Wobble V-core 400
I will literally take any suggestion, test it, and respond.
A previous thread is here and covers some of what was done already, but I'm starting fresh. https://discord.com/channels/582187371529764864/1189252315769753660
Important info:
- Tr8*2 z-screws (rotation distance 2)
- fmmm
- dual linear gantry
- other than that mostly a stock 400
Z1 is still the worst offender when i print tubes right above the bed arms. I'm going to continue focusing my efforts there.
266 Replies
I want to see those leadscrews roll on the table...
This looks like, as I've said, binding somewhere.
From the top down also please images.
Of the leadscrew assembly
With the arms.
You can actually film from top down, and set the bed to go from 0 to 200
For all 3 arms
And see how its spinning
IE: record from this perspective
went through the other thread as well I see you mentioned checking the whole frame for squareness and some improvement when remounting the back stepper, along with suspicion on some angle there, I'm wondering if the extrusion is slightly twisted in the middle a very far fetched idea but worth checking?
either the bottom or the top one maybe
I ordered mandala's oldham couplers and these should deliver today - it was between starting with the threaded rods or the couplers, and I figured even if this doesn't solve my issue there are other printers I can use the current couplers on so this test isn't a complete waste of money. this also gives me a good reason to undo the z axis assembly again and check the rods one more time as well as the extrusion mounting.
Thats weird, one of my Z lead screws is visibly wobbling a lot when turning, especially when looking at it like @VisualTech48 described.
However I have 0 Z-banding or artifacts when printing. The RR couplers working quite well.
Maybe one of your couplers is binding or the lead screw wobbling so much its hitting the cap head screws in the bed arms that hold the couplers
'that's weird' is the motif of troubleshooting this issue lol.
I don't expect couplers to be a magic fix, I don't expect any one part swap to do that to be honest, but what you said is the exact logic for I'm treating it this way - the stock oldhams should be fully capable of reducing any wobble from a bent threaded rod but in my case this doesn't seem to be true so maybe it's something wrong with them.
hmm have you checked if the leadscrews are parallel to the frame
I'm actually printing additional leadscrew constraints to put further down just to see what happens lol
also I'm very bad about calling lead screws threaded rods
Have you watched MirageC's videos on YT on Z-Wobble?
yep, there's a pic in the original thread of one of his slanted towers.
wobbleX isn't going to solve this though
thinkling back on this and just remembered the slanted tower test print is from Mihai's extrusion wobble video, not mirage's z wobble video. still though, I've seen it lol.
miragec from what I remember has has 2 main sources one leadscrews that the wobblex or oldhams should reduce to nearly not visible and the uneven extrusion
Yep, mihai's was about dual gear extruders and mirage's was about the larger Sherpa style gear that led to the ridga.
Either way I've pretty conclusively ruled out an extrusion issue.
Well it wasn't the oldhams
seems too consistent to be extrusion
bent stepper shaft?
comparison of dropping the bed down to 400 in cad vs IRL
the front two arms are only sitting 2-3 revolutions of threading above the couple, the rear is sitting 4-5 revolutions.... but in cad they should all be 4-5 revolutions
wait those are tr8x8 and I'm using x2
counting threads is a shite measurement of length
you could print the zylinder in different diameters, meaning a different amount is extruded per layer.
that way the distance between the artifacts will change if its extrusion related ( so extruder gears, stepper shaft, etc are the culprit) or they will be the exact same if it is Z related (so leadscrews, constraints, bed, etc)
although... you showed in your first pictures that theres a difference between the point on the bed, so its probably not extrusion related
Yeah, extrusion and wobble would show similar on the cylinder, I've done plenty of other shapes that rule out extrusion issues though. I just continue to use the cylinder because it's one wall so very little waste.
Pretty consistent
okay, I've checked squareness of the frame a bajillion times with every tool at my disposal and nothing. Add to this the fact that I've been printing on this thing for months now with no skew (even used a califlower) or any other symptoms that would express from an un-square frame.
I still do not know why the back arm sits slightly higher when the bed is sent to 400mm as compared to the cad.
so timeline is:
1. uninstalled leadscrews - checked them for bends again but nothing all that obvious.
2. reinstalled leadscrews (I did not keep track of their original positions, so they are most likely in new positions) with the new mandala oldhams.
3. tube print shows no change
4. totally disassemble and reinstall rear z motor mount (again)
5. tube print shows no change
6. notice the back arm is sitting slightly higher, verify in cad that should not be like that.
7. check squareness of frame (again)
I'm still just grasping at straws here.
I did print a second set of leadscrew constraints, I'm curious if I install them literally right above the stepper couplers what would happen.
For #6, is the printed arm actually straight? Maybe it warped while printing (which is common) and because of that it is actually at a slight angle facing down instead of straight out from the rail
I'm not noticing any significant warp running a straight edge over the top face of the arm.
What about it being mounted at an angle? Is the face of the arm 90⁰ to the rail?
as far as I can tell
I'll assume you also checked couplers
swapping steppers around?
Swapped steppers positions (one had a short from rubbing against the extrusion, so one of these is actually replaced from when this issue was originally noticed)
Switched to flexible couplers (the kind with the red plastic insert) to no difference.
I have thought about getting different flexible couplers to see if that helps but that goes against a lot of the ethos behind the V-core z design.
usually couplers on triple z are supposed to be rigid IIRC
Exactly, that's what I mean about it being against the ethos, but I'm thinking if flexible couplers reduce/resolve the issue it would at least signify an issue with the current couplers and/or anything past the leadscrew (stepper, mount, the assembly, etc)
But the ones I have on hand that I tried didn't change much, so I doubt other versions would change much either
for what it is worth, I use the "spring" type couple (where a spiral is cut into it and it is flexible) and I use a ball bearing to keep the "spring" from collapsing. So far I have not had Z issues (but I also use ventermech arms)
These? Where does the ball bearing go?
yes. it goes between the top of the stepper shaft, and the bottom of the leadscrew. I pulled the coupler a little while I was tightening the last setscrew so that the spring is trying to compress the leadscrew against the ball bearing against the top of the stepper motor
and making sure the coupler is pressed against the thrust bearing so the stepper isn't taking all the weight
Ah, okay that makes sense now
I'm really tempted to just reprint the motor mount and arm but I can't find a single thing wrong with either.
if I do reprint arms I might look into alternatives instead of reprinting stock arms and experiencing the same issue. I'd feel bad switching from my fancy oldhams to ventermech but if it solves the issue...
I did not know about ventermech interesting design
yeah, back when the vcore 3.0 didn't have anything to fix wobble
out of curiosity is it such an issue on vcore? my current printer has triple z (ZeroG Hydra) but z wobble is not an issue (no oldhams etc)
there was some on the original 3.0. That's why they moved to the oldhams for 3.1
I think this might be my next play
flexible couplers, drop some ball bearings in, test it out.
I think that should change things at least in SOME way to make a decision on the next move. like if this connection allieviates the wobble then we could maybe rule out an issue with the arms/leadscrews/etc because we didn't change anything there, that would mean something is up with the motor/mount/assembly, yeah? alternatively it does absolutely nothing then I can look into replacing the leadscrews and pom nut because this should theoretically improve any issue with the lower assembly/parts.
I think at that point I'll have replaced the oldham coupler, the motor coupler, the lead screw, the pom nut - that's everything in the z assembly except the printed parts.
so if those next two steps still do not change anything I really wont know what to do
I mean... I already didn't know what to do, that's why I was replacing parts, but if that still doesn't solve it I'm out of ideas.
Seems reasonable to me
Neal Wadhwa
YouTube
Phase-Based Video Motion Processing
This video is the supplemental to our SIGGRAPH 2013 paper "Phase-Based Video Motion Processing". See our website for more information: http://people.csail.mit.edu/nwadhwa/phase-video
still messing with this a bit...
not sure what the right frequency is for the bed motion to accentuate it
I'll have to get some better videos of the bed in motion in the morning (just been using older videos since I already had them)
you know what
I don't think this is wobble
I've tried everything I can to get the motion off the bed to show, and nothing. If it truly wobbled as much as it shows in the parts it would show in these videos, but it doesn't.
I'm now starting to think the theory about something wrong with the threads is right.
how is this done
Software called lamda-vue
More info in that YouTube link
It could be your extruder gears, when rotating one could be slightly off and push more material each rotation and it could look like Z wobble. Check out this vid he explains it perfectly:
MirageC
YouTube
Extrusion Quality - Mystery issue resolved !
🍺 SUPPORT ME: https://www.patreon.com/join/MirageC
How I identified and resolved my direct drive extruder inconsistent flow and print surface artifact.
After release of this video I realized that many others have this issue. Thanks to people commenting here I was made aware of:
Prusa Issue 602 - https://github.com/prusa3d/Prusa-Firmware/issues/...
We've fully covered that it is not an extrusion issue
At least from the symptoms present
Also it is an orbiter
seems too consistent to be extrusion, different size objects show the same symptoms, the pattern is too consistent, I had the gear issue on my sherpa and it's very different
@Lemcott I don't even know if it's possible, could it be one of the xy rails?
From my perspective there is no wobble in your leadscrew.
One of mine wobbles significantly, like you can easily tell by eye.
The middle wobbles at least a full mm and I dont get any Z-artifacts (thanks to the oldhams)
Very bizarr, just to check, is your bed temperature consistent?
CNCkitchen had a video on that, but I believe it only applies when using Bang-Bang instead of PID controll of the bed temp
Bed temp graphs are very consistent and pid tuned, yeah
I've really only focused on Z and ignoring XY as squareness/skew is spot on by all accounts.
I think all Z possibilities may be crossed out, xy idlers, belts or pulleys might be options I just don't know how issues on those can cause the issues you're seeing
My working theory right now is that one of the lead screws, or more likely a pom nut, has an issue with the threads. So the bed isn't wobbling the in the x/y directions like we would see with normal "z wobble" but the bed is actually lagging/exceeding on one of the z axis compared to the others
so in theory the bed isn't "wobbling" but more "tilting" every rotation.
I have an order in to replace essentially all but the leadscrews and linear rails, this delivers next Thursday, if this does not resolve the issue the next step is leadscrews (I'm confident enough it is not an issue with the rails)
At that point the only thing I have not replaced in the z axis would be the printed parts (and rails but see above). At that point I'll concede it is not a z issue and start looking into x/y but I might still reprint those parts just to rule things out.
this theory is also emboldened by the fact that the wobble tends to be more exaggerated on one side of the tubes
a wobble should be consistent aorund the tub I think
you know what, I've always rotated the leadscrews but never the pom nuts and the issue has always been concentrated to the rear z assembly so I'm not sure why I never looked at the fucking pom nut
WHY AM I IN AN AIRPORT I WANNA BE WORKING ON MY PRINTER
that makes sense, even more, if it's exaggerated on one side
oh I know that feeling way too well
Gotta fly to work on the printer I make money working on to afford going home to a printer I want to be working on :thonkmatt:
that took me a little while to understand
I reread it like 5 times asking if it made sense then just gave up and posted it lol
For what it's worth, it reads fine to me
That's good, I'm too many airport beers deep to tell lol
non native English issues
you're flying on a printer? I wanna see that
Some of the parts I make do make it into things that fly, so kinda lol
This time tomorrow I should have at the very least some results or ruled out z axis issues entirely
I feel like fusion would be yelling at me that something is overconstrained lol
Decided to totally remove the rear z mount one more time, mostly because it was using normal t-nuts and not the spring slide-in t-nuts (I didn't want to remove it again until I had those because it makes it easier to remove later), and I notice something
I think the screws might be too long
I see what happened here, all the other z motor mount M6 screws are m6x20 except for these horizontal attachments which are m6x12
That at least explains why I noticed everything on the r z sitting so far forward
Might not explain the wobble tho
it could if that was not letting it tighten properly?
this might explain a lot
It was always kind a pain to tighten, but would eventually - I just chalked that up to it's annoying-to-get-at screw positions but apparently I've just been hand drilling stainless steel into aluminum
Only ended up putting on that one lower constraint because... Those three going into the motor mount were 3/4 of my last m6x12 :sweatguy:
I did put the new couplers in though, with 7mm ball bearings inside
did those forced screws bend the extrusion?
doesn't look like it
because... the wobble is gone.
oh my god. End of an era
wait
I might have celebrated too early
it is definitely reduced
flow4enol may be right and your extrusion bent now?
It certainly does not seem so
I can check more thoroughly after this test print
Seems a lot better
other than those small ones with random layer spacing I can't see anything
vase mode?
It's near imperceptible in the photos, yeah, the vertical artifacting stands out more and I am having trouble trying to capture it
You have a different problem that is worse, that sounds like success to me
Yeah... Like at this point if I switched to tr8x8 it would absolutely be impossible to see in person - so I'm still gonna call this resolved as a stock V-core might exhibit the same thing without it ever being noticed
I do wanna find out why every so many random layers the direction of the perimeter changes for one layer tho lol
those sort of vertical lines can be from the model itself, arc welder might fix that too
but clearly the original problem looks fixed
It's still pretty noticeable in that last pic
But yeah, time to try some other models at least
Nah it's still pretty bad
the moire from the camera is starting to make it hard to tell which seems good
pretty visible on these
Yeah and that's with 2 walls
It's like... man I know people are gonna tell me it's not that bad but to me anything I print on this is wholly unusable, completely unprofessional trying to hand someone parts that look like this.
I guess my next order is tr8*8 screws because I can't live with this
it's also hard to judge stuff in photos vs real life
The last photos do a real good job at showing just how bad it is
It's bad
not going to say that, as I agree with you, not good at all
you're making me question if I should get tr8x4 or 8x8 for my build
It would be safe to say that I would definitely suggest the *8 at this point.
it's actually what I have on my merc, BOM wise recommended is 82 and I don't see this issue there, also question how does 82 compare to 8*8 with regards to these kind of artifacts?
the rotation distance goes from 2 to 4 to 8
so these artifacts on tr8x2 go from every 2mm to every 8mm on tr8x8
it could just be that new leadscrews fix it
it could be the delrin nuts I have were machined wrong
it could be that the wobblers simply can't compensate for a wobble every 2mm like they can every 8mm
it could be that all the granite and tempered glass I have access to are actually bent so I can't tell that my leadscrews are bent
it could be so many things that I'm hoping leadscrew replacements will cover all of these bases.
if it's not that, you'll see a post from me in the flea market and a purchase in for a voron kit because I give up lmao
Orbiter can have this issue. I shim mine to centralize the drive gear on the shaft. I designed and printed s jig to measure filament drive gear concentricity with a dial gauge. Robert the Orbititer designer and I chatted about this. He had a very simple clever idea on how to eliminate this issue in future versions....I haven't checked if he has implemented these yet.
The pyramid test print will quickly prove if this is an extruder issue or not.
If it was the orbiter why is it consistently 2mm in z no matter the shape of the print
That's from mihai's video on extruder wobble, same purpose as the print you are thinking of
Also I have tried with two orbiters and a sherpa
Yes extra constraints, will make your decouplers to work harder. It is possible to overwhelm some types of decouplers. normally if this is the case you will see the lead screws wandering around when visually referenced to the holes in the top of your bed arms.
Those constraints had no change on the effect
Very recent last ditch effort just because I already had extra bearings
The videos above have some cool motion processing done if you want to see top down views
Randomly spaced artifacts like the ones in thst particular photo are more likely to be Hula movement artifacts.
That's just the perimeter changing direction
I have a wipe on retract
Correct. The purpose of prints with variable layer times is to prove if you have a lead screw issue or a extruder issue. You have a leadscrew issue and perhaps also a small and typical Hula movement issue which I would ignore at this point.
BTW I do no use bearings in my leadscrew guides. I prefer to use TPU Wiggle wiggles. Avoids any binding issues or over constraint issues. Theoretically it shouldn't matter when you use decouplers....but.
Yes, the latest picture is an example of this
Also the maoi obviously has a range of layer tubes, yet the issue remains a consistent 2mm
All this to say I think we can safely rule out an extrusion issue
As a test to see if it changes anything remove the bearings from your top leadscrew guides. In the old days when we first developed the VenterMech decouplers I didn't even bother with too lead screw guides.
That was in the original thread, but yeah, no change without the top constraints
With the bed about halfway down, grab eack leadscrew and flex it in all directions and make sure that it does not cause its corresponding bed arm to move. I will post a video of this test in a couple of minutes.
I can wiggle them around and watch them wiggle within the wobblers, no real discernable play in the arms
Just like that, yeah
I did recently switch from stock to mandala wobblers as well
The stock Oldham couplers work for nearly everyone. No need to change them. I only use VenterMechs because they are free to print. last forever and make working on the printer much faster and simpler than Oldham decouplers.
So unless your Oldham couplers are too tight and have friction, (my only criticism on them other than they are fiddly is that they have more friction than other solutions) there is no need to change them.
I know it is tempting to throw different parts at the problem. But if all your parts are working properly and everything is aligned as it should be you should have no issues.
The hard part is to find which part is not working properly.
Do you get good repeatable Z tilt rrsults?
Is there clearance between the bed balls and the magnets under the Maxwell coupling pins?
thinking about my triple z (zero g hydra) there are no top constraints one of the reasons IIRC being that if leadscrews are bent it can worsen bed wobble but I'm not 100% sure
Slip a thin piece of paper betwen the magntes and bed balls and check you can withdraw it without any friction.
This was the thought process for replacing them first, yes.
That is not what I am doing, the oldhams are the only things replaced so far because I've been specifically trying to find an issue with the assembly before replacing parts and the theory that the oldhams should be able to compensate for a wobble like this is why I did the replacement I mentioned.
This has been months of work with 0 progress, so yeah, I am getting the point of throwing money at parts because I can't keep throwing time at parts that clearly aren't working.
my z tilts are always a maximum of 2 tries.
It is absolutely critical you run no lead screw constraints on printers with out decouplers in the bed arms. On the Rat Rig 3.1 the decouplers in the bed arms SHOULD eliminate this issue but even so I prefer only loose constraints at the top like the wiggle woggles....but it shouldn't matter.
And if you lower the bed and then raise it 10 mm do you get the Z tilt in one try.
yes
OK good.
I did try that when the thought of something wrong with the threads on the leadscrew might be the cause
OK have you checked the bed ball/magnet clearance?
there are no magnets in the arms
OK what is under the pins...just a hole where the magnets should be?
well the "area" for the magnets and two empty screw holes, yeah
checked the dowels for wear too
OK that will be fine and yes you don't need the magnets unless you are using Z accelerations faster than the acceleration force of gravity 9800mm/s
also a 400 so the bed is quite heavy on its own
Weight of bed makes no difference to gravitation force.
So acceleration threshold is the same for a 300 or 500 bed
I, and I would suspect most people, would not need z to ever accelerate that fast.
the weight comes into play when you try to remove a magnetic bed sheet.
but that's another topic
Yep, but that is as you say a differnt topic and of course the total magenetic force is greater on a 400 bed than a 300 bed...but lets leave that topic aside.
When you dirve your bed up and down 100mm is the sound stay nice and even, on extraneous noise or clicks or anything at any point?
no obvious mechanical noises that I wouldn't expect to hear
Just out of interest when I first started testing different types of decouplers before the days Rat Rig adopted them, (Woble rings first and then VenterMechs) I deliberately bent a lead screws so it had 1mm of runout at the centre an I got no lead screw wobble artifacts in the prints, so slightly bent leadscrews should not be an issue. I straightened that leadscrew afterwards as best as I could and it still has about 0.5 mm of runout by my visual assesment and it causes no issues.
yeah, I would think oldhams would solve the type of wobble I am experiencing, out of all the foreseeable issues building a v-core wobble shouldn't be one I have to deal with.
people keep telling me that too now that I'm dealing with it, but here I am.
Any chance you have an input shaper graphs handy?
Just keen to confirm that this is not and X or Y binding issue (clutching at straws here.)
Nice and clean. No issues there.
Hmm this is a tricky one.'
All the balls nice and snugged up on your bed?
yep, loctited them to be sure
If you grab the front of the bed and wiggle it sideways is it relatively hard to move it?
honestly no discernable play on the bed when I try to wiggle it
Video like this?
these are the videos I did motion processing to above
That lead screw is so straight that there is no apparent wobble within the bed arm. Damn I don't miss that high pitched noise from the top bearing constraints.
Your leadscrews appear much straighter than mine.
are your TPU wiggle constraints included in the gold series? I will probably do those once this is all figured out
yeah I've had people pissed at me because they refuse to believe it is anything other then a bent leadscrew but I can roll these things for a meter on a granite countertop without any wiggle lol
the only reason I want to replace them with tr8*8 is because I would hope that the issue would at least be less noticeable. I don't think it would solve the issue.
Yeah your lead screws are good. Hard to tell from those last videos and I also don't know how stable your camera mount is. But looking down from the top when you view your bed referenced both to the top of the bed arms and some static point on your printer can you discern any bed wobble when it goes up and down (You may want to double Your Z access speed for this test to make any movement more apparent)?
just to confirm those few odd layers that don't stack right are just the perimeter going the opposite direction. lines up on all of my tubes.
the wobble is very apparent on the model in this video
Yep but can you see the bed visually wobble?
nope
Just looked at theat video closer. You should not get that layer stacking issue when you the print head swaps direction....I don't.
What print head are you using?
it's not apparently on a lot of my other prints, I was simulatenously testing retractions/wipes/hops with this tube way back when and just have been using the same tube ever since (and a vase mode version I sliced later, which I'm printing next)
it's just an EVA, rapido+orbiter
When you grap the tip of your hot end and wobble it , is there any free play. Enough forsce will move it but is there any free play? And is that a Rapido 1 or Rapido 2?
2 plus UHF
no play
I would imagine if there were any my IS results would be a lot worse
Yeah my input shaper graphs showed ujp excessive clearance in my old X carriage/rail.
Was that not a single wall print?
it is
Vase mode
Hard to tell from the vido but how does that compare?
Exactly the same
Without those weird reverse perimeters of course
Vase mode pyramid
That last little bit didn't go as well as I thought, but that's just slicer settings I can go ahead and tweak
Hard to tell from photo but are those band sizes identical?
Yep
Also where did you get your Z linear rails and carriages from?
I take it they are non pre-load carriages for Z?
a company here in the states that rebrands hiwins
no preload, yeah
So if you tilt the rail the carriages would run freely?
BTW I realise that I am gong over a lot of stuff yoiu have already considered....but no harm in double checking you haven't missed anything?
like before install? yeah I guess so. like if I remove the wobblers from the arms they drop straight down.
How have you lined them up with each other...I guess I am thinking of binding here.
yeah, it's no problem. I'm not against going back over things already done, simple things are the easiest to miss. some things I might recheck just to verify, other things I'll let you know if I've ruled it out enough to not bother trying again
I'm not too sure what you mean
Yeah I appreciate you have already done a lot of clever thinking on your issue.
Ideally you want your Z rails perfectly parrallel with each other. It is not enough that the extrusions are pefectlly parallel. I am thinking of binding and releasing every 2 mm (yep clutching at straws.
Its why the rule is that whenever you use two or more rails in parrallel you generally want Z0 (Hiwin's term for no preload) clearance carriages).
ah... hmmm I'm not sure how to rule that out or adjust for it. I should get a digital level.
these are definitely no preload
Easier just slack off one so it is barely free to move. run the bed up and down and then nip it up and do the same to the other two rails as a starting point....should be good enough. A bit like you do with the Y rails, except more important because you have three of them and they all lie on different planes.
oh, I have done that once or twice, I could try that again.
Should be enough clearances in the carriages to not need to be perfect..Was real issue with my 1P Z motion system though.....I had to machine face the rear upright.
As I said a little clutching at straws now.
yeah, easy enough to try tho
I need to abandon you at this point. I want to do some work on my truck while I have good weather outside.
I feel that
Sorry I haven't been able to help at this point.
no worries, I'll take any fresh eyes on this issue
I do appreciate it
...but in going over stuff with you I did find a small issue to remedy on my printer! A part that I temporarily printed in PETG and forgot about needs to be reprinted in high temp filament.
lol
if you wanna chew on anything in your brain while working on the truck, I just realzed that I don't think anyone has ever asked about software/config/etc but I have no idea if there's anything software that could do this
Yeah software is not my thing. More fancy my skills on mechanics and kinematics.
software wise I don't really see anything that could cause it, some constant frequency slowdown somewhere in processing maybe but seems too far fetched, different gcode running would show differently IMO.
as for config if you have same microsteps/stealthchop enabled or disabled differently
same current for all 3 etc?
you could toggle stealthchop
yeah I've tried a variety of configs, only thing specified right now is the current. same for all three
put the order in for the TR8*8s :pepe_sad:
I still want to strap an adxl or something to the bed, but I'm not sure how to record raw axis movement in klipper
My second Best idea is just sitting my drone on the bed and recording blackbox data with it's mpu6000
https://github.com/worksasintended/klipper_linear_movement_analysis/blob/main/linear_movement_vibrations.py
But I guess it depends on what you want to do with the raw data?
https://www.klipper3d.org/G-Codes.html?h=query_a#accelerometer_measure there's also this
these are great starting points, I'll have to do a deeper dive
if I can strap the adxl on to individual arms I might be able to at least hone in on where the issue is
anyone want to slice a vase cylinder for a 400mm v-core for me?
I'm just now realizing I've only ever used super slicer so I just want t rule out a slicer thing because why the hell not
I'm gonna try to set up orca when I have a bit
I use prusa slicer, I believe it has built in profiles for vcore3 (though very conservative)
Have you swapped out the thrust washers? I can't remember
yep
took this entire fucking thing apart again
all 3 z assemblies
I'm just honestly done.
nothing changes ever.
I know the definition of stupidity
and it is this.
like if I can't at least make the problem liveable with tr8*8s I am seriously just going to flea market this thing because I just can't keep wasting nay more time on this piece of shit
Prusa slicer, so we can rule out a slicer issue.
The bottom half of shitty layer stacking is me actively pushing against the bed and holding the force for a minute or so to see if that has literally any effect on it and... It did not.
This is not Z-wobble.
Something else is going on and me troubleshooting it as z wobble is becoming more and more apparently a waste of time.
Specifications:
Shaft diameter: 5mm
Shaft length: 20mm
Motor body length: 48mm
Full length: 70mm
Weight: 380g
Step Angle: 1.8°
Step Accuracy: 5%
Holding Torque: 0.59N·m (84oz·in)
Rated Current/phase: 1.7 A
Phase Resistance: 1.8 ohms
Rated Voltage (≠driving voltage): 3.06 V
Inductance: 3.8 mH ±20%
Weight: 380 g
well trying a more conservative 16 microsteps didn't change anything
I'm really just at my wits end
I was going to suggest that, I'm really at a loss with this one too, I believe I saw somewhere that something on xy could cause this but I don't remember what
Did you replace your nozzle before this started happening?
I believe you are looking for the definition of insanity
tried with both a rapido UHF and a Rapido plus UHF, both with different nozzles. same behavior
insanity implies a lack of logic, there's plenty of that going on. wasting time is just stupid.
do you have extra drivers you can/have tried?
I did swap the drivers with each other, just to see if I could follow the wobble from one arm to another, but didn't really see any difference
Have you tried attaching a dial indicator to the bed arms and measuring if the bed is moving when going up and down? If it doesn't, then we need to figure out how to measure if the bed arm is moving.
I have thought about it, but don't have one.
I did do the motion processing on the videos which would have shown any wobble in the x or y directions
I don't know if a video would show fractions of a mm very well
Take a look at the YouTube link I posted above, I used software to exaggerate any motion specifically in the frequency that the leadscrews were rotating
I did watch it. But I trust a dial indicator a lot more
Yeah I'm not gonna say it's a sure thing, but I will use it as an excuse to not drop a bunch of money on a dual indicator lol
Less than $40 doesn't seem like a lot, but it's your money
https://www.amazon.com/gp/aw/d/B001QXR2LA
Dial Indicator Set with On/Off Magnetic Base
Precision measuring, set-up and inspection instrument for machinists, manufacturing, maintenance
That and like I said in the last image, I physically pushed against the bed from the angles of the three arms enough for the layers to shift, held it there for 4+mm, and still saw the wobble while doing this. I have a hard time believing a wobble that slight should still be present when physically pushing against the bed
That's why I'm still thinking it's an issue of the beds up and down motion and no actual x/y wobble
I ordered it anyway
If I updated my BOM with all the parts and tools I've purchased I could've bought two 300mm kits
Like
With electronics
@Lemcott mind if I share one of those pictures on another discord where I believe I saw someone who had a similar issue and it wasn't on Z
Agreed.
Go right ahead, the more eyes the better
That does make me feel a bit better
@Lemcott I'll let you know if there are news
@Lemcott both belts have same length and tension?
https://discord.com/channels/582187371529764864/1198381287208132618
IS seems to think so
whoa tension is wayy better than my printer
I have seen mentions that belts with different lengths could cause something like that even with equal tension but I'm not sure of anything
So it's probably not a config issue, as they are all configured the same.
But obviously that Z1 is struggling.
All one print
I'm gonna frame this fucked up print sheet as a memento if I ever get this fixed.
Have you tried to swap your drivers to see if the problem moves?
A story
In 2 pictures
So
I replaced the entire z1 motor and stepper driver at the same time with new spares and removed the constraint bearing from the back and printed the triangles again, and.... The back motor was actually the best print of the 3.
Then I removed the bearings from all of the z stacks and also upped the z motors to 1.4 per https://discord.com/channels/582187371529764864/1213640370131443783
They were originally turned down for noise and because these motors actually need slightly less than the default motors, but that noise was probably because they were fighting those constraining bearings.
Homed and dropped the bed, reset the couplings grubs, brought it back up and started this... Hopefully last... Cylinder:
Yesss!!!!
Fantastic job, would be great to document it, for other people to troubleshoot it
damn, so it was the bearings that hold the leadscrews on top?
I think it was a mix of things.
I had replaced and even ran without the constraint bearing on z1 before to very little difference. I had swapped it's driver before, I had swapped out the motor before, when I started running these and noticed the issue I ran them at the performance current (higher than what it is right now), so... Everything I did last night has been done before in one way or another.
Maybe the motor was actually bad, so when I swapped the driver it fucked up the new one which in turn fucked up the new motor when I tried that, so maybe replacing them both at the same time was what was needed. Maybe the other constraint bearings played more of a role because I only ever removed the bearings from one Z at a time while testing so just removing one was never enough.
So like... Maybe it was all of that. Who knows. I'm just so glad I can finally start printing
Out of curiosity, the lines on the one on the left, what are they? Where you handling the bed while printing to see if there was any wobble?
bad slicer settings - if you compare it to the right tube with all the wobble you'll notice the exact same layers have the same issue.
could also be a little belt tensioning or maybe binding on the gantry, but those are all much easier to resolve/tune now that I have the bigger issue taken care of
Okay, I've been following this ever since you opened the discussion, I'm glad you found the issue. And didn't have to sell the printer.
feeling very much the same lol
well I'm definitely relieved it's fixed, this was quite puzzling and captured my attention to the point of needing to know the answer.
enjoy your now working printer
Finally broke into my light gray filament
Still visible here, but at least no where near as bad
I sometimes get this if the infill is set 100%. But if I run a vase, there is zero banding apparent.
this is like 18% lightning infill, it's mostly hollow. two walls, .6 nozzle
but also... I noticed something
why am I running z accel at 150
man cranking that down to 20 was a very big improvement
Now I just gotta work on speeds and feeds. Tuning this 4028 for PLA has been an interesting side problem while working with the wobble issue
Strange you had to change the z accel, not sure about v-core, but on my minion stock its 600
Standard Rat Rig supplied Z motors?
I think the restraint bearings provide little tolerance for other issues (and make unneccessary noise) hence recommend replacing them with TPU printed Wiggle Woggles.
nope, I think i posted the specs somewhere in here
you got a link to those? I do want to try and retain them a bit now that the issue has greatly improved
thats why i never saw them, i was only looking at printables lol
he has them on printables too https://www.printables.com/model/595289-gold-series-leadscrew-guides-for-use-with-venterme
wtf i swear i looked all through the gold series
I also noticed that the prusa xl has a bearing constraint but the mount itself flexes
did you fixed it? I got exactly same issue, but with minion belted Z
I don't think this is the same root cause as my issue
did you fixed it? @Lemcott
Mostly
People are now modding Prusas Z axis n a similar fashion to the mods we all came up with to solve Rat Rigs issues.
One thing I have recently done is change to a z1 lightly loaded Carriage on my X rail. A marginal but very satisfying improvement to already excellent layer stacking Can hardly believe the consistency of high quality prints I am getting now.
le
I'm gonna give one final update on this because... it's fully 100% gone away now.
Lube your oldhams and leadscrew. the idea that POM "self lubricates" will only get you so far and my belief is that with TR8x2 the leadscrew is rotating faster than a traditional oldham coupler can compensate for.
I started by greasing the leadscrew and this had a lot of impact on reducing the visible wobble even more so than my last updates. I noticed without the constraint installed that the leadscrew had a few positions I could "pop" it into and they were always in the cardinal directions of the two guides on the oldham couplers so continuing with my theory I attempted to deburr/file the edges the tiniest amount so that there was nothing on the POM slider that would get caught entering/exiting one of the channels. this helped a lot, so I popped em back off and put some lube in those channels and worked them back and forth for a while before installing and... it's 100% fully gone now.
I still have spring couplers installed but I've now reinstalled the bearing constraints at the top of the leadscrew and the issue has not come back despite the fact that removing those in the past was the single most significant improvement.
So my working theory goes something like... with the weight of the bed and no preload on the z the arms can shift just enough to put a slight bend in the leadscrew that isn't visible when the leadscrew isn't installed. this shifts the oldham into sitting in one of the four channels which the oldham simply can not compensate for at the torque/speeds required for TR8x2 and this 'popping in and out' is ultimately what causes the wobbles. reducing friction on both the leadscrew nut and oldham channels allows the leadscrew to more easily turn through the nut and shift around within the oldham.
@Lemcott thank you for the final update, will keep that in mind
that's all folks!
dang thats a pretty print. Off to lube my screws!
mine could use some maintenance too
Very informative and interesting, thanks. We'll done on diagnosing it and fixing it.