kinginnovator

Awesome!! Again thanks for your patience.. it was night and day on this last print.. I just started fresh completely over to eliminate all the rest if the variables.. looking forward to see what she can do ..

Ok everyone... I loaded a brand new copy of Marlin and also went back to cure 4.13 and the skewing went away!! I even printed at some very impressive speeds (see video link)... I honestly have no real clue to what is different or what changed... I still have lots more testing to do.. I really appreciate everyone's help and you guys are the very best!!! https://photos.app.goo.gl/PnNv4mk8LXoS1YH46

Nevermind.. I found it.. About to print a file from this version.. Fingers crossed!

Here are the version options? I don't see it?

Edit out those tiny movements? Like in the g code?

This is an older picture. We got rid of the slide bearings in the x,y and have gone to a track bearing setup.. lighter and much simpler.. if I can control the skew this eliminates alot.. In theory it shouldn't be mechanical.. I can print a single line tube 4 inches with no skew repeatable. I just might try klipper too at this point if I'm able to... we'll see... going to dive into everything today and even try an older version of Cura possibly...

I will definitely try this! Very possible it could be tiny changes from the older version! Thanks 👌

The set screws go into a pre drilled hole guaranteeing no slippage..

I've tried everything... No luck.. Please see list of true's below: 1. I can control the direction of the skew based on seam location. 2. If I choose random seam the skew goes away but I suspect every layer will be a bit off from the previous. 3. I can print a single wall/path line to any geometry without any skewing. 4. I can print a single layer perfectly over and over and over and over.. All the truths above are the bounding box to solving this pandora of fun!!! I have acceleration set to 80mm/sec super slow. I've tried higher accelerations with the exact same results. I've turned off jerk movement and also tried with it on. Wipe distance has been (0).. Most everything has been set to (0).. GR5 said this " Or sometimes it's on a z move possibly. Particularly buggy is if you move Z and another axis at the same time as the original programmers didn't expect this. But cura probably won't do this anyway. But it could be moves just before or after the layer change." This could be it???? My gut tells me it's happening at this moment of movement (see picture again)... This is the only thing I can think of that's different than printing a single layer line/path only.. Btw yes If I print spiral the problem should go away but that is not a solution to the actual problem that will effect all prints hear forward.... small test ring.3mf

Okay finally getting somewhere! I printed a test ring (double path wall). By manually choosing the seam location (front,back and right ) in 3 different prints I can control the direction of the skew (see picture). I also made a short video. I've also included the gcode and cura file. I think that it's actually printing perfect layers but something is shorting the distance most likely when it starts a new layer at the seam location when it tries to make a tiny quick movement to start the new layers outer path. This could be do to the inertia within a larger system like this not being able to correctly respond to such a tiny movement. What are your thoughts on this? Is there a way to compensate for all tiny movements as such or atleast alter the gcode to compensate? All ideas are welcome.. https://photos.app.goo.gl/AE3CrfcWjPtKfzah8 CFFFP_small ring.gcode CFFFP_small ring.3mf

This is a great idea! I will do this tomorrow for sure to 'see into' what could possibly be causing this.... It makes zero sense if I can print perfect circles and walls in both directions but then have skewing happen on more complex shapes.. I know this will take time to figure out... My hunch is something that normally would work fine for a smaller printer (much less inertia) is hidden in the code and was never meant for something this large. I know that when I select randomize for the z seam this appears to solve everything via randomizing each layers start and stop locations and gives an overall average on the layers with everything working out in the end.. But I really need to pin point this because it's driving me crazy to have come so far yet have this happen at this time.. It's very expensive to build such a machine.. I really appreciate your ideas, knowledge and caring of my current situation and It will not go unnoticed!

Hey thanks! Its actually fed by a flexible shaft drive cable from an external stepper (nema 24). The shaft has a worm gear at the end that drive both Bondtechs simultaneously. This allows for some seriously high flows (as much as or more than a pellet system). Yes 2 heaters each 400watt potential.. This is all designed to achieve more that what's ever needed lol..

I can do this soon.. I noticed that cura will put seems in the direction of home. Is there a way to put the seems opposite of this? If I can show you guys that I can control the direction of the skew then this is atleast a step in the right direction..

Ok.... So I printed the same part at 45 and both sides skewed this time not a single side. This makes sense because they share the same direction. But I noticed in the firmware where the stop/start lines are at each layer change and I've been following a hunch. So I set z seam to random instead of shortest path and the skewing went away... So I decided to see if I could investigate further on this by printing a very long wall in both the X and Y direction (picture). No skewing took place in either to my surprise.. At this point there is definitely something different happening about the program in how it sees a more complicated geometry. Yes you mention the layers of complications going on behind the scenes yes. I need to figure out a geometry that can point the finger at the monkey aka (demon lol) hiding. The last wall part had no travel moves or possibly so much else when compared to the square frame.. Any ideas on what time of geometry I could use to say "ah ha!" I use Fusion 360.. Ive owned 8 other (small) printers before this one so I definitely think I could be dealing with a very tiny demon where acceleration isn't the same in a smaller machine when scaled to this. There has to be some geometric shape I could print to test the next step.. Remember when I when to random Z seam everything went away and this makes total sense if the same layer isn't repeated electrically/mechanically..

Thanks for responding.. I'm extremely aware of mechanical skewing. This is not it.. I can print a perfect cylinder over and over and over without any problems. I'm pretty sure if I orientate the part 45 it would go away based on the x,y moving at the same rate just like in a circle they would. The problem is specific to movements based on geometry and how cura does the paths. I do believe there is a possible problem with acceleration somewhere and steps being lost or gained. My acceleration is set to it's lowest 80mm/sec.. I bet if I print a square part without that center geometry and just a frame it will print perfect. I will try this and get back to you. Jerk is off because I can print perfect cylinders.. How would changing layers be related to acceleration? After a layer change does it do something special in it's acceleration? What do you mean also by central bar where cura does 2X? I've limited my acceleration withing cura to be around 120 for travels. I will print this at a 45 and see what happens. Will send pics shortly.

Here is another tough one to solve.. I'm somehow gaining movement in one direction which is causing skewing. I can print a perfect cylinder with no skew. But when I print that test part (square frame) I get a predictable skew based on the parts orientation. Obviously this eliminates all mechanical scenarios based on the ultimakers symmetrical design. I'm predicting some sort of movement within the program that is causing this. The ring is a perfect symmetrical print that does not have the start/stop wall features of the square frame. The square frame has a symmetrical design also just start/stop walls. But what could cause this skew based on path movement?

I can certainly try this.. I appreciate all your help here so much!! I wonder how fast this could react after a stop or end to a line path before starting a new line. I also wonder if I could adjust acceleration at the beginning 🤔 bit one for a split second while the extruder independently turns on and does not adjust itself relative to acceleration and speed? Just ideas.. if I get results from what you say I should try I will certainly let you all know.. This could also be part of a future problem to solve do to how much faster one could print with the idea of having more pre-melt on demand within the potential volume of a heated housing... 🤔

gr5 and GregValient, I turned off retraction for this very problem because when you are extruding so much more material (think 10X the volume within the extruder heated pathway) retraction is pointless at this point if you want to print 10X faster with so much more material. It is actually very responsive to not extruding when the extruder does not move. This type of setup would be similar to a pellet system. Or a Bowden that is 10X less responsive. Is there a way to not shut off the extruder completely in between stop/start moves, like 1/2 movement or speed? I think this would definitely solve this.

Another question.. What do you recommend as a possible solution to this problem with under extrusion of single line starts? This is a wall that is only 1 line path.. CFFFP_Test ring.3mf

https://photos.app.goo.gl/UGENqVYuz39u29gZ8 This makes a lot of sense! I will adjust most likely the radii.. I don't mind stringing on a giant part.. Least of my concerns, its different when you are simply trying to successfully print a large part.. Let me know if this link works

Here is a link to the video. Let me know if your able to view it. Flex drive setup on a worm gear. It's possible it could be trying to infill into tiny areas? Don't know... 90 percent infill because I tried 100 percent to try an eliminate such tiny movements instead of long continuous because the start/stop of this setup is very difficult to toon. Linear advance is very difficult atm.. CFFFP_Test frame.3mf

Hey there! Here is a link to the video let me know if your able to view it. It is possible it's trying to perform an infill into tiny spots? Not sure. This is a flex shaft drive system on a work feeding 2 simultaneous extruders. https://photos.google.com/photo/AF1QipMl9G8s5sFJpooJsKSTadyVOIFku2QRTwHhzJ2D CFFFP_Test frame.3mf

Torgeir. I will also supply the model too. Thanks for joining my lonely battle here! LOL

LOL! I can turn on retract just not ready for it because it's going to be a challenge because of the amount of thermal mass within this setup. I will make a video and post the 3mf project file by tomorrow. I have plans to make it with not one but yes two pellet heads so that's coming! But I'd rather nail down the path of least resistance with the (2) 3mm filament heads because so much more has been done on this side of plastic flow. No reinventing the wheel quite yet my friend.. I truly need help tuning this, there are so many more variables. But with this setup I can extrude more than a pellet system atm (800 watt potential) I'll add a video soon.. I really appreciate your help here..!!