solid infill over extrusion

Hi all,

I have a consistent problem that I need help with.

whenever I do solid infill the nozzle ends up dragging through the previous layer.

I have printed 10x10 test cubes where the final layer infill is 1.5mm higher than the final layer perimeter.

how can I change this?

things I've changed...

infill speed was too high for my printer. I think slic3r thought I needed more filament for a higher speed while my printer was plodding along at a slower speed.

I've tried using 60% width on solid infill. this seemed to help minimally, but the infill took forever.

an thoughts are greatly appreciated.

thanks.

Speed is not the problem. Slic3r outputs the amount of filament to extrude for each move, which will be the same no matter what speed the move is made. It is your printer's controller that computes how fast to extrude in order to feed that amount evenly over the move.

It sounds to me that you are grossly over-extruding. This will make little difference to infill, because the extrusion has room to move sideways and so over-extrusion results only in a thicker line of infill that doesn't notice. Solid infill however must be extruded very accurately so that the line widths are exactly the same as the distance between the lines.

There are only two Slicer settings that affect extrusion amount, which are filament diameter and extrusion multiplier. The printer controller must however also be correctly calibrated for your extruder, and the method of calibrating should be explained in your printer's documentation - if not I can give a general method that will work with most printers. If the printer calibration is correct, first ensure that you have the correct filament diameter set in Slic3r. Then start reducing the extrusion multiplier until the solid infill looks OK. To fine-tune you should set infill to 95% and then examine both the infill and the solid top layer with a magnifier. There should be very small gaps between the lines of infill, but no gaps between the lines of solid top layer. If there are no gaps on the infill you are over-extruding, and if there are gaps on the solid top layer you are under-extruding.

One other thing that could cause the symptom is if the Z move is too small or sometimes skipping - but you should easily see if that is the case because the printed object will not be as tall as it should be.

Dave

thanks, Dave.

I'll try those things tonight.

I agree with everything Dave said.

Also, if the layers are printed in opposite directions (e.g. layer 1 clockwise around the cube, layer 2 counterclockwise), then play in the printer mechanism can cause this. That's particularly true if you use auto-levelling and your bed isn't level.

Frank

ok, I tried your suggestions with no joy. I know it's not bad advice, it's me.

here's what I've tried...

I tested my feed rate by marking off 50mm on the filament and then telling repetier to extrude 50mm. this was at 92.5 steps per mm.

it fed 46.5mm. (note: at this feed rate, my perimeters look good, but the solid infill swell the perimeters and the nozzle drags through the infill.)

BUT, my feed rate is low. so I up'd the feed rate to 93 and a command for 50mm gave me 50mm of filament fed. but now my infill is really over filling.

so I played with the extruder multiplier. lowered it to 95%. this helped, but not enough.

basically the sides of my prints look pretty good, but the tops look horrible anywhere there is solid infill.

in my first post I mentioned adjusting the x/y movement speed. I did this because slic3r's default speeds were way too high for my printer (it's homemade) and I hadn't changed them. so, I reasoned that slic3r was allotting feed for that faster feed rate, but my printer couldn't move fast enough to lay it down properly. when I lowered the speed to something my printer could actually do, it helped, but not enough.

well, there's my story. if anyone can straighten me out, it would be much appreciated.

p.s. different question: my y axis uses 1/4 20 all thread for the lead screw. I'm microstepping. I can only achieve 4.7mm/s speed. what should I be able to do?

thanks.

Quote
n2Jesus
ok, I tried your suggestions with no joy. I know it's not bad advice, it's me.

in my first post I mentioned adjusting the x/y movement speed. I did this because slic3r's default speeds were way too high for my printer (it's homemade) and I hadn't changed them. so, I reasoned that slic3r was allotting feed for that faster feed rate, but my printer couldn't move fast enough to lay it down properly.

As said, Slic3r does not control the extruder speed. In the G-code you will see that the length of filament required to be extruded for each move is given ("E" parameter), together with the XY speed of the move ("F" parameter). Your printer's controller (not Slic3r) calculates the extruder speed from those numbers. When the XY move speed is reduced, only the "F" value will change, the length of filament to be extruded remains the same, so changing the speed cannot affect the extrusion amount (unless your controller firmware is faulty) because Slic3r does not use speed as a factor in any way when calculating the amount to extrude.

If you are over-extruding as much as you indicate, it would indicate a gross error somewhere. Did you check that the filament diameter is set correctly in Slic3r? If you are using 3mm filament but Slic3r is set to 1.75mm for example, it will over-extrude by about double. The other thing to ensure is that Slic3r and your printer are both using the same extruder reference - i.e. either absolute or relative extruder commands. Setting Slic3r to absolute when the printer is set for relative will result in progressively more & more over-extrusion.

As it is a home-made printer and you have already found an error in the E calibration, are you sure that your X, Y and Z moves are correctly calibrated? If the X, Y or Z moves are smaller than commanded (or the stepper motors are skipping steps) it will also result in over-extrusion. In particular check that the Z height is accurate. Perhaps the steps/mm set are for a different pitch screw thread, for example.

Dave

I have found to set the extrusion widht manualy for solid infill in advanced settings has helped with Bulgy infills a bit ,sometimes slic3r will make infill a lot wider then the nozzle size so i have it all set to my nozzle size.

Edited 1 time(s). Last edit at 07/13/2015 05:03PM by Darathy.

"The other thing to ensure is that Slic3r and your printer are both using the same extruder reference - i.e. either absolute or relative extruder commands."

Where might this reference be set?

Quote
RRuser
"The other thing to ensure is that Slic3r and your printer are both using the same extruder reference - i.e. either absolute or relative extruder commands."

Where might this reference be set?

To set Slic3r to relative or absolute mode go to "Printer Settings". Look under "Advanced" for the tick box "Use relative E distances". If ticked it is relative mode, unticked is absolute mode.

To set the printer for relative or absolute you need to put in the custom start G-code the command "M83" to set the printer to relative extruder mode, or the command "M82" to set to absolute.

Always match the two - i.e. if the Slic3r box is ticked you should have M83 in your start code, if unticked put M82 in your start code.

Dave