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Frustrating End stop Issues

Posted by gnex16 
Frustrating End stop Issues
December 13, 2014 11:58AM
Hi Guys!!

I'm done with my prusa i3 build.
Here is the Status

All axes motors work properly.
Extruder motor works properly
Heated bed gets heated up.
Hot end too gets heated up.
I hooked up my endstops and here is the way they are positioned.
X endstop is to the left
Y endstop is to back.
Z endstop is to the bottom
When i home them,the x endstop homes to the LEFT
Y axis homes to the BACK of the printer
Z axis endstop homes to the BOTTOM
All positions are MIN
Have set them To "-1" in the firmware
I use Marlin WITH pronterface
Have used the COM and NC ports of the endstop.
Logic of endstops is
x min-False
y min-False
z min-False
x max-True
y max-True
z max-True

When i have them ALL true they do not home so i have kept it as FALSE itself and its working

Say the motors are in the middle of their axes before i connect printer.
Ex(X axis) Once online if i press X- 10 mm it does not move. But it moves to the right. Can move it to the left only once i move it to the right.
But if home them they home alright!!!
I am just stumped and have no clue what to do.
Its frustrating since this is the only issue stopping me from beginning printing!!

Please Guys if you can provide any solutions it would be of great help!!!

Please Advice

Edited 1 time(s). Last edit at 12/13/2014 12:05PM by gnex16.
Re: Frustrating End stop Issues
December 13, 2014 12:08PM
I was very confused too when I built my first printer because of this, but when you turn on the printer it thinks its at X0 Y0 and Z0, so it doesn't move to the left because it thinks it cant go any further. so when you home it, it ignores that and moves until it hits an endstop and then sets that position as X0 (on the x axis). or do you have it set up so the endstops are at the max. position because I don't know what you mean by x/y/z min false, did you enable Max endstops?

Edited 2 time(s). Last edit at 12/13/2014 12:21PM by Ramon3D.
Re: Frustrating End stop Issues
December 13, 2014 01:07PM
Thanks for the reply.

The Endstops are in the min Position itself.
What i mean by x/y/z min false is the logic of the endstops in the firmware.
To clarify it , this is what i meant
const bool X_MIN_ENDSTOP_INVERTING = false;
const bool Y_MIN_ENDSTOP_INVERTING = false;
const bool Z_MIN_ENDSTOP_INVERTING = false;
const bool X_MAX_ENDSTOP_INVERTING = true;
const bool Y_MAX_ENDSTOP_INVERTING = true;
const bool Z_MAX_ENDSTOP_INVERTING = true;

X endstop is to the left
Y endstop is to back.
Z endstop is to the bottom

This is the direction of the endstops.
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

And yes what you are saying about the printer assuming (0,0,0) is right. But is there anyway i can solve this ??

Thanks again!!
Re: Frustrating End stop Issues
December 13, 2014 01:52PM
It sounds like it's working as it's supposed to.
When you first turn on the printer it doesn't know where the axis are.
If you start pronterface, connect to the printer, heat the bed/hot-end, prime the hot-end, home the printer - will it then print?


My updated Instructable on our Prusa i3 Build
Re: Frustrating End stop Issues
December 13, 2014 01:57PM
Ok no what I wrote is a pretty stupid idea, I think I didn't read your question correctly so... I'm sorry.

[I don't know how you could do this. The printer would probably have to somehow store the information on the position that it is in, or have some sort of an absolute measuring system with an absolute encoder, like in some machine tools, but I'm not really too experienced with the whole firmware stuff, I just have the experiences I've already had, and don't know a lot about the programming. I just home the printer every time I start it up, it doesn't take that long. You can also tell it through the host program on the PC at what position it is with G92, if you really want to. But when it works after just homing the printer, you don't really need to change anything.]

Edited 2 time(s). Last edit at 12/13/2014 02:03PM by Ramon3D.
Re: Frustrating End stop Issues
December 13, 2014 09:57PM
Sorry guys was away a couple of hours.Thanks a lot for the replies though!!!

To be honest haven't started printing yet.

Will print first thing today and let you know how it goes. Thought it was a problem i had to solve so hadn't started printing.
By the way your guide on instructables is really one of the most comprehensive ones out there and helped greatly during the build especially when testing the motors.
Thanks for that.

Will use the G92 code and see how that works and like you said it works after homing.Some relief there.

Will update soon as i print the 20 mm cube.
Hope it works fine!!

Thanks Again Guys!!
Re: Frustrating End stop Issues
December 17, 2014 09:04AM
Hi guys,

Back with an update.
What you guys said was right.
When i print it does print properly or atleast make an effort to.
Thanks for those tips!!

But I haven't been able to finish the 20mm cube print.
My feedstock keeps getting JAMMED.
I think its because the extruder motor is PUSHING it REALLY QUICK and hence jamming it up.
Getting major issues there.
Have to remove the hot end and clean it all over again every single time and i haven't even finished one print yet!!
I have CALIBRATED my extruder motor before beginning printing.

These are MY VALUES of Max feedrate and acceleration from marlin!!!

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,603.01}
#define DEFAULT_MAX_FEEDRATE {350, 350, 1, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {600,600,100,1500}

1) Should i change the FEEDRATE or ACCELERATION to make the extruder motor push slower??

2) Can anybody suggest good values for the feedrate and acceleration??

3) Also what should be the value for feedrate in pronterface under " REVERSE"(mm/min)???

Please advise<

Thanks a lot again Guys!!!

Edited 1 time(s). Last edit at 12/17/2014 09:11AM by gnex16.
Re: Frustrating End stop Issues
December 22, 2014 06:07AM
How did you calibrate your exruder?
Ignore the "reverse" values in pronterface - they are used for manual extrusion and the value applies to both forward and reverse. Typically 200-300 mm/s

Waitaki 3D Printer
Re: Frustrating End stop Issues
December 29, 2014 07:05AM
Thanks for your reply.
Had been away for a while so could not reply.
I calibrated my extruder after reading steveroy's guide on instructables.
Based on that I marked 120mm of filament and extruded 100mm.
Initially wasn't extruding that much but after using the formula and repeating the method a few times, I got it to extrude 100mm .

Thanks again!!
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