Print problems: Cornner Blobs

[coreformula]

I am having problems getting a quality print. I think that I have attempted tweaking almost every setting. Even slowing down my the print speed but the results have been the same. 

I am happy with the dimensions. They are almost dead on. 

Filament: PLA

Hot End: 185c

Heated Bed: 60c

[Russell Shipe]

From the picture.  It needs more squish judging the skirt.  also it needs to be cooled, hot end might be a little hot as well.  are you sure you have the right thermistor set?  I highly recommend printing at 20/30 till you get some quality prints.  first thing to try is cooling if you dont have a fan on the carraige try blowing a fan across the bed.  also turn down the bed temp.  only use what you need to make it stick so it can hlep cool the print.  PLA doesnt  like cooling down enough on its own.  

On Thursday, May 9, 2013 10:11:12 PM UTC-4, coreformula wrote:

I am having problems getting a quality print. I think that I have attempted tweaking almost every setting. Even slowing down my the print speed but the results have been the same. 

I am happy with the dimensions. They are almost dead on. 

Filame

[Sean Mitchell]

I would also recommend tuning your acceleration and jerk settings.  It looks like when it reaches a corner it stops to make the turn, then continues.  The stop is then causing the blob.

+1 to what Russell says, perhaps 0.1mm closer to the bed or so 

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========
Sean Mitchell

echo "zvgp...@tznvy.pbz" | tr '[a-m][n-z][A-M][N-Z]' '[n-z][a-m][N-Z][A-M]'

[JohnD]

What everyone else said - couple of comments -

1] PLA loves heat, and retains it.  This is a "bad thing".   I'm really having good results with just using a big 80mm fan blowing on the object.
2] I find I can print very successfully on blue tape with no bed heat.  See above! :-)
3] I have some Protoparadigm PLA that will happily print at 163c - play with your temperatures a bit see #1 above.  The caveat is that in generally you get a more matte finish in the lower temperature ranges*

I know it sounds counter-intuitive, but slower speeds actually can make print quality worse, particularly on smaller, dense objects - you have the heater block just radiating more heat down into the printed plastic - I usually set my minimum speed in the 20mm/s sorta range.

* My thermister isn't, I'm using a thermocouple and it's pretty close to spot on as measured with another K2, and a FLIR - it's really 163 ! ;-)

[Lee]

i use the same settings as you, but with a 40mm fan blowing  at the hotend... although i think even without the fan, i'd have less oozing... which leads me to believe that you could be using the wrong table for your thermistor like Russel suggested.

[Russell Shipe]

Wish i had a flir!!!  I stuck testing with a silly multi meter and thermocouple.  I have used FLIRS at work to determine levels in Freon receivers its kinda hudu magic....   Actually i chiming in again to say yea what are your Jerk and Accel settings?  before you go playing with them!  they can cause some corner issues..  also is that the lift corner?  

[coreformula]

The addition of the fan helped but am still having issues. I have been jumping back and forth between Slic3r and KISSlicer. Neither seem to be able to get it to come out properly. I have done the wall thickness test. It looks good. I measured it w/ a dial caliper and it appears to be .5mm. I have a digital one coming in as well so I can get a more exact measurement.

I am extruding @ 170c w/ a bed at 40. The first layer seems to be going down well.

The 20mm boxes were coming out better but not perfect. At the root of this problem is what I think to be the retraction. At the start and stop the material oozes out or does not lay enough down fast enough.

I have moved on to a more challenging test shown here in the attachments. I am still having some problems w/ the corners as well as the strings.

So close!!!!

/\/

[Brad Norman]

When I got blobs it was my esteps being too high. Try reducing by 5% and see if it makes a difference. Use M92 EXXX. Where XXX is you new numerical value.
- Brad

[Sean Mitchell]

Well congratulations thus far, your parts already look better than those from terawatt industries!

A few things, can you post the output from M503 (it's around 15 lines long).  When it goes around the edge of the corner, does it stop and pause causing the blob?  Maybe a short video of it printing would help too (though the output of M503 should show us quite a bit)

Between the pillars that looks like a retraction problem.  Remember, more retraction is not always better.  You will reach a point where you are retracting too much, and air is getting in the nozzle and you're losing the vacuum and plastic will ooze out.  Find a simple model (like this one, see oozebane-test.stl though it might be better without the big base) and start with a bit of retraction (0.1mm or so) and work up until it gets better.  For reference most of my stuff is at 0.65mm, and around 0.8 I have problems (but this is dependent on your nozzle, extruder, temperature, moon phase and tide)

Finally, is your filament dry and decent quality stuff?  It looks kind of blobby which might be caused by moisture boiling as you extrude it.

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[coreformula]

This is the M503.

Now we are stepping slowly up w/ the retraction.

Could the problem be that 175c is too hot for the extrusion? There is also a long pause at the moment that the "Z" moves up. Will try to make a video of that.

SENDING:M503

echo:Steps per unit:

echo:  M92 X39.41 Y39.41 Z1515.00 E930.00

echo:Maximum feedrates (mm/s):

echo:  M203 X500.00 Y500.00 Z30.00 E45.00

echo:Maximum Acceleration (mm/s2):

echo:  M201 X9000 Y9000 Z1000 E10000

echo:Acceleration: S=acceleration, T=retract acceleration

echo:  M204 S600.00 T300.00

echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum xY jerk (mm/s),  Z=maximum Z jerk (mm/s)

echo:  M205 S0.00 T0.00 B20000 X10.00 Z0.40 E5.00

echo:Home offset (mm):

echo:  M206 X0.00 Y0.00 Z0.00

echo:PID settings:

echo:   M301 P22.20 I1.08 D114.00

/\//

On Tuesday, May 14, 2013 1:15:48 AM UTC-4, Sean Mitchell wrote:

Well congratulations thus far, your parts already look better than those from terawatt industries!

A few things, can you post the output from M503 (it's around 15 lines long).  When it goes around the edge of the corner, does it stop and pause causing the blob?  Maybe a short video of it printing would help too (though the output of M503 should show us quite a bit)

Between the pillars that looks like a retraction problem.  Remember, more retraction is not always better.  You will reach a point where you are retracting too much, and air is getting in the nozzle and you're losing the vacuum and plastic will ooze out.  Find a simple model (like this one, see oozebane-test.stl though it might be better without the big base) and start with a bit of retraction (0.1mm or so) and work up until it gets better.  For reference most of my stuff is at 0.65mm, and around 0.8 I have problems (but this is dependent on your nozzle, extruder, temperature, moon phase and tide)

Finally, is your filament dry and decent quality stuff?  It looks kind of blobby which might be caused by moisture boiling as you extrude it.

[Russell Shipe]

What extruder are you using??? 930 e steps is really high for anything I've used. My experience is don't trust the single wall with pla. I use length for rough call. Then triffid's infill method for fine cal. What's your nozzle size and extrusion heigtg/width. And free Air extrusion diameter. Is slicer worse then kiss. Slicer uses a rediculus wide extrusion with based on nozzle size(in my opinion) kiss uses nozzle diameter. To much flow causes too much back pressure for my .40 nozzle I never go higher then .25 height and like my diameter to be .40 I force it in slicer. My free air width is .42ish

[Sean Mitchell]

In general those steps_per_mm seem very odd to me: 

M92 X39.41 Y39.41 Z1515.00 E930.00

What do you have for motion on your axes, and what are your motor specs?  The closest numbers I know to what you have given are GT2 belts with 36 teeth should be 44.444 steps_per_mm in standard setups, and 2mm pitch leadscrews on Z should be 1600.

How did you come up with these values?  

Could it be you are not moving the axis far enough (11% too small on X/Y, 5% too short on Z) then overcompensating with extrusions that are too fat, which will bulk out the part to be the "right size" on the outer edge, but all your internal measurements will be wrong.  That's my best guess right now

On Wed, May 15, 2013 at 12:26 PM, Russell Shipe <xoch...@gmail.com> wrote:

What extruder are you using??? 930 e steps is really high for anything I've used.  My experience is don't trust the single wall with pla. I use length for rough call. Then triffid's infill method for fine cal. What's your nozzle size and extrusion heigtg/width. And free Air extrusion diameter. Is slicer worse then kiss. Slicer uses a rediculus wide extrusion with based on nozzle size(in my opinion) kiss uses nozzle diameter. To much flow causes too much back pressure for my .40 nozzle I never go higher then .25 height and like my diameter to be .40 I force it in slicer. My free air width is .42ish

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[Larry Knopp]

+1 Sean

What are the motors, belts, pulley-tooth count, size and pitch of leadscrews, extruder style and gear ratio?

[coreformula]

Not sure what you mean by "What do you have for motion on your axes"?

Kysan 1124090 Nema 17 Stepper Motor

GT2 belts

40 tooth gt2 pulley http://www.thingiverse.com/thing:27676 NOTE: I will replace it with a 16 tooth aluminum version tomorrow.

3/8"-12 Acme

PG35L exruder (http://www.thingiverse.com/thing:43457). I will be replacing this with a geared NEMA11 in the weeks to come.

The values that I came up with were from some online conversion tool. Will have to dig it up.

//\/

[Larry Knopp]

After you replace the 40t for the 16's, recalculate X and Y steps.

Do a "standard" e-steps calibration, then do Triffid's e-steps fine tuning.

Then re-run your test cube and let us know!

[Russell Shipe]

With that extruder your steps should be really close to 760 that's right about where all of us run them I think.