1 Topic by spapadim (edited by spapadim 2013-06-20 18:31:42)

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Topic: Extrusion temperature guidelines / calibration ?

Apologies if this has been answered before, but couldn't find anything.  Yesterday Ian said:

On a Solidoodle PLA should be printed at around 180.  Most printers have the thermistor in the heating block so their temperature readings are higher than the Solidoodle which has the thermistor taped to the nozzle.  So when a vendor says to run their filament at 230 that generally equates to about 195 on the Soidoodle.

I should be getting my first spool of PLA today, from MakerGeeks, which recommends an extrusion temperature of 170-190C (edit: but their picture says 220C on a RepRap??).

1. Are they just playing safe with their numbers?  If not, how should I adapt Ian's recommendation, to choose what temperature to start with? I would guess scale by 195/230?  But 145-160C seems awfully low.  Then again ABS keeps flowing even at ~170C (at least for up to half a minute; I occasionally get such dips with my installed fan).  BTW, if it matters, my extruder has a metal heating block (no ceramic/nichrome?), but thermistor is still on outside.

2. More generally, what tests/calibrations can I do for extrusion temperature? Google turned up this (and variations thereof) -- anything else I can try, or any pictures to help?  What, if anything, non-obvious should I take care not to do while running such a test?  I'm a little wary of running half-unmolten filament through the nozzle for more than a few seconds (as this seems to suggest); or am I being paranoid?

TIA!

2 Reply by LMY

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Re: Extrusion temperature guidelines / calibration ?

Hi there!

I'm starting to calibrate our Solidoodle & Slic3r, printing with ABS. I followed Triffid Hunter's guide on calibrating extruder temperature as well and it worked well for me. I printed a 50mm tower (Thingiverse thing #5573) starting with an extruder temp of 200C and decreasing by 5C every few layers. Eventually the filament started "skipping" - you'll see gaps in the flow as it is printing. This transition was quite obvious in my case, so I only really ran the half-molten filament for less than a second. I then increased the temp again to print a few more layers nicely, also as a way to 'flush' out more filament. Didn't run into problems with my nozzle after.

If you are using Solidoodle, I read on their FAQ page that extruder temp should stay below 210C, so I'd start there as max temp.

Hope that helps!

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3 Reply by LMY

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Re: Extrusion temperature guidelines / calibration ?

Sorry the pic isn't very clear - but that was the tower that I printed, and the gap in the middle was where I printed around 170C and the flow was no longer smooth. Both ends of the tower were printed around 200C.

4 Reply by adrian

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Re: Extrusion temperature guidelines / calibration ?

I print certain PLA's at 155°C ..

Just use the rule of thumb that take a quoted reprap temp and subtract 30-35°C off of that quoted temp. This applies to all the current Solidoodle OEM Hotends due to their Thermistor placement relative to the meltzone...

5 Reply by spapadim

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Re: Extrusion temperature guidelines / calibration ?

Thanks everyone! PLA arrived, I'll try it over weekend. Maybe I'll use this as an excuse to print an Mk4 mount first (just in case it all goes south smile. Pic is helpful, thanks! (And wow, my nozzle temp drops from 195 to 170 or under whenever my fan turns on, for about 20sec, never got anything like this! Interesting..)

6 Reply by adrian

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Re: Extrusion temperature guidelines / calibration ?

Search for PID Tuning to fix the extruder temp issue

7 Reply by spapadim

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Re: Extrusion temperature guidelines / calibration ?

Thanks, tried that some time ago (with and without fan running -- at 190 target, default number of cycles), it helped, but I still have dips.  I'll do another round of tuning, esp since with PLA I get a +/- 5C oscillation around setpoint with fan on (which I don't with ABS).  Interestingly, I observed that if I'm not extruding, then fan does not affect temperature. Dips and oscillations happen only when extruding.  Which makes sense, I guess (system response changes), but that would suggest a different set of PID parameters for fan on vs off, for PLA vs ABS, even for different filament colors.  OTOH I haven't seen this mentioned by anyone, so I'm wondering if I'm doing something else wrong.  Guess I'll need to investigate more.

8 Reply by dkeeling728

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Re: Extrusion temperature guidelines / calibration ?

spapadim wrote:

Thanks everyone! PLA arrived, I'll try it over weekend. Maybe I'll use this as an excuse to print an Mk4 mount first (just in case it all goes south smile. Pic is helpful, thanks! (And wow, my nozzle temp drops from 195 to 170 or under whenever my fan turns on, for about 20sec, never got anything like this! Interesting..)

yeah, definitely print the mk4 in ABS before you switch to PLA. just incase you get an extruder jam while retuning your settings for PLA. the jigsaw that comes with the SD is notorious for breaking with the slightest tampering (even just unscrewing screws. lol).

Lawsy should license his design to the SD guys for shipping with their printers. lol

9 Reply by adrian (edited by adrian 2013-06-24 08:32:03)

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Re: Extrusion temperature guidelines / calibration ?

dkeeling728 wrote:

Lawsy should license his design to the SD guys for shipping with their printers. lol

He already has - to anyone that wants it - all they need to do is say "And now using Lawsy's Jigsaw Replacement":

Thingiverse page for Jigsaw Replacement wrote:

Solidoodle Jigsaw Replacement Extruder mk4 by lawsy is licensed under the Attribution - Creative Commons license.

10 Reply by spapadim

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Re: Extrusion temperature guidelines / calibration ?

Printed, but didn't use yet (almost: initial tests went mostly fine, then next morning I think I got a cold clog but was able to unclog by finger-feeding some soft ABS at slightly lowered temp - I hope, we'll see..).

Btw, any way to extrude while PID tuning? Apparently not an official feature (yet: https://github.com/ErikZalm/Marlin/issues/204 -- at least I know I'm not imagining things? smile, but was wondering if it can be done (eg some script or sth).

11 Reply by adrian (edited by adrian 2013-06-24 13:48:22)

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Re: Extrusion temperature guidelines / calibration ?

spapadim wrote:

Printed, but didn't use yet (almost: initial tests went mostly fine, then next morning I think I got a cold clog but was able to unclog by finger-feeding some soft ABS at slightly lowered temp - I hope, we'll see..).

Btw, any way to extrude while PID tuning? Apparently not an official feature (yet: https://github.com/ErikZalm/Marlin/issues/204 -- at least I know I'm not imagining things? smile, but was wondering if it can be done (eg some script or sth).

Its a feature that doesn't even have code yet, not just not official wink

In practice, across a variety of hot-ends, I must say I have not seen an issue with the Auto-PID generated PID and PID whilst extrusion is in operation.

I personally think its a solution looking for a problem.... *shrug*.. but beauty of opensource someone will eventually code it in I'm sure (but its been 11mths so far with not even a response.. so don't go holding your breath and probably reaffirms the solution looking for a problem angle.....)

12 Reply by spapadim (edited by spapadim 2013-06-24 14:08:19)

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Re: Extrusion temperature guidelines / calibration ?

Yeah, exactly.. but I'm out of ideas on what to try next to stabilize temp, so ill settle with one that's been shelved for 11 mo (ignoring the hint, I guess? smile.

Its not an issue if I keep fan running all the time, which is my "workaround" for now, but it can be a problem if I let slic3r turn it on and off.

Edit: so far I've reprinted the shroud to avoid melting, added extra thermal tape, ran PID tuning with fan on and off at various setpoints for up to 5 cycles, but still... any ideas welcome. I plan to revisit if i still have issues after building enclosure.

adrian wrote:
spapadim wrote:

Printed, but didn't use yet (almost: initial tests went mostly fine, then next morning I think I got a cold clog but was able to unclog by finger-feeding some soft ABS at slightly lowered temp - I hope, we'll see..).

Btw, any way to extrude while PID tuning? Apparently not an official feature (yet: https://github.com/ErikZalm/Marlin/issues/204 -- at least I know I'm not imagining things? smile, but was wondering if it can be done (eg some script or sth).

Its a feature that doesn't even have code yet, not just not official wink

In practice, across a variety of hot-ends, I must say I have not seen an issue with the Auto-PID generated PID and PID whilst extrusion is in operation.

I personally think its a solution looking for a problem.... *shrug*.. but beauty of opensource someone will eventually code it in I'm sure (but its been 11mths so far with not even a response.. so don't go holding your breath and probably reaffirms the solution looking for a problem angle.....)

13 Reply by spapadim

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Re: Extrusion temperature guidelines / calibration ?

FWIW, here is what my extruder temp looks like (after re-tuning, with fan on -- back to ABS for this).  Setpoint is 195.  You can see where the fan turns on and what happens after.  Is this typical (i.e., am I chasing down non-existent problems)?

The main reason I'm still stuck on this is that, re-convergence to setpoint takes about 2min, so if I allow slic3r to turn the fan on and off (e.g., just during bridges, or small layers) and there's a quick succession of on-off-on (with say, the last on at around the -13 to -14min mark on attached curve), then temp occasionally crashes.  But does it really matter if I just leave the fan on all the time?

TIA!

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