<h2>Cause and effect</h2>
<p>Bent screws can cause an effect known as Z-wobble. But, to mitigate this, the non-driven side of the lead screw is left unconstrained. This is intentionally designed as such.</p>
<p>This means that as long as the linear guide (being V-slot with rollers, linear shafts or linear rails) are sufficiently guiding the carriage, a little bent screw would not cause too much problems in the print result.</p>
<p>Note that the animated gif shows the end displacement, this exaggerates the actual displacement experienced by the lead screw nut.</p>
<blockquote>
<p>When is a leadscrew too bent and should be replaced?</p>
</blockquote>
<p><strong>If it causes quality issues in your prints.</strong></p>
<p>E.g.:
<a href="https://i.sstatic.net/94dXC.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/94dXC.jpg" alt="enter image description here" /></a></p>
<h2>Mitigation</h2>
<p>Buying new, straight leadscrews. Usually, the more straight the more expensive, the lead screws from the far East range from acceptable to unusable. Ball screws are much more precise, but also cost more, especially the ground screws.</p>
<p>Some people straighten the lead screws, there are videos to be found how you do that.</p>
<p>But, note that there is an option <strong>not to replace the screws</strong>!</p>
<p>E.g., to completely remove any wobble of the lead screw, you can use something called an <strong>Oldham coupler</strong> to <strong>decouple the X-Y movement from the Z movement</strong>. For Creality Ender printers, there are specific couplers to order to install so that you will not need to buy new lead screws.</p>
<p>Custom printer designed Oldham couplers look similar to:
<a href="https://i.sstatic.net/XOB30.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/XOB30.jpg" alt="enter image description here" /></a></p>
<p>There are also printable versions that work very well, in fact I designed and used my own, inspired by <a href="https://www.thingiverse.com/thing:2910524" rel="nofollow noreferrer">this design</a>:
<a href="https://i.sstatic.net/rcqdn.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/rcqdn.jpg" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2024-01-22T09:20:01.830Z
I took a deep dive in Oldham couplers, never heard of them. Absolutely incredible material online: http://vlabs.iitkgp.ac.in/mr/exp6/index.html. Very interesting. I think I found one that takes out Z-wobbling in any direction including tilting, the WobbelX, do you have any experience with that particular one? https://www.youtube.com/watch?v=4kQZnSzZHD0 and https://www.reddit.com/r/ender3v2/comments/14h69g1/wobblex/.
Bob Ortiz
CC BY-SA 4.0
2024-01-22T16:44:31.780Z
@BobOrtiz Sorry, no I don't.
0scar
CC BY-SA 4.0
2024-01-20T23:36:22.230Z
2024-01-21T22:03:10.680Z
2024-01-21T22:03:10.680Z
0scar
<h2>It's too bent when it starts to cause issues.</h2>
<p>Really, it is that simple. If your prints looks good, you don't hear any screeching sounds, your motors are not losing steps, then you are good and just leave them be. Keep them clean, keep them lubed, and enjoy your hobby.</p>
<p>More specific to your situation, good set of lead screws, with guaranteed straightness and pitch consistency, can cost more than an used Ender 3. Decent &quot;3D printing quality&quot; set will cost less, but still a significant percentage of your machine worth. Enders are good bang for your buck, not because they have a lot of bang, but because how little is the buck. They are designed to be built with imprecise parts, and to still give acceptable quality. You can replace screws, replace V wheels with linear rails or rods and ball bearing, you can add input shaping by changing firmware to Klipper,  upgrade hotend, add enclosure, replace extruder with something lighter, and so on. But why?</p>
<p>By the time you will find and &quot;fix&quot; all the quirks of your Ender, you will spend enough to build Voron or RatRig, or to buy one of the Bambu Labs printers or Prusa kits. And that's what I'd do, but if you prefer to tinker, if that's your hobby, go for it. Just remember, it doesn't make economical sense.</p>
<p>To reiterate, if it works acceptably, don't fix it. Unless it's for fun.</p>

CC BY-SA 4.0
2024-01-20T21:37:13.930Z
The third paragraph is a huge exaggeration, and arguably the second is as well. The way the Z axis is designed using V rollers, the lead screw plays very little role in horizontal offset/Z wobble. It's *designed not to care* if it's bent, until it's so bad that it binds. Whatever problems your Ender 3 might have, you can get it up to excellent quality with under $200. Far less than the options you're claiming are more economical.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2024-01-20T21:59:58.987Z
@R..GitHubSTOPHELPINGICE I wrote that they are designed to not care about imprecise parts. Didn't name bent screws specifically, but in first paragraph I described effects of screw binding in a way easy to understand.  So on that topic you just repeated what I wrote using different words. For the "economical" part you either didn't read what I wrote or misunderstood. I claimed that's more economical to buy a printer that already has all these upgrades than to put them on Ender. And I did say not to do it if someone is happy with the quality.  Your *excellent quality* claim is exaggeration.
Mołot
CC BY-SA 4.0
2024-01-21T03:45:10.900Z
It's really not. During this year's TFT, I had a lot less quality problems than a bunch of Bambu users on the Discord did, running an Ender whose total cost with upgrades was less than half the Bambus. And it was printing a lot faster than them.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2024-01-22T10:34:00.967Z
An Ender is a machine that needs tinkering with now and then. The wheels need frequent tightening because of wear for exmaple. They are built as cheap as possible to get fairly high precision, but with in mind that it won't last forever without some maintenance now and then. Almost all Enders have a bulged build plate for example. Nothing a bltouch won't solve, nevertheless a piece of cheap junk that is worth its place in the market.
Hacky
CC BY-SA 4.0
2024-01-20T15:34:19.387Z
2024-01-20T15:49:18.680Z
2024-01-20T15:49:18.680Z
Mołot
<p>I've bought an additional second hand printer and I noticed that the lead screw has been bent. I did not have any issues so far with prints that are only a few cm tall.</p>
<p>I filmed it from the top, next to a ruler, as shown below and put a grid over it for reference. I think it should be replaced. How bad is this? When should it actually be replaced?</p>
<p><a href="https://i.sstatic.net/qlbA6.gif" rel="nofollow noreferrer"><img src="https://i.sstatic.net/qlbA6.gif" alt="rotating bended leadscrew view from above" /></a></p>

CC BY-SA 4.0
2024-01-20T13:38:45.100Z
It depends on all the rest of your Z axis motion system. It might be a huge deal or no problem at all. To answer,  we would need to see more.
Mołot
CC BY-SA 4.0
2024-01-20T13:52:32.307Z
It's an Ender 3 V2. What would you need to see?
Bob Ortiz
CC BY-SA 4.0
2024-01-20T14:25:31.990Z
Z whells on the Y gantry,  and the way teapezoidal nut is secured to it - can it wobble without entire gantry wobbling?
Mołot
<lead-screw>
When is a leadscrew too bent and should be replaced?
Bob Ortiz
# When is a leadscrew too bent and should be replaced?

(Asked by: username_0 on 2024-01-20)

I've bought an additional second hand printer and I noticed that the lead screw has been bent. I did not have any issues so far with prints that are only a few cm tall.

I filmed it from the top, next to a ruler, as shown below and put a grid over it for reference. I think it should be replaced. How bad is this? When should it actually be replaced?

[![rotating bended leadscrew view from above](https://i.sstatic.net/qlbA6.gif)](https://i.sstatic.net/qlbA6.gif)

**Tags:** lead-screw
> **Comments:**
> **username_1**: It depends on all the rest of your Z axis motion system. It might be a huge deal or no problem at all. To answer,  we would need to see more.  
> **username_0**: It's an Ender 3 V2. What would you need to see?  
> **username_1**: Z whells on the Y gantry,  and the way teapezoidal nut is secured to it - can it wobble without entire gantry wobbling?  

---

## 2 answers

### Answer by username_1 on 2024-01-20. Score: 7 | Accepted answer

## It's too bent when it starts to cause issues.

Really, it is that simple. If your prints looks good, you don't hear any screeching sounds, your motors are not losing steps, then you are good and just leave them be. Keep them clean, keep them lubed, and enjoy your hobby.

More specific to your situation, good set of lead screws, with guaranteed straightness and pitch consistency, can cost more than an used Ender 3. Decent "3D printing quality" set will cost less, but still a significant percentage of your machine worth. Enders are good bang for your buck, not because they have a lot of bang, but because how little is the buck. They are designed to be built with imprecise parts, and to still give acceptable quality. You can replace screws, replace V wheels with linear rails or rods and ball bearing, you can add input shaping by changing firmware to Klipper, upgrade hotend, add enclosure, replace extruder with something lighter, and so on. But why?

By the time you will find and "fix" all the quirks of your Ender, you will spend enough to build Voron or RatRig, or to buy one of the Bambu Labs printers or Prusa kits. And that's what I'd do, but if you prefer to tinker, if that's your hobby, go for it. Just remember, it doesn't make economical sense.

To reiterate, if it works acceptably, don't fix it. Unless it's for fun.

> **Comments:**
> **username_3**: The third paragraph is a huge exaggeration, and arguably the second is as well. The way the Z axis is designed using V rollers, the lead screw plays very little role in horizontal offset/Z wobble. It's *designed not to care* if it's bent, until it's so bad that it binds. Whatever problems your Ender 3 might have, you can get it up to excellent quality with under $200. Far less than the options you're claiming are more economical.  
> **username_1**: @R..GitHubSTOPHELPINGICE I wrote that they are designed to not care about imprecise parts. Didn't name bent screws specifically, but in first paragraph I described effects of screw binding in a way easy to understand.  So on that topic you just repeated what I wrote using different words. For the "economical" part you either didn't read what I wrote or misunderstood. I claimed that's more economical to buy a printer that already has all these upgrades than to put them on Ender. And I did say not to do it if someone is happy with the quality.  Your *excellent quality* claim is exaggeration.  
> **username_3**: It's really not. During this year's TFT, I had a lot less quality problems than a bunch of Bambu users on the Discord did, running an Ender whose total cost with upgrades was less than half the Bambus. And it was printing a lot faster than them.  
> **username_4**: An Ender is a machine that needs tinkering with now and then. The wheels need frequent tightening because of wear for exmaple. They are built as cheap as possible to get fairly high precision, but with in mind that it won't last forever without some maintenance now and then. Almost all Enders have a bulged build plate for example. Nothing a bltouch won't solve, nevertheless a piece of cheap junk that is worth its place in the market.  

---

### Answer by username_2 on 2024-01-20. Score: 3

## Cause and effect

Bent screws can cause an effect known as Z-wobble. But, to mitigate this, the non-driven side of the lead screw is left unconstrained. This is intentionally designed as such.

This means that as long as the linear guide (being V-slot with rollers, linear shafts or linear rails) are sufficiently guiding the carriage, a little bent screw would not cause too much problems in the print result.

Note that the animated gif shows the end displacement, this exaggerates the actual displacement experienced by the lead screw nut.

> When is a leadscrew too bent and should be replaced?

**If it causes quality issues in your prints.**

E.g.:
[![enter image description here](https://i.sstatic.net/94dXC.jpg)](https://i.sstatic.net/94dXC.jpg)

## Mitigation

Buying new, straight leadscrews. Usually, the more straight the more expensive, the lead screws from the far East range from acceptable to unusable. Ball screws are much more precise, but also cost more, especially the ground screws.

Some people straighten the lead screws, there are videos to be found how you do that.

But, note that there is an option **not to replace the screws**!

E.g., to completely remove any wobble of the lead screw, you can use something called an **Oldham coupler** to **decouple the X-Y movement from the Z movement**. For Creality Ender printers, there are specific couplers to order to install so that you will not need to buy new lead screws.

Custom printer designed Oldham couplers look similar to:
[![enter image description here](https://i.sstatic.net/XOB30.jpg)](https://i.sstatic.net/XOB30.jpg)

There are also printable versions that work very well, in fact I designed and used my own, inspired by [this design](https://www.thingiverse.com/thing:2910524):
[![enter image description here](https://i.sstatic.net/rcqdn.jpg)](https://i.sstatic.net/rcqdn.jpg)

> **Comments:**
> **username_0**: I took a deep dive in Oldham couplers, never heard of them. Absolutely incredible material online: http://vlabs.iitkgp.ac.in/mr/exp6/index.html. Very interesting. I think I found one that takes out Z-wobbling in any direction including tilting, the WobbelX, do you have any experience with that particular one? https://www.youtube.com/watch?v=4kQZnSzZHD0 and https://www.reddit.com/r/ender3v2/comments/14h69g1/wobblex/.  
> **username_2**: @BobOrtiz Sorry, no I don't.  

---

