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nssorensen

USB printing - What am I doing wrong

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Hello

I've had an Ultimaker 2+ for a some month.

So far I've used an SD Card to transfer STL files and print from this but I recently hooked the printer up via a USB cable thinking this would be easier.

Cura 2.3.1 immediately recognized the printer and offered an "Print via USB" option. However - when I selected this option with a design - here is what happened.

My printer started immediately attempting to print. It ignored that the temperature of the print-bed and the nozzle were not even close to the temperature set my material settings.

Needless to say that printing something without the material heated to the right temperature yielded nothing.

I then cancel and the printer just stopped. Nozzle stayed were it was and the print bed didn't moved!

I then selected "move the nozzle home" option from the Printer control. This did home the nozzle but the print bed remained where is was resulting the the nozzle hitting the back glass-bed clamp as it returned.

What am I doing wrong ?

thanks in advance,

Robert

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First know that this is not officially supported for a reasonably good reason. You can get it to work but it's just not as reliable. Not just because your computer might go into screen saver mode or upgrade software or simply be busy for a few seconds and this can ruin a print. But also because USB is just not very reliable with UM2. So you might have to try a few different USB cables and a few different computers and you might need a USB buffer for stronger signals before it's reliable. It might work fine and fail 29 hours into a 30 hour print. Certainly if you plan to do this a lot you want to check the log files and the checksum errors. If you get more than 1 checksum error every 10 minutes then you are skirting danger.

Anyway - that doesn't answer your question. The main thing is you have to change the machine settings to be in "reprap" mode. And not "ultigcode" mode. Ultigcode does not work through usb. So once you change this the first thing you should notice is that now the bed and nozzle temperatures are set in Cura and *not* on the machine. The machine will ignore your material temperature when you print through usb. Let us know if you have trouble finding the machine settings in cura.

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Thanks gr5.

I'm a bit confused though.

I supposed the first section of your reply suggest that USB which served the computing community for a couple of decades suddenly has become unreliable when used with UM2+? In my case - I'm not talking about failure after some hours but "unexpected" behaviour right away.

With respect to the 2nd half - I have not found where I can set reprap mode. Appreciate any guidance. That said - if a mode or function in Cura is either not supported or in early beta-state (perhaps even alpha) - shouldn't this be highlighted to the user when selecting this function ? Sure - the software is free but the printer is not and in my case - I do feel that if the combination of the software and the hardware can damage the hardware there ought to be amble warnings.

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The USB connection might be reliable but the printer is running a real-time process expecting data arriving in time otherwise the head will not move to the next location in time. The printer firmware does not have a large buffer to store future commands they would have to come from the computer. Since the operating system on your computer does not know about the real-time requirements of your printer it might decide to do something else and come back later and in this case ruining your print. So if you can guaranty that the computer is streaming data all the time USB printing can work reliably. But most operating systems on every day computers do not give this guaranty. So that is why people claim that USB printing is unreliable since you never know when the operating system interrupts the communication for x amount of time.

Dedicated boards with a local CPU could buffer this data and fulfill the real-time requirements the printer requires.

I hope this gives some background info why people claim it is unreliable. And yes some people use USB printing but they have to be careful what the computer does on the background.

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With respect to the 2nd half - I have not found where I can set reprap mode.

 

It's not only the gcode-flavor, you have to write suitable start/end-scripts as well. If you really want to go further this path: you can use the printer definition of the Octoprint-Plugin as a starting point:

notes-on-ultigcode-ultimaker-2ultimaker-2

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Hmm. Okay - doing it in Cura 2.3 is pretty involved apparently. I think you have to create a new profile and edit the javascript files. I don't know how to do that. Yet.

In Cura 15.04.4 it's pretty easy as shown here. I still use Cura 15.04.4 for my UM2+ (and cura 2.3 for my UM3). Older versions of cura here:

https://ultimaker.com/en/products/cura-software/list

a.png.0a8b6eda1f1eb79a3aa26b9927b736b4.png

a.png.0a8b6eda1f1eb79a3aa26b9927b736b4.png

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First know that this is not officially supported for a reasonably good reason.  You can get it to work but it's just not as reliable.  Not just because your computer might go into screen saver mode or upgrade software or simply be busy for a few seconds and this can ruin a print.  But also because USB is just not very reliable with UM2.  So you might have to try a few different USB cables and a few different computers and you might need a USB buffer for stronger signals before it's reliable.  It might work fine and fail 29 hours into a 30 hour print.  Certainly if you plan to do this a lot you want to check the log files and the checksum errors.  If you get more than 1 checksum error every 10 minutes then you are skirting danger.

Anyway - that doesn't answer your question.   The main thing is you have to change the machine settings to be in "reprap" mode.  And not "ultigcode" mode.  Ultigcode does not work through usb.  So once you change this the first thing you should notice is that now the bed and nozzle temperatures are set in Cura and *not* on the machine.  The machine will ignore your material temperature when you print through usb.   Let us know if you have trouble finding the machine settings in cura.

 

Very helpfull thank you

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