Need Printing Advice

Hi All,
Running Sprinter, Prontaface, Hotend-230C, Bed-110C.

Small parts come out faily decent, taller ones have all these filament bridges in them. How do you recommend I start making changes?
Thanks

It looks like you might be trying to extrude filament that is too thick for your nozzle. In that case instead of it beings stretched slightly you are trying to compress it and it squirms around.

If you extrude some filament into free air and measure it that is the maximum diameter you can use. The cross sectional area of your filament paths (W & T) must be less than pi R^2.

What nozzle are you using and what layer height and width?

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[www.hydraraptor.blogspot.com]

Hi nophead,
I'm running 3mm ABS. My free air filement dia is .46-.47mm dia. out of a .50mm budaschnozzle hot end nozzle ( is that possible?). Pronterface's Settings/SFACT Quick Settings/ Carve is set to .4mm height and .6mm width. The SFACT profile is for PLA. It has no profile for ABS.

Yes that is the problem, your filament is coming out too small for 0.4mm layers. You are trying to fill an area 0.4mm x 0.6mm = 0.2mm^2 with circular filament that is only pi * 0.23^2 = 0.17mm. The only way that can happen is for the filament to be compressed lengthwise. That works to some extent on solid layers as there is nowhere else for it to go, but on sparse layers it squirms about and on bridges is will hang low.

It is very odd you are getting filament smaller than the nozzle, normally ABS swells significantly. With a 0.5mm nozzle I get filament more than 0.6mm, so I can make objects with 0.4mm layers. I suspect you have a 0.35mm nozzle or it is blocked by burnt plastic or perhaps a burr.

You need to have the filament stretched a little for good results, so I would suggest you try 0.35mm layers and 0.525mm width.

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[www.hydraraptor.blogspot.com]

Hi nophead,

Thanks for your response. You were right on with your advice. I used your numbers in the left printing and I went with h/w od .35/.55 with the right printing. I also played with lowerering the bed temp from 110C to 80 C after a few layers were printed. Once the printing of the land in the bearing started, the filament sagged a little so I lowered the head temp from 250C to 220C. Might have had some improvement but minimal at best. Any other suggestions? Thanks again.

> Any other suggestions?
You need sort out the reversal parameters as there shouldn't be any strings.

Edited 1 time(s). Last edit at 12/19/2011 11:31AM by nophead.

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[www.hydraraptor.blogspot.com]