Partially Solved Filament "leaking" at start and end of print

First, let me say that this is in no way an urgent issue, just trying to learn the ins and outs still.

So every time I preheat before a print, and for a short bit after, the extruder will "leak" some filament out as though I had done a manual extrusion. I'm assuming this is due to the heat my hot end is set at, and have noticed as many have mentioned that it varies from roll to roll.

My issue is this. In an attempt to reduce stringing and get better first layers, I reduced the starting temperature of the hot end because my new roll was especially heat sensitive. As a result, when it got up to temp, the extruder motor wouldn't recognize that it had. It wouldn't turn while printing, wouldn't turn on a manual extrusion, nothing. I turned it myself to make sure it was working, and sure enough a nice clean line came out. As soon as I turned the starting heat back up though, the motor was fine.

Is this an issue with MatterControl itself? Is there effectively a "lower limit" that it won't print under? Or something else I'm probably not thinking of?

 

There is a lower limit built into the firmware, but I don't know what it is off hand.

 

Yes, i believe it is in the Firmware and has a limit set to prevent cold extrusions so the stepper motor wont run if it thinks its too cold.

Are you talking about how before the print starts and preheats the hotend it will ooze out the tip, mines does the same thing and gets a bit annoying during the bed leveling process as it strings all over the bed and leaves a blob in the middle of where the print is about to start. have yet to try to fix it tho

Wikid

 

That is precisely what I'm talking about, yes!

Hmm, well, that answers that then. Aside from getting it as low as I can without making it mad at me, do you have any advice for making better first layers? I'm having a problem with this filament due to how much comes out/possibly head height where I'm trying to print something with a bunch of circles and the "end" point will lift up or skew to one side.

I've lowered my initial speed to 20% (which was a bit too slow to be honest), lowered the temp as mentioned earlier, and keep fiddling with the z offset. Is it simply a problem of bed adhesion? Would something like the gluestick method solve it?

 

so is not enough coming out at the start of the first layer? or just trying to avoid waste. I was thinking of adding a line to the end G code to have it retract the filament before cooling down the head. That way when it starts the next time it wont have pressure on the already melted filament but just a theory. Im in the middle of switching slicers ATM

Wikid

 

The opposite, actually. It seems like possibly too much is coming out, so when it pulls away it drags it, or in the case of lines as opposed to circles "smushes" between them giving the bottom layer weird bubbles. They generally don't affect the overall print, but I am a stickler and want as close to a "perfect" first layer as I can have.

 

Can you throw up some pictures of the first layer?

does it drag part of the layer with it or just a stringer, whats the material and temps

extruder may need calibrated check this out


Wikid

 

Well, unfortunately I'm at work right now and can't look away for an 8 minute video but I thank you for the resource, I'll likely check it out later.

Also, for anybody interested, it seems the low end is 195c, which is still a bit high for this filament, so I suppose I'll just have to live with it for now. If that's set in the firmware, I imagine it's not a value that can be fiddled with, nor changed by using a different slicer as it's native to the printer itself, yes?

 

Yep 195 it is, just found it in the firmware and it can be adjusted. There may be a setting in your slicer set to prevent cold extrusions try turning that off if you find it. otherwise it can be adjusted if you feel it needs to be. Some slicers also have the ability to reduce the amount of extrusion for the first layer.

 

Was this in MatterControl? If so, where at? I can't quite seem to find it.

 

Looks like its not an actual check box in MatterControl. However if you go to the custom G code under printer, Add an M302, it allows cold extrudes.

 

Well that's handy. I imagine it'd go into the starting g-code, but still being somewhat unfamiliar with all of this, does it matter where or does it just need to be in there somewhere? Would putting it at the end be the safest bet? (not ending code, of course, the end of the box)

 

I would put it after your bed leveling if you have the latest Robo the (G29 is the autolevel)