y axis skipping at accel > 5k (V-core 3.1 500)
Not sure what's causing this exactly, i don't even know where to look tbh.
I've checked for squareness and it looks fine,
The belt seems to move a little vertically over the course of its motion.
The attached video shows an inverted V motion after homing, which doesn't complete.
This movement works at accels close to 5k and under. Sometimes for >5k. Repeatability is 50-50. Sometimes it works fine.
When i try printing something at those accels i have layer shifts towards the front-right. Each layer prints fine but the next layer considerabl offsets over the previous.
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Obviously for what i've spent i want to print faster, so please don't tell me to print at 1k accel (ender 3 style)
[gcode_macro TEST_BINDING_MOVEMENT_ONLY]
gcode:
g1 x60 y60
g1 x285 y470
g1 x460 y60
This is the macro i created to test for this issue.
after homing it should have come to the center, which was not part of the macro. So it failed that first.
Well first are the belts tight enough, secondly, are the pullies and is the Pully with the Teeth set properly, and firmly?
Too high acceleration can cause the motor or the timing pully to skip.
is 6000 too high for a ratrig ?
belts are tight enough right now around 53hz. Any more and it skips at a lower accel
Depends on a lot of factors, since its a 500 you got to keep in mind massive travel distances of the belt.
But check the timing pullies, if they skip or can't keep up with the belt, they will skip and or not rotate. Also are you runnin gon performance mode as well?
perf mode but i've reduced the current to 1.4 for now
Okey, then I would first check the timing pully
I always put locite here so it doesn't skip and make sure it is properly seated.
btw i have 0.8mm shims right now. 1mm shims are otw. Would those cause such issues. all my shims are 0.8
Secondly, look at the FMMM mode, the printed housing for the belts is not ideal and it can bind.
i see belt dust and a little grime on my bearings
Any wear like that is not a good sign
It means its grinding
my housing is already the visual mod
i'll try the fmmm mod too (my machinist is out of town)
Can you grab me an image of the pullies?
FMMM is gold for these kind of machines as it releases any obstruction to the belt.
Then you can remove one factor from this.
But always keep in mind bigger belt paths give less accelerations and such.
Again check the grub screws of the pullies, make sure they are seated Correctly.
And put loctite when you are sure you put them correctly.
This ensures it won't "skip" the motors shaft
As due to vibrations that screw can come loose.
Belt does seem to be a bit angled, and any grind is not good.
Check the pullies first to eliminate that, and the grub scews on the timing pulleys.
my upper belt pulley could be a little lower im guessing
but would these cause my motor to skip so badly as in the video
its as if my motor is binding hard
Check trully if your belt path and simes are all there. You'd be suprized how on that lenght the belt can seem good but its not.
simes ?
shims
yeah they're all there
i checked twice
Roll it from front to back and if you have a lot of vertical movement you are either not square, or the path is not well made, as in shimes, pullies etc.
As soon as you see grinding like this, you can assume its binding somewhere.
it gets harder to move towards the back compared to front
but not that much
what does this say
ok so i have a few findings for oyu
upper belt is fairly center over the entire motion
lower belt moves lower anywhere in the right half of the printer
and higher in left half
If it gets harder or binding you need to source out the problem. Either belt, either belt path, bad carriage, or not lubricated with oil, or binding in the X gantry as well.
The X gantry needs to be properly paralel when you do the belt tensioning as well
lubricated well with lithium grease
X gantry is butter, slight resistance in Y gantry maybe but even movement just in X axis causes belts to move vertically. So Y is ruled out here kinda atleast in belt alignment
with printhead at X0 Y300 i noted the following belt positions
b -> bottom
t -> top
c -> center
so the belt is angled clearly
Yes but did you tenstion as the wiki says?
So you don't run it coocked
Grese is only for the leadscrews
The rails are lubricated with OIL
As long as you use the correct grease it is fine
MANNOL 9985 Low Viscosity Grease Lithium-Calcium
i think this one is like super recommended for linear rails
yeahh
i'll do it again when i get to it, it's not that hard compared to taking everything apart and building from scratch atleast
Well rarely do you have to do that, unless you messed it up really badly.
Doing a 500 machine is a task indeed.
i squared up really well tbh so i would have to be completely out of options to go back to that
i re-did the gantry alignment
why are my graphs so horrible
125 is toolhead resonance if I'm not mistaken, which means your toolhead has something vibrating in it.
But this graf shows that everything is vibrating 😄
3D Printers & a Whiteboard
YouTube
How to Read and Analyze Input Shaper Graphs Generated by Klipper
This video is supposed to be a brief overview on what the input shaper graphs can tell us. It is the first video of a series of videos which will give a more in depth view on the kinematic system and input shaping in Klipper.
As always: feel free to jump to those parts, that help you with your problems:
00:00 Intro
00:57 What we can learn from...
i just checked and my shims were 9mm OD
0.8mm thick
so they are clamping over the bearing if im correct
can i use printed shims instead ?
Why, just use the proper shims.
They are called precision shims
i ordered some, will take a bit to arrive
This is a precision machine so any cutting corners will correlate to something in the run.
hey
so i've changed out the shims
You don't want a peak < 100 Hz
That typically means something is loose somewhere
Do you hear any rattling when doing the belt tension graphs?
haven't particularly paid any attention
i'll try looking for any sounds
do you mean >100hz ?
because i thought around 75 is where you want a peak
Yes I did haha
>100 Hz
It's late... 😆
HZ peak depends on the machine size.
i noticed the belt is centered when the lower belt motor is turning anti clockwise. While clockwise the belt becomes angled (belt feeding fromm the circled areas.
I had a look and noticed the belts in the circled areas were static towards the bottom half of the idlers
how do i fix this
yeah the belt itself flaps at some point tbh, certain parts of the belts
I had the same issue and would advise you to stop printing as you risk the belt snapping (mine did)
Video would show it best, I'm not sure what you mean.
you want me to take a video of the resonance test ?
i identified where the belt angle is coming from though, the belt is vertically constrained poorly at the printhead (front side) with the 2 bolts
its lower than the rest of the system
so now i have no clue how to fix this
reprint and check dimensions ? But then all my other parts work fine
is there an alternative tensioning mechanism ?
is the ratrig eva build modified compared to the eva site ?
i wish i could somehow shim the belt at this part