I’ve suspected this to be happening for quite a while… I finally got around to setting up a camera to catch it (sorry it’s not brilliant quality, need to address the lighting - and probably should put the camera on the other side.)
In fact I reckon it’s almost always done this (I put it aside after my last attempt to use it some months ago…) and this is the problem that I thought to be poor adhesion.
As you can see I’ve given the job every chance at a brilliant life, skirts, rims, mirror, kapton, freshly greased z axis thread, hell even brand spanking new PLA…
It appears that the extruder is collecting the print (about 1 min in). It hits part of it and dislodges it.
I’m not sure exactly where in the job this is, I suspect it’s immediately following a Z step.
This happens at all sorts of different layers, I’m just lucky it happened on the first one this time.
Any ideas on further diagnosing this? or better, preventing it?
Hi, looks like your printing PLA at what extruder and bed temperatures, do you have different for first layer?
How do you clean the bed before printing?
Is the fan on, if so what is the bed temperature when the print lifts?
The print isn’t lifting, it’s getting knocked loose by the extruder.
As I suspect it has been ever since I got it.
I’ve tried printing this object twice, once it happened on the 4th or 5th layor, this time it happened on the first.
I’ve tried various temperatures for the bed, at the moment I have it set to 80 for the first layer, 60 for every after.
Extruder is 190
Bed is very clean, it was windexed and I installed that Kapton immediately before this print.
The fan is not enabled in the first layer
Hi, normaly if the extruder hits the print it is an over extruded layer that is high and has a rough finish or the print lifts slightly enough for the extruder to hit it. The difference between 80 and 60 deg is quite alot try just a fixed temperaure, I print PLA with the bed at 50 deg & 195 to 205 for the extruder.
This post shows a problem that I had with lifting http://forum.velleman.eu/viewtopic.php?f=51&t=14699
I have previously run it at those temperatures and was having similar issues, it’s why I started upping the temperature.
This is new, fresh, dry, PLA so I’ll try going back to those temps tonight. I’ll also move the camera so it shoots from the opposite side, hopefully can get a clearer picture of what exactly is happening.
edit: Might it be worth upping the voltages on my stepper drivers a little? Mine are bang on 0.425
This might be because the z isn’t stepping up when it’s meant to right?
Yeh I backed the stepper back a half mm from the big gear now there’s a good bit of slack (I can tighten it up later) but this doesn’t seemed to have made it any better, it seems to happen at random - usually after feeding a lot, perhaps it’s a jam/excess feed?
Or perhaps I need to tweek the driver voltages again with the new psu, I only tweaked the z axis…
I definitely still have it impact, I have one print job that actually ripped the tape off the glass, it clearly didn’t fall off, it was struck
Check the stepper driver calibration again and also check if your extrusion length (steps/mm for extruder) is set correctly,
so it pushes 100mm of filament when told so. (do this without the nozzle mounted)
The new PSU clearly has more balls, almost all of the drivers were runing at 0.57v, I backed them down to 0.54v (probably explains why they were getting so hot) - for reference with the stock psu they were all dialed in at 0.50v
Without the nozzle? Is there some way I can do it cold? the firmware i preventing cold extrusion…
You would have to unscrew the hotend (but leave it electrical connected) and the extrude “in the air”.
That way you won’t waste filament by actually extruding it.
As i mentioned earlier 650 steps/mm are a good starting point for calibration.
You really want to calibrate your extruder under realistic conditions, ie. actually pushing filament through the nozzle at normal temperature and feed rate.
So, everything appears to be working next to perfectly for the first time since december last year
I started doing what you suggested ichbinsnur, I changed the eeprom setting to 650 and it borked, it just sat there grunting - then I realised that the screen that entered that into (I’ve never even seen that screen before) had all the other fields set to 0
I promptly shat myself thinking I’d screwed it
A quick search of the forums and I found a screenshot of some sensible defaults, punched them all in… and it’s working again - it’s slower but the quality has gone through the roof.
I’ve also upgraded to an e3d v6, while I was doing that I took apart the extruder gears and took a dremal to those bits of bolts that were interfering with spring loaded idler thingy…
Also, I think I got rid of the impacting of parts by asking slic3r to lift the head 2mm when travelling.
So in summary, to get the k8200 up to a decent spec.
[ul]
[]Replace the z coupling[/]
[]Replace the extruder[/]
[]Make sure you file down those bolts in the step they tell you to do it[/]
[]Add a 24v 150 watt psu for the heat bed (and driver board)[/]
[]Replace the 15v 100 watt psu with a better 15v 150 watt psu[/]
[]Make sure you’re using nice dry filament (I keep mine in a box with a hippo[/]
[]Make sure your driver voltages are between 0.50 and 0.55 - 0.57 will make things just as cranky as 0.40[/]
[]Do put heatsink on your drivers[/]
[]Lift the z-axis when travelling.[/]
[]Use these firmware setting - dl.dropbox.com/s/cdzlx6zcelpp46 … g.jpg?dl=0 (my pid settinggs were greyed out)[/]
[/ul]
I just start singing the praise of this machine and it starts munging prints again
I’ve figured out the mirror is floating a little (The kapton is giving away) which is causing uneven heating and leveling which was resulting in warping and lifting.
Things printed dead center works fine, more than a few cm off and it’s carp.
Tonight I’m going to pop a fresh mirror on it, I printed off the mirror clips so I’ll be getting rid of the kapton - Last time I tried to print clips the machine fell over, this time it actually printed them… so there’s proof it’s getting better.
Try putting thermal compound between mirror (i use simple 3mm floatglass) and Heatbed.
That will help the heat to spread more even.
Insulating the bottom of the heatbed with a sheet of cork also helps to keep the heat better.
