Upgraded to metric rods

I reflashed the board to use 200mm/min (3.3mm/sec) and it's homing slowly without any issue. But when I try a print, even though I set the travel speed way down, it continues to lock up almost immediately. I now cleaned the threaded rods + brass nuts and used some light oil, so that it threads better than the original rods but that didn't help either.
I even went back to the original imperial rods - same thing.

I really have the impression that I killed the steppers. I can fairly easy stop them with 2 fingers, and they'll start to rattle and probably after a timeout of like 3-5 sec it stops.
Can I somehow test those steppers?

Any help appreciated.

 

I am confused by the wavyness picture ( top one ) it would indicate to me to be a problem with x-y orientation rather than a z axis problem. I see changing the z axis rods would change the height of the print but not affect the x - y placement of the print head.

 

The problem is that a "0.2mm" layer height doesn't go evenly into an English rod, and the rounding causes the layers to be different thicknesses, thus causing the different layers to "bulge" differently, most visible on the perimeters.

 

I think that the alignment between the threaded rods and the guide rods have gotten out of kilter...
If you take all the rods off, how hard is it to oppose the stepper by grasping the coupling or stepper shaft?

 

I removed the threaded rods and grasping the coupler while moving is fairly easy. When it stops, it starts to rattle. The stepper doesn't continue if I release the coupler but continues to rattle.
I don't think this is a misalignment. I can move in +z and -z ok, if I do it manually with 200mm/min. Going to 300 locks up, no matter what.
I also have the impression that I can grasp and stop both steppers with about the same force, so I guess I'll try to change the stepper driver from the x or y axis to see if that makes a difference. I could also try to grasp the extruder, just to have some comparison (and hope I don't kill that stepper with this :-S)

 

Short update: I think my steppers are broken (why both?). Reason being: I tryed to grasp my extruder, which is the same type of stepper ( just like anyone else), and I wasn't quite able to stop it, so there's a huge gap in torque compared to the z-axis steppers. As it seems to affect both of them, I tried to change the stepper driver, but that didn't make a difference, so these seem to be ok.

Are those stepper motors known to break like this? I'm asking as I don't have much experience with it, but some of you might have..

Unless anyone else has a better idea, I'll go for that.

These are the ones I'm looking for: https://www.reprapsource.com/en/show/6910

Cheers,

 

@Matthias
Have you tried playing with the pot on the Z driver board? (Might be set too low, and at this point, if you blow your stepper then you might not be at a huge loss.)

 

I find it very unlikely that both of your stepper motors are dead. Your most likely problem is an under-adjusted trim pot on the Z stepper driver board. You need a multimeter to measure the driver voltage but, from there it should be a pretty straightforward process.

 

Agree, this was one of my thoughts last night. I'll need to check this. How would I go about it? What speed, what would be the expected reading?

Another thought : I *think* it started after I flashed the board. Any chance that "something" went wrong? Though I didn't see any errors during compile or upload


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Edit: regarding the stepper driver : I exchanged it from the x axis already, no change..

 

The problem is that the Z axis has two motors so the pot value is different for Z than X/Y. You're pretty safe just swapping X/Y/E around and things would still work. Z needs the pot turned farther to get the same reference voltage reading.

Also, yes, I've had bad firmware uploads. There have also been versions of Repetier firmware that have had problems with overspeed on initial Z move.

 

Hey guys before I change my rods out, As I have been experiencing the same issues. In the firmware where would I change the value for steps per mm? In the Configuration.h File. Assuming is (X, Y, Z, E) as stated below steps per unit? I ordered the rod from mcmaster, after discovered fastenal had the same rod cheaper and could have picked it up.

// Robo3D Default // #define DEFAULT_AXIS_STEPS_PER_UNIT {80.69,80.69,2269.472,747.626} // default steps per unit for Ultimaker
#define DEFAULT_AXIS_STEPS_PER_UNIT {78.33,78.33,3200,747.626} // Steps for Melody's Robo 3D.....
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

 

This is the define you want to change. The 78.33 is one I derived and the 80.69 line is the Robo default.


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Changed values, back to 80.69 and added 3200 for the new metric rods. Part is coming out shorter. Thank you as well Melody! Love the FAQ.

Also having other issues after installing e3d. Corners warping. Firmly attached to bed. Did a series of temperature tests 5 degrees at a time. Belts tight, hot end is firmly seated level. Nothing seemed to improve results. Played with differnt layer heights. Retraction. Slowed down feedrate. Im lost....any ideas would be appreciated!

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So... I get that 0.2mm layer height represents a rounding error for the Robo3d (and for all heights in metric)...
Could that be solved/eliminated by using an "English" layer height-- eg, by using a 0.220315 (1 / 2269.472 * 100*5 ) mm height?

It looks like Repetier sends 3 decimal places, 0.220 would yield a ramping error of 1/3 step/layer (more periodic than 0.1 step/layer), or you could use a layer height of 0.221, which would go under/over on each layer (but still accumulating 0.1 steps every 2 layers)...

I like the idea of metric (mixing metric and English is not for amateurs... not even for NASA!), but I'd really like to find close-tolerance brass nuts or something before I tried moving to metric rods (I might try the z coupling ball bearings though... fixing an axis on a flexible coupling sounds quite daft).

Cmickinney -- Thanks for the Fastenal reference. I'd almost forgotten about them....

 

LOL


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I also am now experiencing the same problem, Was able to print a couple calibration cubes that were 30% smaller in z height.(Melody's Edition) Then switched back firmware to original with change to 3200. Same problem happened. Switched firmware again back to previous that I was able to print on and still occurring. I took weight off the z axis same results.

 

I gladly fixed my issue by simply flashing again. I probably had the printer in a weird state when I flashed it, so now, I switched it off, removed power and usb, then only connected usb and flashed right away..
So, fortunately, nothings broken.

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I found another thread: http://forums.robo3dprinter.com/index.php?threads/topsys-printer.1038/page-2#post-10864

So for those who are pre-metric rods, you can try those to see if your print quality improves.

 

I re-flashed back to the original values and back running again. When I change to any value above original on the z the steppers act the same way with the metric rods.

I've also determined one of my coupler's is bent. Any ideas one replacement specs? Or something that might work better? Something something solid with no movement? Maybe Bend?