Poor print quality with RRF3 - especially 3.2.2.

deckingman

For anyone watching this thread, and for those who have contributed, I just want to say that the Duet team and I have opened up the communication medium that we used at the very start (when Gen 3 was still at the pre-production stage), in order to work together to resolve these issues. That's nothing personal - just that these forums are maybe not the best way to post messages rapidly back and forth between us.

I thought it important to state that fact, in case anyone got the impression that I had been abandoned by the Duet team - that isn't the case and we are working together to try and get to the bottom of wtf is happening.

jens55

Thank you for letting us know.

Luke'sLaboratory

@deckingman

Keep at it and let us know what you find out.

I'm likely affected by many of the issues that you're discussing - also have a large machine with many extruders and i'd love to continue using it

@dc42 keep it up as well! I'm happy and willing to give some tests as well, but I won't have the time to dedicate to all of the detailed troubleshooting that deckingman is doing.

Luke

hackinistrator

@dc42
why are there different driver reports for main board and 3hc . for example main board does not show steps /mm and step req / done .

@deckingman sorry to see your machine damaged , at least its nothing serious . did you consider using some king of fail safe between the carriages ? for example connect a wire that is shorter then rest of the stuff that will disconnect earlier in case of misalignment and stop the machine .

i looked at your gcode , xy and ab positions should be the same right ?
are you using different step/mm for xy and ab ?

i cannot see any relation between the xy driver position and ab position on the main board . maybe this can explain something .

deckingman

@hackinistrator Forget about the AB gantry. That's a force cancelling/load balancing gantry that is completely separate to the XY and UV gantries. It simply carries a container with lumps of lead. It's just another CoreXY mechanism that sits at the very top of the machine and is in no way connected to the hot end or the extruders. The motor directions are reversed so it does the exact opposite of the XY gantry to stop the printer rocking around when I throw my heavy hot end around at high speed. It does nothing for print quality and the only reason it's still there is that I can't be bothered to remove it.

The XY gantry carries the hot end. The UV gantry carries the 6 extruders and two of the expansion boards. The extruders are connected to the hot end with short Bowden tubes. All the wires for the heater, fans, temp sensor, end stop etc for the hot end are connected to the expansion boards that are fitted to the UV gantry above. The UV gantry is the one that "follows" the XY gantry with an "envelope" that is +- 20mm of the XY position.

I've never before seen a wild excursion of the XY gantry that was not mimicked by the UV gantry. Nor did I foresee that possibility.

fcwilt

@deckingman said in Poor print quality with RRF3 - especially 3.2.2.:

That's a force cancelling/load balancing gantry that is completely separate to the XY and UV gantries. It simply carries a container with lumps of lead. It's just another CoreXY mechanism that sits at the very top of the machine and is in no way connected to the hot end or the extruders. The motor directions are reversed so it does the exact opposite of the XY gantry to stop the printer rocking around when I throw my heavy hot end around at high speed.

That is most interesting. Where did you hear about that idea or was it something you devised on your own?

Thanks.

Frederick

hackinistrator

Forget about the AB gantry. That's a force cancelling/load balancing gantry that is completely separate to the XY and UV gantries.

i think in your case its important .
x is related to a , and y is related to b .

so i would expect these relations to stay the same during print . your reports shows otherwise (at least i think so)

deckingman

@fcwilt It was my own idea - another world first that has since been copied. I did a write up of it on my blog. I'm using my phone right now so can't easily provide a link but there is a link to my blog in my signature.

deckingman

@hackinistrator I can't say that I noticed, but yes A should always be the same as X and B should always be the same as Y. The X and Y motors are on expansion board 3 and the A and B motors are on the main board. That might be a clue.....

o_lampe

@deckingman
about the XYUVAB axis':
I read in the Wiki that you have to use definitions of the extra axis in a certain order. E.g. you can't define V-axis without having a U-axis. If you still do, the FW automatically defines a virtual axis.
I believe, that you have to define UVW before using ABC or you have an unknown W-axis in your system, which might do spooky things.
Your printer is running for a long time with this axis', but maybe a newer FW treats theses ghosts different?

deckingman

@o_lampe said in Poor print quality with RRF3 - especially 3.2.2.:

@deckingman
about the XYUVAB axis':
I read in the Wiki that you have to use definitions of the extra axis in a certain order. E.g. you can't define V-axis without having a U-axis. If you still do, the FW automatically defines a virtual axis.
I believe, that you have to define UVW before using ABC or you have an unknown W-axis in your system, which might do spooky things.
Your printer is running for a long time with this axis', but maybe a newer FW treats theses ghosts different?

I have this
M584 X3.2 Y3.1 Z3.0 U0.0 V0.1 A0.2 B0.3 E1.0:1.1:1.2:2.0:2.1:2.2 R0 P7;
and
M669 K8 A0:0:0:0:0:1:1 B0:0:0:0:0:1:-1;

I'm fairly sure using those matrix values should sort out any ghost axes but I'll leave it to @dc42 - he's best placed to know.

deckingman

@fcwilt Here is a link to the first post I did with the load balancing gantry
https://somei3deas.wordpress.com/2018/10/04/dynamic-force-cancellationload-balancing/. Not that it was later discovered that this has no effect on print quality. That is to say, even when the entire printer rocked from side to side, the actual print was fine. So eliminating the rocking was largely a solution to a problem that doesn't exist.

fcwilt

@deckingman said in Poor print quality with RRF3 - especially 3.2.2.:

@fcwilt It was my own idea - another world first that has since been copied. I did a write up of it on my blog. I'm using my phone right now so can't easily provide a link but there is a link to my blog in my signature.

Thanks. That was quite educational.

But I think I've found the source of ALL of your printer problems.

It is not big enough.

Frederick

deckingman

@fcwilt The trouble is, I can't make it much taller because I'm not tall enough. I have to stand on a step to see they very top of it as it is now. I did mention to my wife that if we did away with the freezer in the garage, I could make it wider. But for some reason, she prefers to have that second freezer. Strange creatures women - always have the wrong priorities

hackinistrator

@deckingman said in Poor print quality with RRF3 - especially 3.2.2.:

@o_lampe said in Poor print quality with RRF3 - especially 3.2.2.:

@deckingman
about the XYUVAB axis':
I read in the Wiki that you have to use definitions of the extra axis in a certain order. E.g. you can't define V-axis without having a U-axis. If you still do, the FW automatically defines a virtual axis.
I believe, that you have to define UVW before using ABC or you have an unknown W-axis in your system, which might do spooky things.
Your printer is running for a long time with this axis', but maybe a newer FW treats theses ghosts different?

I have this
M584 X3.2 Y3.1 Z3.0 U0.0 V0.1 A0.2 B0.3 E1.0:1.1:1.2:2.0:2.1:2.2 R0 P7;
and
M669 K8 A0:0:0:0:0:1:1 B0:0:0:0:0:1:-1;

I'm fairly sure using those matrix values should sort out any ghost axes but I'll leave it to @dc42 - he's best placed to know.

did you copy and paste m669 from your config.g , are you sure its not a mistake?

in m584 a and b defined as driver 2 and 3 .
in m669 you are setting a and b to move with drives 5 and 6 ? there is no drive 6 on main board .
i dont know whats going on here .

also in m584 you define x as driver 2 on 3hc(b3) and y as driver 1 ? any reason for that ? usually x comes before y .

this is your motor location per you dump files :
3hc #3
Driver 0: position -1182960 z axis
Driver 1: position 3200 y axis
Driver 2: position -145076 x axis

main board
Driver 0: position 31360 u axis
Driver 1: position 6604 v axis
Driver 2: position 16320 a axis
Driver 3: position 31840 b axis
Driver 4: position 4756 ?
Driver 5: position 31360 ?

when you paused the print , a and b (if they are configured right , not sure anymore) should be :
a around 200mm from its end stop
b around 400mm from its end stop
is this logical ?
i dont know how much steps/mm your xy has . if its same as ab (80steps/mm) your x should be around 1.8meters from end stop . i dont thik your printer is that big
so maybe you're using different steps/mm for xy , but anyways i think their relation to ab is way off .
can you send M669 command and post the report ?

edit :
almost forgot , drives 5,6 on main board not defined , but i still see changing position on them , whats going on ?

deckingman

@hackinistrator Dunno. Driver position (as reported by M122) is fairly new so I've never looked at it before. Maybe there is something odd about the way they are reported - maybe something different for expansion boards and the main board?

Don't forget this is CoreXY kinematics, not Cartesian. So both motors contribute to movement. That's why I prefer to call them Alpha and Beta but for configuration purposes, they have to be called X and Y (or U and V or A and B). Also, the A and B motor directions are reversed. Oh and the axes lengths are a bit longer than the XY.

I can confirm that they all use the same belt and pulley pitch and all motors are 0.9 degree, so the steps per mm are the same for all axes (80). I can also confirm that it all works as it should.

No idea why Drivers 4 and 5 report anything - as you say, they aren't configured and physically, don't have any motors connected. You'll have to ask @dc42.

dc42

On the expansion boards, the driver positions are the net number of microsteps moved since the board was powered up or reset. Therefore, for a drive used to move an axis, the position is where the axis is now compared to where it was at power up. However, if after homing it you move the axis to a particular position and record the corresponding driver position, then when you next move the axis back to that position, the driver position should read the same.

For the main board, if drivers 4 and 5 have never been configured, I would expect the positions to read back as zero.

o_lampe

@hackinistrator said in Poor print quality with RRF3 - especially 3.2.2.:

main board
Driver 0: position 31360 u axis
...
Driver 5: position 31360 ?

Both the same! Coincidence or another ghost axis in the machine?

deckingman

We have another data point. I don't think it's particularly relevant to the issues at hand, but here goes.............

At Davids' request, I've run a test with the belts removed from the motors. So the machine is as configured but obviously the carriages don't move. So no damage will result if there are any sudden wild excursions away from the commanded XY position. I've also unloaded the filament. So the only difference between this and a real print, is that the motors won't have the same load.

Soon after the test is started, I pause the print. My pause.g moves all 3 gantries (XY, UV and AB) to a fixed position away from the part. At this time I run M122 on all boards. Then I resume the print, pause it again at about 98% complete, and repeat the M122s. So the individual driver positions each time the print is paused should be the same (because the gantries are moving to the same position in space).

For the important motors (the X and Y) which are on an expansion board, this is the case. It also true of the UV motors which are on the main board. And it is true for the B motor on the main board. However, there is a difference when looking at the "A" motor. This reports a position of 8480 after the first pause, but 55520 after the second pause. I don't think this "real" because I did not remove the belts from the AB gantry (because it is de-coupled from anything else and I don't care if it crashes because I'll be taking it off when I get around to it). That gantry looked like it was in about the right position throughout the print and I'm pretty sure I'd have spotted such a huge difference in reported position if it was "real".

I don't really want to get hung up about this AB gantry because essentially, it doesn't do anything except move lumps of lead around. If it crashed or did something unexpected, it would have no effect on the print (even it bent the frame that it's on because that is de-coupled from the main printer frame).

I also don't really want to get hung up about the drivers that have nothing connected to them, because it's just a distraction from the real issues at hand.

But for info, driver 4 (unassigned) reports the same position as driver 1 (the "V" motor). That is the case for both pauses. Driver 5 (also unassigned) reports the same position as drivers 0 ("U" motor) and 3 ("B" motor). And yes drivers 0 ( U) and 3 (B) report exactly the same position, which seems to be somewhat implausible although not impossible.

In summary, there might be something odd about reported driver positions for the AB gantry that does nothing more than move lumps of lead around, and for the drivers that have nothing connected to them. But the critical thing is that the XYU and V drivers show repeatable values when the machine is moved to the same, fixed, position.

I'll be running more tests today to try and capture that X shift that I experienced before...............

o_lampe

@deckingman said in Poor print quality with RRF3 - especially 3.2.2.:

I have this
M584 X3.2 Y3.1 Z3.0 U0.0 V0.1 A0.2 B0.3 E1.0:1.1:1.2:2.0:2.1:2.2 R0 P7;
and
M669 K8 A0:0:0:0:0:1:1 B0:0:0:0:0:1:-1;

@hackinistrator already quoted these and mentioned AB weren't mapped right.
Shouldn't it be A0:1:1 and B0:1:-1, since you use the second and third driver of the first board?

You answered, you like to call your axis Alpha and Beta, but I still don't get it, what's what?