IdeaMaker - Change in startup Gcode?

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IdeaMaker - Change in startup Gcode?

Postby shiftyjonno » Fri Apr 14, 2017 1:42 pm

Newbie here with an N2+:

I noticed that when I upgraded Ideamaker to the latest version that when I start a print the starting sequence is a little different.

On the previous version 2.5.0 before printing the extruder would home in on X0 / Y0, then home in on Z0 but would raise about 10mm just before the purge extrusion. Then the extruder would go to the start position of the print and then lower Z to the start layer height and start printing.

On version after homing to X0 / Y0 then Z0 it no longer gives the extra 10mm before the purge extrusion. The purge extrusion commences and then goes straight to the print start position and starts printing at the layer height ...

This change in start up sequence came awfully close to the bed clips and would be possible to catch the extruder tip and cause some serious damage.
In a case where the heated bed may have warped or raised slightly, it would also be possible to hit the bed and cause damage.

My question is how can I revert back to the start up sequence that gave the extra 10mm or so before the purge extrusion / start print? ...
I haven't made any changes to the start Gcode since upgrading to the latest version, so I'm assming that something in Ideamaker has changed.
Can I assume that I can make a change to the start Gcode to add this feature? If so, how and what?

If there were ever any issues with extruder tip to bed heights, I'd prefer that it was immediately before printing rather than before the extruder moves over the bed and clips.

I am very new to 3d printing (this is my first 3d printer), so I'm still learning the basics ... If it is something so stupid basic that I'm missing, please feel free to not answer.

Kind regards

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Re: IdeaMaker - Change in startup Gcode?

Postby Jetguy » Fri Apr 14, 2017 3:12 pm

Starting gcode is the gcode appended to every print to do exactly what you expect, setup the machine from an unknown state to a known controlled state before the actual object print gcode starts.

So yes, editing the starting gcode will affect what it does exactly at the start of the print.
Being dead honest, you should strive to understand gcode in the longer term of owning a 3D printing because gcode is everything to a print.
Gcode is actually pretty simple.
It starts with a G or M and then the command number.
The next are the axis that command applies to XYZ or E for extruder
The next thing is values for an axis are distance in mm (the number next to XYZ, or E
F values are Feedrate, basically the desired speed and also kind of like a speed limit sign for that move.

The KEY to reading gcode is the understanding of sequence and state.
The first line or previous line if reading from the middle is "where you are"
The line you are reading is "where you are going- AKA target position or command"

Another KEY point to understand gcode is relative VS absolute.
If you are in absolute position mode, then moving G0 X100, will move to position X100mm (assuming you homed first)
In relative positioning mode, the X100 is +100mm from where you are currently.
Again, understand the difference. If you send G0 X100 and are at X50 in the current state, it will move 50mm to position X100.
If you were at X200 and sent again G0 X100, it moves back from 200 to 100 in X.
If you change modes prior to sending the command from absolute positioning to relative positioning, then the value is where ever you are + or - the value.

Here is the exact code from the previous version since I have not updated. Comments are in Red
G21 Set units to Millimeters
G90 Set to Absolute positioning
M82 Set the extruder to Absolute positioning (filament pushing into or retracting in the extruder, not the nozzle position)
M107 Turns the gcode controlled fan port on the breakout off (only single extruder printers come with a print cooling fan plugged into this)
G28 X0 Y0 Home X and Y only, and once homed you are now at logical position 0
G28 Z0 Home Z only, and once homed you are now at logical position 0
G1 Z15.0 F{travel_speed} Move the Z axis away from the nozzle to distance 15mm absolute. Since Z axis homed is bed near the nozzle + is away from the nozzle or moving he bed down.
G92 E0 This resets the logical position of E for the extruder to distance 0 (I call G92 the "I am here at position XYZE command")
G1 F140 E29 Extrude 29mm filament from the extruder (purge or prime)
G1 X20 Y0 F140 E30 Move and extrude 1mm more (previous absolute 29mm, now to target of 30mm) of filament while moving to X20 at a speed of F140
G92 E0 Reset the extrusion "I am here" to 0 to both have the extruder purged and be ready for the first segment of actual print gcode E length that assumes a starting point of 0. Failure to have this would mean a short value of say E5 for the first segment, the extruder would reverse trying to get back to logical E5 if it thought it was still at E30
G1 F{travel_speed} travel move
M117 Printing... This would display a message on the LCD if it was attached to the motion control board.

All you need to do is add the line
G1 Z15.0 F{travel_speed}
Right after the G28 Z0 line in your starting gcode.

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Re: IdeaMaker - Change in startup Gcode?

Postby walshlg » Fri Apr 14, 2017 3:59 pm

nice lesson Vernon, hope you don't mind but I may repeat this down the road at the makelab

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Re: IdeaMaker - Change in startup Gcode?

Postby shiftyjonno » Sat Apr 22, 2017 12:31 pm

Thank you very much for your fantastic help Jetguy. This is the exact info I was looking for, and your answer gives me the exact help I need to help myself now and in the future ... (give a man a fish / teach a man how to fish)

The problem seems to be still there, so I'm going to delve into this gcode further ... it's intriguing stuff.

Thanks again.

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