Firmware Update

I have just updated the firmware to have a "Purge 5mm" and "Retract 5mm" option in the "Prepare" menu just below Load and Unload. This should help when you have left the machine warm and it oozes. It will also help when loading and unloading. You can even use it to load and unload the filament manually by holding down the button.

The update also includes an addition to the "unload filament" option of the "Prepare" menu. It now purges 15mm of filament before unloading the filament to ensure it does not have an expanded section of filament to get caught in the bowden tube.

A previous update to the firmware allows you to move the axis into the negatives. This was to accommodate negative Z offsets in Slic3r. It has an unfortunate side effect of allowing you to crash the carriage into the XYends. This should not hurt anything but it can cause the cables to become slack in some cases.

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Thanks for these great updates, Sublime. Looks good.

A further inquiry...

I've noticed that due to thermal expansion, I always seem to get quite a lot of plastic oozing out in the time between when I do a preparatory extrude and when my head has reached temperature, the z-axis has homed, and the print begins.

I heard tell that there was some custom gcode that I could insert in Slic3r that would cause the printer to extrude a little bit right before the print begins. Do you know what that is? And would you recommend doing that?

As it is I keep setting my prints to do a 5 or 6 loop skirt, just to get the plastic back into the head before the actual print begins... not a very useful approach if you're doing a print that might be close to or at the size limits of the build platform.

Yonderboy Wrote:
-------------------------------------------------------
> A further inquiry...
>
> I've noticed that due to thermal expansion, I
> always seem to get quite a lot of plastic oozing
> out in the time between when I do a preparatory
> extrude and when my head has reached temperature,
> the z-axis has homed, and the print begins.
>
> I heard tell that there was some custom gcode that
> I could insert in Slic3r that would cause the
> printer to extrude a little bit right before the
> print begins. Do you know what that is? And
> would you recommend doing that?

You could enter something like "G1 E10 F900" to purge it 10mm's before printing. The problem with this is you have to be there with a pair of tweezers to remove the extruded plastic so it does not get into the print ad cause problems.

>
> As it is I keep setting my prints to do a 5 or 6
> loop skirt, just to get the plastic back into the
> head before the actual print begins... not a very
> useful approach if you're doing a print that might
> be close to or at the size limits of the build
> platform.

I personally feel this is the best option and does not need to be that high as long as the machine does not sit hot for very long. I have mine set to three and never have to purge unless I stop the print manually and let it sit hot. On larger prints having lots of skirts is good, you can actually set the skirt distance to 0 and you end up with a brim that stops curling.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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Sublime Wrote:
-------------------------------------------------------
> Yonderboy Wrote:
> --------------------------------------------------
> > As it is I keep setting my prints to do a 5 or
> 6
> > loop skirt, just to get the plastic back into
> the
> > head before the actual print begins... not a
> very
> > useful approach if you're doing a print that
> might
> > be close to or at the size limits of the build
> > platform.

I switch to a 6 skirt loop after changing filament, or if the hotend has been running for a while without printing. Most of my parts aren't close to the size limitation along both axes - though there are some that come close along one dimension. In that case, I rotate the part to give it enough clearance.

Edited 1 time(s). Last edit at 09/04/2012 07:55AM by Robots-Dreams.

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Lem Fugitt
3D Printing Dreams
Robots Dreams
"The map is not the territory."

I used to have to always babysit my Prusa when I used the stock Slic3r start/end gcode until I used RichRap's excellent Slic3r tutorial (in particular, part 2) which has some custom gcode that basically does this:

• heat the bed (not applicable on Tantillus)
• home X, home Y, home Z (in that order)
• heat hotend
• move to first position and start print

Start gcode:

G28                 ; home all axes
G92 E0  ;reset extruder
G1 E3 F1200 ;Prime extruder 3mm
G1 E2 F1200 ;retract extruder 1mm
G92 E0  ;reset extruder

Since adding this to my Slic3r I can literally just choose the file to print from the LCD and press go and walk away.

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[johnbiehler.com]

I just pushed a fix for a bug in the previous purge before Unload function recently added. Thanks to GeraldO for fixing this.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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