switch doesn't always close or open at the same position of the lever.
This was solved by using a proximity sensor ( TL-Q5MC1 )in place of the switch. Amazon has them for less than $7. Very simple to install and no firmware change is needed. I just made a steel target that screwed to the original adjustment screw. Works perfectly and produces very repeatable results.

Next I'll move the sensor and attach it to the extruder housing. With the proper thickness target used at the start of a print the bed to nozzle clerance will always be the same even if you add a pice of gleass or other print bed material. Not a perfect solution but its cheap . Again no firmware changes. I'll post the results when I do it.
I decided to leave a sensor where the original switch was and add one to the extruder housing. Reason being safety. If I forgot to put the target on the bed and started a print then it would prevent the bed rising into the hot end.

Wiring: The sensor has 3 wires. Brown, Blue and Black. Brown is 5-30vdc vin but since the A/D on the board (Atmel 2560 pin 57) needs to see 0 or 5vdc it must to be connected to 5v, anything over 5v will kill the chip. Blue is ground and Black is the output. Between blue and black theres around 36 meg ohm open and less than 1 0hm closed. So with a voltage on the Brown (Vin) you get 0 or 5v between Blue(gnd) and Black depending if it's open or closed.
Brown - 5v
Blue - Ground
Black- goes to the Z-min connector bottom pin ( pin that goes to the MCU A/D)

I'll do the X and Y end stops at some point but they are not as critical in this respect.

While I'm at it I had a very bad problem with the filament jamming constantly. I tracked it down to the nozzle throat and nozzle not fitting correctly in the hot end. The threads in the aluminum block were just to sloppy for a proper fit. What I did was drill out the threads with a 8mm bit then made a carbon steel sleeve with an OD of 8.0038 (.015" bigger than the hole) and threaded the inside to 6mm. I pressed it into the heat block (I froze the sleeve and heated the aluminum block to let it expand then pressed the sleeve in.). Now I get a perfect seal between the nozzle and nozzle throat . Haven't had a jam since.

Hopefully no one else has these problems but if you do this is how I fixed them. There may be a better way to fix each but for $7 and a few hours this was the best solution for me.

Doug

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