Motors not homing correctly

I recently completed my first build of a prusa i3 rework from scratch.

I have worked through most of the issues and my extruder and bed both heat correctly, the X and Z endstops work, for some reason the Y endstop doesn't seem to be actually stopping the motor.

However, by big issue that I am struggling with now is getting my machine to properly home. In manual control of the repetier-host v1.0.6 software if I click on .1 step everything works fine. If I click on 1 step it still works although it moves slower than with .1, but if I click anything above 1 like 10 or 50 steps then the motors let out a high pitched whine but do not move.

A couple of times I have seen my printer move the Y axis quickly, especially if I click on Measure Heights in the create height map, however other than that I have not been able to get any of the motors to move correctly. Whenever I click on any of the homing buttons I hear the high pitched whine, I assume the printer is trying to move the motors faster than 1 step at a time.

Do I have the motors wired wrong to be causing this? Is there a setting in repetier to have the printer always using .1 steps when homing? I am using an old computers ATX power supply using the two 12 volt 8 amp yellow wires with a small load on the 5 volt wire to keep it from shutting itself off, other people have successfully used ATX supplies so I don't think it is a lack of power.

Edited 2 time(s). Last edit at 02/27/2015 09:52PM by jereme.guenther.

I found a setting in the Firmware EEPROM to adjust how fast the motors home. So now I can get them to start homing, however the X axis is homing in the wrong direction, so I think I have the wires backwards, i'm going to have to play with that.

I'm still concerned about why my motors don't seem to be able to handle bigger steps, they aren't small motors. And now I find out that only my Z axis is correctly stopping the motors. If I manually trigger the X or Y axis none of the axes are stopped from moving in either direction.

I found the
#define ENDSTOP_X_BACK_ON_HOME 1
#define ENDSTOP_Y_BACK_ON_HOME 1
#define ENDSTOP_Z_BACK_ON_HOME 0

and
#define ENDSTOP_X_BACK_MOVE 1
#define ENDSTOP_Y_BACK_MOVE 1
#define ENDSTOP_Z_BACK_MOVE 1

in the Configuration.h file and set those to much smaller numbers. I'm not sure why they were set to high for me in some cases, I think my steps per mm must be configured wrong. Homing is certainly working much better now after these adjustments. However, it still concerns me that my motors will not move when my rate is higher like 5 mm/s

Interestingly my motors seem to be able to run faster during an actual print then they can when homing. Very odd, some sort of acceleration setting maybe?

I noticed that in the Configuration.h file the BACK ON HOME and BACK MOVE values seem to be in inches rather than millimeters. Adjusting their scale based on inches seems to have the desired effect.

While my settings are not quite perfect, I think the only thing preventing me from trying a print is that every time I try a dry print the extruder is sent all the way around the entire 200 x 200 sheet of glass before it starts. naturally this knocks off the clothes pins I have holding it on and I have to hit the emergency stop. That seems like an odd default setting considering 200 x 200 held on by binder clips is the default configuration for a reprap. How do I adjust the settings to avoid this issue?

I'm actually having exactly the same problem. I've just built my first Prusa i3 and mine is reacting exactly the same way. Both in pronterface and Repetier-Host.

To compare notes: I also have an ATX for power and am using the sanguinololu rev 1.3 a using Ice Blue Stepsticks. Motors are Wantai 42byghw811. Firmware is Marlin.

Things I checked:
- Adjusted the current through the potentiometer
- Created the program on Arduino 1.01 and 0.23 and played around with the x, y and z speed settings
- Tested the x and y without belt

None of these things helped and the test without the belt showed that motors were rotating exactly as you described it.

What firmware are you using? I do not have the lines you are referring to in Marlin.

I am using Repetier 0.83.

For some reason when I start up a dry print the motors can move each axis pretty quickly. Homing seems to be the primary time I have an issue with it needing to take small steps, that and manual movement.

However, a dry print also brought to light that the printer is scaling things way out of proportion. I tried loading a .5mm square wall for a test print, in the Repetier preview it shows a small neat little box in the middle of the print area, however when it tries to print the print head swings wildly all around the extreme edge of the print area and seems to be trying to go even further past its limits. I am pretty certain this is still do to my scaling issues. I'm guessing that my printer is moving one centimeter or one inch for every mm it is told to. I am going to have to look at adjusting my steps again, or see if I can find some other setting that dictates what measurement is being used.

I find these particular problems to be very odd. I would expect all the settings in the firmware to have default values that should at least be getting me pretty close.

My printer information says it is a Mendel.

Although the design is actually a Prusa i3 Rework. The dimensions of each type are pretty close, so I don't think that the firmware is my issue, although it could be.

I've just done some checking but haven't figured out yet what the problem is. I'll do some more digging on the forum to see of there is any mention of the this problem. I'll let you know if I find anything.

Edit: [forums.reprap.org] - the problem seems to happen more often. The Vref for the motors (too high?) may be a problem but right now it's too late for me to test. Will see if I have time tomorrow.

Edited 1 time(s). Last edit at 03/02/2015 05:48PM by Minimaker.

I'm fairly new to the electrical side of this. But, it feels like my motors are not getting enough power to turn accurately, especially for the bigger steps. However, that would assume that the small .1 steps they are doing now is accurate. Currently if I press the .1 button on the X axis in the repetier software it moves about a full mm. Which means the default settings for steps / mm are WAY!! off, unless those buttons are all backwards and .1 is actually the larger step; i'm pretty sure that is not true though.

I tried adjusting the trimpot for my x axis, but using needle nose pliers I think I might have been messing it up. I'll have to wait until I find my computer screwdriver kit, it's around here somewhere. The adjustments I did try by increasing it did not have any effect.

I like one suggestion from the thread you found about inserting microsecond Delays. If I press the .1 movement button rapidly the motor actually turns in much larger steps than if I push it slowly.

Again though, why should any of this be necessary? What is so different about my build then everyone elses who is able to use the default settings fairly successfully?

I do have a cheap chinese A4988, which means my R value should be .1 ohm.

My X axis has a Vref of .21V so .2625 amps
My Y axis has a Vref of .78V so .975 amps

which is odd, since the X axis is the one I was turning up. I hope I didn't break it.

the X axis does seem to be turning slower than the Y axis for larger steps, however that might just be because of its heavier load. And none of this sheds light on why I have stepper motors moving a mm for a tenth of a step.

Ok, the learning process continues.

I just adjusted my steps / mm all the way down to 1 for both the X and Y axis, and now the buttons are working much better. So those buttons have nothing to do with steps, they must be in mm or whatever measurement the software is set to use. So, why are my steps / mm not matching up with the norm?

Steve PM'd me and helped me figure out that the reason my motors were stepping too far was because I had forgotten to install the jumpers underneath each driver board. With all 3 jumpers installed it is supposed to reduce it to 1/16 step as you can see in the following link:
[reprap.org]

However, when I installed the jumpers, my board now appears to be shorting out since when I plug in the USB it connects, then quickly disconnects from my computer. Later I will have to pull off all the jumpers and start adding them slowly one at a time to see where the problem is.

Oh! Good call! I just checked and there are no jumpers on my Sanguinololu. The person I bought it from had replaced the Sanguinololu but it looks like he did not move the jumpers as they are still on the old board. I'll see if this helps tomorrow or in the weekend and will let you know.

I hope your board itself is still ok.

My board ended up being just fine.

I took all the jumpers off and slowly put them back on to isolate the issue. Turns out the jumpers under my spare driver board were causing the short. I'm not sure if that is because I am not actually using a second extruder so the board is just sitting there, or if there is actually an issue on the RAMPS board. Since I only have one extruder it is not that big of a deal, I just left those jumpers off and things are working great. I put all my values back to the defaults, and I am getting perfect dry prints now.

Once my filament arrives I can start fine tuning the settings with a ruler. Until then all I have to do is start tightening nuts and bolts and making my frame more solid.

Yipee! I've placed the jumpers and the movement is working correctly now. Aside from some finetuning. And it's good to hear your board is fine.

Thanks for the tip. And thanks to Steve too!