Y-axis shifted a teeth on the belt maybe?

Hi guys, how tight should a belt be tightened? Is there a rule for? Maybe a music note that I can identify?

Story:
So I'm finally printing my real first object to use with the machine (spool holder for Reprap Air 2 XL), and all goes well, but suddenly I see that the Y-axis has shifted! Oh my god, how did that happen!@?

Here is a movie of the printing, and added are three pictures of the moved layer.
[youtu.be]

Now, I will keep this print, because I can scrape off a small part and still use the holder no problem, but for future prints that do have high importance, I would really like to prevent this happening in the future.

Any ideas on how this might've happened, I'd love to hear!

From a new reprapper,
Marinus

You don't show any evidence of a belt loose enough to skip teeth. Your stepper motor skipped some steps.

• From accelerating too hard.
• From short infill moves that result in resonance of the machine. This is similar to accelerating too hard.
• From the driver current being too high. If the current is too high, the driver's thermal protection will shut it down until the temperature recovers. THis can be only a few ms, resulting short displacements.

Okay, I have here a 12v small ventilator motor from a CPU cooler, where can I attach it? And Yes, I did try a higher printing speed for this print, so maybe I should lower it a bit again.

I upped every speed setting with 20%, so I will now set it back to 10% extra speed.

I have extensively calibrated my stepper drivers, but you may be right about this, it is something I have not checked before. Heat! Duh.

There should be a place where I can attach a fan on the Sanguino, but I don't remember where, I assume I can just attach my cooler on there with 2 wires and then just point it toward my sanguino for the time being until I find a better solution?

Thanks for the insight Dale,
- Marinus



Edit:
So, if I just connect a small fan in between one of the stepper-motor's sockets, would that work? I see a GND and a 12v pin there.

http://reprap.org/mediawiki/images/f/fa/Sanguinololu-photo-top.jpg

Edited 5 time(s). Last edit at 04/05/2013 06:19PM by Ohmarinus.

It is still going wrong, I would really like to know if I can just hook up my 12v 0.08a fan to the 12v and gnd pins in between my stepper-motor connection on the sanguino.

I don't know, it doesn't happen with all my prints. But with some it does. I have even re-calibrated my stepper voltage settings.

I think this might be the problem:

[*] From short infill moves that result in resonance of the machine. This is similar to accelerating too hard.


How can I fix this?

Some of the slicers are filtering these moves now. Unfortunately, I don't remember which do. Other than that, you can try lowering max acceleration settings in your firmware.

For whatever reason, I've not yet had to attach a fan to mine. So I can't offer any advice on how to best connect a fan. I should get around to that someday, so I can turn the current up and accelerate harder.

Okay, I really think it's the vibration problem.

I have found a few sources:

Same problem:
[github.com]

Frequency limit (configurable in Slic3r and in Marlin, see the below):
[hydraraptor.blogspot.co.uk]


In the source code for Marlin I have found in Configuration_adv.h:

// Frequency limit
// See nophead's blog for more info
// Not working O
#define XY_FREQUENCY_LIMIT  15

The setting was commented out, so I have commented it and will test this now instead of setting it in Slic3r.

Okay, set the printing speed slower, but now it still happened with a new print... Only on the third layer already!
Damn.

I have set the XY_FREQUENCY_LIMIT 15

Anyone has an idea how to fix this?

I would try to vary you voltage to the Y stepper by adjusting the small potentiometer on the stepper driver.

Ah yes, did that multiple times
I'm afraid to go higher without any way of cooling it to prevent the stepper taking a pause every few seconds.

But I still don't know if I can attach a continously running fan to the 12v pins that are on the sanguino board in between the stepper-connections ;D





Fl0yd Wrote:
-------------------------------------------------------
> I would try to vary you voltage to the Y stepper
> by adjusting the small potentiometer on the
> stepper driver.

Aaaaaaand it happens again. Really, is there anyone who has an idea what might be happening? I have already tried everything I could discover on this subject.

It now happened once the other direction..

It's not the stepper driver overheating
It's not the belt skipping
It's not the frequency, I have set 15Hz in Marlin AND 15Hz in Slic3r

I am currently trying to make the printbed lighter, but I haven't had this problem a lot before, it just suddenly started to happen.

It happened on these prints:
[www.thingiverse.com]
[www.thingiverse.com]

The gears from this one:
[www.thingiverse.com]

And some others, but not on all.

The kinematics of your printer are not significantly different from mine (MakerGear Prusa). Assuming the same or similar electronics (RAMPS with little heat sinks on the stepper drivers), you should be able to turn the current up far enough to prevent lost steps.

Since this is a new problem, you might look into whether your Y axis bearings need lubricated. Or perhaps even go so far as to check all of your mechanics to make sure things aren't wearing or gradually coming out of adjustment. Pop the belts off and make sure everything still moves smoothly with no stiction, etc.

A customer's Mendel90 would do this at his house so he brought it to mine and it worked fine printing the same g-code but failed when he took it back home. Can't explain it but he fixed it by reducing the acceleration in the firmware.

---

[www.hydraraptor.blogspot.com]

Ha, yes thats also what I tried.. Maybe it's my computer? Haha, we are human after all.. We create computers, we write code, we make the machines, we make mistakes, the machines make mistakes.

I have just totally pimped my Air again, lighter printbed, lower printbed, higher hotend, new hotend, re-soldered some stuff, enhanced mechanics, next thing on the machine will be isolating the space underneath the heatbed a bit.

Thanks for your reply, I will see tomorrow if the machine is still having it's weird quirks.
Meanwhile I am looking into the thermistor table story, I really love your info btw nophead, you are a very worthy participant in the community and I as a 'good newb' have read a lot of your documentation and solutions to other problems.

Maybe you would know an answer to this particular situation:
[forums.reprap.org]

Hi

I had side step in one of my prints, once. It coincided with the belt rubbing against one of the guides. I guess this this was causing the motor to skip. Could this be your problem also?

James

Hi James, thanks for your reply, I have a very keen eye for detail, the Y-belt is always neatly in the middle of the bearing when it moves from front all the way back and vice versa. I have re-designed my print area, the bed is much lighter now (but sadly also bends slightly more) and runs smoother than ever. I have since chosen to print my work more slowly and haven't had much stepping ever since.

However, I am also testing my new hotend and am running into a lot of trouble so I am currently figuring that out. When the weird printing errors are fixed I can start producing a bit more again and we will see if the problem still persists. I am very keen on printing a bit faster as I see my printer needs more speed. Speed is the key I think to making my prints look a little bit better. Sometimes the machine just seems to print very slowly. I am actually thinking of taking out the vibration setting because it is slowing down on very unnecessary parts.

Will create a new topic for the printing issues I am having now. Doing a lot of testing and I get some problems that I don't really recognize 1-2-3

The printer prints very inconsistently in various speeds now on a shape in which almost every layer is the same. Weird!!!