Duet/RRF Big printing problems

pro3d

Also did you see this thread? looks like identical issues
https://forum.duet3d.com/topic/3998/retraction-issues-800mm-bowden-bondtech-bmg

pro3d

@phaedrux

Thermistor is what comes with the e3d V6 - Semitec GT something and configured with the online tool
Edit: M305 P1 T100000 B4388 C7.060000e-8 R4700

Phaedrux

@pro3d said in Duet/RRF Big printing problems:

@phaedrux

Also did you see this thread? looks like identical issues
https://forum.duet3d.com/topic/3998/retraction-issues-800mm-bowden-bondtech-bmg

Yes, I saw that thread.

Did you try the retraction tuning as David suggested in the thread?

dc42 ADMINISTRATORS 5 Feb 2018, 06:26
Some suggestions:

Are the blobs are occurring immediately before retractions and travel moves? if so then they are probably mostly retraction-related.
Increase extruder max speed in M203 to 3600 (i.e. 60mm/sec), and configure 60mm/sec retraction in speed in your slicer, or in M208 if you use firmware retraction
800mm is a long Bowden tube, and you will need to tune your retraction settings and pressure advance well to get good results
What retraction amounts have you tried? With no pressure advance applied and an 800mm Bowden tube I would expect you to need around 9mm retraction. Less if you use Capricorn tubing and/or pressure advance.
With a Bowden tube that long, Capricorn tubing may help significantly.
It's probably best to tune retraction using the Lite 6 first, because if you use too much retraction with the all-metal V6 you are likely to get an extruder blockage. When you have found a good combination of pressure advance and minimum needed retraction, you can try the same combination on the V6.
I suggest initially you use no pressure advance, to find the minimum retraction you need to avoid getting zits just before travel moves. When you have found that value, add pressure advance (try 0.2) and see how much you can reduce retraction before the zits reappear.
HTH David

It also looks like someone commented that switch to capricorn tubing helped greatly for such a long bowden tube.

Phaedrux

@pro3d said in Duet/RRF Big printing problems:

@phaedrux

Thermistor is what comes with the e3d V6 - Semitec GT something and configured with the online tool
Edit: M305 P1 T100000 B4388 C7.060000e-8 R4700

That looks correct. Now have you run a PID tune on the hotend?

pro3d

@phaedrux

Yes PID has been applied

As of the tip in the thread I have not been digging to much into it. I disabled PA now to start over again so I will take a closer look. The tube I have should work just fine as for X1000 hours before I think? It is a 1.9mm tube I like to use as the Capricorn can be to tight for my taste

What I dont understand is that the proven settings from marlin will not work with rrf - like the retraction and speed and temp and everything. Does this have to do with that rrf use relative extrusion? Can I turn this off?

pro3d

@phaedrux

I will try to change the hotend. I mistake it has some issues although new

Phaedrux

@pro3d said in Duet/RRF Big printing problems:

Does this have to do with that rrf use relative extrusion? Can I turn this off?

Yes you can switch to absolute extrusion if you like. You can change the command in the config.g and also the slicer.

Phaedrux

Just looking at the differences between your Marlin and RepRap configurations.

E acceleration Marlin=10000mm/s^2, RepRap=1000mm/s^2
E Jerk Marlin=15mm/s, RepRap=10mm/2

This would greatly slow down your retractions.

So here is my suggestions for what to change and test next.

M556 E1200
M201 E10000

Set retraction to 9mm at 60mm/s with pressure advance off.

Print a retraction test model, every 15 layers increase pressure advance from the console by 0.05.

dc42

Your thermistor config is incorrect, it should be B4725. See https://e3d-online.dozuki.com/Guide/V6+RepRap+Firmware+Configuration/26?lang=en. That means you have been printing at the wrong temperature. HTH David

pro3d

@dc42

Thanks - Does this mean the config online tool gives another value than what it should have?

Phaedrux

@dc42 said in Duet/RRF Big printing problems:

Your thermistor config is incorrect, it should be B4725. See https://e3d-online.dozuki.com/Guide/V6+RepRap+Firmware+Configuration/26?lang=en. That means you have been printing at the wrong temperature. HTH David

The configurator gives M305 P1 T100000 B4388 C7.060000e-8 R4700 when The E3D Semitek-104 GT2 option is selected. It looks like that may have been correct for firmware versions older than 1.16, but the configurator seems to have not been updated to give the new values for firmware versions 1.17 and above.

I recently swapped a burnt out PT100 sensor for the E3D Semitek GT2 and used the values from the configurator for it, oddly enough I didn't notice any temperature related issues for the week or so I used it while waiting for a replacement PT100.

pro3d

@phaedrux

Nice catch about the E accel - I did not ever change this at any point in Marlin so I did not know its value. I will test your recommendations

pro3d

@phaedrux

How ever max accel is overided by these values in Marlin no?

#define DEFAULT_ACCELERATION 1000 // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION 2000 // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION 1000 // X, Y, Z acceleration for travel (non printing) moves

Phaedrux

@pro3d That would depend on how the slicer is sending acceleration values, if you are using those settings.

Still, the file you posted has higher limits set than 1000,2000

/**
 * Default Acceleration (change/s) change = mm/s
 * Override with M204
 *
 *   M204 P    Acceleration
 *   M204 R    Retract Acceleration
 *   M204 T    Travel Acceleration
 */
#define DEFAULT_ACCELERATION          1500    // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION   1500    // X, Y, Z acceleration for travel (non printing) moves

pro3d

@phaedrux

I dont know how slicer sends values I am sorry

Phaedrux

Regardless of what the differences in settings between marlin and reprep, the issue as presented is retraction related. And the solution to reduce the blobs at the layer seam is to try and make the extruder more responsive. Faster retractions in combination with pressure advance to reduce the need for retraction distance.

Phaedrux

@pro3d said in Duet/RRF Big printing problems:

@phaedrux

I dont know how slicer sends values I am sorry

For Cura you'd have to specifically enable it. By default the accel and jerk settings are hidden.

In RepRap the M204 command works differently than in Marlin though. In Marlin it controls acceleration for Print moves, Travel Moves, and retraction. Where as in RepRap it's only Print and Travel moves. Retraction acceleration is dictated by M201.

pro3d

Update - Progress is present

So I changed 3 things and I know this is stupid but at least it shows progress. It might just have been the thermistor but I need to run more tests later today

I changed thermistor to B4725
Upped E-accel from 1000 to 3000
Upped E-jerk from 600 to 900

PETG test at same model and filament as before

dc42

@pro3d, I'm glad you are making progress. It sounds that the online configurator is setting the incorrect thermistor B value when you choose the Semitec thermistor. I'm sorry this has caused you so much trouble. We'll get it fixed.

deckingman

If you take a gander at Semitec specs, the GT-2 is now superseded by the NT-4. http://atcsemitec.co.uk/product-category/glass-thermistors/

The 104NT-4 has a quoted B value of either 4267 or 4390 depending on type https://atcsemitec.co.uk/wp-content/uploads/2019/01/Semitec-NT-4-Glass-NTC-Thermistor.pdf

But what is interesting is that the resistance tolerance is quoted as +/-3% and the B value tolerance is +/- 2%.

Which brings me back to what I said earlier that there is no substitute to finding what temperature actually prints best. e.g. if you have one machine that prints fine at 200 deg C and the thermistor is at one end of the tolerance band, then the actual temperature could be 3% or 6 degrees lower so 194 deg C. A second machine using the same thermistor but at other end of the tolerance band might actually print 6 degrees higher so setting 200 deg C could result in an actual temperature of 206 deg C which would likely lead to blobs and stringing. That's an extreme example but I believe it serves to illustrate the point I have been trying to make.