Travel Speed Issue

[gfisch9862 0]

Hello,

In relation to my previous post where I was having trouble printing the infill, I found that changing the "travel speed" in Cura changes the speed of the infill printing.

 

Is that a bug, or is there some relationship between infill and travel that I need to learn about?

 

Thanks.

[GregValiant 1,245]

What version of Cura?

I read your other post BTW.  The travel speed should not be related to the infill speed.  It isn't in my installation of 4.12.1 at any rate.

 

Post a gcode file that shows the problem.  Let us know what printer as well.

 

[gfisch9862 0]

Right now, I'm using 4.13.0 Beta, but had the same issue with the previous version, 4.12.1,

 

I'm using a stock Ender 6, but with a Capricorn Bowden tube, and Overture 1.75mm white PETG.

 

Here is the .gcode file of a 20% XY scaled version of the part, but with 100% Z.  This makes it easier to test.

 

I'm not sure what I'm actually seeing, but it almost looks like the travel speed multiplies the print speed.  Changing the travel speed makes a difference, but changing print speed makes a bigger different when the travel speed is high (100-150), but only when it's printing the infill.

CE6_CE6Mainbody1b.gcode

[GregValiant 1,245]

I went through the Gcode file.

All the extrusions are at 40mm/sec and the jog from one extrusion to the next is at the travel speed of 80mm/sec.  (Cura speeds are in mm/second while the gcode speeds in mm/minute.)

This is the Infill in Layer:21. 

;TYPE:FILL
G1 F2400 X127.156 Y149.58 E1183.7912
G0 F4800 X127.513 Y150.119
G1 F2400 X133.762 Y148.444 E1184.00638
G0 F4800 X133.762 Y149.511
G1 F2400 X114.811 Y130.56 E1184.89778
G0 F4800 X116.15 Y128.317
G1 F2400 X133.762 Y123.598 E1185.50422

 

This is in Layer 82 (I picked it randomly).

G0 F2160 X125.244 Y120.457                    ;Wipeout (90% of print speed)
G0 X124.597 Y120.038                                ;Wipeout
G1 F2700 E2808.09505                               ;Retraction at 45mm/sec
G0 F4800 X124.705 Y119.871                    ;Combing at 80mm/sec
G0 X125.126 Y118.112
G0 X126.339 Y117.503
G0 X142.389 Y109.433
G0 X142.982 Y109.135
G0 X142.773 Y108.664
G0 X143.071 Y108.59
G0 X143.207 Y108.833
G0 X144.043 Y107.718
;TYPE:WALL-INNER
G1 F2700 E2814.09505                                     ;Un-Retract
G1 F2400 X144.378 Y107.644 E2814.10646   ;Print at 40mm/sec
G1 X144.561 Y107.607 E2814.11267               ;Print at 40mm/sec
G1 X144.043 Y107.718 E2814.1158                 ;Print at 40mm/sec
G1 F2700 E2808.1158                                        ;Rectraction at 45mm/sec

Once again the print speed is 40mm/sec and the travel is at 80mm/sec.

 

The skirt is printing at 13.5mm/sec but from what I see you had "number of slower layers" = 2.

I don't see a problem in the Gcode that Cura generated.  I'll think about it, but right now I don't see a way that the speed can be fluctuating like you have observed.  The printer is supposed to do what it's told.

One thing you can try is to shorten the file name.  I know that seems odd, but it has been an issue with CR-10's and if your printer has the same mainboard (and it might) then maybe it will make a difference.

[GregValiant 1,245]

I adjusted the temperatures in that file so I could print it in PLA.  There are no issues at all.

[gfisch9862 0]

Thanks for going through the gcode.  The last time I tried to print the full-size version, the infill was printing REALLY fast... faster than anything I've seen on that printer before.  When I checked the setting, the infill speed (which was calculated) showed 360mm/s.  I certainly didn't set that value.  I think it must have been created while changing some of the other values, but I don't know that for sure.

 

I'll try the shorter file name to see if that makes any difference.

 

After that, I think I'll go back to PLA+.  It was suggested that I use ABS or PETG for these structural parts, but I seem to have too many issues with them even though the Ender 6 is enclosed on the sides and I got the plastic top cover.  Unfortunately, the top cover warped severely when I was using ABS temperatures and fell partially into the printer, jamming the print head.  Another time, the cable assembly got too warm and sagged into the printing area causing another jam.

[GregValiant 1,245]

I don't think the problem would be specific to the material.  If you are out of other options and the problem occurs with PLA you might try to reset the mainboard with M502 followed by M500.  If the mainboard saw some of that heat it may have caused an issue.

[gfisch9862 0]

Thanks, GregValiant.  That sounds like a great idea.

I have had a number of issues with the Ender 6, especially after adding the BLTouch.  I had been in contact with Creality several times and they are sending me a new BLTouch, but I think there is something else happening.

 

A mainboard reset definitely seems to be worth trying.

 

The heat in the enclosure was around 47C according to the little thermometer built into the cover.  Since the main board in underneath, it shouldn't have gotten too warm.

 

Here is a picture of the odd bed leveling I was getting with the BLTouch.  Note the high and low spots.  I now do only manual bed leveling until the new BLTouch arrives.

 

I damaged the build plate with the completed print right before this one.  It started out with the low spots, but I let it print anyway.  Once completed, the low spots were really stuck tight.  Even chilling the plate in the freezer didn't help.  Removing the PETG part took some of the coating, and the glass, with it when I had to finally pry it off.

[gfisch9862 0]

Reset and shorter file name did not make any difference.

[GregValiant 1,245]

This is the last thing to try.  M203 sets the max feedrate for the printer.  Unfortunately, it gets applied to both G0 (Travel) and G1 (Print).  If you put it into the front of that "bad little gcode" it should limit the top speed of the printer.  I would think adding it as the line before ;LAYER:0 should work.

M203 X40 Y40

As I said, that will also limit the travel speed to 40mm/sec.  It may give you another clue as to what is going on.

Edited January 17, 2022 by GregValiant

[gfisch9862 0]

OK, GregValiant, I'll give it a try.  I got another test running now, so I'll try it in the morning.

 

Thanks so much for your help.

Edited January 18, 2022 by gfisch9862

[gfisch9862 0]

GregValiant, I sent you a PM, but thought others might benefit, so I'm posting it here again.  Thanks.

 

After seeing other people's success printing the same R2D2 parts using PETG, I noticed one major difference... they all had direct drive extruders, or very short Bowden tubes.  My Ender 6 has a very long (0.85m) Bowden tube.  That might explain why small parts look great, but the large ones have issues.  The large parts are flexing the Bowden tube quite a bit and with the flexible and stretchy PETG, the extrusion amount varies considerably.  That would also explain why the different extrusion settings had little, or no, effect.  That might also explain why the stiffer materials, like PLA, were less affected by the long Bowden tube.

 

What do you think?

[GregValiant 1,245]

I saw the PM but I'll answer here.

What I think is:  That's a really long bowden tube!

Bowden systems are simple and cheap to produce.  Any of the softer filaments are going to have problems with a bowden system.  My Ender 3Pro HATES TPU.  I print some things with it because it's fuel proof and makes good gaskets, but flat gaskets is where I stop.  I'm printing at 10mm/sec with 0 retraction and I have to stand there to maintain the loop coming off the spool and lube the filament once in a while.  PITA.

DD's add weight (sometimes a lot of weight) to the X.  That has to be accelerated and decelerated constantly during a print.  Cura itself doesn't have an option for using different acceleration settings on X vs Y but an M201 X300 (or something) in the startup gcode would keep the heavier print head from beating up the printer on starts and stops.  Also, that extra weight is cantilevered off the X beam and so the front side is going to want to droop unless you are meticulous in maintaining the print head carriage wheels and belt.

Over on Reddit there are constant posts regarding problems with DD systems.  I think a person with some decent mechanic skills would not have problems and the DD can certainly be tuned in.

In regards to PETG - it's soupy.  With the limited retractions possible with most DD's I don't know if you can pull back enough material to keep it from being stringy.  With your current bowden setup (and considering that it's about a mile long) you might need to go to 7 or 8 or 9mm of retraction in order to pull back the filament a couple of mm's at the nozzle.  There is a lot of slop in a bowden system that long.

I haven't been 3D printing all that long but one thing I know is true - throwing more money at a problem doesn't guarantee that it will be solved.