Will this Z axis anti backlash nut improve your 3D printer accuracy?
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- เผยแพร่เมื่อ 6 ม.ค. 2023
- In this video I will install the commonly available spring loaded anti backlash nut for the T8 lead screw on my 3d printer Z axis. Then I will use the dial indicator to verify if it does anything to eliminate the backlash.
Fundamentally the anti-backlash nut you are using is a anti-slip nut if you use a sized spring load. For anti-backlash, the two opposing nuts should be adjusted to minimize play (limit friction) and the spacing locked. The spring should only be used to aid in the adjustment only. That means the spring load needs to be greater that the maximum applied load. The moment your applied force exceed the spring force you will get backlash if you don't have fixed nut spacing or the play is too large.
After prolong use the spacing will need to be adjusted due to wear or the lead screw needs to be replaced due to uneven wear.
In the previous video, you showed that there is a spring in the stepper motor that is responsible for the shift in the Z axis. I personally found that on my Ender 5 Plus printer, the 2 motors have a clearance of about 2 mm from the axis. And I wrote to you that I solved it with an axial bearing between the motor and the trapezoidal thread coupling... It works perfectly. Now I have all the layers exactly the same. On all 12 printers where I made this modification. Greet from Slovakia.
Impresive! Can you post a link to get this bearing? Thank you
hi can u add photo after the mod
Ratrig Mini z bearing
@@NIKOLAZ621 Here he talks about the stepper motor problem.. th-cam.com/video/RXgwOikiBdg/w-d-xo.html
@@1vyrobca can you please post somwhere your mods to the Ender 5 Plus, to see, how you've done it exactly?
This series is so good! Where is the rest of the videos where you finish upgrading your ender 3? Im do adicted to them, replicating almost all of these upgrades to my own ender 3. Great work!
I found that the backlash in the z-axis is due to the in and out play in the stepper motor spindle.
On the last shot, you can see the build plate deform under the pressure applied by the measuring gauge.
That probably won't help either.
I had issues with my Sidewinder X2 (uneven layers) and several people told me "get anti backlash nuts". I just didn't get their advise - nothing an anti backlash nut could do, would improve my problem - rather make it worse.
Then they said "replace the coupler! It's caused by a bent lead screw". I removed the lead screws, they had a slight bent to them but nothing major, bought perfectly straight lead screws and the problem persisted. THEN I bought special couplers called plum couplers (they give the lead screw some more freedom preventing binding - generally good couplers to use) but again, it didn't fix the issue.
At this point I stopped listening to advice because they insisted I replace the board with one with dual Z drivers (the X2 uses one driver to direct two Z motors) which was just ridiculous.
Instead I opened up the hot-end and found out that Artillery had the bright idea of attaching the entire hot-end to the extruder system. The extruder system was driven by a huge gear that revolved ... except the hole in the center wasn't perfectly centered so the gear would wobble and the entire hot-end would move up and down along with it during prints causing the weird uneven Z layers. I replaced the crappy extruder system with a full metal one and it fixed the issue.
My point with this hole story is: don't just blindly believe all the typical "solutions" people profess and think how each part would impact the printer and think about whether it would actually fix it. It could save you a ton of money. Do plenty of test prints that are designed to make the problem worse or clearer - don't just reprint the same object but print multiple objects and see how the problem changes depending on prints.
That is very good info. The problem with 3d printers is that one problem can have many root causes. So it is necessary to test and troubleshoot rather than blindly following advice.
Having started my desktop CNC experience in CNC mills, I can see one flaw in your final testing and conclusion. The two nut halves need little to to play between them. You can clearly see a degree or two of movement of the small nut when moving the lead screw back and forth. This shows there will be no improvement in backlash. Effectively, Only additional friction has been added for no benefit. To fit/patch a bad nut set, use a point punch to expand the brass at two points on either side for the small nut's tabs. Then, file the protruding metal down to create a tight fit and eliminate the slack. This will make the anti-backlash screws actually anti backlash.
I was about to point that out, but it’s good that you done it already.
Also, that backlash nut design is poor if it has that much play between the two pieces.
The best solution would be a combination of a quality machined lead screw, a well designed backlash nut that has four precision rods , two embedded on each half and sliding on the other half, and a decent spring to maintain tension/compression between both threaded halves. And yes, the spring would have to be balanced in a way that it can maintain ideally zero backlash with rigidity without creating so much friction that the steppers can no longer move.
Z-Sync kit is one of the most important in my short experience... it even kind of solves the screw engagement issue because the gantry is somewhat un even and the Sync Kit forces the sync to be even at all times
It does solve many of the problems and if you could do only one upgrade, in my opinion that would be the one.
I installed the anti-backlash nut and spring on the top of the fixed nut, This keeps pressure downward on the gantry, Put the fixed nut in from the bottom, and the spring and backlash nut on the top of the bracket. This way the spring is working with the weight of the gantry to maintain a firm downward position on the lead screws.
Thanks for the explanation. It was very elucidating.
In my opinion, there could be a software solution to this lacklash problem. We could and a small Z axis turn just after the printer finishes homing the Z axis. How much turning of the Z axis would have to be gaged through trial and error.
Just found your channel and became a subscriber.
Keep it up! 😊👍
Nice video again
Literally the ONLY video on all of TH-cam where they didn't install the anti-backlash screws upside down, LMAO.
Well done , sir.
Is that sarcasm?
you can put that system on or under, it depend of your 3d printer
That's nice work. New subscriber. Thanks.
The video is top notch. The attention to detail is superb.
Thanks
Man, thak you for this!
I've been using POM anti-backlash nuts, one-start lead screws, and live Z for years with no concerns. My print quality is better than printers with standard lead screw nits.
I get elephants foot on my printer, is it worth buying an ani backlash nut?
@@henrydendorf4847 chamfer the bottom of your prints slightly or calibrate the extruder for horizontal expansion
This would lead one to suspect structural flexing rather than backlash in the threads alone. Place the indicator between different assemblies to locate lost motion appearing as backlash. Like bearing supports to screw shaft ends? Compensating nut to screw end? Bed to gantry in different planes? Bed to base? This could ultimately be a stack up of several points which can appear insignificant on their own. Write yourself a looping G-code Z move and go on the hunt?
That is certainly food for thought. I have seen some flex in the plates that hold the lead nuts so that would be a good starting point.
This is interesting. This might be smart in the future if i have the issue of it falling down. I am planning on upgrading to rails, but got some other things to fix first.
For my part, once I accepted that pretty much everything but the frame is a consumable, I went with POM nuts. They last pretty long but are cheap to replace when needed and make z movement slightly more accurate. Most importantly, they eliminated gantry drop, when the power goes off. 😁
@@adrianrubio5396 thank you for the tip! That's great idea!
Great but sad story, I love it!
Kerk motion products has had a near zero backlash nut for decades. It's accuracy is 50 Micro-inch (0.0013 mm). I used them with extremely accurate positioning. The design you chose will never work for precision location. It's a 2 piece spline assemble with the spring only for opposing force. the backlash is adjusted out by rotating the 2 nuts and locking them in place. 30 years ago they were using Teflon coated ss lead screws that were very precise with extreme location accuracy. you can always build a lookup reference table to account for any positional error.
I feel like if it's that big of an issue on a particular machine, it's a good use case for switching to ball screws.
Hello, by carefully observing the video and the mechanical movements, I realized that the Backlash is in the Coupling Coupler. This is seen between the period of 3.43 minutes to 3.46 minutes.
Greetings from Panamá City, Panamá
What's wrong with the "olde worlde" method of spacing two nuts with threaded studs and dialing out the backlash that way? I understand that this method requires periodic adjustment as the nuts wear, but at least it's as close to zero backlash as makes no difference when set up correctly and produces close to zero drag unless the lead screw is badly bent.
Your video is very good, and if you used a belt on the Z axis instead of the tr8 spindle would it improve the accuracy? Can you perform this test and film it?
When changing direction, the screw moves along the radius of the hole. Only a plastic nut with an interference fit will save from such a displacement.
Ever do some testing to show the before and after of all the Z upgrades?
Its ongoing. Will upload the results soon.
@@bluemonxterDIY Thanks I look forward to it!
Creality cr10; dual z-axis steppers.
Backlash nuts keep the threads and gantry in sync each side.
Ie longer periods of bed-level stability.
In the z axis backlash is not important as the print initialisation always has the print growing in one direction.
First layer though
I disagree i had a strange problem where when i changed layer and went up 0.2 my gantry would then drop down point of point of a mil and the nozzle would scar the next layer, installing 2 of these eliminated this problem for me and the dimensional accuracy of parts on the z height is spot on
So what’s the solution? To put the nut above the gantry? How do you align the axis and remove points of binding?
first thing i'll point out is that in Z axis applications there is already always a screw/nut preload equal to the weight of the gantry and you cannot change the faces in contact by changing directions in Z (like in 00:49) unless you are doing so faster than g=9,800 mms-2. are anti backlash nuts a scam? of course not. they work exactly as advertised.....in X and Y screws like those in CNC machines. NOT Z screws in 3D printers for the reason I mentioned above.
secondly, and not related to backlash, by mounting the oldham coupling above the gantry, it is in constant tension and not working in the optimal manner. it is supposed to be mounted under the gantry so that its horizontal surfaces can bear the load while the coupling is being compressed. while upside down, that same load puts the nut in tension, and the weight of the gantry is now transmitted to the dovetails interfaces instead, which have a much smaller total surface area than the flat faces and were meant only slide past each other instead of now also being loaded. faster wear and reduced capability to perform its original function.
unless you're accelerating more than 9,800mm/s^2 on the z, there's no point for anti backlash nuts.
I also went to POM nuts. They virtually eliminate backlash
Measure the backslash on the center of the bed where it is stiffest.
Would be interested in belt driven z accuracy vs this. (Like the model by KevinAkaSam)
i want to see that too
I do have a plan to make a comparison between the two sometime in the future.
I don't use brass nuts anymore, no matter how well greased up i kept them after a few months they always ended up like a baggy sock , get way better results with POM leads screw nuts.
Okay. Been in 3D Printing for many many years, but I will admit when I have not heard of something. What is a POM leads screw nut? How expensive are they? Got any links? Thanks in advance.
@@the-300lb-gorilla Pom is kind of black plastic. Not any more expensive than brass
@@Favmir Acetal aka Delrin
@@the-300lb-gorilla pom is the same material as the black wheels on your carriage
What about a belt driven z-axis?
Certainly a viable option, does have its own set of pros and cons though
So you had a theory about the backlash nut not working if installed like everyone else because the spring wouldn't overcome the weight but did you ever install and do your test with the indicator in that orientation. Or just installed it upside down and assume the normal way would not work either?
I did test it in that orientation on my other stock Ender 3 and it made no difference at all to the amount of backlash. If anything, it was more inaccurate because there was more binding due to the additional spring force from the springs.
@BlUeMoNxTeR! great info thanks for the response 👍
Z axis backlash should be fitted with x axis weight unless your z axiss cant move free.
mgn rails arent design for t8 screw backlash they work great withbelts but with t screws they get stuck till they get a little push from the other side of the nut.
thats why you wont see a good printer with mgn and screw un z
you print always up and you dont see that but if you go 2 up and .050 you will see how sometimes mgn get locked and dont go down
Instead of a Z screw perhaps a Z belt system could reduce backlash due to more malleable parts?
you are right, similar to the x and y axis, a belted Z would ideally have zero backlash. I am working on an all metal belted z axis because I don't trust printed parts to be reliable over the long term due to plastic creep. If everything works out I will make a comparison video between the leadscrew and the belted Z.
Huh you've shown your backlash is mesurable, so the question is, is it consistent or atleast a percise enough change that you could alter the firmware as to hsve a backlash adjusting setting? same as having a z off set. When fhanging directions you could set the value he motors will add to their travel inorder to midigate slop in the screw and nut.
Lathe logic "if its not accurate, make it extremely adaptable.* something along those lines.
I've seen other youtubers doing this kind of upgrades, even many years back, and they all came to the very same conclusions: it does not work or at best is not worth the time and money, at a certain point we are better off buying a way more expensive 3D FDM printer, that is based on other technologies, specially because every year their prices falls
Y’all watch out for that back current burnin’ up the z stepper drivers now, ya hear? Ez to do with z axis maintenance
Can't this backlash be avoided by always following all downward movements by a movement up, equal to whichever is smaller, the downward movement or the backlash amount? This is possible on the Z-Axis due to the nature of layered printing where the Z axis is stationary during extrusion.
👍👍👍
Seems like a lot of work to fix a fundamentally flawed setup. Does something like a corexz (Switchwire) setup fix these issues? Or does it trade one set of issues for another?
To remove backlash after homeing you can add some extra movement using marlin commands or just set first layer height a little bit higher.
Absolutely.
got the mainboard yet can't wait to see print lol
Yea working on the new video. Will upload it over the weekend :)
@@bluemonxterDIY cant wait :D
@@bluemonxterDIY still can't wait i am ready to buy the needed part
Solve the problem with belt drive Z axis.
m.th-cam.com/video/oUdoJUs8Zcg/w-d-xo.html
not so easy. but I think a better solution would be ballscrews. there are already kits to convert to i think 1204, or 1605. it's possible, however resolution is not the same, steps/mm for the Z axis need to be halved. so from a 0.125mm resolution per step, it's 0.25mm.
@@heyitsdrew I don't want to sound harsh but ball screws are expensive and requires a very precise mount. This is impossible to achieve properly without expensive machinist measuring tools otherwise you will still have some artifacts. The structure of most of current printers are not ready to receive ball screws: 20 module profiles are not stiff enough and the grooves are not compatible.
On the other hand, there's a lot of examples of belt driven Z axis since 2010 which are inexpensive, very permissive and easy to setup. A belt, a bag of pulleys, a geared nema17 and there will be no Z artifacts first time, any time.
Ball screws are expensive wearing parts while changing a belt is no big deal. Better, simpler, cheaper. The die is cast.
At 3:59 there's still some play at the upper nut causing the backlash.
an easy way to eliminate this is to just convert your Z axis to be belt driven instead of leadscrew driven. That, or switch to ball screws.
great video. but what is a real fix then?
Thanks. You could go belted Z but honestly you don't need to fix the backlash. Once you start printing, the Z axis only moves up so it shouldn't be of any concern.
Besides mesh leveling, when the bed moves all the time.
Thanks for proving that these things are just snake oil.... not only do large numbers of people think they are important, they, as you point out, also install them wrong (ie under the gantry) to boot.
This content is needed to educate people to stop buying pointless additional hardware (yes they can be cheap, but other snake oil options can be expensive).
I'm still on the fence as to the benefits of a z-motor bearing block and thrust bearing to take load away from motor spindle considering how cheap stepper motors.
Would like to know your opinion on POM lead screw nuts as well in terms of their wear and tear (some swear by them, others suggest the same snake oil claims as with these antibacklash nuts). I suppose they are cheap enough that its easy to just buy them when you inevitably have to replace the brass ones (phosphor bronze is seen as the ideal material but is very expensive for 3d printer usage and brass is much much cheaper)....
Thanks for the content.
The only advantage I see of the POM nuts is that you probably don't need to lubricate them because POM itself is a slippery material. Other than that, it would suffer from the same problems. In the beginning it might be better because the clearances are supposedly tighter than brass nuts. But the wear of POM is going to be higher than brass and pretty soon they will be in the same state as the brass nuts.
The spring is used to add tension to the nuts, it's obvious that your springs are the wrong ones (no tension). Looks like you changed the springs or order without the ability to understand the context of what you are doing. If the springs are not compressed then they're not adding tension to the system. Hope this helps you understand your mistake even though I think you did it on purpose.
I am going to have to disagree with you there. I ordered the generic anti backlash nuts available on Amazon and aliexpress for the T8 lead screw and I used them as is. But the whole point is that you don't need them for the z axis of your 3d printer as I have explained in my video.
the oldham thingy should be resting on the flat and not on the dovetail.... oh, wait there is no adjustment so it makes no diff..... I think you should try without it? just install the nut under
And really this is FDM, not EDM.... Your tolerances are going to be much wider due to the fundamental nature of the process.
True, very small changes in other parameters like temperature fluctuations, filament diameters etc. can also add to the artifacts.
Parts on top of parts to fix issues with screw drive lol. And they wear. Just go belted. The speed and acceleration of your z axis alone will be worth it. Let alone accuracy.
Totally agree with you. But as an engineer, I like to test everything and try to explain what doesn't work and why.
@@bluemonxterDIY that I understand for sure
Why would anyone want more speed and acceleration on the Z axis? it is only moving less than 1mm.
Do you have data on the accuracy? The belts are not perfectly stiff, add to that the acceleration of the whole x axis, and I am curious how all interacts.
thats true for smaller printers, but for larger machines like my vcore 3 500mm, i need the strength of lead screws.
well i bought the stuff todo it myself
and im still too lasy to start doing the part i need xD
use a ball screw
Ballscrews!
Expensive
To eliminate your backlash / play you need a screw ball spindle with the stepper motor in direct drive (same axis than the spindle) , without pullies and belts.
Of course this comes at a cost increase
no one has done x and y axis though :S
Dude... the backlash comes from your dial indicator...
You want no ZZ back-lash?! Buy ball screws...
Unnecessary expense, unless your accel is set higher than 9800 mm/s2. Ender 3 is set to 100
But what you are saying is incorrect. th-cam.com/video/kmqLz-AmzVw/w-d-xo.htmlfeature=shared&t=185 you can clearly see that the Z axis is moving when you push the spring upwards. But I agree with your conclusion. The spring loaded anti backlash nut is pretty pointless because gravity is working in your favour.
Yeah this video is lacking a lot of basic understanding
I’m going with the belted ender mod by kevinakasam. It’s double the dual lead screw price, but claims to do the job much better and more. Hopefully that’s true when I get the hardware needed off Ali express.
100% recommand had it for a while runs perfectly no more dealing with horrible lead screws, although i am removing it to upgrade it to a voron switchwire setup
Belted z has been better than any of my leadscrew printers! Have set it up multiple times
@@otroe yep to solve all the lead screw problem simple dont use one and the issue goes away, there is just too much issue with lead screw unless you get lucky. Although do need good quality belts and tension them correctly
@@8bits955 yeah. I have everything printed,and the hardware kit is arriving today. just waiting on the screws. They’ve been stuck in a warehouse for a week now. The thing I’m concerned about is tensioning the belts, it sounds difficult but I’ll cross that bridge when I get there.