Anet A8 3D Printer.

[DAPPH]

I'm so pleased you feel it's the filament,
Joe Prusa has gone to great lengths to get his own made on site filaments department running . When you think about it as such the filament is really the only variable there is everything else is fixed once you commit to the print session after set up . With the filament you get what's on the reel , so the slightest bad mix of plastic or drawn too thin or left too thick is going to mess with your prints and & delivery motors disastrously and you don't realise it .

I will only use true Prusa filaments because of that reason . Somewhere on the Joe Prusa original You Tubes clips there is a lengthy discussion about filaments . He shows the lengths he's gone to, to produce a consistent filament inhouse rather than buy in a lumpy diarrhoea one that come out in fits & starts . Plus if it is faulty he will replace it .

 

[bigegg]

I'm so pleased you feel it's the filament,

touch wood, thats all it is.
i'm printing a fan duct at the moment, then I'll run a few more experiments to "dial in" my settings.

the *very* expensive rigid ink reel is due on Wednesday,

 

[DAPPH]

I've not used my Prusa for four months or more and by the end of summer it will be nearer 8 months .. I'm wondering if deeper in the reel flats will a have appeared due to differing temps & humidity and turned the round filament into squarish with round corners . Think I will buy in two new Prusa reels , one PLA and a harder higher melt temp plastic as well such as ABS .

 

[DAPPH]

I don't know if it's the same for other guys with their 3 D printers but at the start of every session I find I have to print a simple flat logo to see that I have the height of the nozzle perfectly set as it seems to vary a little . It can be anything from 0.0009 to 0.0018 on the scale settings on my machine . It might be to do with the humidity & air temp and how fast the extruded plastic cools . If I don't do that initial check /test and cure any fine hairs of plastic waving about the odds are the prints for the rest of the session will mess up .

Off hand I can't remember what the basic Z axis height settings are but as soon as I open the cabinet I can see the figures … for I've written them with a permanent marker Sharpie pen inside the cabinet as an reference check .

 

[PhillipM]

Depends a lot on the rigidity of the machine, bed, etc.
I used to have to relevel my bed every other day as it would warp around a little with heat, until I ripped the stock one off and switched to a cast tooling plate bed, and removed the clamping bolts and instead bonded the heater to one side and the glass to the other with a flexible thermal adhesive - so they wouldn't try to warp it as everything heated up at different rates.
Since then I've never touched it.

Now all I do is the odd quick tweak for the Z-offset depending on what filament I'm using as the first layers skirt is going down.

 

[bigegg]

well, touch wood, i'm getting consistent prints now.

consistently rubbish.

but.
its just a matter of playing with the settings.

latest print: 0.8mm nozzle. 0.4mm layer height. 1mm line width. 1mm retraction.

i'm just slicing a new fan + mount for post cooling.
a lot of my quality problrms seem to be because i'm laying down filament onto a still liquid previous layer.

 

[PhillipM]

Large nozzles need a lot of cooling on small parts - your laying down huge amount more volumetrically to start with and each line you lay down cools slower because it has more mass vs surface area, things get tricky in terms of balancing cooling vs warping issues.

Sometimes you just have to slow down a bit and accept longer layer times on small parts as a downside of larger nozzles.

 

[PhillipM]

E.G - These parts are only about 7/8 of an inch across with the same size nozzle as yours, and I had to slow the layer times down to the point where a 0.4mm nozzle would have been just as fast per layer (but needed twice as many layers so still would take twice as long for the whole part) - just to be able to get them cool enough before the next layer went down:

 

[bigegg]

E.G - These parts are only about 7/8 of an inch across with the same size nozzle as yours, and I had to slow the layer times down to the point where a 0.4mm nozzle would have been just as fast per layer (but needed twice as many layers so still would take twice as long for the whole part) - just to be able to get them cool enough before the next layer went down:

what speed do you run at? - i'm at 50m/s and havent altered it in my experiments.

 

[PhillipM]

I think those were run at about 35 or 40mm/s, but with a 17.5s minimum layer time, which slowed most of it down apart from the flared ends.

edit - yes, the smaller diameter area's slowed to around 25mm/s

 

[bigegg]

I think those were run at about 35 or 40mm/s, but with a 17.5s minimum layer time, which slowed most of it down apart from the flared ends.

edit - yes, the smaller diameter area's slowed to around 25mm/s

so is there a setting (in cura?) to pause for a certain time at the end of each layer?

 

[PhillipM]

I don't know in Cura, I use S3D for the most part.

 

[AndersK]

Yes, you can set that in Cura.

Minimum Layer Time, if a layer prints faster than this it will slow down.
However, too slow speed can cause poor quality so there's Minimum Speed to fiddle with.

Lift Head is another option to use together with minimum time and speed. If you are at minimum speed but not yet at minimum time, the head will move away until minimum time is achieved.

 

[bigegg]

getting there, i think.
30mm/s
180° nozzle
65° deg bed
1mm line width
0.8mm nozzle
0.4mm layers.
1mm retraction
17s (just because!) layer time.

 

[tflnemesis]

@bigegg

Have you calibrated your printer?
XYZ Steps per mm
Extruder Steps per mm
Hotend and bed PID tune.

Checked all guide rails are straight and not bent, levelled bed to the X axis?
Checked the hotend is secure and has no movement?

Your print also looks like you could do with upping the retraction a mm or 2...

Also try printing a temperature tower.

(to print a temp tower, download a suitable model from thingiverse and slice it using the lowest temp on the tower.
Then in the file menus find extensions/ post processing/ modify G-code.
Click 'Add a script' /ChangeAtZ and set the next temperature jump at the 'Change height'. Repeat until you have all temp changes at each height.
This should give you a good idea of what temp to set the hotend to produce better prints.)

All the filament I have used has been cheap stuff and 95% of my problems has been caused by printing too cold or too hot.

The other 5% is mainly down to me fiddling all the time trying to dial in the settings, experimenting or the bed is out of level (I level my bed manually).

I have managed to get decent prints with all the filaments I have tried after some experimentation and like I say I tend to buy the cheapest I can get from amazon.

Atm I am experimenting with my first reel of TPU filament, took me about 6 hours and about 10m of filament to dial it in. It only took this long because I have never tried printing flexible filament before.

With ABS and PLA I can usually dial it in within an hour. I have several go to prints for bed levelling, XYZ calibration and temperature settings.

Also I have had more than one filament from the same company, same material but different colours, different colours can sometimes mean I need to change the hotend temp by up to 20c.

I haven't used any larger nozzles yet as I like the detail and speed of the standard 0.4mm nozzle.

 

[PhillipM]

To be fair it's far harder to tune in as you go up nozzle sizes, pressure compensation, drool, gap fill/overlap, starting defects, etc, all become very magnified, but there's still something weird going on if that benchy is the best you can get after a few goes.

 

[bigegg]

latest prints:

one at 80% flow rate, the other at 120%

 

[tflnemesis]

There is definitely something wrong...

The gaps between print lines is too big.

Are you certain your nozzle is 0.8? Those gaps look more like a 0.4 nozzle set to print 0.8 lines.
I would ignore flow rate for the moment and play with line width a little see if you can get those gaps to close up.
Your first layer looks spot on but if your nozzle is slightly too close to the bed the 'squish' would close the gaps if your line width is wrong.

If you lived locally to me I would suggest a visit to see if I could see whats going wrong as its printing but I don't get up to Leeds very often...

 

[bigegg]

further investigation - checking calibration of the extruder feed.
100mm indicated = 63mm of filament out of end of bowden tube.

so i need 100/63 = 158% flow rate.

cura only goes to 150%

i'll give it another go at that setting later tonight.

 

[PhillipM]

Try putting a bit of drag on the filament and see if changes, rule out a slipping extruder first.