New to 3D printing, makerfarm 10"

[printbus]

...Option #1 sounds like it would require that I reprogram something, presumably the main board on my printer, which is something I've never done... Is that something that can be done via USB, and what software/interface do I need to learn how to use? I couldn't find an option in the printer itself to adjust that, but is there a way to add that setting?

You are correct. This would involve replacing the firmware programmed into the flash memory on the processor on your electronics board. It's not necessarily a hard thing to do, but it can be a bit scary or daunting the first time through it. The printers from MakerFarm run Marlin firmware, which is compiled in the Arduino development environment. There should be a section in your printer build guide that walks you through the basics of downloading the source code, obtaining the Arduino environment, building (compiling) the Arduino "sketch", and uploading the result to the printer via USB. You'd edit the referenced line in the configuration.h file to whatever threshold you wanted.

Technically, yes you should be able to add an LCD menu entry for setting the extrusion mintemp, but that would involve having to update the firmware as well. I'd want to leave the details on doing that to someone else - I don't have an Arduino/Marlin configuration to test with.

EDIT: I see the current build guides provide a link to a separate document that now provides the firmware info.

[hernejj]

Both of those options are a bit beyond my ability at the moment, as I'm not sure how to do either of them. Not that I don't understand.

Option #1 sounds like it would require that I reprogram something, presumably the main board on my printer, which is something I've never done. ..., and what software/interface do I need to learn how to use? I couldn't find an option in the printer itself to adjust that, but is there a way to add that setting?

I would like to retain the min temp for extrusion, as I do leave the printer running overnight. Doesn't sound like there's a way to do that with the gcode.

To flash the firmware, you'll need to do the following:
1. Install the Arduino software which allows you to compile/upload firmware to your controller board. http://arduino.cc/en/Main/Software
2. Obtain a copy of the Marlin firmware. Preferably whatever version you are already running. If you have not flashed it yourself then your Makerfarm build guide should have the link to download your exact firmware.
3. Make the firmware code modification that Printbus suggested above.
4. Use the software you downloaded in step #1 to compile and upload the new firmware.

There are youtube videos that explain this stuff in far greater detail, if you wish.

As for the M302 suggestion:
Every software I've ever used to slice and print something has some way to manually execute Gcode. Find that mechanism in your software and issue the M302 command to the printer. This should cause it to attempt extruding at any temperature. BE WARNED: If you accidentally attempt to extrude when the filament is not melty you can ruin gears/belts/motors/etc. Thankfully, even if you execute M302 you can reset the printers state by simply powering the printer off and on again.

[printbus]

MattStrike - what electronics/display do you have? RAMPS vs RUMBA, and standard LCD vs graphical LCD? Bad weather here left some spare time on my hands and I started pondering the software changes related to the cold extrusion limit.

EDIT: Actually, it looks like the question is moot. Pursuing the firmware change revealed some interesting wrinkles. I'll post an update later today or tomorrow.

[MattStrike]

I've got the RAMPS with a standard LCD. For the moment, I've changed the EXTRUDE_MINTEMP value to work with the wax.

[printbus]

I've got the RAMPS with a standard LCD. For the moment, I've changed the EXTRUDE_MINTEMP value to work with the wax.

OK. If changing the EXTRUDE_MINTEMP doesn't cut it, there are some options. The rest of the post goes into the gory detail on what I learned. Any readers running the dacb Marlin fork from late 2014 should take note - you already have a gcode means to change the extrusion minimum temperature threshold. That's not documented in the reprap gcode Wiki, so finding that was a bit of a surprise.

Marlin has a pretty slick means of building the LCD menus. It's really easy to change the order of menu items or to add new rows to menus. IIRC, menu rows are essentially a single row of code that specifies fundamentals like the menu text, the variable name to be adjusted, and the adjustment step size. Yesterday before posting that a menu change should be possible, I glanced at the Marlin baseline I had last used a year ago and verified that the EXTRUDE_MINTEMP constant is in fact copied into a variable, which it was. FWIW, the variable name is extruder_min_temp, and the initialization occurred in file planner.cpp. So, I figured it should only take that one line of code to add the menu item to tweak it.

Today, to test the change (before I had actually made it), I hacked together a 12V power supply, my old MEGA2560 & RAMPS, LCD, a thermistor, and a stepper motor connected to the extruder stepper driver. Downloaded Arduino 1.0.6 specified by MakerFarm. Then I went to the firmware download link provided by MakerFarm to revise the code. No extruder_min_temp variable in the code. The threshold check just uses the EXTRUDE_MINTEMP constant directly. Huh?

MakerFarm has never been assertive as far as updating their baselines. When I shelved Arduino/RAMPS over a year ago, I was using the late-2014 baseline dacb had put together and documented in thread Marlin firmware fork for MakerFarm i3v w/ auto bed level & Roxy's enhancements. Turns out that the "current" MakerFarm baselines are from before that.

So why does this matter to the extruder minimum temp threshold? Here's the good part for those running the dacb fork. Somewhere between early 2014 for the MakerFarm firmware baselines and the later Marlin fork dacb provided, the M302 cold extrusion gcode command support was expanded to include the ability to set the minimum threshold temperature by adding a parameter prefaced with S. For example, sending the printer M302 S100 sets the extruder minimum temperature threshold to 100 degrees C. Maybe this is one of the Roxy enhancements - IDK.

I did go ahead and test my printer hack-up and verified the S parameter on M302 works.

Various options are on the table at this point. MattStrike could just keep changing the EXTRUDE_MINTEMP constant when he wants to run the low temp waxy filament. He could migrate to the dacb fork and pick up the ability to tweak the setting via gcode. He could wait for a bit and see what happens with the upcoming new Marlin release, and determine whether the M302 parameter support is in that new baseline. Another option would be to modify his current (albeit dated) Marlin baseline to replicate the gcode support for the M302 S parameter. The current usage of extrude_min_temp is private to planner.cpp, and that may have some ramifications to adding a LCD adjustment for it.

Now y'all know more than you probably wanted to.