Makerbot Replicator 2X Extruder Heating Issues

[jonwienke 0]

I recently acquired a Makerbot Replicator 2X for cheap, and have been getting it set up to work in Cura. I've gotten it working, but there are two annoying issues:

 

At the beginning of printing, Cura adds some code to heat the extruders before the start gcode, but it's done in the stupidest way possible. It starts heating the right extruder to the standby temp, waits for it to heat fully, then starts heating the left extruder and forces a second wait until it also hits the standby temp. Then it runs the start gcode where the bed is heated and the extruders are heated the rest of the way. This adds several minutes delay to the print job because they are heated sequentially instead of simultaneously. How can I prevent the highlighted commands Cura adds before the start gcode from being inserted? I want the bed to heat first, then both extruders to heat simultaneously once the bed is up to temp. I can't just edit the gcode file because Makerbot uses the x3g file format which isn't editable, I need to stop Cura from putting them in in the first place. How?

 

;FLAVOR:Makerbot
;TIME:6785
;MINX:-46.615
;MINY:-53.263
;MINZ:0.3
;MAXX:116.614
;MAXY:41.084
;MAXZ:17
;TARGET_MACHINE.NAME:Unknown
;Generated with Cura_SteamEngine 5.7.2
T1
M104 S240
M104 T0 S230
M116
M104 S240
M116
M82 ;absolute extrusion mode
;
; begin start gcode
;M136; enable build
M73 P0; build progress 0%
G21 (set units to mm)
M92 X88.8 Y88.8 Z400 A75 B75; sets steps per mm for Replicator 2X
G162 X Y F2000; home XY axes maximum
G90; set positioning to absolute
G161 Z F900; home Z axis minimum
G92 X0 Y0 Z-5 A0 B0; set Z to -5
G1 Z0.0 F900; move Z to '0'
G161 Z F100; home Z axis minimum
M132 X Y Z A B; Recall stored home offsets for XYZAB axis
G92 X152 Y72 Z0 A-15 B-15; reset positions
G1 X-112 Y-73 Z150 F3300.0; move to waiting position
G130 X20 Y20 A20 B20; Lower stepper Vrefs while heating
M109 S110 T0; Heat bed to startup temp
M134 T0; wait for bed to heat
M104 S240 T0; Heat extruder 0
M104 S240 T1; Heat extruder 1
M133 T0; Wait for extruder 0 to heat
M133 T1; Wait for extruder 1 to heat

 

The second issue is easier (I think). Cura starts heating the idle extruder from standby temp to print temp shortly before switching. How can I increase that time interval so that the idle extruder reaches print temp just before the switch, instead of having to wait 10-15 seconds to finish heating each time it switches extruders?

[Slashee_the_Cow 409]

The added temperature instructions are a known bug in Cura 5.7.2. You can either try using the 5.8 beta or I wrote a post-processing script that will automatically delete them. So that's almost certainly the easier issue 🙂

 

I'm not an expert on dual extruder printers (I'd really like to have one though 🥲) I've had a look through all the settings and can't find anything that seems like what you want. It's probably just being Cura being conservative to prevent the extruder that's being switched to from drooling while it's waiting at printing temperature, plus having a hot end with no filament in it stay hot for a while is bad (although so is having a hot end with filament in it stay hot).

[jonwienke 0]

Unfortunately that's not an option. The Makerbot uses .x3g files instead of .gcode, so if I save the file in the format the script can use, the printer can't use it and vice versa. I guess I'll just have to wait for the bug to be fixed.

 

It would be really nice if there was a heating time parameter you could set so the hotend gets to run temp a second or two before it needs to start extruding. That wouldn't cause drooling or filament burn, but wouldn't waste time, either.

[Slashee_the_Cow 409]

Avoiding the bug is easy enough, either use the 5.8 beta or a slightly older version (like 5.7.1 or 5.7). It only affects 5.7.2. Given the code you posted above looks very close to regular Marlin, I don't actually know whether Cura will still run a post-processor on it even if you're not saving in a .gcode file extension - personally I wouldn't bother testing that theory, the 5.8 beta seems pretty stable so I'd use that 🙂

 

15 minutes ago, jonwienke said:

It would be really nice if there was a heating time parameter you could set so the hotend gets to run temp a second or two before it needs to start extruding. That wouldn't cause drooling or filament burn, but wouldn't waste time, either.

You can submit a feature request for that if you'd like. Due to the number of factors involved - especially the printer - it's very hard to try and calculate accurately (which is why Cura doesn't even try) but it's possible it could work with it if the user supplies a value.

[jonwienke 0]

7 hours ago, Slashee_the_Cow said:

but it's possible it could work with it if the user supplies a value.

That's all I want. It's simple enough to time how long it takes for the hotend to go from temperature X to temperature Y and add ~5 seconds. All Cura needs to do is use that value to work out how far back in the gcode to insert the preheat command.