[RRF] Extruder max speed vs. retraction setup

I had to reduce max. E-speed to 250mm/min, otherwise the filament got pushed backwards through the drive gear. Now ( I hope ) the planner will reduce overall printspeed in case I set it up to fast.
But I also have the firmware retraction enabled in config.g with 4800mm/min.
It seems this isn't working, because retraction is very slow...
IMHO these are two different cases

Anyway, maybe this is an old bug, since I'm stuck with RADDS RRF V1.14?

PS: When I setup a mixing ratio of e0.5:0.5:0, would the planner allow to run twice as fast then?

It's normal for the extruder to skip steps if you try to extrude too fast. That is not a reason to setting the maximum E speed to a very low value such as 250mm/min, because that speed limit will also apply to retraction moves and when you load filament.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

There's another thing I've noticed related to hardware retraction:
I'm often using only 2 of 3 filaments with my diamond hotend. The mixing ratio clearly shows which filament isn't used. But still it is retracted/unretracted over and over again, until the drive gear has chewed through it. ( almost )
The parameter that only allows retraction after XXmm of extrusion should relate to the mixing ratio and treat each extruder separately.
The unused extruder doesn't apply pressure to the melting chamber, so there is no need to retract it anyways.

Apologies, if this has long been done, I'm still running RRF V1.14 on a RADDS.

Edited 2 time(s). Last edit at 11/29/2016 07:15AM by o_lampe.

Quote
o_lampe
There's another thing I've noticed related to hardware retraction:
I'm often using only 2 of 3 filaments with my diamond hotend. The mixing ratio clearly shows which filament isn't used. But still it is retracted/unretracted over and over again, until the drive gear has chewed through it. ( almost )
The parameter that only allows retraction after XXmm of extrusion should relate to the mixing ratio and treat each extruder separately.
The unused extruder doesn't apply pressure to the melting chamber, so there is no need to retract it anyways.

Apologies, if this has long been done, I'm still running RRF V1.14 on a RADDS.

You can have the retraction done proportionally to the mixing ratio if you want, all you need to do is have your slicer generate the retraction instead of selecting "Use hardware retraction". But according to another Diamond hot end owner, if you don't retract all 3 filaments then molten filament will creep up the heat breaks of the filaments that you are not using and jam them.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks David,
I also found another issue with hardware retraction/Slic3r/ RRF:


I've enabled hardware retraction and in slic3r settings I set retract before toolchange to 0, but instead of using slic3rs settings for the toolchange, it inserts a G10.
That cause the filament to retract twice, but unretract only once.

Was that the reason to implement the R-parameter in M207?

...
G1 X-0.893 Y3.332 E1.26709
G1 X-0.893 Y21.465 E0.65279
G10 ; retract
T3
G10 ; retract
G1 X8.035 Y16.198 F4800.000
G11 ; unretract
G1 X1.094 Y9.256 E0.35494 F1800.000
G1 X1.094 Y9.748 E0.01779
...

Edited 1 time(s). Last edit at 11/30/2016 05:28AM by o_lampe.

What I think is happening is that slic3r thinks that each tool has its own extruder and its own nozzle. So it is retracting the old tool, and when you switch back to it again you will probably get a G11 immediately afterwards. Obviously this won't work when the different tools are really the same tool and the same extruder.

It would be possible to have the firmware detect the multiple retraction, but not trivial because when the tools really are using different extruders, the double retraction is correct.

Edited 1 time(s). Last edit at 11/30/2016 03:44PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Maybe the M563 extruder heater parameter is telling enough about the configuration? One heater ( same on every virtual tool ) = single nozzle. More heaters = more nozzles

A workaround would be to put a G11 command in each tfree#.g file.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].