# Cura with Pronterface UI stops printing

When I use Cura with the Pronterface UI it sometime just stops printing.

When it stops the printer just stops, the UI looks like it's still printing but nothing is moving in the printer, also, trying to control the printer from the UI does nothing.

It always stops early in the printing process, usually during the auto-leveling process or while printing the skirt, the latest it happened was during the first solid layer of a raft.

Usually closing the printing window and re-opening it solves the problem but not always, this never happened to me with the basic UI, I couldn't find any settings that makes the problem better or worse, it just happens randomly.

Anyone knows how to stop that from happening?

My printer is a Robo 3D R1+

Update

After installing a screen on my printer I discovered Pronterface is sending a "Wait for user" G Code to the printer.

Because this changes the question too much and invalidates the existing answer I've asked a new question at What makes Pronterface wait for user?

• Have you tried to printing from a different source, such as a SD card? If this works well, it is probably not the printer itself that is the problem. Does the screen go blank for a moment before it happens? If it does, it could be that the arduino receives a "connect" command from some other process, and cuts it current action. Could it be any of these, you think? – Tormod Haugene Jan 20 '16 at 21:30
• @TormodHaugene the problem happens only with cura and the pronterface ui, both SD card and cura with the basic ui don't have this problem. I really don't know if the problem is in the printer or the software – Nir Jan 21 '16 at 9:20
• So if you leave Pronterface out of it all, everything works just fine? Then I would reconsider using Pronterface for direct printing altogether. In my opinion, needing to have a computer always connected is sort of unnecessary. Are there any particular reason why you want to print directly from Pronterface? – Tormod Haugene Jan 21 '16 at 21:44
• @TormodHaugene my printer does not have a screen, so if I want any manual control what so ever I don't really have a choice (a screen is currently on its way from China, but it takes a while to arrive) – Nir Jan 22 '16 at 6:57
• Oh, I see. That makes it a bit more complicated! – Tormod Haugene Jan 22 '16 at 8:03

A problem I have come across when using Pronterface is that the operating system starves the resources of the program if the program's window is not in the front.

If I, for instance, started a print, then started browsing the web, it would sometimes suddenly stop. When bringing Pronterface back to the front, it would take a few seconds, and then continue (if I remember correctly).

On OS X - which I am using - I believe this is called app nap, while a similar mechanism exist for Windows. I ended up printing form an SD card myself after this, but you might want to try manually setting the resource priority for Pronterface in your OS.

In Windows, you could trying to increase the resource allocation for Pronterface by going to Task Manager -> Details -> Right click the Pronterface process -> Set Priority. I would be careful to set it too high, since you are basically allowing the program more juice to potentially do something wrong.

In OS X you could try to disable app nap for Pronterface.

• That's not it, just happened to me while the Pronterface window was the active foreground window – Nir Jan 20 '16 at 20:19

After installing a screen on my printer I discovered Pronterface is sending a "Wait for user" G Code to the printer.

Because this changes the question too much and invalidates the existing answer I've asked a new question at What makes Pronterface wait for user?