# Build plate cools during print

I am using a Flashforge Creator Dual Extrusion 3D Printer with RepG (ReplicatorG), and tonight a print completely detached from the build plate.

I reset everything and watched it closely. It is a simple abs print at 230/110 degrees.

A few seconds after start of print, I noticed that the print bed temp had dropped to 109... and kept dropping.

This is new behavior. I haven't started to troubleshoot yet. I am looking for suggestions on how to troubleshoot the issue.

Edit 1:

Tonight RepG would not connect to the printer. I reseated the USB cord and now it does.

The test print is ABS at 230/110 from this open scad.

difference()
{
cylinder(d = 10, h = 2);
cylinder(d = 9,  h = 2);
}


Pᴀᴜʟsᴛᴇʀ2/Oscar Once the print starts the print bed begins cooling. It is cooling before any filament is laid down.

Edit 2:

Examination of the gcode shows the root cause. It does contain

M104 S230 T1 (set extruder temperature)


It does not contain a

M109 S110 (set build plate temperature)


When I manually add the M109 to the gcode file, the model prints normally, and the build plate temperature holds for the duration of the print.

The drop in temperature last week is due to the fact that I tend to preheat the printer before actually starting the print. Since there was no M109 the bed plate cooled to ambient temperature.

There isn't a hardware issue here. Most likely it is a Rep G configuration error of some sort.

Edit 3:

I resolved the issue by a fresh install of the latest Rep G. I rebuilt the profiles from scratch with G Code to set the correct bed temp. Thank you for your suggestions.

• Is the bed losing connection for the heating element once the bed starts moving? Jul 23 '18 at 1:18
• Is this happening while depositing the first layer, or after the first layer?
– 0scar
Jul 23 '18 at 6:02
– 0scar
Jul 24 '18 at 5:34
• I will be investigating it this weekend. There will be an edit after that. Jul 24 '18 at 15:09
– 0scar
Jul 30 '18 at 15:33

Check your slicer settings. Some slicers allow the temperature to change at a specified layer. You may have programmed the slic3r to turn off the bed after the first (or maybe zeroth) layer.

You call also examine the G-code for M140, M144, and M190 commands.

Of course, the usual intermittent electric connections, power supply failures, etc. should be checked, but don't overlook the possibility that it is working exactly as you are asking it to work.

• @EvilTeach That came to my mind also, hence the question for more information, we'll see after the update.
– 0scar
Jul 25 '18 at 6:32

Your bed is obviously capable of heating up, so I would double check your cable for any kinks, cuts, blow-outs, or general connection issues both where your machine rests during warm-up and Z0 where your machine begins printing.

Most likely there is a poor connector or kinked/cut wire for the build plate.

If that doesn't appear to be the issue, I might also suggest checking your power supply. I've heard of other similar machines' power supplies not being quite strong enough to support two extruders AND a heated bed.

Preheating the bed is a commonly used approach to shorten the time to print. I'll explain; it actually does not shorten the physical print time itself, but before you start a print there is always stuff to do like inserting the SD-card or loading the model in the print server, while you do that, the bed will be heating, so time gained.

When you load a model it apparently resets the temperatures, so preheating will only have an effect when you also actually set the bed temperature in the G-code file. This means that either your G-code file has some codes that influence the temperature, the connector is loose or loading a print over the program you use must reset the bed temperature, there aren't any other options.

To comment on your G-code, M109 is used to set the extruder temperature and wait till it is reached, M190 is used to set the bed temperature and wait till it is reached. Usually M190 is used to set the bed temperature before the first layer is being printed; the printer waits until the temperature is reached before the printer continues to the next command (usually the heating of the hotend). If you have selected a different temperature for the rest of the print you will find the M140 G-code command prior to printing the second layer.

I have tested on my Prusa i3 clone running a Marlin fork to print a model with all references to M190 and M140 removed. I pre-heated to 70 °C (for PETG) and loaded the model in OctoPrint print server and commenced the print. The printer retained the bed value and did not drop.

Basically, it is needed to take a closer look at your G-code file. The answer must be in there. If there is nothing to find in the G-code file and electronic connections are fine, the answer must be found in ReplicatorG, this might send reset signals prior to sending the print, but that sounds really strange.