Extruder (MK4) issues

[danie...@yahoo.com.ar]

Hello everybody,
im having a few problems with my extruder
(MK4). The first issue is with temperature. The only way i can get to
extrude something is by raising the temperature up to 255 C on the
control panel. And even so, i get an intermittent brownish filament
with popping explosions and smoke from burned plastic coming from
inside the nozzle tip.
I already tried to fix this by following the calibration instructions
on the wiki.makerbot site but with no results. I suspect it has
something to do with the voltage regulator of the extruder board
because im getting 6.5V instead of 5V when measuring the 7805 with a
multimeter.
I also tried unclogging the PTFE, thermal barrier and the nozzle with
acetone (overnight) but im still getting the same negative results.

The following link contains a video of my MK4 extruding ABS at 255 C.
(note that i had to push the filament with my hand because the DC
motor wasnt strong enough)

http://www.youtube.com/watch?v=339FzCV7Sts

I would appreciate any suggestions

Thank you
Daniel

[Zip Zap]

Everything you mentioned is what I went through with MK4.  Temperature is unreliable.  Your pushing filament through is because your idler wheel is not pushing against it tight enough.  It's not due to a weak motor.  Even if you get it tight enough, it will loosen later and awkward to adjust. Get an MK5.  If not, then print out and build a  brutstruder from thinkiverse.  The reason why MK5 and the brutstruder are good designs is because of the screw tightening feature.  Also, if your going to stick with the brass barrel/nichrome wire setup then go on Makergear.com and purchase their setup.

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From: "danie...@yahoo.com.ar" <danie...@yahoo.com.ar>
To: MakerBot Operators <make...@googlegroups.com>
Sent: Tue, October 19, 2010 9:00:09 PM
Subject: [MakerBot] Extruder (MK4) issues

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[Chris Connors]

This looks very similar to the problem I had a few weeks ago. If your
filiment is getting all burned up, then your thermistor is likely
reading an accurate temp at 255 C. Soaking in Acetone will soften it a
bit, but you will still have some caked onto the surfaces of the hot
end. Here is the photoset with links to the previous thread examining
the problem and video of the solution I came up with:
http://www.flickr.com/photos/connors934/sets/72157625078352430/

What I think worked the best for me was to drill out the extruder
orifice with a very small drill bit. I purchased the bit set and a
handle for about 5 bucks from Harbor Freight. Since the repair, mine
has been working for at least five hours of printing, not a huge
amount of time, but no problems so far.

On Oct 20, 12:00 am, "danieli...@yahoo.com.ar"

[Emerson Suguimoto]

Similar to my mk4 extruder, I´m really disappointed with mk4. It skips the filament everytime.
I´ve followed every step from the wiki, i also ordered a mk5 gear, but it still doesn´t work properlly :(.
If my idler wheel is heavily tight or not, it just doesnt work.

I could not even print the calibration cube yet. I´ve ordered a compact plastruder and i´m gonna toss mk4 on the carbage can.

Daniel, I´m pretty sure that your problem is the idler wheel and not a clogged hot end. Try to swap its side in the plastruder.

good luck.

2010/10/20 Chris Connors <conno...@gmail.com>

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[ddurant]

> Daniel, I´m pretty sure that your problem is the idler wheel and not a
> clogged hot end. Try to swap its side in the plastruder.

That's definitely the weak point on the MK4.. Getting an extra wide
idler or an aluminum one (ebay has some) will make your life a lot
easier. That and the MK5 gear from the makerbot store. Total should be
under $25, plus shipping.

On Oct 20, 9:03 am, Emerson Suguimoto <emerson.suguim...@gmail.com>
wrote:

> Similar to my mk4 extruder, I´m really disappointed with mk4. It skips the
> filament everytime.
> I´ve followed every step from the wiki, i also ordered a mk5 gear, but it
> still doesn´t work properlly :(.
> If my idler wheel is heavily tight or not, it just doesnt work.
>
> I could not even print the calibration cube yet. I´ve ordered a compact
> plastruder and i´m gonna toss mk4 on the carbage can.
>
> Daniel, I´m pretty sure that your problem is the idler wheel and not a
> clogged hot end. Try to swap its side in the plastruder.
>
> good luck.
>

> 2010/10/20 Chris Connors <connors...@gmail.com>

> > makerbot+u...@googlegroups.com<makerbot%2Bunsubscribe@googlegroups.c­om>
> > .

> > For more options, visit this group at

> >http://groups.google.com/group/makerbot?hl=en.- Hide quoted text -
>
> - Show quoted text -

[colehard]

I agree with ddurant, it seems very likely that the issue is the
drive. It is coming out and it is burnt at 255 meaning your
thermistor/heating appear ok. I think you may not realize how hard
you have to push to get filament to extrude - there is no way I could
push mine through with it balanced on its side like that. If my Mk4
has been off for a few days I always have to set the nozzle to 230
degrees and spend a couple of minutes going backward and forward with
the extruder motor with me pushing VERY hard on the filament in the
forward direction to get it to start extruding. After I have done
this it will run fine for the next few days until I give it a multi-
day rest (doesn't really make sense to me that 3 days rest would let
it set harder than 12 hours rest but it does.) I am running the stock
gear and single acrylic idler until my work around starts failing.

Upgrading to make the drive better certainly can't hurt - let us know
how you get on.

> > > makerbot+u...@googlegroups.com<makerbot%2Bunsubscr...@googlegroups.c­om>

> > > .
> > > For more options, visit this group at

> > >http://groups.google.com/group/makerbot?hl=en.-Hide quoted text -

[wurp]

On Oct 20, 1:03 pm, Emerson Suguimoto <emerson.suguim...@gmail.com>
wrote:

> Similar to my mk4 extruder, I´m really disappointed with mk4. It skips the
> filament everytime.
> I´ve followed every step from the wiki, i also ordered a mk5 gear, but it
> still doesn´t work properlly :(.
> If my idler wheel is heavily tight or not, it just doesnt work.

I had the same trouble. I upgraded to the mk5 gear and also the 4.5
mm idler wheel from MakerGear. That, plus another careful adjustment
session, got my filament pushing through consistently (even on an
otherwise Mk4 extruder).

I also ended up getting a modular hot end from MakerGear, but that was
because my insulator was leaking and it ended up pushing the heater
barrel out of the insulator (breaking the insulator and the insulator
retainer in the process). The new PEEK insulator took care of that,
and the collar style heater has made working on the hot end easier in
general.

If it were me, I would try to get your Mk4 working well enough with a
4.5 mm idler wheel to print a Printruder II or Brutstruder rather than
buy the compact plastruder. But that's just because I'm a cheap
bastard.

Bobby

[James McCracken]

Ditto on everything bobby said, minus the cheap bastard part.

Mk5 gear, large idler wheel, makergear hot end... I tinkered enough
without these upgrades, I know they were NECESSARY to get my Mk4
running reliably for more than 30 minutes or so...

The makergear and ebay idler wheels have matching grooves to guide the
filament through. You can really clamp them down on the calibration
rod that came with your Mk5 gear - I literally had to turn my motor on
reverse to pull it out. Haven't had a filament strip or skip since...

I also had the bulging insulator issue... the makergear hot ends are
a lot more stable IMHO...

[Ethan Dicks]

On 10/20/10, colehard <jasi...@gmail.com> wrote:
> I agree with ddurant, it seems very likely that the issue is the
> drive. It is coming out and it is burnt at 255 meaning your
> thermistor/heating appear ok.

If you are getting charring and popping, I'd say a) you really are
heating up the barrel, and b) you are running too hot - probably
because you are compensating for a problem elsewhere.

> I think you may not realize how hard you have to push to get filament to extrude

Yes and no. One thing I did while assembling #330 that was discussed
at length on the list last year (but seems to be not as commonly
spoken of recently) was to ensure I had a smooth transition between
the PFTE barrier and the top of the brass barrel. I did many test
fits before I installed the 0.5mm nozzle and wrapped my heater core -
I found that threading the brass into the PFTE very loosely (too
loosely for real use) gave me a very smooth even transition of the
filament down the PFTE and into the brass. If I gave the brass even a
two-finger twisting to seat it, the mating surface of the PFTE would
bulge inward slightly and I could feel the lip. If I tightened it
with any force, it was almost impossible for me to manually feed the
filament through the PFTE-brass transition. That interface should be
as low-impact as possible.

To "fix" the problem, I lightly tightened the brass into the PFTE then
manually scraped out the inside bulge with a drill bit. After I did
that, the filament smoothly transition from one part of the feed
assembly to the other. I have had fiddly issues with the MK4 idler
wheel (like everyone else), but not the catastrophic issues some
people have reported. I didn't even break the original insulation
retainer until a couple of months ago when I had numerous problems
caused by trying to run the Makerbot in the same shop as an active arc
welder (summary: don't try this at home). Fortunately, I had spares
made well in advance and now have a 6mm retainer installed.

I believe my thermistor to be reasonably well calibrated. I print ABS
with settings around 220-225C and have no problems emitting yards of
0.5mm "noodle" prior to printing.

If you already have charred ABS in your hot end, it's probably worth
trying to get it out before spending more time trying to shove fresh
filament down a rough or partially-blocked barrel.

-ethan

[Nick Ames]

No one has mentioned this, but it seems to me that the 6.5 V reading on
the 5V rail is probably the cause of the problem. 6.5V is beyond the
absolute maximum voltage of the atmega microcontroller, and could easily
be the cause of your problem (until the chip burns out).

If you aren't sure if your multimeter is accurate, try measuring the
main power supply 5V rail. It should be the red wire on any of the
four-pin molex connectors.

[danie...@yahoo.com.ar]

Hello again, thank you very much for all the suggestions. A little
update:

Today i bought a .5 mm drill bit and drilled the nozzle tip (thanks
chris). The hot filament is now a bit thicker but the feedrate has
increased a little.
Regarding the idler wheel i think it has become now my biggest
problem. The wheel gets stuck between the inmediate upper acrylic
layer and the filament passing trough the gear. with the wheel in that
position the drive mechanism cant push the filament with sufficient
strenght. I think i should build a thicker idler wheel (perhaps 4.5 mm
acrylic, or aluminum).
I also considered upgrading the system to an MK5 or compact plastruder
(suggestions?) altough they are very expensive adding the fact that i
live in Argentina.

Regarding the 5V rail: I measured it again with another multimeter and
i keep getting the same read. I also get 5V on the molex connectors.
Should i be worried with this reading?

Thank you very much!
Daniel

[Nick Ames]

On 10/20/2010 08:04 PM, danie...@yahoo.com.ar wrote:
> Regarding the 5V rail: I measured it again with another multimeter and
> i keep getting the same read. I also get 5V on the molex connectors.
> Should i be worried with this reading?
>
>

Yes. Getting 6.5V on the output of the 7805 means the regulator is
broken. If I were you I would look into replacing it; it's an extremely
common part, so hopefully you can find one locally. Or, you could
desolder the defective one and patch in 5V from the main power supply.

[Zip Zap]

Anything but the MK4.  You can print the brutstruder from Thingiverse.  Of course, you'll have to push down on the filament with your MK4 when printing.

---

From: "danie...@yahoo.com.ar" <danie...@yahoo.com.ar>
To: MakerBot Operators <make...@googlegroups.com>

Sent: Wed, October 20, 2010 8:04:01 PM
Subject: [MakerBot] Re: Extruder (MK4) issues

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[Bryan Silversten]

Try this... If you have a lathe put the idler wheel in your chuck with the teeth turned outward.(have to remove your bearing) Then use a cut off tool (or equivalent) at a 45deg angle to cut a slight V in the DEAD CENTER of the idler wheel. (I do mean slight -> depth less than 1/5th the thickness of the filament) Then put it back together.  I have had zero problems with my mk4. This mod using a single idler wheel automatically centers the filament. You can use less pressure on the idler wheel and get rock solid performance using this method.. Hope this helps.