SF layer boundry cut off + or -

Hi SFers,

If a z axis cubical extrusion has a height of 10mm and layer height is set to 0.3mm and a cylinder extrudes up from the top surface of the cube.... & 10·/.3 means that the first layer of the cylindrical extrusion starts - below or above the 10mm cube top surface¿??
& i had another q but its gone now
oh yeah what would be the end gcode for : on finish move up in the Z axis by 1 layer (or #mm) and then go home?¿

woohoo

I'm afraid I don't understand what you are asking in your first question.

As answer to your second question, my end.gcode looks as follows:

G91                ;set relative positioning
G1 F50             ;set move speed to suit Z-axes
G1 Z5 F50          ;move up 5mm from the finished object
G90                ;set absolute positioning
G1 F2300           ;set move speed to suit XY-axes
G1 X100 Y200 F2300 ;move table out to remove object

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

thnks for the end gcode, I'll give it a go.

as for the 1st question, I thought it would be a bit unclear,
if layer height is .3mm and an cube object height is 1mm .... when it wants to do the next layer to start the cylinder ...
it can only start at a Z height of 0.9 or 1.2mm.

It can't actually do 1mm if you tell it to go up in .3 steps. no¿
so would SF start building the cylinder from the 3rd layer (0.9) or at 4th (1.2)

How would this affect overall build height, would tall objects end up actually being taller/shorter?


mmmmm

Yes, of course, with quantization of 0.3 mm a 1mm object would either be 3 or 4 layers (which means it would be either .1mm too short or .2mm too tall depending on how it is implemented). Based on what I have seen so far it looks like Skeinforge truncates, in other words it will always be shorter but never taller.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I was under the impression that skeinforge took slices from the middle of the layer - i.e. the first slice is actually taken from 1/2 the layer height above the bottom of the object.

If so, it would always be within 1/2 the layer height of correct, but seldom exactly correct.

I was unable to verify that with a quick code dive though.

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I'm building it with Baling Wire

I'm afraid I have not looked at the code - maybe Enrique will provide your answer.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

ok thanks for your thoughts
cheers

I am sure it samples in the middle of each layer, so for 1mm it would be 0.15, 0.45 0.75 giving 0.9mm of cube and the next sample at 1.05 would be the start of the cyclinder. Each layer should be extruded with the nozzle 0.15 higher of course so the first layer of the cylinder is from 0.9 to 1.2.

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[www.hydraraptor.blogspot.com]

also thanks for the end code - works great!