Uneven belts tension and square xy

Hi. I keep struggling with un even belt tension reported by belt-tension script, but my x gantry seems to be perpendicular to y rail (checked by moving it to the front and measuring distance from extrusion by calipers)...
No description
102 Replies
Maba_Kalox
Maba_Kalox•2y ago
or should I just accept it as belt tension seems to much at 50hz?
Maba_Kalox
Maba_Kalox•2y ago
This weird graph start to appear after I swapped xy-joints and top motor cages, so it did not just start to show up from nowhere, before it looked like that:
No description
blacksmithforlife
blacksmithforlife•2y ago
4.0 on 1e6 - that seems overly tight to me. mine is like 1.5
Maba_Kalox
Maba_Kalox•2y ago
Oh, So I should make them less tight?
Maba_Kalox
Maba_Kalox•2y ago
my shaper graphs if it might help:
No description
No description
Maba_Kalox
Maba_Kalox•2y ago
I will try to unscrew both tension screw by two rotations then Though @miklschmidt said on similar graph in #general that this is perfectly normal.. (4.0 on 1e6)
blacksmithforlife
blacksmithforlife•2y ago
to each their own - I run mine at 1.5 and that works fine for me and with less tension things will last longer
Maba_Kalox
Maba_Kalox•2y ago
Got it. Running script after lowering tension by 2 rotations
blacksmithforlife
blacksmithforlife•2y ago
I would also keep in mind - your machine will still print well even if things aren't perfect
Maba_Kalox
Maba_Kalox•2y ago
welp, I lowered tension, but still keep getting same uneven results
No description
Maba_Kalox
Maba_Kalox•2y ago
If I try to tight lower belt, my x rail becomes not perpendicular to y rails
blacksmithforlife
blacksmithforlife•2y ago
It says your upper belt is tighter than the lower one
Maba_Kalox
Maba_Kalox•2y ago
yep, but if I change it - axis become not perpendicular...
Maba_Kalox
Maba_Kalox•2y ago
btw, after lowering tension I got this:
No description
blacksmithforlife
blacksmithforlife•2y ago
you might have uneven belts or you didn't ensure your jointer plates are square
Maba_Kalox
Maba_Kalox•2y ago
jounters plates are square? Sorry, how whould I check it and fix it?
blacksmithforlife
blacksmithforlife•2y ago
I used 123 blocks to hold the X axis parallel to the front of the frame with clamps and then tightened the jointers down
Maba_Kalox
Maba_Kalox•2y ago
hmm, so your suggestions is to completly remove belt tension from the equation by loosing them completly and then try to reasemble xy joints?
miklschmidt
miklschmidt•2y ago
The most important part of the belt tension graph is that the peaks line up
Maba_Kalox
Maba_Kalox•2y ago
but they dont xD Hi
miklschmidt
miklschmidt•2y ago
the difference in amplitude does indicate that one belt is stiffer than the other, this can be due to stretching. the first one you posted did
Maba_Kalox
Maba_Kalox•2y ago
Oh
miklschmidt
miklschmidt•2y ago
It can also be caused by loose screws / parts etc etc Or belt riding on idler flanges etc etc
Maba_Kalox
Maba_Kalox•2y ago
Okay, that is... intresting. Thanks
Maba_Kalox
Maba_Kalox•2y ago
Hmm, it seams to get... Better? I lowered tension in both belts and then realign axes
No description
Maba_Kalox
Maba_Kalox•2y ago
Sorry for stupid questions and chaotic conversation, just have no expirince with that stuff,
miklschmidt
miklschmidt•2y ago
Gotta start somewhere! 🙂
Maba_Kalox
Maba_Kalox•2y ago
And I tweaked a bit more on got this… just a bit of turns back and fort
No description
Maba_Kalox
Maba_Kalox•2y ago
I looked into guide on how to read graph, and as you said - peak alignment is important, height is not So I guess I will just stop on archived 😂 Or would you recommend try to fix it?
Nebulator
Nebulator•2y ago
If I interpret you right, you measured squareness of your gantry by using calibers to the front extrusion. If so then what you measured is not perpendicularity but whether the two are parallel to each other. Just saying because if your top plane is not really square but you take it as such, and then use that as a measure for your gantry perpendicularity, you're graphs are going to confuse you.
Maba_Kalox
Maba_Kalox•2y ago
Probably you are right, but I tried my best during assembly of the frame, don’t know better method to check if axes are perpendicular😅
Nebulator
Nebulator•2y ago
Triangle Calculator
This free triangle calculator computes the edges, angles, area, height, perimeter, median, as well as other values and a diagram of the resulting triangle.
Maba_Kalox
Maba_Kalox•2y ago
Then I will try to get same results again😂 Thx
Maba_Kalox
Maba_Kalox•2y ago
Okay. So, with such graph I have axes not perpendicular but at least 1mm, I checked it by machinery square and calipers.
No description
Maba_Kalox
Maba_Kalox•2y ago
And for this check I used same machinery angle which I used to assemble the frame, so this is for sure not machinery square fault....
Nebulator
Nebulator•2y ago
I think that means your belts arent the same length
Helge Keck
Helge Keck•2y ago
your belts are probalby binding somewhere you should have 2 main peaks means your belt grinds somewhere some metall or most likely plastik forgotten shims can also be a cause
Maba_Kalox
Maba_Kalox•2y ago
hmmm. Good guess, I did not make sure that I have equal belt lenght, as I thoough it wont matter As there is decent belt tension mechinism, which works hmmm, my carrege moves super easily
Helge Keck
Helge Keck•2y ago
is this a 200?
Maba_Kalox
Maba_Kalox•2y ago
It is 300mm
Helge Keck
Helge Keck•2y ago
if you think your bvetls are fine then try to change the tension
No description
Helge Keck
Helge Keck•2y ago
you were almsot there the left peak jsut should be a bit higher not as high as the second one
Maba_Kalox
Maba_Kalox•2y ago
It was at lower belt tension, and if I remember right - at that graph axes were not square… I tried to check squareness of the frame by measuring diagonals, seems in +-0.25mm
Helge Keck
Helge Keck•2y ago
No description
Helge Keck
Helge Keck•2y ago
this is the goal
Maba_Kalox
Maba_Kalox•2y ago
But what is more important, equal belt tension or perpendicular axes?
Helge Keck
Helge Keck•2y ago
both equal belt tension, same belt length, squareness, .... its all needed
Maba_Kalox
Maba_Kalox•2y ago
Welp, if my frame won’t be square, equal belt tension not equal squrness Or idk what makes my axes square at uneven tension
Helge Keck
Helge Keck•2y ago
test if your belts have the EXACT same length
Maba_Kalox
Maba_Kalox•2y ago
Okay, I will check for it, thanks
Helge Keck
Helge Keck•2y ago
i mean really exact like the exact same tooth count
Maba_Kalox
Maba_Kalox•2y ago
But won’t tension mechanism compensate it? How could I check belt equality without removing belt completely? I don’t have fmmm mod and this is struggle to put it back in Or there is no such way?
Helge Keck
Helge Keck•2y ago
you cant
Maba_Kalox
Maba_Kalox•2y ago
All clear, task understood Thanks
Helge Keck
Helge Keck•2y ago
dont do it now try to get the FMMM Mod and then do it
Maba_Kalox
Maba_Kalox•2y ago
Welp, my frame was not square, and my square is not square too as it report >90 deg angle on all corners I need good machinist square before I put printer back together 🤡 I bough more reliable square, checked again, I some how have ~90deg angle at left and right top corner and >90deg ad back corners How could this be possible?
Helge Keck
Helge Keck•2y ago
some extrusions must be skewed
Nebulator
Nebulator•2y ago
or unequal length, or/and with gaps
Maba_Kalox
Maba_Kalox•2y ago
Hmm, maybe maybe, but unfertenatly, no method to check it. Kit is original ratrig kit.
Helge Keck
Helge Keck•2y ago
what i mean is that you havent squared the frame well enough
Maba_Kalox
Maba_Kalox•2y ago
As I remeber from trigonometry, it is impossible to assemble shape out of 4 sticks, which will have two 90deg angles and other two >90deg xD So, ither sticks are not strait, or my top part of the frame is not in the same plane but my bed mesh has only 0.15mm diff, so - I guess it is - in the ~same plane
Nebulator
Nebulator•2y ago
You said ~90deg 😉 and not meaning to argue or prove my right, I thought it was helpful to give you something to check that you could have possibly overlooked.
Maba_Kalox
Maba_Kalox•2y ago
yep. it is definitely helpful, thank you! I thing I found source of all of mine problems
Maba_Kalox
Maba_Kalox•2y ago
Just what the fuck
No description
Maba_Kalox
Maba_Kalox•2y ago
I have been looking into some random graphs because mainsail did sort them like piece of garbage timestamps on fs are correct btw
Nebulator
Nebulator•2y ago
Wow that sucks 😟 ps. I just checked and have the same issue
ptegler
ptegler•2y ago
sorted by name by default. ZERO always lists off first. Simply click on the ' modified' column title if you wanted it sorted by date. seems normal to me. Linux and windows both do that
Maba_Kalox
Maba_Kalox•2y ago
Check ‘modified’ column, it is selected (arrow next to it) But result is still sorted by names
Nebulator
Nebulator•2y ago
In a terminal, when I use ls -alht, where t sorts by time and, as the man page for ls explains, uses modified time by default, the output for the input_shaper files is different than in mainsail when clicking the last modified column header. Its not sorting correctly IMO. @maba_kalox screenshot above shows its not correct.
Maba_Kalox
Maba_Kalox•2y ago
How could I measure belt tension without using macros? I feel like something could be wrong with adxl or something else, because if I follow graph and tight until graphs matches, by hand I can feel that belts actually have different tension
Nebulator
Nebulator•2y ago
There are people who use the microphone on their mobile device to measure the frequency when picking the belt like a snare on a guitar. Personally I don't trust that method for several reasons I don't want to get into, but you could give that a try. Did you ensure your belts are equal length? I mean, to the tooth, equal?
Maba_Kalox
Maba_Kalox•2y ago
issue resolved, the reason seems to be - a table... Graph on table:
No description
Maba_Kalox
Maba_Kalox•2y ago
Graph on floor:
No description
Maba_Kalox
Maba_Kalox•2y ago
aside from the base for the printer (floor/table) nothing was changed, so gaentry is still perpendicular and belt tension was not changed.
Mietzekatzi
Mietzekatzi•2y ago
Shouldn’t the Y axis have a second peak at ~40-50Hz?
Maba_Kalox
Maba_Kalox•2y ago
it should, but I have no idea what could it be. I mean. I have small peak...
Maba_Kalox
Maba_Kalox•2y ago
No description
Maba_Kalox
Maba_Kalox•2y ago
but something cancels it out. IDK what
Mietzekatzi
Mietzekatzi•2y ago
That’s a bit better, yes
Maba_Kalox
Maba_Kalox•2y ago
that is graph on the (fixed) table by fixed I mean - I added/removed pads under the legs, to make it more stable
Maba_Kalox
Maba_Kalox•2y ago
my shaper graphs:
No description
No description
Maba_Kalox
Maba_Kalox•2y ago
though this boob on y axes around 60hz looks suspicious xD
Mietzekatzi
Mietzekatzi•2y ago
The „hill“ around 50-70Hz on Y looks not right, yeah. Did it move smoothly without the belts?
Maba_Kalox
Maba_Kalox•2y ago
hard question, I aligned gantry by belt tension and only after fasten it
Mietzekatzi
Mietzekatzi•2y ago
How large is your printer?
Maba_Kalox
Maba_Kalox•2y ago
300mm
Mietzekatzi
Mietzekatzi•2y ago
Then I think that the resonance frequencies are a bit low. It could be that both belts need to be tighter (by the same amount). But maybe wait for experts on this, before you ruin it As long as you don’t hear the belts slapping against the extrusions during resonance testing, it may be ok
Maba_Kalox
Maba_Kalox•2y ago
Opinion differs, someone suggest to have 410^6 power density, someone sugges aroud 2 10^6 they slap xD
Mietzekatzi
Mietzekatzi•2y ago
I don‘t mean the peak value, but the frequency, where the peak is Ok, if it slaps, then it’s definitely too low
Maba_Kalox
Maba_Kalox•2y ago
For me, tightning, change the peak height too so, they should be, that tight, that during belt tension test they dont slap at all?
Nebulator
Nebulator•2y ago
I was told that slapping during the test does not mean the belts are too loose.
Maba_Kalox
Maba_Kalox•2y ago
Hmm. Lets wait for third opinion xD
Nebulator
Nebulator•2y ago
by someone on the R&D team 😉
Mietzekatzi
Mietzekatzi•2y ago
Yeah, better to wait ;) But during normal printing they should not slap
Maba_Kalox
Maba_Kalox•2y ago
I will try to print calibration cube with current tension, and check how bad is it. they slap for me only on reasonance frequencies So not all the time, but rather at peaks
Mietzekatzi
Mietzekatzi•2y ago
That makes sense
blacksmithforlife
blacksmithforlife•2y ago
best bet - take a video of this slapping and show it too us
ptegler
ptegler•2y ago
Gates (the belt mfr) even sells a device for belt tension via sound. This method is ages old and widely used in industry. Even my CNC mill lists the belt tension via a resonant frequency (and it's a tiny center to center vs the RR machines.) Florent posted a great write up he did for the RR machines (BRS-Engineering website) He used Gates own belt data and the spreadsheet to produce the freqs for 300, 400 & 500 sized machines. It works spot on. I own a rather expensive mechanical belt tension gauge and the numbers match quite well doing the frequency method to the Gates specifications. From Florent's doc.... peaks should be 300 86-100 hz 400 66-75 hz 500 53-62 hz I personally am running right at 72 hz on my VC500 and get no belt slap on that belt section parallelizing the Y extrusions. I use to be able to watch the belts start vibrating during the resonance test. don't see it anymore. MPE... YMMV
Nebulator
Nebulator•2y ago
@ptegler I looked at their website and searched around for that write up and couldn't find it, if you have the link would you share that please?
ptegler
ptegler•2y ago
Nebulator
Nebulator•2y ago
Thanks, that was fast :D. I'll read up. PS. Its not that I don't believe the method works or is unreliable, its phone microphones, apps and the procedure a person has to follow that I think is likely to produce unreliable results (hence i didnt really want to get into it 😉 ).
Want results from more Discord servers?
Add your server