Gap in print...

I've been going crazy trying to solve this with no luck, hopefully you guys can shed some light:

When printing a single-wall box I get a consistant break (about 3mm) after completing and starting a loop per layer. I tried turning on & off carve and fishing around with countless other parameters. I've tried running at various speeds, no matter how slow I still get the break (around 17mm - 40mm)

Do you guys know what may be the cause?:





What I'm running:
mendel
Gen6 with latest firmware (2011)
makergear plastruder kit, .35 nozzle
PLA 185f
Skeinforge 40
Repsnapper mac

Source file:
Link to the thingiverse file by spacexula

your nozzle is leaking during the z move.

are you using retract? try to retract faster/further
is your z speed highish? try highter
is your temperature as low as it can go and still reliably extruder? try lower.

Thanks Greg!
Currently retract is off (will experiment with it next...)

So far I:
•Lowered temp to 175 (you were right, my temp was too high resulting in leaking (not oozing))
•Increased travel speed from 40 to 50mm/s in an attempt to speed up z axis travel.
•Increased the feed rate
Result:
•gap is smaller but still enlarges gradually as print layers progress
there was improvement but the z travel does seem a bit too slow accompanied by a small pause

How do you control the z speed? Is this done with travel rate, another SF setting or in the firmware?

Quote
Adrian
How do you control the z speed? Is this done with travel rate, another SF setting or in the firmware?

It depends slightly on the firmware you are using. Most need to be adjusted in the firmware but some use the limit feature in skeinforge to set it.

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Could it be a too high value for clip? Try turning it off and see.

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Do you have cool enabled? If I were to print that object, it would be really slow because cool would makle it be a min of 30 seconds per layer... if you tell it to wait after each layer it will sit there and possibly ooze. when it restarts it may delay extracting again.

I use limit for my z speed, currently set at 16.

My initial though when seeing this was also the Dimension plugin. You could play with it by having the restart be slightly higher than the retract etc.

On e more thing to look at would be the temp at the time of the gap. It may be dipping below a threshol and taking a second to build up enough heat and pressure. I was having problem with this on some older firmware that did a 100% on or off for the heater instead of setting some mid ranges to maintain temp close to setting.