Steps Lost

Hi guys, my name is Gabriel, I'm new with 3d printing and I'm having a little big trouble: steps lost on X and Y axis stepper motors.

As you can see in the attached files, it's an aleatory lost of steps (not always on the same slice neither the same amount of steps).

I have already tried the following:

To adjust the steppers controller giving more or less current. (photo attached).
To put a fan on the electronic circuit to avoid any overheating problem.
To slow down the printing speed (initially, on 50mm/s, then 30mm/s and finally on 20mm/s).
To slow down the travel speed (initially, on 150mm/s and finally on 50mm/s).
To disassemble any mechanical part related to the movement of X and Y axis.

I can't solve this problem. It only happens with pieces of +1 inch high, it never happened on smaller pieces. I would appreciate any help.

Hi there Gabriel

That's a lot of steps.

I think it's one of the following:
1 - Like you mentioned (and you have a fan now) a stepper driver may be doing a thermal reset. Less likely now that you have a fan on it. Make it a strong fan. When I had this problem it was about a second reset on one driver.
2 - The print head may be hitting. You didn't mention what kind of slicer you use, but in Slic3r there is a setting called Lift Z on the Printer, Extruder 1 tab. This lifts the head slightly when a retraction is called for, and can help things print smoother. Try half a layer eight.
3 - You did not mention your acceleration settings. I had many problems with missed steps because of too much acceleration. Try reducing the acceleration by 3/4 and see if that fixes it. If it does then you can increase your speeds, and slowly increase the acceleration. I think this is the most likely problem.
4 - Jerk setting. Normally this defaults to 20, try reducing to 17. You do not want to lower this too much tho.
5 - Make sure there is a flat ground on the steppers, so the pulleys do not slip. You can also draw a line on the shaft to the pulley to see if it is slipping.
6 - Belts are tight?
7 - Make sure the wiring for the end stops is not next to the stepper motor wiring - could cause the end stops to trip.
8 - Make sure nothing is binding.

-Paul

---

My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

aleatory? I had to look that word up.

I have just been through a similar problem with my printer. As well as the above advice, use a meter to set the stepper voltages.
Also it may be your computer. It was with mine. You can set the slicer program to high priority in task manager and don't do anything else at the same time, like surfing the web. If you can, run the printer direct from an SD card.

Quote
Paul Wanamaker
Hi there Gabriel

That's a lot of steps.

I think it's one of the following:
1 - Like you mentioned (and you have a fan now) a stepper driver may be doing a thermal reset. Less likely now that you have a fan on it. Make it a strong fan. When I had this problem it was about a second reset on one driver.
2 - The print head may be hitting. You didn't mention what kind of slicer you use, but in Slic3r there is a setting called Lift Z on the Printer, Extruder 1 tab. This lifts the head slightly when a retraction is called for, and can help things print smoother. Try half a layer eight.
3 - You did not mention your acceleration settings. I had many problems with missed steps because of too much acceleration. Try reducing the acceleration by 3/4 and see if that fixes it. If it does then you can increase your speeds, and slowly increase the acceleration. I think this is the most likely problem.
4 - Jerk setting. Normally this defaults to 20, try reducing to 17. You do not want to lower this too much tho.
5 - Make sure there is a flat ground on the steppers, so the pulleys do not slip. You can also draw a line on the shaft to the pulley to see if it is slipping.
6 - Belts are tight?
7 - Make sure the wiring for the end stops is not next to the stepper motor wiring - could cause the end stops to trip.
8 - Make sure nothing is binding.

-Paul

Hi Paul and thank you for your detailed answer. Let's go step by step:

1.- I put the fan well closed to the stepper driver and controlled the temperature via IR temperature gun. It's a normal range, so I should discard a thermal reset.
2.- I use Cura slicer. But when the printer fails, I don't see any hit (also tested lifting z axis).
3.- Acceleration: How do I set this value?? I can't find it on Cura, and I think it could be a good option.
4.- Jerk: the same as above, how do I set it?
5.- The pulleys do not slip. Steppers do never lost steps on first slice.
6.- Belts are tight. I disassemble the mechanical parts and readjusted.
7.- I have just tested it, but they aren't switched when the printer fails.
8.- It's all clean, nothing is binding.

Conclusion: If I could set acceleration and jerk it may help, but I don't know how to do it. I would appreciate any explanation concerning.

Thanks again. Gabriel.

Quote
dave3d
aleatory? I had to look that word up.

I have just been through a similar problem with my printer. As well as the above advice, use a meter to set the stepper voltages.
Also it may be your computer. It was with mine. You can set the slicer program to high priority in task manager and don't do anything else at the same time, like surfing the web. If you can, run the printer direct from an SD card.

Hi Dave! Sorry about my English, I'm from Argentina.. I'll have to improve it.

"Aleatory" = Randomly..

I now tried it and also tried with different computers thinking the same, but it didn't work. As the printer doesn't have SD slot, also tried changing the USB wire.. Nothing happened...

I'm still stuck on it.. Thanks for your answer. Gabriel.

Gabriel,

I recommend getting an LCD with an SD card slot. You will have much more reliable printing, and you computer does not have to be dedicated.

Note that it would be pure luck if your firmware ran your printer well as-is. The person who posted up the firmware very likely had a different setup.

For all major firmware flavors you can adjust the acceleration settings in the Configuration.h, and recompile/upload using the Arduino environment.
Some firmware (like Repetier which I use) allow you to change most of the acceleration settings using the LCD.

For more help you will need to list:
- What kind of printer you have
- What controller board
- And what Firmware name and version.
- You can also attach your configuration.h. Someone here will be able to suggest some reasonable values for acceleration.

---

My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

Quote
Paul Wanamaker
Gabriel,

I recommend getting an LCD with an SD card slot. You will have much more reliable printing, and you computer does not have to be dedicated.

Note that it would be pure luck if your firmware ran your printer well as-is. The person who posted up the firmware very likely had a different setup.

For all major firmware flavors you can adjust the acceleration settings in the Configuration.h, and recompile/upload using the Arduino environment.
Some firmware (like Repetier which I use) allow you to change most of the acceleration settings using the LCD.

For more help you will need to list:
- What kind of printer you have
- What controller board
- And what Firmware name and version.
- You can also attach your configuration.h. Someone here will be able to suggest some reasonable values for acceleration.

Hi Paul:

Thanks for your answer. I bought the printer already made here in my place; so I don't have any of what you are asking me. I only know that it's a Prusa I2 working on an Arduino Mega 2506.

The printer was working fine almost 2 months till few days ago, but suddenly started with this fail, and the manufacturer has no idea of what it could be happening He only told me to replace the stepper drivers, but it didn't work.

Even if I'm an electronics engineer, I have never mounted a 3d Printer (and I had not intentions to do so, I needed the printer to my business and that's why I bought it), so I don't know if it's able to download a new Firmware to change this configuration and upload to the Arduino.

Otherwise, I will have to buy a full new Arduino kit and design my own new 3d Printer as I think you guys did.

Updating:

After several testings, I could catch just the moment of the fail.

The steppers not always lose steps. They just (randomly) stand quiet a moment or suddenly moves a distance (on X axis, Y or diagonal) and resume printing right there. I was really concerned at this point, because a random diagonal movement is not just an acceleration fail or stepper driver fail.

Now, I'm even more confused than before...

Gabriel, I have the same Arduino as yours. Check your stepper driver voltage settings first so that can be eliminated. It is easy to do but needs a digital voltmeter. Are your motors NEMA 17?

Gabriel,

The symptom you are describing is exactly what happens when a stepper driver does a thermal shutdown. That axis misses a bunch of steps.

One of mine (extruder) was doing that this morning for instance. It was sitting still (preheating) and I heard a clunk sound about every 15 seconds. I pulled on the filament and waited a few seconds, and when it happened again I could move the motor freely. Ah! So I just turned the current down a bit on that driver until that stopped happening.

Does it always happen with the same axis, X or Y?

If that does not work, since you have socketed drivers, you can switch them, between x and y for instance (make sure power is off first), and then see if the problem follows the driver.
A driver may just have gone bad.

Or turn down the current even more on the axis that is misbehaving.

That's all I can think of.
-Paul

Quote
dave3d
Gabriel, I have the same Arduino as yours. Check your stepper driver voltage settings first so that can be eliminated. It is easy to do but needs a digital voltmeter. Are your motors NEMA 17?

Hi Dave

Yes, the motors are Nema 17. What voltages values should I spect to find? I moved the trimpot and found different values according to the power the steppers were taking.

Quote
Paul Wanamaker
Gabriel,

The symptom you are describing is exactly what happens when a stepper driver does a thermal shutdown. That axis misses a bunch of steps.

One of mine (extruder) was doing that this morning for instance. It was sitting still (preheating) and I heard a clunk sound about every 15 seconds. I pulled on the filament and waited a few seconds, and when it happened again I could move the motor freely. Ah! So I just turned the current down a bit on that driver until that stopped happening.

Does it always happen with the same axis, X or Y?

If that does not work, since you have socketed drivers, you can switch them, between x and y for instance (make sure power is off first), and then see if the problem follows the driver.
A driver may just have gone bad.

Or turn down the current even more on the axis that is misbehaving.

That's all I can think of.
-Paul

Hi Paul!

I tried giving more and less power, up to the limit to make the steppers to fail because of not having power enoght. But the fail keeps existing.

The fail happens on X and Y randomly (not always the same).

New updating:

Just getting bored of seeing the printer fail, I bought 4 new drivers to replace them all. What do you think? The machine keeps failing...

Talking to the manufacturer, I managed to get the firmware. So I attach the configuration.h that you guys asked me.

Also, I attach a photo where you can see clearly the fail. It's on both axis (x and y).

I hope this may help. Thank you so much! Gabriel.

Gabriel,
Perhaps someone here that has your model printer can compare the configuration.h. I doubt that's it since your printer was working, and now not, with no firmware or hardware change.

Good idea to try new drivers.

While you're waiting for them, since you've tried lower current, and now it's failing in 2 directions, try higher current (clockwise a bit).

Quote
Paul Wanamaker
Gabriel,
Perhaps someone here that has your model printer can compare the configuration.h. I doubt that's it since your printer was working, and now not, with no firmware or hardware change.

Good idea to try new drivers.

While you're waiting for them, since you've tried lower current, and now it's failing in 2 directions, try higher current (clockwise a bit).

Hi Paul.

Thanks again for your answer. I have already replaced the 4 drivers. And also I adjusted the current (clockwise and counter-clockwise), but it didn't help.

I uploaded the firmware 'as it' again to discard any system failure and then started trying different acceleration and jerk values. But it keeps failing.

A few days before the fail started there was a strong thunderstorm in the area. I think this should not affect (if it would have affected, it's supposed that the printer wouldn't started, but it does).

I'm now thinking on replacing the RAMPS or the Arduino... I don't know if it would help.

Quote
gabgomez
Yes, the motors are Nema 17. What voltages values should I spect to find? I moved the trimpot and found different values according to the power the steppers were taking.

I set my steppers on 0.32v to start with:

Max amps say 0.4A for nema 17

ref. volts = 0.4A x 8 x 0.1 = 0.32v

I have since turned them up a bit to 0.36v.

When measuring with the voltmeter, I used the -ve to a common ground on the Ramps and a crocodile clip on a small insulated screwdriver to the +ve trimpot. It is very sensitive to adjust. On my printer I have two z axis motors running in parallel off one Z stepper so the voltage needs to be double.

Note that you must temporarily jumper the drivers to Single Step Mode to get an accurate voltage measurement when setting the current.

Note that there is another way of setting current, it doesn't have to be exact. See Motor Calibration
It needs to be enough so it moves consistently, but not so much that it overheats the drivers or the motors.
Hope that works.

If not, anyone have any other ideas what could be causing it?

Paul; Dave:

Thank you so much for your help.

I just calibrated the steppers (0,36 x and y axis and 0,72 z axis, with a little error, the voltage isn't so exact), and the printer failed again.

I moved a little around those values, re-calibrated the acceleration and jerk in the firmware... But nothing happened.

I get a friend that is going to bring me a new Arduino, just to test if it could be the problem. I will be updating tomorrow again to let you know what happened.

Gabriel, as I said, my problems were caused by my computer. I am using an old slow Panasonic Toughbook on XP.

I know you say you have tried another computer, however shut everything down that you don't need, particularly the WiFi. Also stop things like hibernating, screen saver, virus scans, updates, power saving modes ect. It may be trying to power down com ports. Use Task Manager and shut down what you don't need. Stop any antivirus programs. If using a laptop run it on the mains not battery.
I tried several baud rates and the most reliable is 115200 ANSI. Make sure baud rates all set the same - device manager, firmware and slicer. I also switched from Marlin to Repetier firmware v 0.92. The online configuration tool is a big, big help. Repetier firmware is binary so should eliminate delays. Also be aware your slicer may be over ruling your firmware settings if the eeprom is enabled.

Always good to have spare Arduino, Ramps and steppers. Can't think of anything else at the moment.

Also think about buying the Reprap Discount LCD screen. It plugs into the RAMPS and has an SD card slot.

Might also be a bad connection somewhere. Cables can fail intermittently which might mimic what you are seeing here. I would check the cables and soldering on the on board connectors.

Dave, Paul, Bryan:

Solved!! I finally found the problem: The Arduino board.

As told you yesterday, I borrowed from a friend a new board. We tried it and: Worked!!

So today morning I bought a new Arduino, and now it's printing fine again!! It seems that Arduino boards are very sensitive to the thunderstorms (even with a good voltage protectors as the one I have installed).

Anyway, I want to thank you all. Because of you I learnt lots of new things about my printer and now I'm decided to add a LCD with SD card as Dave advised. I see it's really cheap and useful.

Gabriel,
That's great news!
I'm glad you stuck with it, we all learned something.

Yes, well done Gabriel. You can now advise others!