Retraction and Firmware Help

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08-10-2015, 06:34 PM
BLKKROW

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Retraction and Firmware Help

I am looking for help with retraction as most objects I print are cylindrical and with retraction issues the part ends up looking like trash.

I am slicing with Simplify 3D 3.0.1 and have a lot of settings but the best results have been with the following:

Retraction Distance: 2.5mm
Extra Restart Distance 0.00mm
Vertical Lift 0.00mm
Retraction Speed 15mm/s
Coasting Distance 0.1mm - 0.2mm
Wipe Nozzle - Off

These settings produce the vein that you can see in the attachments. I have even tried the following settings:

Retraction Distance 2.00mm
Extra Restart Distance 0.00mm
Vertical Lift 0.00mm
Retraction Speed 12mm/s
Coasting Distance 0.5mm - 0.8mm
Wipe Nozzle - Off

My thought was to attempt to relief pressure by coasting more, but this provides the same results. One thing I have noticed is the time it takes to finish a loop and then move the nozzle along +Z is pretty high. This results in the nozzle staying close to the print while it oozes, which is why I am getting such a big vein of plastic.

I am using a 1.75mm hexagon nozzle.

Now is there a way to change the amount of time it takes to move the nozzle in the +Z direction? The only option in Simplify 3D is when the machine is not printing, so it is useless can I do this in the firmware?

Now onto my second issue, I cannot update my firmware no matter what I do. I have been trying to change the E Steps for the extruder as it is slightly under extruding. I update the value in the configuration.h file and then upload it using the Arduino software and I confirm the numbers have been changed before uploading to the Rumba board. Then after that nothing changes in LCD screen. Has anyone run into this issue or have any idea on how to fix this?

Also, please help me fix my retraction! Give me any advice you would like. Is it worth looking into getting a different extruder?
08-10-2015, 08:15 PM
printbus

Quote:

... I cannot update my firmware no matter what I do. I have been trying to change the E Steps for the extruder as it is slightly under extruding. I update the value in the configuration.h file and then upload it using the Arduino software and I confirm the numbers have been changed before uploading to the Rumba board. Then after that nothing changes in LCD screen. Has anyone run into this issue or have any idea on how to fix this?

This sounds like you have EEPROM settings turned on. If so, the settings you have saved in EEPROM take priority over what you flash in new firmware. One way around that is to, after uploading new firmware, send the printer an M502 command followed by an M500 command. M502 updates the processor variable space with data from the firmware, and M500 will then save that variable space into EEPROM.

Quote:

Originally Posted by BLKKROW

...Now is there a way to change the amount of time it takes to move the nozzle in the +Z direction? The only option in Simplify 3D is when the machine is not printing, so it is useless can I do this in the firmware?

I haven't migrated to S3D v3.x yet, but 2.x used to have a Z-axis movement speed on the Other pane. Of course, the slicer can't achieve a speed faster than the printer firmware allows, so that'd be a place to start. Marlin file configuration.h DEFAULT_MAX_FEEDRATE sets the speed limit for each axis; the third number is for the Z axis. The other thing you can do is try increasing the acceleration allowed on the Z-axis. This is done through the the DEFAULT_MAX_ACCELERATION settings for each axis, with DEFAULT_ACCELERATION acting as an aggregate limit over all axes.

I discuss my optimization of these and other Marlin motion related settings in thread Marlin Motion Related Configuration.h Settings for MakerFarm i3v. I found the weight of the x-carriage on my 8-inch printer kept me from being able to drive Z faster than about 2.5mm/sec (IIRC the theoretical limit should be around 5mm/sec), but that I could make a noticeable reduction in the layer shift time by increasing Z acceleration in DEFAULT_MAX_ACCELERATION to 500 instead of MakerFarm's value of just 5 mm/sec per second.
08-10-2015, 10:21 PM
BLKKROW

Quote:

Originally Posted by printbus

This sounds like you have EEPROM settings turned on. If so, the settings you have saved in EEPROM take priority over what you flash in new firmware. One way around that is to, after uploading new firmware, send the printer an M502 command followed by an M500 command. M502 updates the processor variable space with data from the firmware, and M500 will then save that variable space into EEPROM.

I haven't migrated to S3D v3.x yet, but 2.x used to have a Z-axis movement speed on the Other pane. Of course, the slicer can't achieve a speed faster than the printer firmware allows, so that'd be a place to start. Marlin file configuration.h DEFAULT_MAX_FEEDRATE sets the speed limit for each axis; the third number is for the Z axis. The other thing you can do is try increasing the acceleration allowed on the Z-axis. This is done through the the DEFAULT_MAX_ACCELERATION settings for each axis, with DEFAULT_ACCELERATION acting as an aggregate limit over all axes.

I discuss my optimization of these and other Marlin motion related settings in thread Marlin Motion Related Configuration.h Settings for MakerFarm i3v. I found the weight of the x-carriage on my 8-inch printer kept me from being able to drive Z faster than about 2.5mm/sec (IIRC the theoretical limit should be around 5mm/sec), but that I could make a noticeable reduction in the layer shift time by increasing Z acceleration in DEFAULT_MAX_ACCELERATION to 500 instead of MakerFarm's value of just 5 mm/sec per second.

Thank you for replying! Using your tips I was able to update the firmware!

I will start playing with the speed of the Z movement soon. I think I found the secret to retraction after posting this thread. I found that for the "Extra Restart Distance" it accepts negative values.

So if you have it set to retract 2mm's it will then push 2mm's of filament through before starting the next loop. However, if you set the "Extra Restart Distance" to a negative value such as -0.2mm's it then only pushes 1.8mm's of filament. This solved a lot of the issues, there is still a vein but it is smooth on the outside of the print.

However, now I am getting terrible Z banding. I do have the anti-backlash modification on the printer so I am going to play with some of the retraction settings a little more and see if it helps.
08-11-2015, 09:49 AM
printbus

On the Z-banding, are you printing on a heated bed? Some have noticed the heater cycling on and off causes the glass print surface to shift a bit, leading to Z artifacts.

I forgot to mention increasing the Z axis jerk setting as part of minimizing the time spent on layer shift points. I increased the DEFAULT_ZJERK setting from 0.4mm/sec to 10 mm/sec when I was using Marlin. Marlin applies the worst-case jerk limit on multi-axis moves, so the 0.4mm/sec setting on Z requires XY movements to decelerate to a near-stop as the nozzle approaches the layer shift, and then accelerate from that near-stop after the Z-axis move completes. So, the combination of jerk, acceleration, and feed rate settings all affect the time spent to accomplish a z-axis move.