Printing in microns - how to overcome cura limitations?

[jemma-redmond 0]

Hey all,

So I want to print a grid for calibration... so what I am trying to do is print one layer at 1mm and create a spacing of 1mm between the lines however cura won't let you do this, you have to print with at least 2mm height.

Is there any way to fine tune cura to allow one to print grids like this? ultimately I want to move from say 1mm spacing to 0.5mm spacing down as low as I can go.

Is it possible to do this with cura? or is there other software I can use? Thanks!

[nallath 1,124]

Might be that I understand you wrong; but I've been able to print objects that were 0.3 mm high.

 

[anon4321 16]

I agree, can you explain what you want to do differently? Maybe sketch it out in an image and post here?

I've had no problem printing down to .3mm and lower but you would need to change the first layer height.

Also you can always drop down to gcode to do things Cura won't let you.

 

[gr5 2,271]

When she says "high" I think she is talking about Y axis.

If you want to print very thin lines you can do this by lowering the "shell" thickness. I have been printing a lot of text recently and I did a lot of experiments and you can tell cura to use a shell of .3mm or .2mm and it will print much thinner. You might also need to increase the flow a little bit. You will need very good first layer leveling and I recommend the finest adjustment to be done only by turning leveling screws and not to touch the bed leveling procedure.

 

 

 

[jemma-redmond 0]

gr5, you got it! that's what we have been trying to do.... however we have been designing grids on autocad and then loading it into cura, (any version)... what we want to do really is get teh machine to draw one line (xy) but it seems to sweep back over the same line no matter what we do.

We are printing biogoop, not plastic and when it prints a layer on top, it tends to spread out, not build up, unless you give it time. Anyway what we really want is one line, one sweep, no redrawing the lines. Is that doable?

 

[anon4321 16]

Still not sure what you are trying to do. However, if you have a model with a thin "object" on it, Cura might be trying to do a shell.

BY default, the shell thickness is .8mm or two nozzle widths so Cura will make two passes. If you make your object .41mm wide and set the shell thickness to .4, Cura might do it in one pass.

Note that when I did some stiff that was exactly .4mm wide, Cura (or rather the slicer) removed it so you might need to do something like .41 or .4001.

 

[anon4321 16]

Oh wait, if you are getting a single width line but the printer is printing on top of it again then (not next to it as I previously thought) --

Make sure the top/bottom thickness is the same as your layer thickness and then go into the Advance tab and set the first layer thickness to your layer thickness.

 

[Daid 306]

BY default, the shell thickness is .8mm or two nozzle widths so Cura will make two passes. If you make your object .41mm wide and set the shell thickness to .4, Cura might do it in one pass.

 

Cura always does two passes. Always.

 

[anon4321 16]

If you really want fine grain control, you can hand build the gcode to do what you want.

The primary gcode is:

G1 X<xpos> Y<ypos> Z<zpos> E<epos> F<feedrate>

where <xpos>, <ypos>, <zpos> and <epos> are the X, Y, Z and extruder coordinates and <feedrate> is the mm per minute.

So if you home the printer, you are a (0,0,0). If you wanted to draw a line to the opposite corner, you would do something like this sequence below (partially taking from the start code in the Start/End-GCode tab in Cura). However, first you need to figure out the extrusion amount.

If we go to close to the opposite corner to 200,200 then this will create a line that is 282.84mm long. The line will be .4mm wide and however high you make the layer but let's say .2mm. That means that 22.627mm3 of material will be needed. If you are using 2.85mm filament (not really sure what you are doing but let's start there), the area of the filament is 6.3794. So we divide the volume of material we need by the area of the filament and it will give us the length of filament to extrude or in this case, 3.5469mm

Note that for speed, Cura uses mm/s whereas gcode specifies it in mm/min.

; Draw a line from the home position (0,0) to the opposite corner (200, 200)

; at a height of 0.2mm and at the width of the nozzle (0.4mm) at a speed of

; 40mm/s

G21 ;metric values

G90 ;absolute positioning

M82 ;set extruder to absolute mode

M107 ;start with the fan off

M190 S70 ;bed temperature

M109 S210 ;temperature line

G92 E0 ;zero the extruded length

G1 Z0 X0 Y0 F9000 ; (0, 0, 0)

G1 Z0.2 F9000 ;move the platform down .2mm to (0, 0, 0.2) for a 0.2mm high line at the default speed.of 150mm/s

G1 Z0.2 X200 Y200 E3.5469 F2400 ; move to (200, 200, 0.2) making a line that is 282.84 mm long at 40mm/s

 

Place the above in a file with a .gcode extension and load with Cura. Set the temperature you desire and home the printer. The press print.

 

[anon4321 16]

Based on Daid's response, you will need to hand build the gcode or modify the gcode Cura generates by saving it.

 

[gr5 2,271]

If you print a "wall" cura will print "both sides" of the wall. One pass in one direction, a second pass in the other direction. Always. The only way to get only one pass would be to write your own gcode. You can do it with excel spreadsheets and some text editing commands (substitute/replace). I recommend this over trying to get Cura to do this very specialized function.

I recommend also you get repetier host and send your ultimaker some gcodes manually to get a feel for how AMAZINGLY SIMPLE this printer is to control. G0 and G1 do the same thing on Ultimakers - they "go".

pronterface is here:

http://koti.kapsi.fi/~kliment/printrun/

 

It's free and very easy to use. It connects to your printer through USB. You can send one command at a time like G0 X5 and it will move only X axis to position 5mm. More details in anon's post above.

Or google "marlin gcodes".

 

[anon4321 16]

To add to GR5's info, the current versions of Cura has a Pronterface like printer interface that you can use to issue gcodes piecemeal to the printer.

Select in File->Preferences.