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Overhang Issues

Posted by ayouden 
Overhang Issues
December 30, 2013 07:11AM
Hey,

I have printed out this test piece: [www.thingiverse.com]

but I can't get it to stop having lifted edges up at the tips of the point. even on the most shallow of overhangs it raises up.

I have a fan attached and I am doing the outermost layer at 50% (15mm/s) of my normal perimeter speed (30mm/s).

Does anyone have any hints or tips on how to fix this?

Thanks! ayouden


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Attachments:
open | download - IMAG0222.jpg (520.8 KB)
open | download - IMAG0221.jpg (567.8 KB)
Re: Overhang Issues
December 30, 2013 07:41AM
Hi,..

looking at the general quality of your prints, I'd say it looks like your belts aren't tight ? and you may be printing too hot/and/or extruding too much plastic.

That's going to be a hard piece to print without your extruder and temperature dialled in I'd say.

What are you printing in, is that ABS? I can print stuff like this is in PLA, each extruder is different, but I print at 186 degrees, what are you printing at ?

tighten your belts
check your temp
calibrate your extruder
be fanatical about your first layer Z height
Re: Overhang Issues
December 30, 2013 07:51AM
My extruder is set to 180*C and my belts are tight.

My extruder, may be a bit too much, but we are talking 5%-10% either way.

Why does the first layer have to be perfect?

and thanks.


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Re: Overhang Issues
December 30, 2013 08:10AM
5-10% is a lot.

You are saying for every 100mm of filament, you extrude an extra 5mm to 10mm. That's a lot of extra plastic around.

I have noticed if my first layer is out, then my subsequent layers are affected, this seems logically to me, as my extruder moves up 1 layer after printing the first layer, and it expects there to be room for the next layer after the previous layer.

So your head is too tight to the bed, it extrudes plastic that won't fit in the gap, when layer 2 is printed, the top of layer 1 isn't quite at the height it should be. Layer 2 goes wrong, if layer 2 is also over extruded, well... you get the idea.

I'd calibrate and go again.
Re: Overhang Issues
December 30, 2013 08:53AM
Yea, that is a very fair comment about 10% being large!

My extruder seems to be "overflowing" with plastic which is very odd (see image). So again, what you are saying with it being high makes sense.

Thanks

Edited 1 time(s). Last edit at 12/30/2013 08:56AM by ayouden.


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Attachments:
open | download - IMAG0224.jpg (474 KB)
Re: Overhang Issues
December 30, 2013 11:30AM
I have configured my steps per mm and it still looked as if it was "overflowing" so I altered the extrusion multiplier.

Again, This hasn't worked and the edges rise up. I never had this issue before, so I am not sure what has caused it...

any ideas?

thanks


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Re: Overhang Issues
December 30, 2013 12:53PM
I don't know if this would be the cause of the rising up of the overhang, but It is now clear that I have a filament leak from the hot end!!!

I have no idea how I will fix this, But i am sure i will find a way!


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