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. fix-my-printDDEX print issues and tuning log.

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.

VisualTech48•1/30/24, 9:11 PM

I want to see those leadscrews roll on the table...

VisualTech48•1/30/24, 9:11 PM

This looks like, as I've said, binding somewhere.

VisualTech48•1/30/24, 9:11 PM

From the top down also please images.

VisualTech48•1/30/24, 9:11 PM

Of the leadscrew assembly

VisualTech48•1/30/24, 9:11 PM

With the arms.

VisualTech48•1/30/24, 9:12 PM

You can actually film from top down, and set the bed to go from 0 to 200

VisualTech48•1/30/24, 9:12 PM

For all 3 arms

VisualTech48•1/30/24, 9:12 PM

And see how its spinning

VisualTech48•1/30/24, 9:12 PM

IE: record from this perspective

flow4enol•2/18/24, 11:10 AM

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?

flow4enol•2/18/24, 11:12 AM

either the bottom or the top one maybe

LemcottOP•2/20/24, 2:29 PM

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.

Oskait•2/20/24, 3:45 PM

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

LemcottOP•2/20/24, 4:03 PM

'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.

flow4enol•2/20/24, 5:16 PM

hmm have you checked if the leadscrews are parallel to the frame

LemcottOP•2/20/24, 6:17 PM

I'm actually printing additional leadscrew constraints to put further down just to see what happens lol

LemcottOP•2/20/24, 6:17 PM

also I'm very bad about calling lead screws threaded rods

Jar of Goo•2/20/24, 8:11 PM

Have you watched MirageC's videos on YT on Z-Wobble?

LemcottOP•2/20/24, 8:50 PM

yep, there's a pic in the original thread of one of his slanted towers.

LemcottOP•2/20/24, 8:51 PM

wobbleX isn't going to solve this though

LemcottOP•2/20/24, 9:18 PM

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.

flow4enol•2/20/24, 11:12 PM

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

LemcottOP•2/21/24, 2:40 AM

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.

LemcottOP•2/21/24, 7:28 AM

Well it wasn't the oldhams

flow4enol•2/21/24, 11:32 AM

seems too consistent to be extrusion

flow4enol•2/21/24, 11:32 AM

bent stepper shaft?

LemcottOP•2/21/24, 5:24 PM

LemcottOP•2/21/24, 5:25 PM

LemcottOP•2/21/24, 5:26 PM

comparison of dropping the bed down to 400 in cad vs IRL

LemcottOP•2/21/24, 5:27 PM

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

LemcottOP•2/21/24, 5:27 PM

wait those are tr8x8 and I'm using x2

LemcottOP•2/21/24, 5:27 PM

counting threads is a shite measurement of length

LemcottOP•2/21/24, 7:42 PM

Oskait•2/21/24, 7:45 PM

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)

Oskait•2/21/24, 7:46 PM

although... you showed in your first pictures that theres a difference between the point on the bed, so its probably not extrusion related

LemcottOP•2/21/24, 7:47 PM

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.

LemcottOP•2/21/24, 7:48 PM

LemcottOP•2/21/24, 7:49 PM

Pretty consistent

LemcottOP•2/22/24, 2:18 AM

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.

LemcottOP•2/22/24, 2:23 AM

so timeline is:

uninstalled leadscrews - checked them for bends again but nothing all that obvious.
reinstalled leadscrews (I did not keep track of their original positions, so they are most likely in new positions) with the new mandala oldhams.
tube print shows no change
totally disassemble and reinstall rear z motor mount (again)
tube print shows no change
notice the back arm is sitting slightly higher, verify in cad that should not be like that.
check squareness of frame (again)

LemcottOP•2/22/24, 2:24 AM

I'm still just grasping at straws here.

LemcottOP•2/22/24, 2:44 AM

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.

LLemcott so timeline is: 1. uninstalled leadscrews - checked them for bends again but not...

blacksmithforlife•2/22/24, 2:49 AM

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

LemcottOP•2/22/24, 2:55 AM

I'm not noticing any significant warp running a straight edge over the top face of the arm.

blacksmithforlife•2/22/24, 3:46 AM

What about it being mounted at an angle? Is the face of the arm 90⁰ to the rail?

LemcottOP•2/22/24, 4:01 AM

as far as I can tell

flow4enol•2/22/24, 2:51 PM

I'll assume you also checked couplers

flow4enol•2/22/24, 2:51 PM

swapping steppers around?

LemcottOP•2/22/24, 3:05 PM

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.

flow4enol•2/22/24, 3:29 PM

usually couplers on triple z are supposed to be rigid IIRC