Print quality help please

Hi everyone;

I've been trying to get my makerfarm prusa i3 dialed in and have been having a few problems. The thin wall box print comes out perfect and measures 0.46 mm in free extrude mode. I've calibrated the esteps and adjusted the the hotend temp up and down in 1 degree increments from 223 up to 235 and it doesn't seem to make it better.

The pictures are a little fuzzy but I hope they show something. the block on the right was printed not to badly but the exact same settings a few minutes later came out like the block on the left. I've tried changing the extrusion multiplier and just about everything else that I can think of and I could use a little help. I reduced the nozzle size from .035 to .034 and that seemed to help but my issue is blobs on the print and not being able to print a solid top layer.

it seems like the first layers print fine but then when it tries to do a solid infill it loses it's mind but only sometimes. the cube on the left is printed with 99% infill the cube on the right is as well but I added a solid infill every 5 layers so I could see if the solid top layer problem had been solved. the 5mm cube shows what I mean it prints okay except for at the end where the filament pulled tight due to a supply problem but then there is no solid top layers or they aren't filled in enough. If I increase e-steps it blobs and the print self destructs in a few layers. can someone help please? I've tried richraps slicer calibration pages but I am stuck trying to finish.

would the first layer height as set by the z axis limit cause this? something like the first layer being too squished causes the other layers not to be located correctly hence they don't squish properly or the nozzle drags? not even sure if that's the way it works or not seems like it would get corrected over time and I can't see why it works then changes idler is tight no slippage the extruder has its acceleration set at 2000 and there is enough current to prevent slips the extruder multiplier was set after measuring a free extrusion and using the calculator on the prusa site.







Edited 3 time(s). Last edit at 04/17/2013 07:37PM by Lizardboy.

Okay so I was able to fix my problems and things are looking much better. I made a 15mm cube 5mm high in openscad and sliced it with 95% infill and the same settings as above. Then I kept printing the same cube over and over adjusting the flow parameter in the marlin firmware down each time. I first started with 85 then 83 82,81,80,79,78,77,76,75 the best print was at 77 below this the lines started looking a bit dotty. The smoothest surface finish was at 77.

What I in the end found most helpful was looking closely at the extrusion lines with a magnifier when looking from the side it was easy to see the extruded plastic looking like furrows in a field. the nozzle was creating the trench part of the furrow and the excess plastic was squishing up around the sides to make the raise portions. As I kept reducing the flow the raised parts on either side of the furrows got smaller until I reached a point where I started to see the sides of these furrows being smaller than the center of the extrusion at this point I stopped and backed up to the most level extrusion I could get. I could probably fine tune it more if I had a smaller setting for flow but after this much trial and error i'm just going to leave it alone

printing the blocks reminded me a lot of the process you go through when installing a new cartridge in an ink jet printer. you print off the alignment sheets and pick the best image from each. Something like this would really be the answer for calibration. if you could set up a tray of these low squares I've been printing each with a small step up or down in the extrusion flow then you could easily pick the smoothest by just running your fingertip over them over looking as I did with a magnifier.

I printed in total 12 blocks that covered from to much to too little extrusion and the 45 degree infill made it easy to see the effect I think similar trays or sheets could be made for hotend temperature.

Hope this helps what it showed me is that the zone for good and bad is very small bumping the number up or down just one click from the ultimate setting makes a visible difference. I think you could easily miss the perfect setting if you went in even steps of two I got blobbing at to0 high a setting and at too low a setting and its hard to tell what you have. Look at the furrows is their excess or not enough.

Today i'm going to measure the free extruded width again and set the extrusion width parameters in the advanced tab to match whats being extruded at this setting that should tighten up the line spacing it's not a big change but I see more squares in my printing future...

Cheers

Edited 1 time(s). Last edit at 04/18/2013 12:48PM by Lizardboy.

To be honest, I have never done anything in Marling for the flow rate...

Is there a guide for that?

All I knew that I could adjust in marlin was steps/mm, PID settings and frequency limiter etc.

I would really like to know what else I can adjust in Marlin!

Can't you adjust the flow rate in your slicer as well?

Extrusion multiplier does the same thing I believe.

I like the idea of the calibration cubes with different flow rates. Is it possible to put that into gcode? Presumably it is?

yes the calibration squares helped a lot but now my problem has gotten weird. I've been trying to print nopheads calibration object for the mendel 90 basically it prints nut traps m3,m4 and m6... my problem is while the outsides of the object are exacly the right size the nut traps are coming up 1mm too small. I used netfabb and the nut traps are the correct size in the STL but when I check the Gcode the nut traps are the smaller size. to make it even weirder the m3 nut trap fit perfectly but the m4 and m6 don't fit.
My only thought is somehow Slic3r is squeezing the traps cause they are close to the edge and it needs room to laydown 3 perimeters? this is really weird. I downloaded and tried kissslicer but it locks up everytime I try to slice. I've tried printing other objects but the same thing happens the test cubes are accurate to within .05mm so I cant see ehats causing this.

I think I read somewhere that Nophead uses skeinforge to get correct dimensions on parts. Could you post s link to his calibration piece and I'll try it on my Mendel90 too. It would be interesting to see if it does the same thing

Hi; I downloaded the mendel90 master files from github here. [github.com] I just downloaded the whole thing as he has quite a few included files. The "cal" object is in the scad directory. He prints with polygons which seems to work a bit better. When I look at the stl and the gcode they are not the same the gcode seems to give a nuttrap 1mm smaller than the scad stl shows. I've used the measuring feature in netfabb and I can see that the printer is printing pretty much exactly what the gcode is telling it. The thing I can't figure out is why the gcode has smaller nuttrap sizes than the STL

Let me know your results I'm using Slic3r so results may vary... I'd try skeinforge but the idea of getting another software calibrated is a bit scary.

I'm struggling to get from the scad file to an stl. I have no idea how to use Openscad which is obviously very limiting. I'm used to sketchup so it's a steep learning curve! Can you tell me how to creats the stl (or send it to me ) and I'll try printing it.

You select in the Menu Design - "Compile and Render (CGAL) F6" and when it is done then Menu Design - "Export as STL...".

---

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

Bob, thanks but I am having issues with the code I got from Github. I think it's 'looking up' previous components or elements and it can't find them. Do I need to load in a complete model or something? I've copied the cal.scad code over but it won't fully compile. This is the code (apologies for post length and hijack!):-

//
// Mendel90
//
// GNU GPL v2
// nop.head@gmail.com
// hydraraptor.blogspot.com
//
// A test object for calibration
//
include

module cal_stl() {
difference() {
union() {
cube([10,40,5]);
cube([40,10,6]);
cube([25,25,10]);
translate([10, 10])
cylinder(r = 10, h = 15);
}
translate([10,10,15])
nut_trap(Z_screw_dia / 2, Z_nut_radius, Z_nut_depth);

translate([5,30,5])
rotate([0,0,90])
nut_trap(M3_clearance_radius, M3_nut_radius, M3_nut_trap_depth);

translate([0, 18, 5])
rotate([90,0, 90])
nut_trap(M3_clearance_radius, M3_nut_radius, M3_nut_trap_depth, true);

translate([30,5,6])
nut_trap(M4_clearance_radius, M4_nut_radius, M4_nut_trap_depth);

translate([18, 0, 5])
rotate([90, 0, 0])
nut_trap(M4_clearance_radius, M4_nut_radius, M4_nut_trap_depth, true);
}
}

cal_stl();

All the STL files are on github, you only need to compile the scad if you want to change something.

I only get nut traps and holes the right size with Skeinforge. Slic3r and Kissslicer come out way too small.

---

[www.hydraraptor.blogspot.com]

I tried looking at skeinforge but I couldn't seem to get any sort of front end to come up. Guess I need to do some research on skeinforge and figure out how to use it. I wouldn't know where to start with finding all new settings for a new program. if anyone has a successful config file I could get started with that might help. I'am using a .35mm nozzle.

Well okay then trying skeinforge

Edited 1 time(s). Last edit at 04/23/2013 03:06PM by Lizardboy.

we.

Edited 3 time(s). Last edit at 04/23/2013 05:57PM by Lizardboy.