Clear the insulator of ABS

[Ryan]

Just had my second plastic pushing through the ptfe insulator crash
(second of that specific type). It looks like the insulator may be
more or less intact, but plastic has sealed the bottom of it off.
What is the best way to clear this in order to get back operating? I
realized I can order a new one, but since this is my second one I
wanted to see if there is any good ways to refurb it. I know abs has
a lower melting temp obviously, but I'm also reading people try
acetone. I may be willing to do that as long as it doesn't eat the
ptfe too.

Once I get a valid insulator I'll attempt the m6 nut mod to get in
front of this issue.

As an aside, has anyone got good results running below 220 with ABS to
reduce heating up the barrel?

[Rick Pollack]

Ryan -

If you can't push or pull out the ABS blocking the insulator then you can always heat up (using the extruder controller board) the brass threaded piece and then grab it with pliers and press it against the blockage. Once it heats up push out the softened ABS.

I've run as low at 205C but I typically run at 215C.

Rick

[Peter Charles]

Ryan-

PTFE (Teflon) is extremely resistant to acetone.  ABS is fairly soluble in it, so you can dissolve the ABS clog with acetone.  Just beware that acetone has a very high vapor pressure, and a very low flash point.  And don't dump it down the drain!

We tried the M6 nut mod, but still got molten ABS escaping through the threads of the connection between the heater barrel and the PTFE insulator.  I am considering wrapping the threads of the brass with PTFE pipe sealing tape plus the M6 nut mod, or switching to an alumina ceramic insulator barrel.

peter

[Rick Pollack]

Peter -

Before you do what you are considering...try cooling down the barrel. Run at a lower temp (what temp are you using?) and/or use less ceramic insulating tape. The problems you are encountering are a symptom of running too hot.

Rick

[Ryan]

I'm soaking them in acetone now. This seems to work better than
cleaning the barrel with it did. Thanks for the advice on acetone
handling.

I'd agree most of these issues can be attributed to temperature. I
had molten plastic far up the barrel each time. Hopefully removing
the insulator will help with that.

Ryan

On Nov 1, 8:30 pm, Rick Pollack <rick.poll...@gmail.com> wrote:
> Peter -
>
> Before you do what you are considering...try cooling down the barrel. Run at
> a lower temp (what temp are you using?) and/or use less ceramic insulating
> tape. The problems you are encountering are a symptom of running too hot.
>
> Rick
>

> On Sun, Nov 1, 2009 at 8:05 PM, Peter Charles <petercchar...@gmail.com>wrote:
>
> > Ryan-
>
> > PTFE (Teflon) is extremely resistant to acetone.  ABS is fairly soluble in
> > it, so you can dissolve the ABS clog with acetone.  Just beware that acetone
> > has a very high vapor pressure, and a very low flash point.  And don't dump
> > it down the drain!
>
> > We tried the M6 nut mod, but still got molten ABS escaping through the
> > threads of the connection between the heater barrel and the PTFE insulator.
> > I am considering wrapping the threads of the brass with PTFE pipe sealing
> > tape plus the M6 nut mod, or switching to an alumina ceramic insulator
> > barrel.
>
> > peter
>

[Peter Charles]

Rick-

To get a decent feed rate we have been running the barrel at 235 to 240 Deg C.  Temps lower than that have produced extremely slow flow rates.  We will try running it cooler again, just to verify, though.

On another note- I am switching to alumina ceramic lined with PTFE tubing for a different design anyway...the dreaded cryobiobot is on the way...

;)


peter

[Rick Pollack]

Not sure what a cyrobiobot is but it sounds interesting!! Post pictures :)

Being forced to run at ~240C is also a symptom of running too hot...it is the brute force extrusion method...get rid of some of that heat going up the pipe and I expect you will be able to run in the 215C to 220 range without plastic backing into the PTFE...

Rick

[Rick Pollack]

Peter -

I posted a short video of my 0.5mm (nozzle) plastruder printing. It is running at 210C on v1.6 extruder firmware (PID controlled) and a 255 flowrate. The filament is tensioned at 2.5mm (not 2mm) and there is not bearing on the motor.

Just want to illustrate that when you find the sweet-spot configuration for your plastruder it runs very well at lower temperatures, there are no clogging issues and tension really isn't even an issue.

Rick

[Peter Charles]

Rick-

Thanks!  I think we have been trying to hit the sweet spot by running as hot as possible, as fast as possible.  Perhaps not the nest way to do things...

We will experiment more with lower temps today.

The CryoBioBot is an experimental device we are working on for a specific biomedical application.  There is a ton more engineering that needs to go into it before we have any results, but I will be posting pics and vids as soon as they are available.

peter

[R. Mark Adams]

Rick-

We are finding that we need to run at 240deg to get printing, and even
that is sometimes a bit spotty. What specific suggestions do you have
for getting the print temp down into a more manageable range? Just
backing the ceramic tape off a bit? other suggestions? Thanks for
the help! We are trying to get into a "production: mode so every hint
would be very welcome.

Thanks-
Mark

On Nov 1, 10:08 pm, Rick Pollack <rick.poll...@gmail.com> wrote:
> Not sure what a cyrobiobot is but it sounds interesting!! Post pictures :)
>
> Being forced to run at ~240C is also a symptom of running too hot...it is
> the brute force extrusion method...get rid of some of that heat going up the
> pipe and I expect you will be able to run in the 215C to 220 range without
> plastic backing into the PTFE...
>
> Rick
>

> On Sun, Nov 1, 2009 at 9:14 PM, Peter Charles <petercchar...@gmail.com>wrote:
>
> > Rick-
>
> > To get a decent feed rate we have been running the barrel at 235 to 240 Deg
> > C.  Temps lower than that have produced extremely slow flow rates.  We will
> > try running it cooler again, just to verify, though.
>
> > On another note- I am switching to alumina ceramic lined with PTFE tubing
> > for a different design anyway...the dreaded cryobiobot is on the way...
>
> > ;)
>
> > peter
>

> > On Sun, Nov 1, 2009 at 9:30 PM, Rick Pollack <rick.poll...@gmail.com>wrote:
>
> >> Peter -
>
> >> Before you do what you are considering...try cooling down the barrel. Run
> >> at a lower temp (what temp are you using?) and/or use less ceramic
> >> insulating tape. The problems you are encountering are a symptom of running
> >> too hot.
>
> >> Rick
>

> >> On Sun, Nov 1, 2009 at 8:05 PM, Peter Charles <petercchar...@gmail.com>wrote:
>
> >>> Ryan-
>
> >>> PTFE (Teflon) is extremely resistant to acetone.  ABS is fairly soluble
> >>> in it, so you can dissolve the ABS clog with acetone.  Just beware that
> >>> acetone has a very high vapor pressure, and a very low flash point.  And
> >>> don't dump it down the drain!
>
> >>> We tried the M6 nut mod, but still got molten ABS escaping through the
> >>> threads of the connection between the heater barrel and the PTFE insulator.
> >>> I am considering wrapping the threads of the brass with PTFE pipe sealing
> >>> tape plus the M6 nut mod, or switching to an alumina ceramic insulator
> >>> barrel.
>
> >>> peter
>

[Andrew Plumb]

Mark,

When you print, do you start right from cold or do you manually warm
things up from the control panel first?

I always open the control panel, warm up to 220C and pump some ABS
through at 255 at first power-up. After that extrusion I set the
heater temperature target back down to ~20C and let the sensed
temperature drop below 160C before beginning my first print of the
session.

Also, remember to close the control panel GUI before starting any
build. Don't know if it's still an issue with latest firmware+RepG
but all the extra temperature-sense related comms traffic gave people
grief in the past.

Andrew.

--

"The future is already here. It's just not very evenly distributed"
-- William Gibson

[Rick Pollack]

Peter - when you say "as fast as possible" what speed are you using? (255 is the fastest) I look forward to more info on the cyrobiobot...all kinds of cool stuff going on!!

Mark - my guess is that the plastic is melting too far up the tube and by using a higher temp you are using brute force to get it to flow. What I would do is totally clean out the brass tube and nozzle - some people here use acetone, I use a plumbers torch (the Bre method). If there is plastic in the PTFE lining, I'd probably leave it for now as long as it is not blocking anything.

Then, re-wrap with 200mm of fresh nichrome. I start 3 or 4 threads above the nozzle, wrap down with the thread, do two loops around the nozzle/rod joint and then go back up so there is - more or less - a two layer wrap. (Mine it not perfect - photo here)  I place the thermistor within a few mm of the tip. Then I test it just like that...no wrap and just enough kapton to keep everything secure (you don't want the thermistor to come loose while heating!!)  At this point, slowly heat it to 220C (I heat it slowly in case I've made a mistake - short or something comes loose). If it works and works well, then you can make adjustments like adding ceramic tape.

Another thing - are you using a double idler wheel? If not and you don't have an extra, send me your address and I will drop a 4.5mm idler wheel in the mail. The extruder in the video has either a double idler wheel (5mm) or a 4.5mm idler wheel. And, as you can see in the video, I also remove the outer flange on the idler pulley. That way (if you don't have a bearing on) you can see exactly what is going on where the filament meets the wheel.

Since I am frequently removing and adjusting the extruders...here are a few efficiency tips:

- I use half the dinos (back half) - they are still plenty stable for printing but make it a lot easier to disassemble the upper assembly. You don't have to take the dinos off and put them back on. That gets to be a total pain after a few iterations.

- There are two acrylic layers (feet) for the dinos that are supposed to be glued together. I pried those apart and leave one layer screwed into the Z platform. This way you can just remove your extruder without unscrewing anything. It still works fine for printing. Also, if your print nozzle bumps into some hard plastic...the extruder will lift but not try and take the Z platform with it.

- mount the extruder controller board off to one side so you can see what is going on with the pulley and filament.

Finally, when I print all I do is heat up the extruder to operating temp (215C or so) for a couple of minutes and then print. Also, I don't remove the filament when I'm done - I just shut down repg and turn off the bot. But I do back out the filament when it is about to run out (rather than chase one piece with another - too many problems). And, when inserting a piece of filament it is always fresh, I don't use backed out pieces (those go into the filament recycle bin). This is what works consistently for me...

Hope this helps...
Rick

[Rick Pollack]

Here are a couple of photos to illustrate some of the points in the previous comment...
Standard plastruder configuration - front
Standard plastruder configuration - back

[wulfdesign]

thanks for all the info...
I may try and reduce my operation temperature to have this not happen
again.
(been going at 220 deg C)

I'm having a similar problem.

I was having the 'Blob' issue with the print 'pausing'
and had to cancel the a 'build'

however I forgot to go into the control panel afterward and reduce the
temp setting
and left it on while troubleshooting the pausing issue online.

I fixed the pausing issue (version 1.4 on mobo instead of 1.6)
but then ABS started to leak out at the Teflon junction on the next
print.
and now the ABS sticks in the barrel as well.

I had to go out and get some 10mm wrenches to fit the nut.
I already put a nut on the barrel as a precautionary measure but
I don't think I tightened it and/or the barrel down enough against the
Teflon
as well as letting it heat too long (therefor the leak).

So it looks like I need to heat up the whole unit to get it to
unfreeze and back it out of the Teflon.
(I'm guessing channel locks on the Teflon and 10mm wrench on the nut
will do the trick)

hopefully I can get to that in the next day or two and salvage the
Teflon/Barrel combo.

I'll post how it went and if the unit is salvageable.

I'll cross this bridge when I come to it but...
also I was thinking that if the threading needed an little extra help
cause it got messed up I could wrap
the heat barrel with some Teflon Tape (plumbers tape) to help seal up
the threads?
anyone have any luck with that?
( I thought I saw someones post that they used it for insulating the
heat barrel from shorts)

-L

On Nov 1, 4:06 pm, Rick Pollack <rick.poll...@gmail.com> wrote:
> Ryan -
>
> If you can't push or pull out the ABS blocking the insulator then you can
> always heat up (using the extruder controller board) the brass threaded
> piece and then grab it with pliers and press it against the blockage. Once
> it heats up push out the softened ABS.
>
> I've run as low at 205C but I typically run at 215C.
>
> Rick
>