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Need help troubleshooting your BoXZY 3D Print Head? You're in the right place!

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Intermittent freezing mid-print. Firmware unresponsive.

I’ve been having an issue where the firmware on the Mega2560 board no longer responds to g-code commands and the machine freezes in place mid-print. Obviously this ruins the part I am printing and eventually led to the printer nozzle itself becoming blocked.

Once the machine is frozen, the only way to recover it is turn off it’s power, then unplug the usb lead, wait a moment then reconnect the usb lead, power on the printer and hit the “connect” button in the software.

Is there a watchdog or status on the Mega 2560 that can give me some kind of insight as to what is going wrong?

I am comfortable with changing the arduino code if anyone has a way of indicating status.

Any info would be welcome.

Thanks

Maz

Answer this question I have this problem too

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7 Answers

Hi Maz,

This is exactly what happens when there is EMI over the USB. Does your USB cable and 3d Printer Cable have ferrites (cylindrical pieces) on each end, and is your USB no more than 6 feet long?

This can also happen if there is a short in your heater circuit or a driver has shorted.

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It's a 6ft cable with ferrites. I've also tried a different cable which I think was only 3ft with ferrites when I moved the machine.

My heating circuit is entirely indepenent of the Boxzy system and appears to work perfectly. Unless the external relay for the heater turning on and off somehow introduces EMI via boxzy's power system, it should be separate. I'd do a few tests without the heated bed except that I'm currently printing ABS and it really does require that heater.

How does the EMI cause the system to fail? I'm wondering if its possible to write a separate watchdog / serial monitor so that I could see exactly what is dying. Does the Arduino itself stop running or is it the stepper controllers and that somehow halts the arduino's replies to g-code?

It hapens rather infrequently, but more often when there are lots of small little X/Y movements.

Thanks for the reply.

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It is likely it is your independent heated bed. The issue is common with external heated bed setups. They introduce significant EMI. Twisting wire pairs and placing ferrites on each end of the DC cables and one on the AC cable usually resolves it. Do you not have ferrites on your 3D printer quick change harness and motor cables? This is important too. They were introduced in the first revision.

From what I understand, the interference is with the feedback the board is providing to the computer when a series of commands have been competed, as well as the temperature feedback. The usb connection is left open awaiting feedback for further communication and temperature adjustment, information that has already been provided but was corrupted. You could probably add a timeout that would resend the response after a given period of non-response, but I can't say how this could be implemented. The interface will not shut down until it has received requested feedback or it is manually closed.

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I have swapped back to the 3ft usb cable (with ferrites) and it’s routed nowhere near the power leads.

The heated bed and main printer power supply are nowhere near each other either (except where they’re plugged in).

While I was tinkering with the insides of the printer, I found the second serial header on the ultimaker board so if the problem happens again, I’ll start modifying the firmware to output some logging data on that connection. It really should be able to resume from a failed message and its really frustrating that it can’t be left printing or it stops at random and cooks the filament into the head.

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It still freezes even with the heated bed off and the 3ft usb cable with ferrites.

Nothing obvious in the log. It just stops working.

I’m guessing some part of it is faulty, but it’s hard to tell what given how much of the machine I’ve replaced in trying to debug this problem. This is an identical print (same g-code) as I printed yesterday without issue.

Any hints would be appreciated.

Maz

Attached piece of log:

READ: ok 0

SENT: G92 E0

READ: T:237.50 /238 @:146

READ: ok 0

SENT: G1 X60.107 Y62.205 E0.0687 F3600

READ: ok 0

READ: ok 0

SENT: G1 X62.369 Y62.205 E0.1636

READ: ok 0

SENT: G1 X61.209 Y63.365 E0.2323

READ: ok 0

SENT: G1 X61.935 Y63.365 E0.2627

READ: ok 0

SENT: M105

SENT: G1 X61.935 Y64.902 E0.3272

WARNING: Firmware unresponsive. Attempting to force continue...

SENT: M105

WARNING: Firmware unresponsive. Attempting to force continue...

SENT: M105

WARNING: Firmware unresponsive. Attempting to force continue...

SENT: M105

SENT: G1 X63.095 Y63.742 E0.3959

WARNING: Firmware unresponsive. Attempting to force continue...

SENT: M105

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This is getting increasingly frustrating and means that the machine can't be used without literally sitting next to it and babysitting even small prints. Is anyone else having this issue or do I still have a faulty part somewhere?

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The tentative fix appears to be replace the whole machine with a $300 tarantula tevo.

I’ve had 3 out of 4 prints fail on boxzy today and 0 out of 7 on it.

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There's definitely something going on, we should find a way to track down. Does the failure correlate with anything? 3D printer fan kicking on, temperature drop, anything you can think of?

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Sorry. I didn't get an email notification for a comment reply.

My best guess right now is that its a usb / data throughput issue. It seems to mostly happen on parts with intricate detail or a lot of small movements. My next move is going to be to replace the PC (because I'm running out of other things to test with.)

Do you know if there is any kind of flow control on the gcode serial connection? Could that perhaps be set incorrectly in windows and it's not listening for a request to send messages slower?

I'm not sure why that would cause it to freeze rather than just miss a message, but I'll keep trying to investigate.

I have the fan on at about 20% after layer 3, so it doesn't seem to be related to that. The last time it froze I was sitting there looking at the machine and it didn't seem to coincide with anything that I could see.

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Can anyone print this file for me?

http://maz.net.au/Files/Public/TRex_Ribs...

It has frozen the printer 5 times so far. Usually within the first 50 layers.

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It's an ABS print at 245°C. You can see the settings at the top of the gcode file before printing. Or if you want to slice it yourself,

https://www.thingiverse.com/thing:275091 left and right ribs together.

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I bought a new pc. i5 with 8gb of ram and the first print completed okay. I wonder if the old pc had either a USB issue or was simply too slow. I’ll see how it goes after a few more prints.

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Maz will be eternally grateful.
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