reprap Prusa control direction

I just built a reprap Prusa i3 and have everything ready to go. However, while testing with the manual controls I noticed that the x axis did not move as expected. When I click the left arrow it would move right, clicking right moved it left. When I clicked the "home" button it would move to the right as expected until it hit the endstop. I read in another post here where someone said that one should envision themselves siting on the extruder, and the direction arrows would correspond to the directions relative to your position. Is this correct? That really doesn't make any sense; "right" should be "right" as you are facing the machine as you would during normal use.

The instructions state that "home" is back right. I take that to mean the bed is in the front and the extruder is on the right side when facing the machine. That is where it goes when I click the "home" button. The up arrow moves the y axis so that the bed moves toward the back, and down moves it toward the front. Clicking the z axis up arrow moves the extruder up, clicking the down moves it down; just as I would expect. The extruder also works in reverse, up feeds and down ejects, but that is simply a matter of reversing the connection. Reversing the x axis connection makes the manual control work as I expect, but then it tries to home to the left side.

I am guessing that simple movement and homing are handled differently in the code: that home is at zero. But how does it know which direction to go to get there?

I contacted the people I bought it from, but they haven't been much help. They just said something about the end stops as if they thought it wouldn't move at all. Is there a firmware problem, or does Repetier work differently than I expect it to? Can it be used like it is?

It is sad that no one seems to be able to provide a simple explanation to this question. It is also strange that there seems to be so many different opinions about just how to build this machine.

However, I found a logical explanation on another site about something else. The direction the axis moves is in relation to the workpiece. Just like screwing a bolt into a nut. Turning the bolt clockwise is the same as turning the nut counter-clockwise. Moving the workpiece to the right is the same as moving the extruder to the left. So clicking the right arrow to move the x axis to the left is normal.

Why not a single person I have seen has mentioned that vital fact in any of the many videos and instructions I can't imagine.

I understand the confusion. It comes from different printers moving different parts to achieve the same.

Just think your beds left front is 0,0 and right top is xmyx,ymax.

So if x homing goes right I assume you have a xmax endstop or you have a mirrored x axis adding even more to your confusions.

Normal positioning is how extruder changes position over the bed coordinate system. So if you write xy axis on bed the nozzle marks the position on the bed.

For users who have problems with the cross there is in printer settings->Printe->Invert Direction in Controls for where you can change direction of each axis if controlled by the cross.

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repetier
I understand the confusion. It comes from different printers moving different parts to achieve the same.

Just think your beds left front is 0,0 and right top is xmyx,ymax.

So if x homing goes right I assume you have a xmax endstop or you have a mirrored x axis adding even more to your confusions.

Normal positioning is how extruder changes position over the bed coordinate system. So if you write xy axis on bed the nozzle marks the position on the bed.

For users who have problems with the cross there is in printer settings->Printe->Invert Direction in Controls for where you can change direction of each axis if controlled by the cross.

Yes, one thing I am finding is that there is no standard for building or setting up one of these printers. Mine is a Folger, which is part of the problem. They seem to think they have to do things differently than everyone else. One would think that if everyone used the same dimensions, the same size rods, same belts, same electronics, etc. that they could use the same settings and it would all work, but instead some have to put the motors on the other side, move the endstops to another location, and other things that make "standard" settings impossible.

Mine homes to back right, at 0, 0, making the left front 200, 200. That, it turns out, is the cause of the other problem I posted about here. Once I got those issues figured out it works as far as movement is concerned. Now I have an issue with the extruder, but that will require its own thread.