Rippels and Ghosting on Y-Axis of converted Ender 3
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You said you know your system can do better. Do you mean you have seen others do better or your system did better pre Duet? With age thing do wear out, and the duet has come second! May be worth a nozzle swap if it is old.
At least 4 areas for optimisation being investigated here and improving one can easily make another look worse when all thats really happening is you are reducing a randomising effect by curing one issue which was hiding the magnitude of a second. Very frustrating, but it's the nature of the beast.
In no specific order:
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Ringing/ghosting - you've mentioned your stock pully a few times. Assume this is at most £5 to swap out with a gates model? Some other threads indicated that gates may not be the best, but at least they are respected for quality control. Creality not so much. Also try to get the belt running without scuffing the sides of the pulleys. That said as the pitch changed with speed I think this maybe a mode of oscillation in your frame somewhere. I've no experience with enders, is it easy to brace the top on the z-axis back down to the front or rear of the machine? To treat the oscillation you need to make the thing that's exciting it vibrate differently (less or at a different frequency; quieter stepper setup, belt/pulley choice, belt tension, etc), or change the natural frequencies in your frame by making it stiffer or more compliant. More drive current on the motor will likely reduce the amplitude of oscillation of the motor around it's target position. Keep check on how warm the steppers are. Ok you don't want to run higher currents than specced, but a stone cold stepper would indicate it's not working particually hard.
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Z wobble. In one of your pictures there appears to be heavy scoring on your right hand inner delrin wheel. That shouldn't happen. Check the extrusions to ensure the v-slot is very smooth. If anything that the wheels run on can scratch or be felt as uneven by your finger then it needs to be fettled or replaced. Check all other wheels for wear and that the bearings run smooth (remove wheel to check). With no z axis screws connected the axis should move up and down easy with no tight spots. The wheels should be tight enough to the rail to limit wobble, but not so tight as to overload the bearings. There is a big difference between quality bearings and wide tollerance cheap bearings. I have found heavy duty wheels (polycarbonate I think) harder wearing. Linear rail z maybe asking for trouble with an extrusion based machine as you are likely to end up spending an age trying to align the two rails close enough to each other to get the axis running smoothly. A bit like the issue Tom3D discussed on YouTube when trying a twin linear rail y-axis setup on another bed slinger. You may also need to (as far as possible) de-couple (in x/y-plane) the z nuts from the motor and idler ends of the x-axis. A popular mod on P3Steel machines. My next step is belted z-axis with a worm reduction drive to stop axis drop on power down.
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Your "///\" pattern is often referred to as "Vertical Fine Artifacts" or VFA. Somewhere in this forum there is a link to a long thread on a Prusa forum about trying to tackle them. From memory specific motors (despite similar spec sheets) do make a difference. There seem to be a few quality stepper motor brands rising up at the moment. LRO are making noise on twitter (and I think they supply E3D) but I have no experience of them. I'd be a little cautious about definitively saying it was vibrations from the fan causing issues. I'd wonder if for example it was more electrical noise? Can you check for electrical noise and would you know what to look for? Ensuring there is good continuity from your stepper motors (and maybe hotend) to the mains protective earth would be wise first principles step. likewise on the noise front can you lock your toolchanger and run with the magnets off in a trial?
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Irregular extrusion. Direct is easier as you are about to find out! Have you run the calcs to check the stepper can run at the commanded speeds? I suspect the loud odd noises you mention on some retracts are skipped steps. Have you already checked e-steps carefully (slow extruder drive with nothing after extruder), linear & non-linear extrusion correction, before doing detailed pressure advance and retraction calibration? Ideally the retracts should be minimal but slightly excessive to avoid occasion stringing.
Final point... Plan your experiments or you will spend way over the odds on this. Try to find ways of quantifying/measuring the issues you can see. Tackle maintenance issues (scored wheels, bearings etc) first and always check system for loose bolts, couplers, and signs of wear. I have - as most of us have - got history of missing a simple problem while searching for a complex one. Be warey of compairing your prints too much to others. Some are dishonest with lighting to hide artefacts etc, but to be fair I've not seen too much of that on this forum. A walk around TCT Show last year and I saw many worse examples of ringing than what I thought was critical on my machines on both demo machines and parts trying to sell commercial level services.
Running 3 P3Steel with Duet 2. Duet 3 on the shelf looking for a suitable machine. One first generation Duet in a Logo/Turtle style robot!
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Possibly somewhere I can help at last...
I've just ordered the Ender 3 pro as a backup printer, and at first sight I ordered the dual Z axis (single motor belt drive model) mod kit. I would say not quite certainly but highly likely that your X axis is sagging, especially as the previous poster notes delrin wheel wear.
This guy's got some good tips:
https://www.youtube.com/watch?v=4bFYH0X3qjk
If you watch all his vids, he goes into how to tension those wheels and align the chassis. I've got a feeling some of your problems lies there.
Regarding extrusion, that's a pretty short bowden tube with some pretty big settings.
I would try less retraction and also slower. I've seen reports of really slow retraction speeds working well...why not try 4mm retraction at 15mm/sec? Can't hurt to try.
I think you've got a couple of problems, both mechanical and settings. That guys performance build video would be a good place to start.
Hope that helps!
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Thanks very much for the detailed answer!
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Do you mean you have seen others do better
Yes, a couple examples include this, this, this, this, and I could continue on... These were all printed on an Ender 3, so I know it can do better.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Ringing/ghosting - you've mentioned your stock pully a few times.
As I mentioned too, I've already replaced my stock belt on Y with a GATES-LL-GT2, which wasn't cheap either. It sadly made no difference compated to the stock belt, and I have not yet replaced the X-Axis, and it barely shows any ringing/ghosting. I will soon swap the X-Axis belt too.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
That said as the pitch changed with speed I think this maybe a mode of oscillation in your frame somewhere.
I agree with you here, the frame must vibrate / oscillate somehow. I have already ordered some parts like T-Brackets and V-Slot corner brackets to make the frame more sturdy, but it will take a while for them to get here.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
More drive current on the motor will likely reduce the amplitude of oscillation of the motor around it's target position. Keep check on how warm the steppers are.
Both (X and Y) steppers take 1.68A, and I'm currently running them at 75%, so 1.26A. I had also tried 85%, but they only got louder and hotter and the pattern didn't change. With 75%, they get to around 40-45 C after 2 hours.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
With no z axis screws connected the axis should move up and down easy with no tight spots. The wheels should be tight enough to the rail to limit wobble, but not so tight as to overload the bearings.
It moves up and down very easily, doesn't get stuck anywhere, and has no woblle. The extrusion is smooth, and yes, I do see some wear on the wheel, but it's minimal. I haven't checked the bearings individually yet, but will do so. I will try to source some polycarbonate wheels too.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Linear rail z maybe asking for trouble with an extrusion based machine as you are likely to end up spending an age trying to align the two rails close enough to each other to get the axis running smoothly. A bit like the issue Tom3D discussed on YouTube when trying a twin linear rail y-axis setup on another bed slinger.
You're right, there's going to be lots of fiddeling around to get everything to move smoothly, but people have done it before, and I think I should be able to achieve it too, even if it takes a while.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
You may also need to (as far as possible) de-couple (in x/y-plane) the z nuts from the motor and idler ends of the x-axis. A popular mod on P3Steel machines.
Can you elaborate a bit what you mean? I think what you mean is to allow the Z-Nut to move a bit in X/Y? The XZ-bracket I'm using for my brass nut already allows for some adjustability in the Y-Direction when not fully tightened. I've tightened the screws just enough so that it won't wobble in Z, but will allow the lead screw to move the brass nut in Y (and a little bit in X).
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Your "///" pattern is often referred to as "Vertical Fine Artifacts" or VFA. Somewhere in this forum there is a link to a long thread on a Prusa forum about trying to tackle them.
Yeah, I've stumled upon that thread as well. It's long, very long, and I've already read some pages.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
here seem to be a few quality stepper motor brands rising up at the moment. LRO are making noise on twitter
The steppers I have right now are definitely not the highest quality. I would be willing to invest better ones, however I found nothing when I searched for LRO steppers on Google. Could you link me to their shop or somwhere I can buy them?
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
I'd be a little cautious about definitively saying it was vibrations from the fan causing issues. I'd wonder if for example it was more electrical noise? Can you check for electrical noise and would you know what to look for? Ensuring there is good continuity from your stepper motors (and maybe hotend) to the mains protective earth would be wise first principles step.
The pattern was definitely gone once I disabled the fans, and I can definitely feel the fan vibrating everything quite violently when it's running. It's a super cheapo 5015 blower fan, and it shows.
How could I check for electrical noise? I have a multimeter, but no oscilloscope. I will also check ground continuitiy.@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
likewise on the noise front can you lock your toolchanger and run with the magnets off in a trial?
I was suspecting that some of the vibration came from the magnetic mount as well, so I had it very firmly clamped down so that absolutely nothing could move, and it made no visible difference. I have added even more magnets now, and the new piece I just finished printing for the direct mount is also a very tight fit, so there's absolutely no wobble there.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Irregular extrusion. Direct is easier as you are about to find out! Have you run the calcs to check the stepper can run at the commanded speeds? I suspect the loud odd noises you mention on some retracts are skipped steps. Have you already checked e-steps carefully (slow extruder drive with nothing after extruder), linear & non-linear extrusion correction, before doing detailed pressure advance and retraction calibration? Ideally the retracts should be minimal but slightly excessive to avoid occasion stringing.
The new pancake stepper (17HS4023) will arrive this evening, and I'll install it tonight together with the BMG for the direct drive. Could you explain how I can calculate the max speeds it could handle with the BMG? Since this is a new stepper, I will also be redoing the e-steps calibration. Maybe I'll also do the non-linear extrusion correction, but from what I've heard, it doesn't really make that much of a difference?
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Final point... Plan your experiments or you will spend way over the odds on this. Try to find ways of quantifying/measuring the issues you can see. Tackle maintenance issues (scored wheels, bearings etc) first and always check system for loose bolts, couplers, and signs of wear. I have - as most of us have - got history of missing a simple problem while searching for a complex one. Be warey of compairing your prints too much to others. Some are dishonest with lighting to hide artefacts etc, but to be fair I've not seen too much of that on this forum. A walk around TCT Show last year and I saw many worse examples of ringing than what I thought was critical on my machines on both demo machines and parts trying to sell commercial level services.
You're absolutely right. I will try not to change too many things at once to keep things comparable, even if it takes more time. I will check my whole printer for wear and see if I can find something obvious.
You could be right about hiding artifacts. My prints too look flawless when viewed from a certain angle, but look totally different when viewed from another angle.
Thanks again for your very detailed answer!
Well, I'll report back once I have my direct drive installed and tuned in. Let's hope it makes a difference!
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@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Possibly somewhere I can help at last...
I've just ordered the Ender 3 pro as a backup printer, and at first sight I ordered the dual Z axis (single motor belt drive model) mod kit. I would say not quite certainly but highly likely that your X axis is sagging, especially as the previous poster notes delrin wheel wear.
This guy's got some good tips:
https://www.youtube.com/watch?v=4bFYH0X3qjk
If you watch all his vids, he goes into how to tension those wheels and align the chassis. I've got a feeling some of your problems lies there.
Regarding extrusion, that's a pretty short bowden tube with some pretty big settings.
I would try less retraction and also slower. I've seen reports of really slow retraction speeds working well...why not try 4mm retraction at 15mm/sec? Can't hurt to try.
I think you've got a couple of problems, both mechanical and settings. That guys performance build video would be a good place to start.
Hope that helps!
Thanks, I'll watch his video. As I will go direct drive for now, my retraction settings will be completely different anyways. But I'll try slow and high retraction speeds and see if it makes a difference!
I do agree though, my x-axis definitely does sag on the right side a little bit, which is why I have to have the wheel a bit tighter to reduce (not eliminate) wobble. Do you already have your dual z-axis mod installed? Could you link me to it? What do you think of it?
I hope the linear rails for Z will also reduce the x-axis sagging, after all the the carriages have no play and should provide sturdiness.
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No worries,
Here's the one I got. They all seem to be the same thing, so I just bought it off the cheapest seller with the best feedback.
Seriously mate I'd watch the money you throw at that printer...I'd save linear rails etc for a larger cube framed printer, too much for an E3 IMHO.
For mine I'm more inclined to leave the rollers on the X axis and if I was to use linear rails anywhere, it would be the bed/Y axis only. If you don't like the ringing now, you might be more concerned when you're swinging a heavy direct drive extruder on the unsupported X axis.
For my money, I'll be assembling mine very straight and true form the start, and I'll fit the dual Z axis from the start. Haven't got the printer yet, but I've had one with the X supported on one side like that, and it's not ideal.
I plan to use the stock hot end with a PTFE liner/fan shroud mod, but I've got a brand new genuine Bondech BMG here that I will fit with some Capricorn tube and better couplers.
Speaking of couplers....if yours are the stock ones they are known to fail. Might pay to change them and fit the retaining clips. Forgot to mention that earlier.
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Thanks for the link, I'll consider it. I might just get two nema 17s with integrated lead screws instead, though, just like on the prusa. I know that both steppers will not be aligned after they loose power, but for that I could just copy the "stall into the top until aligned" routine that the Prusa does too.
That way I don't have to worry about belt tension and a complicated setup on the top of the printer (where I would like to store my hotswappable tools anyways).@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Seriously mate I'd watch the money you throw at that printer...I'd save linear rails etc for a larger cube framed printer, too much for an E3 IMHO.
Well... Too late haha. I already have all the rails here. I'm still well under the cost of a new Pursa Mk3 though.. So there's that..
I just watched the video, and it's very similar to another video I followed just recently. https://youtu.be/AN0MlQMMew0
My axis is perfectly aligned with the frame, and when I measure the distance from the top bar to left and right, it's the same. Before I had followed that video, not all my wheels on the X axis would grip the extrusion, even when the eccentric nut was tight. Now all the wheels grip the extrusion, so it seems all is lined up well.What I'm going to try next is to put my printer on the floor instead of the ikea table, as it is still a bit wobbely. Maybe the ringing is coming from the table! Ideally, I should get something like a very heavy granite plate to put under the printer...
@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Speaking of couplers....if yours are the stock ones they are known to fail. Might pay to change them and fit the retaining clips. Forgot to mention that earlier.
I changed them a long time ago... I agree, the stock ones are pretty bad...
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Actually, I can tell you first hand that a wobbly table certainly doesn't help anything.
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@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Actually, I can tell you first hand that a wobbly table certainly doesn't help anything.
So, I went to the hardware store and got a granite plate, with around 13kg. I will place my ender 3 on that soon.
In the meanwhile, I've placed the ender on a sturdier table.Anyways, without further ado, here's the direct drive!
Can you tell which print is which?
The left is the one with direct drive - same GCode.
Let's light them up! This is the cube from before the direct drive upgrade (the right one):
Let's now compare it to the cube printed with the direct drive:
Hoo... Hooray? At least it's consistently bad now, with a very clear pattern.
@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
At least 4 areas for optimisation being investigated here and improving one can easily make another look worse when all thats really happening is you are reducing a randomising effect by curing one issue which was hiding the magnitude of a second. Very frustrating, but it's the nature of the beast.
So, you were right
Two down (irregular extrusion and VFA), two to go (z wobble, ringing).I guess I'm batteling something in the Z-Axis now, right? Like a bent lead screw, bad bearing or bad wheel.
Or could it still be extruder related? It seems like a too low of a frequency of banding to be able to come from the BMG, but I'm not sure. Also, upon closer look, I can see many of the same artifacts in the same heights.Anyways, I think for my next step, I'll be swapping in the old stock leadscrew (T8*8mm). If the pattern stays the exactly the same, I know it's not the leadscrew or related parts and I should take a closer look at the extruder. I"ll also experiment with using normal brass nuts, the anti-backlash one, and a POM one, which should be here any day now...
On a related note, both leadscrews are definitely bent. Does anyone know where I could source a good quality, non bent lead screw? I'll have a look if I can source something locally.
Edit: Trying to find a lead screw online and they talk about left threaded and right threaded... Uh.. Also, I seem to only be able to find T8x1.5... -
That's definitely Z banding, almost certainly due to the X gantry wobbling on the X axis. I'm actually surprised it isn't worse with the direct drive extruder weight added.
I'd really look to that dual Z axis, either dual or single stepper.
Also, is the lead screw fixed at both ends? Some manufacturers like to leave the lead screw nut bolts slightly loose on the bed mount/bracket so that it allows a bit of "off center" movement of the screw without pulling at the Z axis. Others sometimes leave the screw completely unsecured at the top for the same reason.
It really looks like you've got a mechanical/alignment issue there.
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@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
That's definitely Z banding, almost certainly due to the X gantry wobbling on the X axis. I'm actually surprised it isn't worse with the direct drive extruder weight added.
I mean, it is "worse" in a sense now because the pattern is more clear and consistent, instead of being irregular.
@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
I'd really look to that dual Z axis, either dual or single stepper.
Will order some parts for it, probably just two steppers with integrated lead screws.
First im going to install the linear rails on Z though, as this should already help a lot with sagging.@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Also, is the lead screw fixed at both ends? Some manufacturers like to leave the lead screw nut bolts slightly loose on the bed mount/bracket so that it allows a bit of "off center" movement of the screw without pulling at the Z axis. Others sometimes leave the screw completely unsecured at the top for the same reason.
I did at one point had the lead screw fixed at both ends, and the brass nut tight on the mount. This got me really bad Z-wobble, because, who would have thought, the leadscrew is bent.
The last print was done with the lead screw free at the top, and during fast Z-movements (like probing), you can clearly see it wobble and that it's bent. Bummer, I just got it new a couple days ago! The brass nut is also a little bit loose on the Xz-bracket, allowing for slight movement in X and Y, but not Z.
Once I get an actual non bent leadscrew, I will fix it at the bottom, gantry and top.
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Just a very quick update, I have removed the leadscrew and slowly moved the x-gantry up and down the z-axis. I can feel a very, very light bump in regular intervals. Guess it must be one of the wheels. I will try if I can figure out which wheel it is.
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@devleon said in Rippels and Ghosting on Y-Axis of converted Ender 3:
@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
That's definitely Z banding, almost certainly due to the X gantry wobbling on the X axis. I'm actually surprised it isn't worse with the direct drive extruder weight added.
I mean, it is "worse" in a sense now because the pattern is more clear and consistent, instead of being irregular.
@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
I'd really look to that dual Z axis, either dual or single stepper.
Will order some parts for it, probably just two steppers with integrated lead screws.
First im going to install the linear rails on Z though, as this should already help a lot with sagging.@Corexy said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Also, is the lead screw fixed at both ends? Some manufacturers like to leave the lead screw nut bolts slightly loose on the bed mount/bracket so that it allows a bit of "off center" movement of the screw without pulling at the Z axis. Others sometimes leave the screw completely unsecured at the top for the same reason.
I did at one point had the lead screw fixed at both ends, and the brass nut tight on the mount. This got me really bad Z-wobble, because, who would have thought, the leadscrew is bent.
The last print was done with the lead screw free at the top, and during fast Z-movements (like probing), you can clearly see it wobble and that it's bent. Bummer, I just got it new a couple days ago! The brass nut is also a little bit loose on the Xz-bracket, allowing for slight movement in X and Y, but not Z.
Once I get an actual non bent leadscrew, I will fix it at the bottom, gantry and top.
Yes, it has been my experience that lead screws almost always wobble, and you'll often see them left unsecured at the top for that reason. The movement in X and Y, but not Z is desirable IMHO.
@devleon said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Just a very quick update, I have removed the leadscrew and slowly moved the x-gantry up and down the z-axis. I can feel a very, very light bump in regular intervals. Guess it must be one of the wheels. I will try if I can figure out which wheel it is.
That won't help anything either, but probably isn't the main cause if it's that light. It seems tensioning those little wheels is an ongoing and fickle process. I'll be finding out soon enough when mine arrives.
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Well, I put in the old leadscrew (T8x8), and a matching anti-backlash brass nut, which already had a LOT less play than the T8x2 brass nut, and I fiddled around with the frame and eccentric nuts until I got the least amount of bumps, with still all rolls rolling.
This is the result:
Sure, it's still not perfect, but I think it's definitely getting better
Finally, some progress...
I think as I next step I'll be installing the linear rails in Z then, see if it improves even more, since I could still feel very very tiny bumps, which also explains the line in the top third, which has been in all of my prints so far. -
Check over those wheels before going full hog on the linear rail.
You mentioned a 2mm pitch on your screws but I think that's a 2mm pitch with a 8mm lead? In other words turn the screw 360 degrees and the x axis moves up by 8mm rather than 2?
Even if not the pitch on your parts of the "defect" looks more like 1.0-1.5mm rather than 1mm? My gut instinct at the moment is get some decent bearings in the wheels and replace the "tyres" with the heavy duty poly carbonate wheel rather than delrin. After rubbing your finger up and down the guide slot to ensure it hasn't been nicked or damaged.
Running 3 P3Steel with Duet 2. Duet 3 on the shelf looking for a suitable machine. One first generation Duet in a Logo/Turtle style robot!
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@Corexy @devleon Z isolators are a thing, and have been for a long time with lifting-x-gantry bed-slingers, as the X/Z axes are over constrained when the Z lead screw is bolted to the X axis, and it’s even worse if the leadscrew is constrained at both ends. Any eccentricity of movement fights the linear rail for position of the X axis. The Z isolators decouple the Z axis from the X axis, and allow the X axis to ‘float’ on the Z, while the linear rail gets on with its job of guiding the X axis.
Edit: See https://www.thingiverse.com/search?q=z+isolator
Ian
Cartesian bed-slinger with Duet 3 Mini 5+ WiFi and 1LC : RRP Fisher Delta v1 with Duet 2 Maestro : TronXY X5S with Duet 3 MB6HC and Roto toolboard
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@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
You mentioned a 2mm pitch on your screws but I think that's a 2mm pitch with a 8mm lead? In other words turn the screw 360 degrees and the x axis moves up by 8mm rather than 2?
Yeah, 2mm pitch with 4 leads, so 8mm with one full rotation.
The new (and more bent one) is 2mm with a single start, and the stock (old) one is 2mm with 4 starts.@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Even if not the pitch on your parts of the "defect" looks more like 1.0-1.5mm rather than 1mm?
Not sure what you want to hint at? The new print doesn't seem to have any regular occuring defects. However, I also just measured the distance of the ripples in the cube that I printed right after upgrading to the direct drive, and with the bent 2mm single start lead screw... The distance is exactly 2mm, except for the wobbles at the bottom, which for some reason are closer together at around 1mm distance, peak to peak.
I tried to relate any ripples on the new print with a 8mm distance, but found nothing that would match it.
@droftarts said in Rippels and Ghosting on Y-Axis of converted Ender 3:
@Corexy @devleon Z isolators are a thing, and have been for a long time with lifting-x-gantry bed-slingers, as the X/Z axes are over constrained when the Z lead screw is bolted to the X axis, and it’s even worse if the leadscrew is constrained at both ends. Any eccentricity of movement fights the linear rail for position of the X axis. The Z isolators decouple the Z axis from the X axis, and allow the X axis to ‘float’ on the Z, while the linear rail gets on with its job of guiding the X axis.
Thanks Ian! Yeah, I've heard of them before, and saw them on a couple i3 style printers as well, but it seems they all require a linear rod to ride on, which I don't have in my setup, and I'm not quite sure how to adapt it to what I'm using.
In their design, creality uses oval holes and spring washers between the brass nut and then suggest in their manual to not tighten screws holding the brass nut too far, so that there's still some play in the Y direction. You can see in the picture below.
However, they only made the hole oval in a new revision, and I have a version of the bracket that has a completely round hole that allows for no play at all. I even had ordered a new plate directly from creality, but got the old version again. I tried to explain to the customer service that I wanted the new part, but they didn't understand what I wanted. They asked if I wanted extra holes
Plus, I couldn't mount any standart brass nut to this anyways.The X/Z-bracket I'm using right now also has oval holes, and allows for some movement along the y-direction, but only if not tightened fully. I will experiment with adding some washers and even spring-washers and will see if I can get a compromise between play in x/y but not y.
I appreciate the input from everyone so far!
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@DocTrucker said in Rippels and Ghosting on Y-Axis of converted Ender 3:
My gut instinct at the moment is get some decent bearings in the wheels and replace the "tyres" with the heavy duty poly carbonate wheel rather than delrin. After rubbing your finger up and down the guide slot to ensure it hasn't been nicked or damaged.
I almost forgot, I tried to find some poly carbonate wheels on amazon, and there's only one seller that has them and the very first review complains about how bad and low quality the bearings are and that from 10, already 4 had failed after around 20 hours. So.. Yeah no.
And anything I order from china now won't arrive for a couple months sadly...
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@droftarts said in Rippels and Ghosting on Y-Axis of converted Ender 3:
@Corexy @devleon Z isolators are a thing, and have been for a long time with lifting-x-gantry bed-slingers, as the X/Z axes are over constrained when the Z lead screw is bolted to the X axis, and it’s even worse if the leadscrew is constrained at both ends. Any eccentricity of movement fights the linear rail for position of the X axis. The Z isolators decouple the Z axis from the X axis, and allow the X axis to ‘float’ on the Z, while the linear rail gets on with its job of guiding the X axis.
Edit: See https://www.thingiverse.com/search?q=z+isolator
Ian
OK, yes I did notice something about them when I was researching about the one I just bought. I was actually already looking at an "Oldham Coupler".
It looks like a combination of the Oldham/plum coupler with a Z isolator would be a much cheaper place to start.
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@devleon after all this, I would love to find out what the ender was like that produced this cube you posted above. That is a great print imo. Was it pure stock? If do we know its not the wheels or the bearings or sag, etc. My ender 3 has only been modded with direct drive and the duet maestro. It definitely printed at least simple things better before the mod. https://cdn.thingiverse.com/assets/c9/8d/6f/3e/d5/featured_preview_speedDrive_cube.jpg
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@devleon said in Rippels and Ghosting on Y-Axis of converted Ender 3:
Not sure what you want to hint at? The new print doesn't seem to have any regular occuring defects. However, I also just measured the distance of the ripples in the cube that I printed right after upgrading to the direct drive, and with the bent 2mm single start lead screw... The distance is exactly 2mm, except for the wobbles at the bottom, which for some reason are closer together at around 1mm distance, peak to peak.
My bad, missed the complete lack of them on he latest print, and with a single start 2mm pitch with a 2mm pitch on the old part it is fairly conclusive.
Regards z-isolator I mentioned the P3steel ones. You are right, mine relies on the smooth rod to constrain the nut so it can't rotate with the screw. It then has a cylinder that clears the screw by 1 or 2mm that raises up from the nut and pushes on the x-axis. This allows a little movement of the screw before it can wobble the x-axis. It may not work quite as well but you could consider having a couple of fingers going either side of the extrusion that the x-axis rides up and down on to constrain the nut. This would allow a little movement in y axis for the nut but not so much in x.
An extreme version would be attach the z-nut to a second pair of carriages that run above the x-axis which 'carry' the x-axis via a small scrap of belt and rely on gravity to pull the x-axis down. Down side would be a loss in z-axis until you got new extrusions cut.
I've had difficulty getting straight z-axis screws to. I've shelved any effort to make it better so I can design a belt z-axis which I must get on with!
I used ooznest for the heavy duty wheels which are open build parts. Likey more expensive than Chinese imports, but hopefully reasonable bearings. What country are you based?
