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Setting up end stops

Posted by Ukrobotman 
Setting up end stops
March 11, 2013 06:03PM
Hi folks, I've just finished assembling my Mendel 90.
This is my 1st time setting up a 3d printer so please bear with me.
I've run pronterface for the 1st time and everything is working ok. Heater bed and extruder work fine,
I even extruded plastic tonight!
I don't quite understand the Home positions of the three axis and how the motors know when to turn off at
The end of the rods.
The Z axis seems fine, press the home button and it goes all the way to the top, hits the micro switch and stops
The X axis is a problem. When I send it to the right it goes till it hits the micro switch and stops.
If I send it left it keeps going and hits the end and the motor keeps turning.
This vibrates everything with the belt slipping on the pulley, then it turns itself off after a few seconds!
I can't understand why there isn't a micro switch at this end as well.
Can anyone advise me please, have I missed something?

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Re: Setting up end stops
March 12, 2013 06:18AM
Each axis has a switch at one end and a software limit at the other. Once the axis is homed you should not be able to hit the other end because the firmware limits the movement to 200mm.

For Z you need to fine tune the distance in the firmware as described in the manual but X and Y should be correct as there is 200mm of travel plus some clearance each end. If you can hit the end after it is homed there is something wrong with the firmware configuration. Are you using the firmware it comes with? Does the axis more the correct distance?

Re: Setting up end stops
March 12, 2013 07:16AM
If you ARE using Nophead's firmware as provided, It might be worth posting the values returned when you hit the "GET POS" button in Pronterface when the axis is pushing and trying to go where it shouldn't.

Adding to Nophead's reply, the CONFIGURATION.H file in the Marlin source carries values which set the maximum values for X,Y and Z maximum e.g. #define X_MAX_POS 100

There is also a line which enables these software endstops: #define max_software_endstops true


Edited 1 time(s). Last edit at 03/12/2013 07:16AM by Alzibiff.
Re: Setting up end stops
March 15, 2013 11:01AM

As a rule of thumb, I personally click "home" as soon as I turn on my printer and connect to pronterface. Which resets x, y, and z. Then you can move the extruder around in pronterface and it won't allow you to move past the 200mm boundary in each direction. (If your Marlin firmware is setup correctly).

You can also type M114 in pronterface to see the extruder's current location in each axis.
Re: Setting up end stops
March 15, 2013 03:02PM
Ok here is what happens
I switch on machine.
Open up pronterface
Connect pronterface
Press home for Y ... Bed move forward and stops when it hits end stop
Press home for Z .... Extruded moves up till it hits end stop
Press home for X ..... Extruded moves to the left and keeps going , belt slips on pulley, loads of vibration untill it turns itself off

From what I've read on this set of postings I'm not sure if the Marlin firmware is set up properly
What do I do next??
Re: Setting up end stops
March 15, 2013 03:06PM
How exactly do you install the Marlin firmware, I don't appear to have done this
Re: Setting up end stops
March 15, 2013 04:23PM
Ukrobotman: I suspect that your problem is that you need to flip the value of X_HOME_DIR in the Marlin firmware from -1 to 1 or vice versa. Either that, or INVERT_X_DIR.

You install it using a USB connection and the Arduino software; I'm sure instructions are elsewhere online :-)
Re: Setting up end stops
March 15, 2013 04:48PM
Being a total newbie on this kind of thing please tell me where to start on this.......
I don't understand what you mean ... What is Arduino exactly and how do I use it to update marlin firmware.
Re: Setting up end stops
March 16, 2013 06:13AM
Why not do a bit of Googling, a bit of reading, and then come back if you have specific questions? :-)
Re: Setting up end stops
March 16, 2013 11:50AM
The Melzi supplied in the kit already has Marlin firmware installed and the instructions with the kit have a step by step procedure for updating it. If the motor spins the wrong way it is wired wrong as the firmware is correctly configured for Mendel90.

Re: Setting up end stops
March 18, 2013 03:24PM

If you are still testing and it starts move the wrong way you should be able to stop it by closing the end stop with your finger before you get belt slips on pulley, loads of vibration untill it turns itself off.


Re: Setting up end stops
March 18, 2013 05:02PM
Hopheads was correct, two motor wires were round the wrong way,, now fixed and I've done my 1st print
Result folks, thanks for your help
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