1 Topic by Photog

  • Photog
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Topic: first layer burns when first extruding (discoloration) and other

I finally revamped all my settings to stop the lifting/warping problems I was having. I did this by resetting all slic3r settings to default instead of using the SD3 profiles that came with R-H. I also changed the first layer width to 200% as per Slic3r documentation to reduce lifting, lowered printing speed of first layer to also help adhesion to the bed, and slowed outside walls printing speed to give the print a nicer outside finish. To compensate for slower speeds I upped the infill printing speed from slic3r default of 60 up to 75.

I also am now using bed temp of 105 and extruder temp of 203 (as set in R-H), because I read a post on the forums saying those were the magic numbers for temp with ABS. I was using the default SD temps of 195/95 before.

Well now, after those changes, I'm getting a weird problem. On the first layer, for about the first 100mm or so, the light orange ABS I'm using comes out a very dark color almost brown or black. As the print builts up, this goes away and goes back to it's normal color. But when print is finished, on the bottom layer I have this stripe of darker filament that goes around the print. I printed a vase and this wasn't a problem because I used a brim and just chipped the brim off. But I also printed a comb which has a very large surface area on the bottom and this dark string of filament wraps all the way around the comb on one of the inner perimeters.

Any suggestions? I could probably fix it by using a longer skirt at the start of the print (the thingy it puts down before it prints the shape) but that seems like a huge waste of filament and I would rather solve the core problem not put a band aid on it.


The other problem I'm having is I made a diamond-shape vase. The outside looks wonderful, almost perfect. The inside is horrible, lots of random strings of filament sticking out and strands of it crosses the points of the diamond where it shouldn't be. Any suggestions?

My SD3:  Clear plexiglass case, case heater, X axis stabilizer, Z axis stabilizer, thumb screws, filament guide, heatsinks on all motors, extruder fan, controller fan, heatsinks on motherboard, Y rod pillow block, USB and Power on/off switch, fully calibrated including trimpot tuning. Am I missing anything?

2 Reply by ronsii

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Re: first layer burns when first extruding (discoloration) and other

The discoloration is most likely from the temps being high as red is probably one of the more susceptible colors to do this, when you hotend is at or near the bed level temps at the tip are greatly increased from the beds heat zone.

3 Reply by Photog

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Re: first layer burns when first extruding (discoloration) and other

ronsii wrote:

The discoloration is most likely from the temps being high as red is probably one of the more susceptible colors to do this, when you hotend is at or near the bed level temps at the tip are greatly increased from the beds heat zone.

I tried it with my green ABS and got the same thing, a dark green stripe through the bottom of my print. It doesn't appear to do it to all of the solid infill on the bottom surface, just for the first 100mm so of extrusion.

What temp settings SHOULD I be using? There's so much conflicting information out there. My orange ABS recommends 230c to 240c for temp.

The SD3 runs 30mm hotter than what you set in R-H, from what I've read on the forums. is this true? So I shouldn't go higher than 210c in R-H and no lower than 200c in R-H. So why is it burning up at the beginning of the print?

My SD3:  Clear plexiglass case, case heater, X axis stabilizer, Z axis stabilizer, thumb screws, filament guide, heatsinks on all motors, extruder fan, controller fan, heatsinks on motherboard, Y rod pillow block, USB and Power on/off switch, fully calibrated including trimpot tuning. Am I missing anything?

4 Reply by ronsii

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Re: first layer burns when first extruding (discoloration) and other

The temps will vary depending on your particular printer and roll of filament... I have personally seen two rolls of filament(same color) from the same supplier take 6 degrees of temp difference to get the same results.

As I have said in other posts the SD printer is usually ~30 degrees C lower indicated than real temp numbers, this number can vary with how SD built the printers hotend or the PID settings or a number of other factors....

When printing I find that 4 degrees of difference is all that is needed to make a noticeable change in print quality so it can take some trial's on your part to determine what temp is best smile

5 Reply by Photog

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Re: first layer burns when first extruding (discoloration) and other

ronsii wrote:

The temps will vary depending on your particular printer and roll of filament... I have personally seen two rolls of filament(same color) from the same supplier take 6 degrees of temp difference to get the same results.

As I have said in other posts the SD printer is usually ~30 degrees C lower indicated than real temp numbers, this number can vary with how SD built the printers hotend or the PID settings or a number of other factors....

When printing I find that 4 degrees of difference is all that is needed to make a noticeable change in print quality so it can take some trial's on your part to determine what temp is best smile

'

Would the heated bed being too hot cause that first filament to turn dark too? Or should I leave the heated bed at 105c if it's making my prints stick well without lifting? I notice there is settings to have the heated bed be at a different temperature for the first layer. Should I use that? If so, should I start first layer with hotter setting that goes cooler after the first layer, or vice versa?

My SD3:  Clear plexiglass case, case heater, X axis stabilizer, Z axis stabilizer, thumb screws, filament guide, heatsinks on all motors, extruder fan, controller fan, heatsinks on motherboard, Y rod pillow block, USB and Power on/off switch, fully calibrated including trimpot tuning. Am I missing anything?

6 Reply by Photog

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Re: first layer burns when first extruding (discoloration) and other

here's a pic of what I'm getting. any suggestions where to start?

http://s28.postimg.org/8vp8gy4e5/IMG_20131207_243911_716.jpg

My SD3:  Clear plexiglass case, case heater, X axis stabilizer, Z axis stabilizer, thumb screws, filament guide, heatsinks on all motors, extruder fan, controller fan, heatsinks on motherboard, Y rod pillow block, USB and Power on/off switch, fully calibrated including trimpot tuning. Am I missing anything?