Welcome to the SeeMeCNC Community

Err... like I haven't done that for the last 6 months

Well I spent yet another day tweeking around without success. I just don't know what the heck I am doing wrong.
First off, I spent a while making sure the machine was properly set up - it was perfect.

So, tried the PETG again. The inital problems I have are it seems to ooze all over the place.
If you started with default PLA settings, I was ending up with large clumps of melted crap dropped randomly over the print, which the head then crashes into later on.
I did a bit of research, and this appears to possibly be due to the head dragging and building up on the hotend.
So I tried small increases in the Z print height, but it doesn't seem to fix it (in fact, it gets worse).
The first layer is particularly bad and a very rough print. I makes piles of filament at the direction change points. I have tried lower hotend temps (245 is the recommended, 230 and it stops extruding properly).
I have retraction set to 2mm, as more than that appears to create issues with the E3D V6 hotend.

Some advice would be welcome, as this thing is just a useless monument to a pile of cash at the moment.

Is there a PETG recommended settings anywhere?

After half a roll of filament, you would think I could get it dialed in at least slightly better

It seems that on the far side of the picture you are pressing too deeply in to the bed. I.e. the Z height is too low over there. Because of this, the molten filament does not exit the nozzle and the filament in the bowden tube acts like a spring. WHen the pressure is released (gap between nozzle and bed increases again) the spring discharges CRAPPING molten filament.

Atleast that is how i interpret it.

PETG does not like to be squished for the 1st layer.

Mmm. Well I have the first laer set at 0.4mm, then 0.25mm after that.
Thing is, it doesn't always do it all the time.

Not sure why the filament is different thicknesses either. The bed calibration shows it equal over the whole bed.

My "standard" settings are .3 first layer, .2 after that. Retraction is 4mm at 23mm/s. My filament is around 1.8mm in diameter, check yours, it can vary across the roll. Bed is at 60 and the hot end is at 240. I run the fan on everything other than the first two layers.

Stevolution wrote:Mmm. Well I have the first laer set at 0.4mm, then 0.25mm after that.
Thing is, it doesn't always do it all the time.

Not sure why the filament is different thicknesses either. The bed calibration shows it equal over the whole bed.

If that is the case your calibration is wayy off. That 1st layer is no way near 0.4mm.

Your Z=0 is too deep in to the bed. So it goes to where it thinks is 0.4 mm above the bed, and starts extruding but it is actually 0.1mm or less above the bed.


I would say, use the lcd and set Z=0 0.2mm above what it is now. BUT it also seems that the height is not uniform. So some fiddling with the individual towers will also be necessary.

Would you mind posting more pictures?

What i am looking for is to how high the extrusion is, i.e. Is it really 0.4mm. And is it uniform accross your whole first layer.

Would you mind expanding on it doesnt do it all the time?

Sometimes you get 0.4mm and sometimes 0.1mm?

Stevolution wrote:Well I spent yet another day tweeking around without success. I just don't know what the heck I am doing wrong.
First off, I spent a while making sure the machine was properly set up - it was perfect.

So, tried the PETG again. The inital problems I have are it seems to ooze all over the place.
If you started with default PLA settings, I was ending up with large clumps of melted crap dropped randomly over the print, which the head then crashes into later on.
I did a bit of research, and this appears to possibly be due to the head dragging and building up on the hotend.
So I tried small increases in the Z print height, but it doesn't seem to fix it (in fact, it gets worse).
The first layer is particularly bad and a very rough print. I makes piles of filament at the direction change points. I have tried lower hotend temps (245 is the recommended, 230 and it stops extruding properly).
I have retraction set to 2mm, as more than that appears to create issues with the E3D V6 hotend.

Some advice would be welcome, as this thing is just a useless monument to a pile of cash at the moment.

Is there a PETG recommended settings anywhere?

After half a roll of filament, you would think I could get it dialed in at least slightly better

Based on this you're starting around 200c? Try 240-260c. PETG always has laid down nicely for me right on PVA glue(50%glue-all, 50% water) at 75C

.2-.3mm layer with .4 nozzle doing .44-.45mm extrusion width.

I calibrated the nozzle to the bed using a piece of paper dragging under the tip, using the LCD control panel.
Once I have done that, I run the G-code that moves the nozzle to centre, then to each tower. I get the same paper 'drag' all over the glass hotbed.
I will try re-calibrating a little higher.

That image is probably screwy, as I was tweaking all sorts of settings in frustration, trying to get it to lay down properly.
I certainly don't get any issues with it sticking to the hotbed.... if fact, its quite hard to remove the print (UHU).

I have been running the hotend at 240. I will stick with that for now.

I will try again tomorrow evening and post back pictures and a report

It gets under your skin, doesn't it.

Before I wrote my auto-calibration system, I spent hundreds of hours trying to figure out why the nozzle was dipping badly between the towers. Many dozens of GeneB 3-point calibrations, bolt-on mods like the Trick Laser arms, re-aligning the towers several times, and many other strategies, failed to produce any results. I eventually extended Smoothieware to be able to do an automatic calibration with a Z-probe, and that did it. The problem went away because I made it go away. It was like an enemy to me, to some primitive part of my mind. That part of me couldn't let it be. I had to defeat it. The money spent was only slightly annoying. The time was what killed me. I just couldn't stand the idea of making myself an expert in delta robots, only to bail and get a boring Cartesian machine. There is a finite list of things that could be causing this problem. It's not supernatural in origin. It can be fixed.

To a builder, a misbehaving machine is a constant source of irritation, especially when others have the same machine and it works for them. Thoughts of abandoning it, or stomping it into bent wreckage, provide only temporary relief. There has to be something. This machine owes you a good print. Others are more dispassionate about this, but to me, it would've felt like a personal failure to give up. That feeling is what motivated me to add several thousand lines of code to Smoothie - and to get far enough to decide to do that in the first place.

If you're like me in this respect, you will not leave the machine alone. You will make it work.

If it isn't a simple matter of Z height setting, perhaps a video of the first layer would help. I feel like I almost understand what it's doing, but not quite. If you could shoot a short video of the 1st layer and put it on YouTube, it might make the issue easier to diagnose. I do think PETG is a good starter filament because it won't swell up and jam in the hot end like PLA, and it doesn't have delamination and first-layer curling issues like ABS.

Wow, thanks for this peptalk! I could use that too...

This printer has SO MANY TIMES nearly become an airbourne frustration target

Well re-calibrated again. Must have messed that up, as the hotend slammed into the glass bed

So... checked 'Z' height AGAIN and re-tried the print.

I reset all the settings to standard again but put 0.35 as the first layer and 0.25 for the rest.
Retraction is 3mm at 100mm/s

Its splooging filament worse than ever now - so I stopped the print. Not in the mood for this tonight, so best I walk away for now.

https://youtu.be/CGzcMHazpQg

Video is private.

100mm/sec is WAY too fast. Try 30 or less.

g.

Yeah, 20-30mm/sec is good for the first layer max speed. I would also use that for the outer loop speed. Infill can be faster, but not too fast or it'll encourage oozing. I usually do inside loops and infill at less than 50mm/sec. Less exciting, but the result looks way better.

626Pilot wrote:Yeah, 20-30mm/sec is good for the first layer max speed. I would also use that for the outer loop speed...

I think OP is talking about the retraction speed. Although 100mm/s for the retraction is also way too fast. Printing at faster speeds is possible, but it brings in even more variables that have to be controlled for a successful print. I use similar speeds 20-30 1st layer, and 40-50 for the rest on critical prints. Depending on the design and other circumstances I often use 80-100 mm/s for prints.
On a separate note, after putting together the printer, it is easy to think that this is it, but in reality, without a robust calibration it's a hit and miss game. 3-point calibration and eyeballing or using paper may work, but not for everyone. It would be nice is we had a more detailed instructions for advanced calibration in one place. Equipping Rostock with a Smoothieware and using your Heuristic auto-calibration should also work:) I have used OpenDACT with some success, which have helped to a degree, but I have also wasted a lot of time with it.

Video should work. I thought if it was set to private, only people with the link could see it. Obviously not.

The only calibration method I know is the paper and 3 points of the towers. I think it is printing pretty evenly.

I did notice however, after this messy print (in the video), that the print was barely attached to the glass, where as it is normal stuck fast.
So now possibly too high? How the heck are you supposed to know what is the ideal height, and hit that every time you calibrate?

100mm was the retraction speed. Surely if I lower that, then the ooze will be even worse. Its on the changes of direction that I cam getting bad build up.
The actual print speed is 53mm (at the moment), as I read that as a recommended speed. I tried 60mm before that.

I usually try to slow my first layer prints to ensure a decent stick, but then I also have to dial back the extrusion as well.

I will have a run at this over the bank holiday weekend. If I cannot make progress, then I think its time to invest in a milling machine instead (which is what I wish I had done now!)
Thanks all

Counter intuitively, e3d hotends tend to ooze less when the retract os slower (to a point) because then the filament will actually pull the molten material, rather than friction and gravity sticking it in place.

Best of luck with it. I understand frustration with these machines ( I get most of mine from mills, rather than printers)

Slowed the retraction to 30mm

Still laying down too much and leaving lumps that it later crashes into... then it failed anyway

I'd slow it down even more. I think I'm running 10 mm/s retraction on my v6. For overextrusion, have you calibrated your extruder steps per mm? Do you have an extrusion multiplier set in your slicer?

I am still using Matterslice (which I find fine).
Extrusion multiplier is left at 1. If I lower that, I tend to get gaps in the print.
I also tend to slow the first layer to 0.77 which has helped the current print lay down a reasonably flat layer (for a change)

This current print is going 'better', but it is still crashing into lumps of crap every so often.
I read that the lumps might be filament being scraped off the print as the head is moved around. I have layers set at 0.28.
The lumps of filament make a horrible cracking sound as the printer head is moving around.

OK. Stopped that print half way through.
Its messy, but a slight improvement.
However, the nozzle is bashing off clumps of melted filament all over the place (see the photo of the bed).
So, still not correct by a long way. The finish is pretty poor as well. Almost seems to be over-extruding? Calibrated the extruder, so that should be OK.