Problems when i print overhangs

Hello,

Can someon tell me whats wrong here? What can be the cause?

I printed a lot of these extruders and never got problems but now i have this problem and don't know what the cause is.

Charlie

Looks like you are trying to print a hole in mid air. That is never going to be pretty because the outline has nothing to land on.

Normally for something like that there is a one layer membrane across the hole which is cut out later. Perhaps you have re-sliced it and it is now missing? To be exactly one layer in the model it has to be sliced with the correct height.

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[www.hydraraptor.blogspot.com]

I dont fully understand what you mean.

Can you show an example ?

Can you upload an stl? These extruders normally have a diaphragm that you drill out after to support the over hang. If this is missing then you will get what you see as bridging needs continuous threads to work properly. Saying that, I have got away with it in the past.

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Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

OK,

Here is the stl.

[www.dropbox.com]

Greeting

NO - that is the .gcode file and NOT the .stl file!

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

ow ok sorry :p

here is the right one [www.dropbox.com]

The .stl file appears to be O.K. (except for a support tab on one end that isn't needed).
I see you used Slic3r to generate the gcode.
Does it also have an option for generating bridge in the direction of the infill (or similar)?

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

No i dont think it has that. What do you use to generate gcodes?

The g-code looks to span the hole correctly. I think you need to watch what happens when it prints that layer. Perhaps the filament is snapping due to being stretched too much.

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[www.hydraraptor.blogspot.com]

I'm a bit of a n00b, but, i have just found out that if I set my skeinforge fill settings to "Loops>Fill>Perimeter" I get best results with overhangs/holes - although as this hole is infact being printed in 'mid air' it's possible that Fill>Loops>Perimeter would work better, as well as having "infill in direction of bridge" turned on - really not sure what the slicer equivalent is, but it's obviously going to be hard to print if the "hole" is printed first cos as nophead says, it's got NOTHING to stick to, so the "hole" would stay stuck to the hot end and deposited wherever the hot end ended up going to next!

If you've done these right in the past have a think, what settings have you changed?

Hello,

I cleaned my nozzle and now the problem is fixed. So i think for overhangs the nozzle was not perfectly clean so when it needed to feed a lot of ABS the nozle cauldn't provide it. So thx for all the help!

Charlie