Y-axis Drift (Large steps) with loud rumbling noise(Mendel_3)(Cradle Alignment?)

I've seen some threads about axis drift, but none with steps this large. Other than the occasional jump, the printer seams to run fine and i don't have any distortion otherwise. this has happened a few times now with different models. Is this perhaps a problems with Slic3r? The picture is of a model I made using blender, and converted to g-code with Slicer. Does anyone know what causes this problem?

thanks



Edited 4 time(s). Last edit at 10/08/2015 12:21PM by kippbits.

Check you Y axis. It should travel freely. I had a similar problem when I had a plastic Y axis cradle. I replaced it with an aluminum one and cured a lot of my problems. Your stepping motor is slipping. Since there is really no feedback to your controller, it continues the print with a new registration.

Check if the y carriage without binding, check the bearings, grease the smooth rods, check acceleration and velocity, try 1000mm/s2 and 100mm/s respectively.

I have the same problem with the y axis. My bearings don't last very long even with greased rods. Rod alignment is right on. I get a few excellent priints and then back to the same problem. Have to look at another method for the y axis.

It's a good idea to get good quality bearings, although I also use cheap ones and only had to replace them once. I also put a little tension on the y smoothrods, pulling them slightly apart so that the bearings are tighter without binding. It removes some backlash but nothing like the binding as the OP. It can take some trial and error to get the tension just right and evenly spread over the length of the smoothrods.

Hi, everything moves freely and smoothly. I'm not sure if I'm checking acceleration right.
I'm doing the following in the web interface:
home all axis
Y +10
G0 Y100 F9000 S1
G0 Y-100 F9000 S1

It doesn't travel the full distance out, and comes back and trips the endstop. It then seems to get stuck there, and makes some rumbling before moving out again.

is it the motor? why is it only in one direction? could it be a software issue? I'm noticing some funny behavior with it overshooting plate dimensions using the quick controls in the web interface

Also, are those the correct G-codes for the test?

Edited 1 time(s). Last edit at 10/07/2015 11:21AM by kippbits.

I'm wondering if it could be something with the STL file? It printed a different model perfectly just before this one. I am little new to Blender, and there were a lot of corrections in Slic3r on this model that messed up.
I'm currently doing a test print with a new version of the same Blender file. I had some weirdness in the mesh at a few spots. I'd like to wait and see if that fixes it.

For those who say it a problem of bearings, I'm using a 2015 Mendel kit from RepRapPro, and I spent a lot of time getting everything square and moving freely in the assembly. So lets hope that is not the problem.

You can set maximum acceleration in the gcode, in firmware and/or using the display if you own one.

It also depends on how your origin is defined. If you're using Marlin, by default it uses 0,0 as the origin and negative numbers are not used. By default it also uses absolute coordinates so if you move from 0,0 to 100,100 you would use
G1 X100 Y100 F9000
And to move back you use:
G1 X0 Y0 F9000

You're using -100,-100 which moves the head outside the print area unless you've setup your printer to use 0,0 at the center of the print bed.

If you've disabled minimum end stops it will rumble as it tries to go to -100,-100 which is outside the bed area and tries to go 'through' the endstops.

This still doesn't explain why it's not printing properly, I'd check the maximum acceleration settings in firmware/display (marlin it's located in control/motion menu, Amax X, Amax Y).

You can control absolute and relative positioning using
G90 (absolute positioning)
G91 (relative positioning)

I think slic3r assumes absolute positioning and I recommend to do the same.

If you're in need for a quick print, you can consider to home x and y only during layer changes. You can add gcode on layer change in slic3r.
G28 X Y

Don't home Z as that may crash the hot end into your print. It's not a real solution to the problem.

You can also use slic3r advanced options to limit the maximum acceleration if you don't want to change the firmware. At some point it's a good idea to familiarize with changing the firmware as you may want to change the configuration like auto bed leveling or adding a second hot end.

G0 and G1 are exactly the same btw. I'm used to G1 more

Thanks Imqqmi, I'd redo the test with G1 but I'm currently doing a reprint with my new file. So far it hasn't messed up. I think the problem might have been with my mesh.

I'll give you an update when it finishes

If it was a problem with the mesh, you would see it in the sliced preview, right? I always check the sliced gcode using repetiers preview, set the layer sliders and walk through the layers from bottom to top to see if there's anything that wouldn't print well without support. Many problems can be caught in the preview.

Hopefully it will print well!

Funny I didn't notice it in the preview. well I seemed to have fixed itself anyway. Here is the finished product.



p.s. I did get that same rumbling noise when the print finished; is this normal?
I'm pretty sure I'm using the latest firmware.

Edited 1 time(s). Last edit at 10/07/2015 01:58PM by kippbits.

Congrats on the good print!

It may depend on the end gcode in the slicer, if it says G1 X-100 Y-100, it might try to go to these out of bounds coordinates. Sometimes when all three axes move my printer makes more resonating sounds, could be referred to as rumbling but without skipping steps. It's also slow at that point. I haven't found out what the conditions are to reproduce it though, but it doesn't affect the print in any way so I'm not worried about it.

Well it happened again:

Perhaps it IS the bearings. I tried to make a second copy of my thingamajig, and this happened^^^

I also ran the Y-axis back and forth a few times to find where it was binding. The binding doesn't seem connected to any particular place in the travel. I'll try your tightening trick imqqmi. And I guess if that doesn't work I need new bearings

Thanks for all the help!

Edited 1 time(s). Last edit at 10/07/2015 06:06PM by kippbits.

cleaned bearings(broke some extraneous plastic in the process), and it did not fix the problem. I think it might be my cradle alignment. I noticed my pulley was shifting to one side of the roller, and rubbing the side. will adjust and get back to you all....

Cleaning the bearings will not help if the small balls are damaged. I am going to look at a V groove system.

Well,l after fiddling with my y-cradle I did get it moving back and forth smoothly using the machine controls in the web interface. I am still having a problem occasionally and still can't print a full file without it messing up.
it messed up on my most recent print after the first layer:
.
.
.
G1 X106.256 Y36.622 F9000.000
G1 X105.366 Y35.732 E0.11929 F900.000
G1 X103.433 Y34.875 F9000.000
G1 X108.755 Y40.197 E0.71336 F900.000
G1 E-3.50000 F2400.00000
G1 Z0.300 F9000.000
G1 X100.029 Y112.731 F9000.000 //----------this seems to be where it happens
G1 E3.50000 F2400.00000
G1 X101.455 Y114.945 E0.24165 F900.000
G1 X103.373 Y113.066 E0.24632
G1 X104.340 Y115.515 E0.24165
G1 X106.587 Y114.047 E0.24632
.
.
.

I'm going to try and modify my Slic3r settings and see if that helps

Try lowering your Speed for non-print moves in the "Print Settings" tab. It adds time to your print, but if it makes good parts. . . .

Well lowering the speed seemed to help, although i did have 1 misprint before i got a success. I had some accidents during commissioning, and my rubber pulley is kind of messed up. I think I might try changing it next if this keeps up.

Thanks for all the help

I figured it out, and i feel dumb. my pulley was threaded the wrong way. Rethreaded, and it seems to be working. here are pictures of before and after just in case someone else is also dumb enough to make my mistake.

before:


after:


printing:


Edited 3 time(s). Last edit at 10/25/2015 10:20AM by kippbits.

is there a way I can mark this topic as solved?

(i'd also like to change the title to match the actual problem)

Edited 1 time(s). Last edit at 10/25/2015 10:19AM by kippbits.