DIY build from scratch .. bleeds plastic from WAY above the print bed

everything seems normal till I try to print a test cube.

repetier host connects .. manual controls allow homing all axis .. home all button or G28 all repeat and end with Z axis parked 2cm above the bed

load cube in slicer and slice it .. can view it and move it and center it etc. and it LOOKS like it is sitting on the bed.

when I tried to print it .. I turned on the fan and heater manually .. when up to temp I manually extrude 1mm to see plastic at nozzle

when I click print .. machine does G28 again ...... THEN moves the bed down (away from the nozzle) another 13cm (total 15cm) and starts Buzzing (attempting to move to .3mm for first layer I think cause that is what is in the box for Z height) and plastic starts extruding while x and y move like it is depositing the first layer (what is displayed on the screen is the perimeter being printed.

I can't find any explination for this

Any ideas?

dmac257

figured it out ... sort of ... slicer placed code like :

G1 Z15 F100


which moved the z axis to 15 ... but centimeters???? where is the default units defined???

later the gcode from slicer says

G0 F9000 X221.399 Y218.399 Z0.300

if the F9000 is the movement rate I think, that is the equivalent to "ludicrous speed" for the Z axis, so I am not surprised
that the stepper just buzzes horribly ... just don't know how to fix that other than editing the gcode file

all movement only (non extruder) are G0 F9000 so I could edit fairly easily but what is good number?

am I right that all movement after F9000 will be that fast for all axis unless changed in the line of gcode?

any thoughts on what would be sane numbers?

what slicer are you using ?

Your firmware shouldn't let the z axis move that fast, unless it's configured very optimistically. As for the default units, it's typically mm. And from what I'm aware, that F9000 only applies to that line of Gcode.

You say the stepper starts buzzing, has it hit the limit of it's travel (i.e. the end of the lead screw)?