Trouble all of a sudden

A forum dedicated to the stock LulzBot TAZ 3D Printer
wantmys2000
Posts: 83
Joined: Fri Mar 06, 2015 11:01 am

Re: Trouble all of a sudden

Post by wantmys2000 » Tue Apr 07, 2015 7:02 pm

@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?

Thanks!
Steven

wantmys2000
Posts: 83
Joined: Fri Mar 06, 2015 11:01 am

Re: Trouble all of a sudden

Post by wantmys2000 » Tue Apr 07, 2015 7:04 pm

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.

Thanks!
Steven

Muggs
Posts: 98
Joined: Wed Feb 25, 2015 7:35 am

Re: Trouble all of a sudden

Post by Muggs » Tue Apr 07, 2015 8:21 pm

3 hours into a 3 1/2 hour print and all is well.

@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.

Thank you all! Update in the morning.

kcchen_00
Posts: 1721
Joined: Thu Feb 19, 2015 12:42 am

Re: Trouble all of a sudden

Post by kcchen_00 » Tue Apr 07, 2015 11:27 pm

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...

Muggs
Posts: 98
Joined: Wed Feb 25, 2015 7:35 am

Re: Trouble all of a sudden

Post by Muggs » Wed Apr 08, 2015 6:37 am

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!
IMG_0045.JPG
IMG_0046.JPG
So far so good; I'll build some more today and see what happens.

kcchen_00
Posts: 1721
Joined: Thu Feb 19, 2015 12:42 am

Re: Trouble all of a sudden

Post by kcchen_00 » Wed Apr 08, 2015 10:47 am

Those look nice. So it was the cleaning?

Muggs
Posts: 98
Joined: Wed Feb 25, 2015 7:35 am

Re: Trouble all of a sudden

Post by Muggs » Wed Apr 08, 2015 12:18 pm

kc,

Well, I suppose.

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!

wantmys2000
Posts: 83
Joined: Fri Mar 06, 2015 11:01 am

Re: Trouble all of a sudden

Post by wantmys2000 » Wed Apr 08, 2015 1:44 pm

WOOT!! Got to love alignment tools. I think my garage has one on the shelf for every car I have replaced a clutch in.

BaltimoreBully
Posts: 47
Joined: Sun Feb 22, 2015 10:43 am

Re: Trouble all of a sudden

Post by BaltimoreBully » Wed Apr 08, 2015 3:28 pm

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.

Muggs
Posts: 98
Joined: Wed Feb 25, 2015 7:35 am

Re: Trouble all of a sudden

Post by Muggs » Wed Apr 08, 2015 3:34 pm

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!

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