Print quality varies within one print, weird features appear disappear

[Elripster]

I have been working with ABS using my DotBit extruder with V6 hotend which is working wolds better than the stock set up. Some prints now come out great but some just plain don't. Below are the settings I am using in Slic3r...

And this is the part with support material still attached. At least that seems to be working. It detaches quite nicely.

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I have been slowing speeds and accelerations. I check hardware for looseness but everything seems tight. Temperatures are very stable. 235C target is +- 3 degrees.

Any ideas?

Frank

[carefudundae]

A couple of things...

1. If you want help on a specific thing, clearly point out what you are asking for help on. Saying "here, look at these pics, how do I fix?" may not produce the best results... What I see as an issue may not be what you are asking about. For example, is the very top the part you are asking about, cause if so that might be cooling/layer duration related. If its printing too fast from one layer to the next and doesn't give ample time for the previous layer to cool enough, it can start getting blobby. It also might be accel settings, drivers overheating, bad filament, retraction, print speed, etc. Which brings me to my next point...
2. I can't read the slic3r settings you uploaded. its like the images aren't linked like the ABS print pics are... they are low resolution and I can't read them, sorry... Could you resend that info?
3. Why ABS? You likely have valid reasons, but I'm mostly just checking to make sure you are aware of potentially better alternatives that are easier to print with (e.g., PETG).

[Elripster]

Good points.

1. I will take some better pictures. I made a load of test prints and adjustments yesterday (reduced accel, jerk, tightened belts, reduced extrusion to 90% which is likely too low, check and unchecked a plethora of options...) and ultimately am still getting that anomaly you see in the first picture lower right. Other issues will require close up pictures which I will get tonight.

2. I will make the settings easier to read.

3. This is a center console for my friend's diesel swapped FJ60 so it will house the transmission control screen, pyrometer, and boost gauge. Because it is an interior cart part it will see heat levels typical which in the past have warped PLA prints.

Frank

[Elripster]

Some setting information:

I have had the printer for over a year and somethings it prints very nicely.

• Nozzle .4mm
• Speeds 40-60mm, top surface is 25 mm/s as is the first layer
• Extrusion widths are default except for top surfaces which are .4mm
• Accel is 100mm/s2 for all but E
• Jerk is 7.5, 7.5 .5 - the print is not moving ever so gently
• Belts have been tightened
• Rails have been greased
• 2 150W heat lamps on the print area
• Extrusion at 95%, have measured filament use, 10mm commanded measures 10mm intake to the extruder
• Nozzle Temp 240C and holding with about 3 degC of target
• Bed temp is 110C first layer, 100C rest
• 8 mm retract at 100 mm/s
• 1mm Z hop
• Hatchbox ABS, using silver since car has gray interior

The print below is .75 scale to speed things up but the anomaly is present at .5, .75, and 1 scaling. Bed adhesion appears to be perfect. The flat surfaces are quite good to excellent. Although changing various settings will not get odd vertical bulge to go away changing the nearest, random, aligned... seems to have it change the side it appears on.

I stopped the print before the holes but this clearly shows the major issue on the left side.

A close up.. That feature you see forming on the up facing surface is causing the extruder to hang up.

The other side shows some surface issues...

I have no idea if this is relevant to the issue. This is an interior surface so not very critical to the finished part, but there is an odd pattern here...

Frank

[Elripster]

I saved the slic3r settings so I could open in notepad and applied them to the stand alone Cura. The results are very promising.

I noticed the print seems under extruded (brittle) at 95% so am increasing 100%. However the surface finish for the most part is good.

Though things are much improved but that anomaly still appears now on the right upper portion.

Noting the gaps in the right inner seam I am thinking I am over retracting so will reduce the speed and distance a bit next print.

There are still the same issues around the holes though not as severe...

That the anomaly carried over suggests the Slicer is not entirely to blame so I will get a wrench on every fastener I can and check for something loose somewhere.

Frank

[carefudundae]

Thanks for sending those, much easier to see what is going on. The acceleration you have set (100mm/s^2) seems really low. It could be whats causing your issues where oozing may come into play when approaching or accelerating away from corners. Try temporarily setting your accelerations (make sure you set x, y, print, travel all to at least 600 or so)?

Also, I don't think this is the issue, but an 8mm retraction seems pretty high. Is this still configured as direct drive? If so, ~1mm should be sufficient.

Just other things that come to mind:
Is there stuttering or anything else noteworthy happening when printing that part? I'm wondering if there is a ridiculously high amount amount of triangles in that area that could cause too many short moves (some slicers filter those out, but not sure) that could bog down an 8-bit control board. I don't think this is it, but just trying to think of anything...

Based on one of those pics, it seems like its fine for the first ~10mm or so. Anything you can think of that changes at that point?

Take a look at the gcode preview for that area. Are there retractions (might be too slow with 8mm) and travel moves that correspond to that area?

[Elripster]

You ask some good questions. One thing I did notice last night was an audible clunk during moves and found the X motor and X rail mounts loosening. I am thinking that is at least part of it.

I agree the retract is too high. I am using the Dotbit extruder which I believe is direct drive. I am seeing gaps in fact which you can see a bit of in the second to last picture. I am reducing.

My friend is adding some switch mounting holes, tire pressure gauge mount, and tire deflater mount so I will reprint in a day or two.

Thanks for the help!

Frank

[carefudundae]

McClunkey! (semi-obscure Star Wars Ep IV reference)

The dotbit extruder is just an extruder, it depends on how you mounted it to determine if it's direct drive. Does it move (e.g., mounted on the x-rail) while printing, or it is stationary (mounted on the side of the printer somewhere)? The former is direct drive, the latter is a bowden style. If you have a direct drive, and most FT5s are, your retraction should be in the 1-2mm range.

After tightening the rails, please check the acceleration settings. Those should be in the 500-1000 range for this printer.

Good luck!

[Elripster]

My Dotbit is mounted like the production extruder to the x-rail so moves in the X and Y direction with the rails. I am working on reducing the retraction but I do seem to still get "tails" at 4mm and 80mm/s. That's at 245C.

I have accel at 200 mm/s^2 but agree it can be increased. It seems that keeping the jerk low is helping more.

I added some wing nuts to act as jam nuts due to the existing thumb screws constantly self adjusting even at very low accel/jerk settings.

Frank

[Elripster]

To wrap this up. Tightening the rail / motor hardware and adding the wing nuts have made a large improvement. I increased the accel to 200mm/s2 and am getting very good results. I reduced the retract to 4mm and will reduce it further.

It's nice to see some good work coming off of this printer.

Thanks for everyone's help.

Frank

[carefudundae]

Glad you fixed it. Send us a pic of the improved results is you can!