Printer / Hot End Issues

[Dave @dodgydave80 My Robox is a Blue Commercial Version]

When changing materials I normally manually heat the hot end using the M104 command from the G code window; once up to temperature, open each nozzle in turn and manually feed material using the arrow buttons in automaker. In this instance I was using Colorfabb XT and set the temperature to 240°C.

Last night something weird happened. For some reason the printer lost USB connection with my PC while the hot end was heating up and the head began to smoke. I immediately killed the power, unplugged the USB and plugged everything back in. It took a couple goes to get the printer to talk to the PC again but once it did, the hot end fan kicked in to cool the hot end down and Automaker reported the temperature to be exactly 300°C for a while. I assume the temperature reading maxes out and the actual temperature was way beyond 300°C.

After I got Automaker talking to the printer again I set the hot end temperature to 240°C and purged the material again before it cooled down.

Has anyone reported an issue like this in the past?

I ran two 6 hours prints following this issue and everything seems to be ok.

I am running Windows 10 Pro with Automaker V2.00.03

 

I have also been experiencing a problem with the needle valve on the 0.3mm nozzle of my single material head. It has a slight leak from the nozzle even after running the clean nozzle commands from maintenance and recalibrating the valves. Is this something that is covered by my warranty?

The head serial number begins RBX01-SM-2215 and is a replacement I received a few months back as the original head seals failed.

Cheers

Dave

[BHudson @bhudson I have several Robox units Kickstarter and Commercial Arizona, USA]

@dodgydave80 Why don’t you use the automated “Eject stuck material” command or the eject material command? Why don’t you use the purge command? These commands are all programmed to allow you to safely change materials without risk to the printer.

The problem is usually related to the connection to the head or a bad USB cable, but as you are using Advanced Mode and are sending gcode to the printer there is a chance that any resulting damage will not be covered under warranty. You will need to open a support request to resolve any issues.

I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[Dave @dodgydave80 My Robox is a Blue Commercial Version]

@bhudson the “eject” and “eject stuck material” commands usually don’t work on their own for me. I find that heating the head using G code and extruding a small amount of material before running the eject command does the trick.

The purge command uses the bed which takes time to heat up and seems unnecessary. I find that doing things manually is a lot quicker and also gives me the opportunity to clean the nozzles while they are hot just after.

If I send a temperature via G code, surely the temperature is then controlled by the printer firmware once sent. I also assume that the maximum temperature of 260C is written into the firmware which shouldn’t have allowed the temperature to rise above 260C regardless of the USB status.

My main concern is this maybe a firmware error which could affect other users unless I’m wrong about the way it operates.

[BHudson @bhudson I have several Robox units Kickstarter and Commercial Arizona, USA]

@dodgydave80 The eject stuck material command heats the head to the print temperature, extrudes a small amount of material, and ejects the material. Seems like it is an automated way to do what you already are doing.

The purge process uses the bed to control where the material goes. By observing the purge results, you can often spot problems before they become issues. It also purges enough material to avoid building up degraded material in the print head, which can lead to blocked nozzles.

Note the warranty on page 16 of your user manual.

There is no firmware issue - there is a communications issue with your printer and that caused the head to overheat. You should open a support ticket.

I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[Dave @dodgydave80 My Robox is a Blue Commercial Version]

@bhudson do you know if the new head designs address the connection issues? I’ve not removed the head on my printer for sometime which leads me to think the head has moved over time causing the connection problem. If connection problems can lead to a situation where the head temperature runs away like that, then this could be quite serious if it happened while the printer was unattended.

I know that when changing the head, the connection can sometimes be hit or miss. Maybe cup shaped contacts on the rear of the head would help locate the pogo pins and prevent connection issues rather than the current PCB pads.

I’ll open a support ticket as suggested for the needle valve issue.

Cheers

[BHudson @bhudson I have several Robox units Kickstarter and Commercial Arizona, USA]

@dodgydave80 The new head design coupled with a new head carrier will address the connection issue.

The connection issue is related to the retention force from the head carrier to head that doesn’t keep the pins in solid contact. It can also be faulty pins; a few older machines have shown failed or worn out POGO pins. If you have connection issues while changing the head, make sure you tighten your connection screw as tight as possible.

I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[Martin @pythag My Robox is a Blue Commercial Version]

I think Dave has a point - there is something wrong with the current implementation of ‘Eject’ - see my thread http://www.cel-robox.com/forums/topic/filament-eject-issues-from-cold/

I’m pretty sure the issue wasn’t present in earlier firmware versions, but I can’t be sure of that.

Personally I just do a purge both before and after a filament swap. I agree it wastes a bit of time, but not much. After all, the bed needs to be heated up to do the post-swap purge, so the addition of one extra purge doesn’t seem a big deal.

What Dave describes sounds to me like the micro in the Robox crashed, thus preventing it communicating or turning the heater off.

Out of curiosity: Does the Robox have a hardware watchdog in it? With fairly powerful heaters a crash of the micro has quite scary consequences….

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