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treep78

Where do the endstop wires go?

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A while back I purchased an ultimaker electronics kit that I've slowly been building. However I have become totally stalled with the end stops. The stops that came with the kit have 4 wires. I beleive its the usual +, -, blank, signal, arangement. However I can't figure out which wires go where on the board. The endstop spots only have 2 positions and I have 3 wires I need to plug in, on top of that I don't know which one goes where. I would be really greatful if someone could help me out with this.

Thanks in advance. :)

 

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So the switch itself has 4 wires? I think you have the wrong kind - those are probably optical end stops. You need simpler mechanical ones that are normally open. When you push on the tiny metal bar it should short out like a light switch turning on.

The one in this picture has 3 connections - usually the middle one is common (connects to the outer 2) and one of the outer connections is "normally open" meaning it is open when switch isn't engaged. The other one is "normally closed" meaning it is closed, or shorted, or connected when switch isn't touched/engaged. You want "normally open" one. Check with ohmmeter.

48-600x450.jpg

 

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Wow - fancy switch! It comes with a circuit board!

Do you have the schematic? Can you post it?

Well you can just remove that part from the board - that's probably what I would do. See those three labels:

COM = common

NC = normally connected

NO = normally open

Connect the COM and NO to the ultimaker but there looks to be an LED and maybe other parts that might get damaged from the voltages from the UM so I'd like to see the schematic first. Best to just remove the switch from the board.

 

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I think you need to connect just two pins, signal and gnd.

http://www.sainsmart.com/sainsmart-mechanical-endstop-for-cnc-3d-printer-reprap-makerbot-prusa-mendel-ramps.html

Seems overly complicated.

I believe Marlin will turn on internal pullups so you just need to connect gnd to gnd and sig to the other pin. The ATMEGA will pull up the sig and the switch should ground it.

If you are using a UM shield when text ofo the end stop connectors are oriented so you can read it. GND is the left pin sign is the right.

Be careful if the LED lights up. I'm not sure how much current the ATMEGA can source.

 

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Thanks for all the responses! I was able to get it sorted after knowing I only needed the ground and signal. Some pics online and a multimeter got me the rest of the way (and trial and error of course). One problem solved and on the the next! Does anyone know where I hook up the thermistor? (that's the things for measuring the temp of the extruder right?)

 

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In general most thermistors can't handle temps above around 240 or 250C (they get permanently damaged such that their accuracy changes by maybe 20% each time). So for that reason UM chose to use a thermocouple combined with the AD595 circuit board.

If you truly have a thermistor - hopefully it is in the range of 100 ohms to 100k ohms in which case there's a temp1 or similar connection. When you build Marlin you have to select the correct temperature sensor for the nozzle (thermistor, thermocouple, etc). Note that there is typically only one type of thermocouple out there in printers but 100 completely different thermistors each with it's own 25C temperature (typically 100K) and it's own curve (alpha/beta values).

If you have a heated bed - that's usually a thermistor.

 

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1) What value and part number thermistor do you have?

2) Did you plug in the 4.7k resistor - often you have to solder the 4.7K resistor in if you go the thermistor route.

3) Where did you get your Marlin? You might want to build a custom Marlin - for example here:

http://marlinbuilder.robotfuzz.com/

or

https://bultimaker.bulles.eu/

 

You have to select the EXACT correct thermistor. There are 100's of thermistor types but only 10 or 20 are in these versions of Marlin.

 

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