@muggs – If you think it is the filament catching, I would tear apart the extruder assembly, look for burrs on the top of the hot end, then reassemble making sure the hole in the extruder aligns dead nuts perfect with the hole in the top of the hot end. The assembly has room to get that out of alignment which would cause a high probability of catching on the filament burrs created from the hobbed bolt.
After that, start exchanging parts till it works 100% of the time. I have screwed up some prints on the TAZ from my own mistakes with slicing etc, but my TAZ itself has been 100% reliable and has never stripped filament like you show. That should be the mark you aim for, 100% reliability.
One other thing I have thought of is an ohmic power lead to the hotend fan. It seems like that fan stops mid print and the hotend jams from heat creep. The wires in the wiring harness, or an ohmic connector on the Rambo maybe. Can you set up a high def camera pointing at that squirrel cage fan and record a print to see if it is stopping mid print?
The more I think about it, I bet there is a power problem to that little fan. It cuts out for some reason causing the jam, starts back up, filament starts moving again, get a few more layers, then it stops again, etc… See if you can get a camera on that fan.
@kvar14
I have done ALL of the tests. My bed is perfectly level and mostly flat. My first layers are again perfect.
I do clean the hobbed bolt before each print. I also do a minimum of two 10mm extrudes that come out straight and nice.
Extrusion height is .25 and width is .4
But NONE of this should really matter; as I’ve said, sometimes with these same settings, I get perfect prints.
@wantmys2000
I did just as you suggest in the next to last post; I tore apart the extruder assembly, no real burrs to mension, but I did use a straightened piece of 3mm PLA to use as a horse cock (you’ll know what I mean if you’ve ever installed a clutch) to line everything up when tightening down the two SHCS that hold everything together.
The fan is an interesting thought! I have been aware of the little fan and it has been running each and every time I have looked, BUT I have never “been there” at the time of failure. I will look into getting my Nikon setup to record some video. Not sure how much video I can get on a card.
I disassembled mine this evening to check on what was “catching” the filament. Nothing stood out. I compared it to a spare normal reprapdiscount hexagon hotend. There was friction, but less than that of the LB hexagon… Probably from usage. Also noted that the curvature or kinks in the filament contributed to the friction.
So if you look at the whole assembly, there may be a gap between the extruder and the top of the hotend. It almost looks as though the top of the hotend is countersunk. That might be enough to catch the filament.
The brass insert at the top hotend caught my eye… probably for a bowden tube fitment. I removed it, but nothing fell out or dissasembled.
The tight fit of heatbreak, can be bad for retraction of softened filament… my blower points towards the top of the heat sink, it should probably point at the lower heatsink fins to minimize any heat creep…
Well, I’ve posted all of my failures, it’s only fair that I post my SUCCESSES!
Last night I made a 3+ hour print - success! So I thought I would try another right after, so I started another and went to bed, and this morning another success, YEAH!
I think it was more that I was able to line up the extruder and the hotend together using a piece of straightened PLA as a guide. I may actually turn up a piece of Delrin to use as an alingment tool when reassembling the extruder after a tear-down. Just to have something that keeps everything in line while you tighten it all up.
Anyway, I printed another piece this morning and that printed fine as well.
So here’s hoping that my troubles are behind me.
THANK YOU - kc, mhackney, baltimorebully, piercet, wantmys2000, and all!
Glad everything worked out well for you and you are back up and running good. The best thing about these printers is they make beautiful prints when they are working well. The worst thing is the downtime you sometimes get if something goes awry. Had my nozzle jam again this weekend and couldn’t print. Got everything sorted out by Sunday night and now my baby is doing her job well again.
Yeah, this is working REALLY well now. After this mornings long (3+hours) print I have made two different multi-part prints and all is well in the land of TAZ!
So I have printed several (maybe 8) different builds, some large 3+ hours, some small 20 minutes and some groups of small pieces.
All have been flawless.
So bottom line; IF you take apart your extruder/hotend make sure you REALINE it well using some sort of alinement tool.
My vote is still on the hotend shifting around and getting out of alignment. I print with ABS so it seems less an issue, but definitely something going on there…
@wantmys2000
There have been at least two instances where I have been watching when it failed (I’ve been doing theat a lot lately) and the little fan is running the whole time. ???
BTW, what is an S2000?
@kcchen_00
Last night I did a total tear-down of the extruder and did the re-aliment with no joy!
I have had some pretty good results with ABS; maybe I’ll try to do some ABS parts and see what happens.
I didn’t read the entire thread(allot), but perhaps try to go back to the roots, for troubleshooting purposes?
-Try printing a LB RocktaPuss or whatever it’s called…<-- known as a good print and base your prints off of it
-Use LulzBot Cura…<–for support reasons
-Different computer…
-Different OS
-Different SD Card(size and format(allocation size)
-Different USB cable
-Different USB Port
Just throwing it out there…
I know I’ve seen some weird issues on some of my machines with regards to microcontrollers…
Especially because most of my machines have at least, at one time, had CPLD, Arduino and Raspberry IDE’s installed… And let’s face it, they are not without their own bugs…
S2000 - a 2 seat convertible made by Honda, with a 4cyl 2.2L capable of 245hp. Redlines at ~9000 or 8200 RPM depending on the model year. VTEC at 6500 RPM… A blast to drive. . Well… I could be w really off base, but that’s what S2000 means to me…
Have you tries seasoning the hotend for PLA? I think it was suggested somewhere in the thread.
You know what I did try that, and that is when it started printing really well!!
I’m going to do that again and give it another try. Thanks for the reminder.
@dawgbone, yeah I have done most of what you mentioned. The problem is there doesn’t seem to be any rhyme or reason to the success or failure, save one thing; see above.
@muggs – kcchen_00 nailed it. Back in the day I was saving up for a Honda S2000, it was an all encompassing goal so it ended up becoming my alias as well, as in I want my S2000!
This has been a long thread and I forget if you have checked out the Rambo board for overheating or anything that might make the extruder stepper seize for a bit. Make sure the big cooling fan in the rambo enclosure is spinning, etc…
I would see if Lulzbot would be willing to send you a whole new hotend extruder assembly to see if there is something odd with yours. Mainly just for curiosity sake at this point as I am sure you are fed up messing with it.
I just find it strange as I print a ton of cheap PLA, 3mm and 1.75mm, with zero problems. I have done no seasoning or anything. Only thing I have done is added a second cooling fan on the left side of the extruder head for better overhangs. Not sure how that would make any difference.
. Well… I could be w really off base, but that’s what S2000 means to me…