Can't print from SD card

So I am having trouble printing from an SD card. I can get to the point where it heats up both the nozzle and the bed but refuses to do anything else.

At first I thought it was the naming then I thought maybe it was due to the bed only getting to 84C when it’s set to 85C but if I wait long enough the display says 85C.

The bottom of the screen says Heating done but nothing else happens.

I have printed the same files using Repetier host from my machine but some of these prints are 8-15 hours long and I want to use the computer. I was just 4 hours into a 5 hour print and needed to print a label and when I had to unplug the USB on my label printer (it sometimes forgets it’s attached) my TAZ 4 went offline and ruined the print.

The file I am printing is a bit over 6MB in size, does that matter? If not why won’t it start?

SD printing on the TAZ does seem a bit problematic. I’ve had some success, but it’s touchy. It seems to work best when you warm things up in Pronterface, then use the Pronterface SD menu to select the print file. You can then monitor things for a bit before disconnecting the laptop and letting the TAZ continue on its own.

The printer waits until it reaches the exact temperature. And it can take even 20min or so
I also use pronterface to set the temperature, even if printing from SD
Then I just press Print in the sd card menu using the controller button on the LCD screed

There are two ways you can set a 3d printer nozzle and bed temperature. From the gcode file, or from the printer control interface. If you have tinkered with your slic3r profile and added the temperatures in there, say 230c for the nozzle and 85c for the bed for a Taz, then the printer will NOT print until it is at exactly 230.00 for the nozzle, and exactly 85.00 for the bed. Not 229.99 and 85.00, not 230.00 and 84.99, they have to both be spot on exact to start.

What happens is that you end up chasing the temperature range. The nozzle heats up and automatically starts to cool as it nears temperature. If the bed is not yet caught up and at that temperature, it can be difficult to keep the hot end at the exact temperature it needs to start. a .01 degree fluctuation is pretty much normal and expected. That coupled with the slowdown once the bed nears its target temperature can cause it to literally take 45 minutes after both temperatures are “near” their final reading before the printer will actually print.

My reccommendation would be to strip those temperatures out of your Slic3r profile entirely. You can try printing the existing lulzbot bed calibration gcode to see if that is the issue. if that print starts instantly when you hit the print button, then you know its that pesky temperature settings.