Pronterface.... Setting up end stops etc

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?
Regards
Steve

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Endstops are for position detection, not to stop the machine if its sent past the end of the axis. In heavier machines there would be greater protection, but reprap motors don't have the force to damage the machine so we only use endstops to find 0,0,0.

You can set a soft endstop in firmware so that it will reject any move that takes it out of the build area, but if you are careful with the manual controls in pronterface, and keep the print area in mind while preparing models to print, you can get by without the limits.

Thanks for that Andrew, I'm still getting my head round the firmware. One fundamental I don't understand is
When you send info to the printer, does the printer remember it or does the firmware on the computer remember it?
I don't seem to be saving anything like it would on any other computer program I am used to
Regards Steve

What exactly do you mean by "send info to the printer" - what 'info' are you referring to?

When you send data to the printer - either via USB or from the onboard SD Card (which does nothing more than carry GCODE - instructions for the printer to work with), it is the firmware which acts on those instructions by sending out signals to move motors, switch heaters and fans on or off and so on. The firmware also interprets voltages across the thermistors to determine temperatures.


The hardware on the MELZI controller board includes a chip which CAN remember certain settings which may otherwise be transitory, that is settings which are only valid whilst the system is powered up - lost when you switch off. Such settings relate to maximum velocity and such but to store them permanently, two things need to happen. First of all, the firmware needs to be set up to store them and secondly, you need to issue a command (M500) via something like Pronterface which commands the firmware to store them. From memory the Nophead version of MARLIN on the Mendel90 kits does not have EPROM storage enabled which makes the command, M500 redundant. You CAN enable such storage by changing two lines in the CONFIGURATION.H file and then uploading the changes using the Arduino software should you so wish.
Alan

Sorry don't mean to sound stupid. The word Firmware is a bit new to me.
I am running Prontaface on the computer and sending commands to the printer.
Are the commands stored on the printer. What happens if I run Prontacface on another computer and plug it into the printer, do I have to set it up again from scratch ?

Pronterface has to be configured on each computer - basic settings which tell it the size of the print bed, location of the slicer program you wish to use (if you wish to invoke the slicer from Pronterface that is) and I think that is about it. Take a look at the Options in Pronterface.
Settings such as maximum Z, X and Y, steps per mm for the extruder and so on are held in the firmware which sits on the controller board of the printer.
Ask as many questions as you like, if you don't know the answer, it does not make you stupid, just interested!

Alan

confused...

Edited 1 time(s). Last edit at 06/17/2013 08:58AM by adi_sen_cah.

Dear Alzibiff and Andrew Smith,
Nice to meet you all
This is my first contact with Rep Rap 3d printer
and
I think i got the same problem with Ukrobotman

First i install the ftpi driver
Second i install the arduino firmware
Third i intall the pronterface (pyhton, etc)
then
Inside the pronterface
The extruder works fine
The Z axis works fine

The bed heater is not even getting hot
The x and y axis only able to go 1 direction and if we reverse the direction, only

go 0.1 step

i need anyone advice

Thanks before
Adi S