BFTB design: Z axis wobble, lead screws and bearing blocks
ฝัง
- เผยแพร่เมื่อ 8 พ.ค. 2024
- This series of videos explain the design choices, experiments, research and theory behind the design choices and trade-offs I made when designing the 'bang for the buck' live stream printer.
This particular video is an overview of the lead screw arrangement for the Z-axis. I will be covering the Z-axis as a whole in a future video. Of course, this is all subjective, but I tried to include enough theory, history, and experimentation to make the video informative as well. Feel free to post your own experiences and design choices in the comments below.
TIME INDEX:
0:55 intro
3:00 background and history
7:26 theory and demonstrations
17:05 Linear actuator design
23:42 trade-offs and budget choices
28:42 bearing types
30:24 upgrades, alternatives, and future plans
My contribution links:
MONTHLY SUBSCRIPTION:
/ alexkenis
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PayPal.me/AlexKenis
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I've watched a lot of 3d printing videos but never came across the depth of mechanical knowledge this guy here pumps out on his videos. Simply excellent and well explained. Know that you helped me, and more than once.
Thanks for clear explanations on the various options we have. This will definitely help troubleshoot and also my future printer designs.
Have been building and designing some CNCs lately and was frequently confused by thingiverse and similar "solutions" for z-woble in 3d printing. This is the first really good overview of the topic I've seen so far in 3dprinting world.
Where have you been from my 3D printing life....very useful video! you explain the issues with great details and then give ideas on how to solve them. Keep up the good work.
Thank you for this video! This is a great demonstration of issues that can come with bearing blocks and overconstraint. I have shared and mentioned this video many times to help others with their banding issues
Discovered your channel now. High level explainations but you are very pedagogical and things end up sticking :D Very good content and i like your 3d printer design.
Thanks for making this video! I've been contemplating making a similar video because I'm sick of all the people claiming that constricting the Z-axis on both ends will solve z-banding. Your illustration is precisely what I was thinking of doing to explain the problem. I'm by far no expert on these matters, but it seems so obvious that constricting a Z-axis isn't a solution. In my opinion, you should always have two parts to an axis - one part that performs the motion and that doesn't have to be 100% straight. Then you also need a 100000% straight part that is constricting the motion of the axis. These two parts could be the same in theory, but for a home gamer that is probably not very cost efficient.
I always appreciate your videos. They always explain things, rather than state them. For me, I can't remember jack about "what should be done," unless I know "why something should be done." The part about the different constraining setups (bearings on both ends, etc.) was a little hard to follow because the bearings were metaphorical placeholders for the actual things in some cases, but overall this video is probably going to help me fix my janky printer design.
Great video, easy to watch and lots of info. Thanks
Thank you for the thorough explanation of your reasoning behind the design of your Z Axis system. Do you have a build video based on this where you go into in-depth explanation of HOW to assemble this setup?
This way you have one in-depth video explaining WHY and then one explaining HOW.
Thank you!
Nice explanation and very clear what the problem is!
Thanks for sharing :-)
This is amazing content! thank you!
Good video, eagerly awaiting a video on those TMC5160s !!
awesome, thanks for the explanation!
In my build i used Ball Screws with BK/BF10 Mounting Blocks and I mounted the Motors on the Top. It works fine and it looks really cool...
Thanks for the lesson. Very helpful. Hope your doing well. Happy New Year 👍👍😎👍👍
12:45 Not the editor’s note we needed, the editor’s note we deserved.
amazing info. i learnt a lot.
Thanks for the video, very clear and informative!
At 14:40 I've seen that style of coupler called a "Lovejoy" style.
* quality parts that were straight before they were given to the shipping department, run though the whole pickup, distribution, delivery process, unpacked, dropped, maybe someone thought fencing with them would be fun, ... If you see a bent part, don't automatically assume it was(or wasn't) the manufacturer.
Really enjoying your channel! Subbed!
When you said damping and not dampening, finally someone that understand me
yup. in my dynamics class, we studied damping and for the life of me, i would call it dampening hahaha
I decided to build my own 3D printer as well. My history went kinda like this, I got an Anet A8, then I used it and decided upon what I didn't like. This was a couple years ago ish. I used linear rails on all axis, belts for X/Y and an acme rod for Z but I captured the rod in bearing blocks (much like what you have done but my steppers are at the top of the printer). My acme screws are straight and Z is completely constrained by linear rails anyway. Glad I got into printing when I did because components were cheap when I was buying. Now I have ball screws that I just purchased for my Z, looking forward to installing them.
Anti-backlash has never been an issue for me because my Z gantry is overly heavy, gravity takes care of backlash quite well. I've learned quite a few things along the process of minor changes mostly related to extruders and filament types, but I've learned nothing when it comes to z-banding because I've never had an issue with it in the first place. My layers look awesome (provided I didn't key in a bad value into the slicer on accident or out of ignorance, yes I've done this).
My printer is a heavy monstrosity (kinda). My X movement is the lightest part by far, the moving parts are a direct drive with 2 bearing blocks. The Y axis has far to much weight in it, two 1/8th inch aluminum plates makes fast prints difficult (well super quality at high speeds anyway). In fact I am going to cut some holes into the plates to remove some of the weight. All axis run on 2 linear rails each. This is not a whisper quite machine, but I can grab ANY section of the printer and lift, the entire printer moves when I do this. I don't have alignment issues anywhere and the bed is flat within about 0.001" actually a bit less. I can move the printer around and never have to adjust bed leveling. I don't regret my design at all because I never have to mess with the machine ever (in fact I might use the ballscrews for the CNC machine instead of the printer). I've switched to a all metal hot end (titan aero) and have to forget much of what I knew about extrusion and filament. I've got it mostly figured out.
you all probably dont give a shit but does someone know a tool to get back into an instagram account..?
I stupidly lost my login password. I appreciate any help you can give me.
@Weston Deacon Instablaster =)
@Alvin Apollo I really appreciate your reply. I found the site on google and I'm trying it out atm.
Seems to take a while so I will get back to you later when my account password hopefully is recovered.
@Alvin Apollo It did the trick and I now got access to my account again. Im so happy!
Thanks so much, you saved my account!
@Weston Deacon Glad I could help xD
amazing explanations thx
Very good video, once again! :D
But did I miss a part? In the beginning you hinted that the nut design was the solution- but the video didn't cover different nut designs.
Awesome video, thank you!
Makes a lot of sense thanks
Alex.. Thankyou for this video. I found it very informative. I have fought through so many issues with Z on various printers, the worst being trying to have two motors on Z. I am going to get rid of the brass threaded fittings that are attached to the Z gantry (box frame). They do not sit straight on the threaded rod (probably because of the play that you pointed out in your video) I get movement across the bed that changes height at the outside edges. (Suggestions welcome)
You need some way to synchronise the motors. When the motor power is turned off and on again, there's nothing preventing one motor from snapping into the next lower halfstep, and the other into the next higher one - considering one of the sides of the gantry is going to always be heavier, and one of the sides may have a higher skew or friction, the issue will be systematic and will accumulate over time.
If you have ABL sensing, you can just get a separate stepper driver to straighten out the Z.
A possibility is to have a print start G-code which goes ahead and rams the gantry against a hard stop at the very top, realigning the motors.
Outside edges... of what? Extremes of Z axis movement? Or just at the same Z across the bed? The latter is... pretty normal. Borosilicate glass cut by Geeetech is often bowed for some reason. Extruded aluminium bows when it's heated. The smooth rods of the X gantry might have a slight bow in them, and during assembly they will usually orient themselves such that the middle sags rather than rides up.
YOU ARE A GENIUS
Try some wave washers for preloading the bearings. They are available in various thicknesses and strengths are off the shelf and are fairly cheap.
Yeah, very interesting to hear your opinion about belt driven Z-axis!!
I don't think it is a good idea. If we talking about GT2 belts, a 16T pulley moves 32mm in one revolution which is 0.16mm Z resolution per full step. Using a four lead TR8*2 screw, the resolution is 4 times better, 0.04mm. I am actually replacing the rod with a TR10*2 rod which has one lead only, which will give 0.01mm resolution per/full step. Please take in to consideration that microstepping without any feedback (encoder) isn't guaranteed to be precise. Does something, and worth using it as interpolation between steps to reduce noise and vibrations, but the actual position will depend on the load.
And we didn't talk about the rigidity of the belt yet. Side effects, like the plarform will fall if the motors are not energized, etc...
I think, a belt driven Z axis is a terrible idea...
Great Video
I LOVE YOU thanks for the vids buddy!
Awesome 👏🏼
@Alex Kenis, thanks for this video, have you posted the STLs or more info anywhere for the design you show around 30 minutes in? Seems to bring fantastic result and I'd love to implement it on my printer.
very helpful, thanks! :)
great info thanks
Very cool. Are your models for your flexible coupler plus bearing block design posted anywhere?
Decoupling is not Damping, Sensei.
Thank you, Sensei.
A pity these's no Tapered Roller Bearing small enough to use here.
At 29:05 what collar are you using? Ruland from Grainger? Thanks for the useful info in the video.
Love the vids Alex, how about a 2mm lead screw? Thinking of making this upgrade to my ender 3, do you think it’s an worthy upgrade?
I adjusted the lead screw nut and coupler as good as possible (y=0.02 & x=0.4mm) and for the rest i hang the motor in a damper. Until now works good...
thank you for the proper use of damping vs a wet towel.
One more thing to mention is that most cheaper bearing ("pillow") blocks usually come with the regular old grooved ball bearings instead of angular contact, tapered roller or other axial-constrain-capable bearings. This is mostly fine for a small 3D printer, but it can be pretty deceptive when your entire X axis (i3 style) or bed (corexy/ultimaker) can accumulate significant weight and it all rests on a weak ball bearing (in a block, or - when using integrated leadscrews - inside the motor!).
Especially the wave spring washer (shown during the violent disassembly of the NEMA17 motor) has only limited preload and has a specific point at which it stops preloading and starts bouncing (axially) when the axis of the motor, the leadscrew, is loaded "down".
That's just for people who praise the integrated leadscrew as a cure-all. :)
Are there Tapered Roller Bearing small enough to use here? My corexy bed is going to be on the heavy side....
Good call. I had a section on angular contact bearings that I cut out because I didn't have on handy to take apart. i probably should have flashed up a deep groove data sheet at lease since they specify axial load max usually. @cthulpiss I have not personally seen tapered rollers or similar self-aligning axial load bearing in sizes small enough for this stuff (I think the smallest I have seen are around 3/4" for cranksets), but if you are worried about load, I'd look probably into ball screw support bearings. The good ones are angular contact and have load ratings
@@AlexKenis I went for rollers because I love them from retrobike field.
Sure, angular ball are available - from quick search I see that ball screw support bearings are still quite large, but Angular Contact Ball Bearings are available in 708 size - with perfect 8mm bore.
I'm not sure if I'm worried about heatbed assembly weight, as it's my first 3D printer, and seems I went for overkill in many places :)
@@cthulpiss Gotcha. Let me know if you come across any small enough.
Hey Alex. Would building a lexan enclosure, heating the whole printer with some kind of space heater would eliminate the bed warping? Using a thicker aluminum bed and no separate bed heater. Maybe the enclosure temp could be controlled with a temp sensor and an andrino?
At 27:18, what prevents the lead screw from moving in the vertical direction? The flange bearing appears to only constrain the screw motion in the x, y, and -z directions, the +z appears to be unconstrained, except by the return spring force (-z direction) of the helical shaft coupler.
In that printed mounting, what is the purpose of the screw/lock nut protruding from the left side ?
Thanks for very nice presentation on this z-axis wobble, and on the MGNx linear bearing/guide series.
tldr : dont put anything on the free floating end of the z screw.
Thanks for all your powerful video. One question is becoming more and more pushing in my mondo, di you se couplers of Genius Artillery, they are on Oldham style. What do you think about it.?
I like the tone of this channel. 😊 Sub!
Another tip:
I have a couple of lead screws in storage.
The longer ones, I hang them, to keep them straight.
And you can always heat them up, even if it is a hair dryer, to straighten them out a bit.
Do you heat the entire road or part of it? For how long?
Im using the "Plum" spyder coupler connecting 5mm motor to 8mm lead screw.
Good point on the set screws, im glad these are clamping style.
Recap on my setup: 1) Rubber dampener/Aluminum coupler on motor to leadscrew & 2) Machined flexible aluminum coupler connecting top of leadscrew to drop-thru shaft which is riding on a skate bearing.
After watching this video I have decided to incorporate a bearing pillow block with lock collar above my motor coupling.
Question#1: Is there any reason why you arent using the dampening style coupler with the rubber insert on the z axis? I thought those were superior.
Question#2: if i use you final solution plus I constrain at free end.... based off your suggestion, my line of thought is that ill have to set my preload and use thrust bearing?
I did that Aquarium tubing fix with a boiling water bath so it would stretch and it worked for a short time but while getting it on the motors I pulled the first two, or three, layers of my skin off due to friction. Never again for me.
Could you share your BFTB design somewhere? I couldn't find it.
Also, not sure if I got the conclusion right.
For best results, I should get a not-bend leadscrew, and constrain right above the (flexible) coupling as well as the top, with a bearing pillow block. Did I get that right?
You also need to look at Oldham Couplers - zero backlash!
I second this option. Pricey but accurate. CNC router tables use them.
Is the STL for your motor bracket somewhere, (I take it you have a KP3S, like I have on order)? Affiliate links for bearings, ball screw, etc?
For preloading the thrust bearing, would it be possible to press the motor shaft up from the bottom while attaching the coupler?
One downside is it wouldn't allow you to adjust the stepper side of the coupler once you've mounted the stepper back onto the frame, at least with most printer designs I've seen where the Z stepper's bottom is flush with the frame.
I have a Railcore which has had intractable moderate banding it's whole life. Zyltech 8mm x 750mm lead screws. Installed bearing risers & thrust bearings - remarkably similar to what you describe here, but tooled aluminum. Didn't seem better, so I got "wobblers". Lead screws go through a 21 mm hole in the wobblers, with the anti-backlash nut with about 11 mm diameter inside that hole, so there's 5 mm available in all directions.
The anti-backlash nuts bang against the side of the wobbler hole. The big question in my mind right now is, are my lead screws really bad, or is it a misalignment problem? Is it the rigid plum couplers that is the problem? I honestly don't know.
I actually didn't understand the different between dampening and decoupling :D but i think it'smore like damping absorbs the material while decouple allows the other end to move freely without moving the bottom?
I just got my dual z setup for my Ender 3 Pro, and it came with two little pieces to hold the tops of both lead screws. Should I just throw these away then? Thanks!
Another question. If you remember, We talked before about using high quality linear rails and ballsscrews. In addition with closed loop steppers/servos. Hypothetically speaking, In a perfect Scenario. how fast do you think printing could be done and what pitch would you choose for a ball screw to make that speed happen? I'm building a way over built 700mmx700mmx900mm printer. Id love to make ABS intake manifolds and a lot of molds for sand castings. Being a machinist, i want to print with a .001" accuracy. What control would you suggest? Smootie or duet?
To my knowledge, the accuracy you request has never been achieved in FDM 3D printing regardless of effort put into construction. You are requesting 0.02mm accuracy but typical FDM accuracy is in 0.1-0.3mm range. The issue is rather fundamental rather than mechanical - you are depositing a particular matching volume of melt corresponding to where you want the material to go, but it doesn't stay exactly where you put it, it's pulled along the nozzle, it shrinks under surface tension, and it both balloons outwards in the middle of the layer and leaves a gap at the top and bottom of the layer.
Furthermore you probably don't want 2-week long prints, so you may end up using a 0.7mm or larger nozzle, which will severely limit accuracy again. The extrusion flow rate limits will determine usable printing speed; chances are, you don't have to aim at high movement speeds at all. From this point of view, control board choice is also largely irrelevant. That being said, i'm consistently impressed with the work dc42 is putting into RepRapFirmware, and Duet is the premier platform for that. Other interesting option may be Klipper, a firmware that runs on a combination of a Linux single-board computer such as Raspberry Pi for motion processing and any old 8-bit printer board for actual execution. I don't have an assessment as to which may be better.
I think it is to be kept in mind that there are very many people in the world who have a mechanical grasp and education to create a high-quality mechanical device, so essentially every mechanical problem has been solved by somebody at some point, and yet, it didn't create a perfect printer. The FDM part of the process is fundamentally more limiting and more opaque. It is very tempting to focus on something comfortable, something you know rather than something neither you nor almost anybody does, and yet not fruitful.
I reduced a lot the wobbling simply replacing a brass trapezoidal nut with a tighter Delrin nut.
Very interesting, I wish this video came out earlier xD would have saved me so much money. I had this issue with a z wobble, but interesting it was only near the top of the height the printer could go to. Although later on I found out it was also happening at lower levels randomly. What fixed it for me (and with lots of help from the guys over at the Duet forum) was this:
1. lead screw diameter should if possible be smaller than the diameter of the smooth rods (if you are using them). I was using 12mm rods and lead screws, and apparently if they are the same diameter they could overcome the deflection/alignment that the rods provided
2. Changed from Flex coupler to high quality jaw/plum couplers (or oldham couplers if you can afford them). That provided lots more torque for me and more accurate
3. Thrust bearings between Motor and coupler. So apparently with such a huge bed and height like mines (500 x 500 x 770mm build size), there could be "float"issues especially with such a big and heavy bed.
4. I didn't have them on at first, but I did what you said in the video, bearing on top to prevent the rods from spinning, I thought it was too wobbly, so did that, and that only made it worse, so removed them. According to the guys at Duet, you should never have both sides be rigid, always have one side open.
Doing those three, along with overkill metal plates brackets everywhere I could apparenly was what did it for me. So no more flex couplers :D
Oh yeah as you said, the Duet guys also said always try to go for clamping style instead of set screw style couplers, lots more holding area and more force and more accurate.
Thank you very much for the video and I look forward to the TMC 5160 vid!
Alex, this may be a bit of a crazy idea, but why cant we fix something like a threaded ACME rod in place and find a way to belt drive (spin) the ACME Nut instead. It sounds ridiculous, I know, but it has the advantage of removing z-banding and replacing it with a different engineering problem instead. For something like a coreXY build I don't see an issue with moving the stepper on to the bed and printing some GT2 pulley teeth sleeve thing to slide over those brass ACME nuts. Then simply drive them up against a bearing or thrust bearing.
where did you get those super straight super expensive lead screws from man?
What's the pro's on the tmc5160, compared to TB67S109 ?
Because I recently bought those.
Related to lead screws:
When I started my first build, there were only TR12x3 , but 3mm lead is terrible
considering a stepper motor cannot divide 200 steps into 3.
I contacted a lot of manufacturers about this, who all acknowledged that this
really made sense. And then came v-slot with the acme lead screw.
Never been happier about anything.
I got a good deal on them at some point ( until they doubled their prices).
Silly to think, lead screws makes people happy.
Looks like these manufacturers have been paying attention to the public, as
3D printing became more popular.
I have not tried the TB67S109, but I have some on order to include in an eventual torque test comparison. If i remember correctly, the toshiba drivers have a lower maximum input pulserate and up to 1.32 microstepping. They have been showing up in CNC motor driver 'bricks' so they should be able to push a decent amount of current if the stepstick boards are designed well and they are properly cooled (4 amps I think?). The 5160 will do slightly higher voltage and up to 1/256 microsteping, and has all the trinamic fancy features like SPI control and error reporting, sensorless homing, and they drive an external mosfet H-bridge. They won't do as much current as the toshiba chips, but should be enough for just about any nema17 that would be used in 3d printers.
how in the world is your setup dealing with bent leadscrews? that looks like the number one problem
hi! where did you get the tmc5160 stepsticks from? I ordered some from aliexpress for a printer I plan on building but they look different (black pcb)
EDIT: sorry, realised it was watterott. the aliexpress ones seem to have the exact same pcb layout, so hopefully they work well
They should use the same reference design, but I have not even had a chance to take them out of the plastic yet
Finally someone says it..
did u ever make a video on z axis with a belt? i'm kind of curious and wanna make my printer have a belt! right now i leave my nut's barely tightened so they can spin around and move a bit in their slot. ads a ton of backlash in theory but eh I don't use z hop and the weight of heavy 300x300bed with extrusion keeps it always at the bottom, so it's only the spinning
EDIT: oh you mentioned it!
I wish people would send me stuff like that too >_
What about using lead screws over belts for X and Y? Would this be a more reliable better setup? What about ball screws? I'm going to be using linear rails on all axis for my next build and accuracy and speed are what I am concerned about as well as maintenance.
People have done it, and there are pluses and minuses. Screws can avoid ringing artifacts from belt stretch and oscillation, but they have some tradeoffs, and are "probably" best for large, heavy machines that move slow-ish unless they are closed-loop like a pick and place machine. Compared to belts, they require higher rotational speed and have quite a bit more rotational inertia, both of which put the motors at a disadvantage for med-to-high speeds, and even though they are more efficient than leadscrews, they are still less efficient than belts... I.e. you would need to spec a lot more torque... probably 3-5x more, but that is just a guesstimation. They are also much more noisy from what I have seen. The vector of the force at direction change is also different and MAY need to be taken into account in the design of the kinematics and mounts. Leadscrews are similar, but have slightly lower inertia and can be spec'd with higher pitch, BUT it is a tradeoff because backlash becomes an issue. Alignment of any screw + linear rail is much more important as well, as you can bind up or cause premature wear on the rails and bearings if you're not careful (many of the vertically-moving bed printers I have seen with screws and parallel rail have that problem, and several have switched to Z belts as a result).
@@AlexKenis dude this is exactly the info I needed. I have 92oz nema 17 and was going to try a nema 23 on the Y axis as that's the only one that skips on my current printer but currently the motors are 56 oz I think and that's only on prints above a 35 mm/s speed. It's a Openbuilds platform and a 12in by 26 inch bed. I was hoping to print bezzels for car dashboards, which I can do now but there's a lot of waves so a lot of filler is required. And a single 5 inch by 17 inch bezzle takes about 18 hours. If I could get the quality of prints u show in ur example with that black part I would be Soo happy. I love your channel and how well you explain everything. Keep it up!
I've heard pros and cons about having the motor on top for the z axis. In what regard the coupling could be afected to? I'm running actually the motor on top of the lead screw for my 3d printer and looking for the best mecanical thing to setup in order to reduced the wobbling effect. Any idea what could be the solution in that case? Thanks
SOmeone else posted that they run a top-mount setup with the coupler riding on a bearing and had good results. I mentioned in that comment that originally the motors were moved to the bottom because leadscrews could handle the weight without deflecting as much as old theraded rod, and to prevent motor vibration from causing print artifacts, but we have better motors and drivers these days, so it may be worth trying. Whether the motors are top or bottom, you just have to make sure everything is aligned, and that there is nothing pushing the leadscrew to the aide in an eccentric motion (like a bent leadscrew, off-center coupling, etc)
@@AlexKenis Got it, Thanks.
What do you think of this coupler if mounted on with the motor on top?
fr.aliexpress.com/item/Flexible-arbre-coupleur-GND-en-aluminium-double-diaphragmes-pince-D26-L30-pour-3D-Imprimer-Couplage-servo/32862693235.html?spm=a2g0w.10010108.addToWishlist.12.368fded3s0QoB1&pvid=893cbfc6-9d59-4fae-88b4-85295c1f3d13&gps-id=pcDetailFavMayLike&scm=1007.12873.83260.0&scm-url=1007.12873.83260.0&scm_id=1007.12873.83260.0
Now awaiting the BFTB installment where you go full jungle on gray cast iron frames and then, to save some bucks, or Euros, or Pounds, you get out the epoxy, granite dust, and form boards to pour a really well-damped Hypercube Evolution Squared 1m frame, complete with all fastener embedded in the matrix.
... or, did you already do that episode and I missed it ?
And where did you get that nice straight threaded rod
Mcmaster Carr. I THINK that was the anodized aluminum lightweight rod that I bought for a high-speed crossed gantry design experiment that I never finished up (hopefully I can get back to it)
i'm confused how does the collar get rid of the wobble? isn't it lose on top of the flanged bearing?
EDIT: OOOOH because it can't tilt!
so this wobble is what causes ridges and protruding lines to show up in certain spots???
Now I am a bit confused. U demonstrated that z wobble gets worst if it is constrained on both ends, but then you showed that you made a pillows block on your printer to constrain the movement of the rod. And that made the layers better? What would I have to do if I have a Creality c10/ Tevo tornado type setup? Get a better rod, or try and do what you did?
He specifically stated that Z wobble gets worse with double-full constraint ***IF*** you have a non-straight or misaligned shaft. My understanding from that, and from websites I've read in the past with instructions on building gantries for CNC mills, is that if your shaft is straight AND properly aligned then double-full constraint offers the best rigidity, efficiency, and accuracy. Of course, I've never actually built any of these myself yet, so all I can go by is what I've read and watched.
Yes, pretty much what Claws said. I probably should have put a better summary in there. Best case scenario in a perfect world would be a perfectly aligned machine with perfectly straight leadscrew and a fixed/fixed setup, BUT if alignment is off, or the leadscrew is not perfect, a fixed/fixed would just make things worse. A bearing block + flexible coupler or a floating nut, with one end either floating or not rigidly constrained is a safer bet in cases where you can't guarantee straightness and/or alignment. Printers like the creality have a few small issues, and they don't show up an every printer: 1) they can bind up if you have one where the stamped steel gantry mount is a little off because it sets the nut at an angle 2) the motor mount may not line up the leadscrew perfectly with the nut after it is tightened down. I actually have an Ender on the way, so I'll do some vids about checking for those issues it when it gets here, and I'll post some tests and mods if it looks like it's needed.
Thank you both for the answers. I have been trying to make smoother walls and I initially did what I can with lowering the moving bed mass and adding diagonal support for the z axis. So now I am looking at the z rod.
awesome video...where to donate for your new haircut?
This was great, though think I need to go through it one more time. The thing is I am upgrading the Y-axis not Z. Interesting to note, the Delrin nut can have a lot of play that causes the wobble, sorry if that isn't the technical term, see here th-cam.com/video/eBvjl-5Z7XQ/w-d-xo.html and here to see play in the nut th-cam.com/video/YCBOTWydh1g/w-d-xo.html. Another way I am experimenting with is the stepper driver A4988, and changed the potentiometer to the lowest value to actually move the axis and trigger the stopper, plus changed the acceleration and velocity down to reduce the "wobble" and made it less likely to skip steps on large moves. Yeah, I know it is new and should skip, which in its own strange way, points out that the nut is pretty damn important too. Cheers for the video :)
Build it right the first time is all I can say. Everything must be square and true.
Ever bent a wire coat hanger back and forth to break it? That's metal fatigue.
One concern with the spiral coupler; aluminum is subject to fatigue failure: bend it back and forth and it *will* break.
en.wikipedia.org/wiki/Fatigue_limit
This means that aligning shafts well will extend the coupler life.
Alignment (and how much you use it) controls whether it lasts 10 hours or 100,000,000 hours.
Let your head explode...
damp·en
/ˈdampən/..................
1.........(make wet, part)
2.
make less strong or intense.
"nothing could dampen her enthusiasm"
synonyms: lessen, decrease, diminish, reduce, lower, moderate, damp, damp down, put a damper on, throw cold water on, calm, cool, chill, dull, blunt, tone down, deaden, temper, discourage;
Trinamic has yet another controller driver called TMC5161 which seems far more superior to TMC5160. It's got integrated mosfets and a much better pin less package at the botthom for better heat dissipation and more compact PCB.
I saw that chip mentioned on the page with a bunch of 'TBA' for the specs, so I'm interested to see what they come up with
I own solidworks. It has an add-in to splice the part and send it to a "Windows Based" 3d printer. Do you know of any stand alone boards that can operate windows based software? Have you even heard of anything with splicing out of solidworks ?
For "Windows Based" I suspect you're either going to be looking at something that communicates across USB and SW is just being silly in its terminology ***OR*** you'll want an IoT device like an Intel NUC or the RasPi version of Win10 - in which case you probably still want to connect that board to a more purpose-designed motor control board, given that PC-type processors ***supposedly*** don't handle these operations well in real-time and that all official iterations of the RasPi have unavoidable interrupt calls where the GPU polls and overrides the CPU at a specific interval for a specific and non-negligible duration.
The squeaky wheel gets the grease... And it's the first one you replace.
I've read a lot of material that says double-full or double-fixed constraint is best for ensuring a rigid gantry and to eliminate the problems that result from whipping on longer axes, but I've also read a few mentions and been told face-to-face that it amplifies any wobble present (as you yourself explain with specific regard to warped or misaligned shafts) and invites binding complications.
- Is it the case, as I mention to id104335409 below, that a straight and properly aligned shaft with double-full constraint is the best design option, if available? Why or why not?
- I used to see a lot of linear rods on the commercial websites that were 'fully anchored' along the length of the axis by a sort of mounting wedge. Where might this fit into the equation, so to speak?
You pointed out that the carriage on a floating-free or fixed-free rod or screw decreases whipping as it passes through the mid-lengths of the shaft because it acts as a support in its own right. This relates to a question I've asked on a previous video regarding nested or telescoping supports. I understand that in any gantry where both ends of an axis are even partially constrained these 'mobile supports' extend beyond the carriage in both directions. Recalling your previous declaration that you don't know much of how these work yourself...
- ...do you think a nested or telescoping system of support 'nuts' would work for a floating shaft if it extends only between the carriage and the motor?
I've read online in several different places including a few whitepapers that herringbone and paired helical planetary gearsets can function in the place of both radial and thrust bearings.
- What is your opinion on using printed herringbone gears ***OR*** herringbone planetary gearsets in place of traditional bearings in a shaft support?
You briefly described one part of your experiences with printing out support blocks.
- Since polymer filaments are often used to print linear bushings, how important is it for a printed support block to hold a bearing assembly instead of holding the shaft directly?
- How well do printed support blocks perform in your general experience?
- In the interest of repeatable parallel alignment, would you recommend for or against supporting multiple shafts in the same printed block?
Thanks for everything, Alex!
OI! Big question. Let me see what I can say:
--In terms of fixed/fixed, if everything is aligned, well-machined, well-assembled and reasonable flex-free... then fixed/fixed is likely best (especially with heavy a heavy gantry and/or long z-axis) . For very light/short situations, it's not quite necessary (esp. since that usually indicates a budget machine), and for situations with possible misalignment (stamped steel parts, home-assembly kits for beginners, etc) fixed/fixed may cause more headaches than it is worth.
--The fully anchored rail is usually called 'fully supported linear rail'. Typically, the 'wedge' is a separate part, but not always. It is a nice, extremely stiff option, but you have to have 2 rails to support a cart, and alignment is important, whereas with shaped rail/guideway (like Hiwin) you only require one rail for the cart to be self-supporting
--Yes, I don't have hands-on experience with telescoping actuators, unfortunately, except various stage rigs. If I come across one that seems workable, I think it would make an interesting machine though
--I haven't used planetary gears as bearing replacements, only for ratio translation. One of the prototypes for the 3:1 belted extruder actually used a planetary herringbone gearbox. Backlash was a bit high and it was noisy, so I moved to belts instead. As for use as a bearing, it may be worth a try, but I expect it to be noisy and less precise than bearings (at least if 3d printed), an to have more friction/resistance. I did a little work translating a popular open SCAD gear generator to English, so if you are interested, it is on my GitHub page called "translated_comments" tree: github.com/AletheianAlex/gears/tree/translated_comments That's the generator I used for the experiments
--as for 3d printed bushing in place of bearing block: It may be worth a try. Wear MAY be an issue, but then again, there is not much movement. Polymer bushings (3d printed or IGUS, etc) have different issues as opposed to bearings. They have a slip-stick movement profile since they slide instead of roll (except for the micro-bearing rolling action of lubricant), so they MAY require lower acceleration and/or higher torque to overcome initial stiction from a stationary state to prevent missing steps. I HAVE used them for linear motion, and what I usually did was to have a 'sacrificial' linear rod that I would either heat up and use the to melt the contact surface slightly, then spray it down with lubricant and run it along the rail until it ran smooth (or use a shaft in a drill to heat up the surface and burnish it smooth). That + silicone spray seemed to work okay-enough back in the day before linear bearings got so cheap, although stiction was always a slight issue
--if you mean 3d printed BEARING support blocks, then they work very well since the bearing itself does all the hard work. If you mean 3d printed STRUCTURAL support blocks, then I always try to have some kind of secondary support. For example, on the old 'testbed' printer, all the3d printed linear motion cart blocks don't provide much structural support -- I run m3 bolts through them in tension to provide the actual support -- and the printed parts are used in compression, which is where they have the most strength. Actually, I should make a video about that sometime.
--multiple shafts in the same block: 3d prints are fine for alignment, but poor for heavy structural rigidity, so as long as either A) you don't need much rigidity or B) you provide some other members for rigidity, or C) parallelize several 3d printed members to stiffen-up/assure-alignment if possible (an example is the belted extruder... using a 3d printed backplane would never take the belt tension, but sandwiching the pulleys between two 3d printed layers is quite rigid), then 3d printed parts are fine. Otherwise, it's better to bolt to a stronger material and use the 3d printed part to provide mounting points, etc.
Thanks, Alex! This should help a lot, though I might have to come back and ask for more elaboration later... especially if you don't make those follow-up videos ;3
OpenSCAD gears, huh? I tried to figure out some of that a few months ago but a lot of it went over my head and a lot of the rest seemed like they weren't using all the terminology or equations correctly... though that was with the gear 'generator' included with the base program. This looks like a different one, I think. (I should watch some OpenSCAD tutorials soon)
Took a couple of deep looks into that gears library you recommended. Haven't gotten around to actually trying it out yet, though I plan to in the next day or two. I did make 'a few' corrections to the translations that I'd like for you to look at in your Pull Requests when you get a chance. Thanks again, Alex!
Regarding your bearing + collar contraption, the KFL-08 miniature flange housing unit only runs about 3€-4€ locally. They're pretty much designed for this, preventing any vertical play. And here's an appropriate bracket for em: www.thingiverse.com/thing:3823246
That's a clean looking setup. I'll have to grab some and check them out
@@AlexKenis After playing around with the ones I received: The advertised "self alignment" feature pretty much means that the bearing housing itself has a sort of ball-type outer surface, sitting inside the zinc housing, sort of mushing around and requiring substantial force to align. Personally, I couldn't get it properly aligned and I'll be going back to just the "ball bearing in a flex coupler", since it seems to work fine for 3d printing purposes. Would have been nice restricting upwards movement of the leadscrew for light milling purposes, though.
owwwww 5160's been looking at them but carnt afford since i just bought a set of 2130's :-(
I just purchased 2208's x 5 as one of the 5160 costs as much as almost 3 of the 2208's.
This is an argument for replacing bent lead screws, not an argument against Z-axis supports.
I don't really see any of these solutions as viable for the printer I have, the openbench solution you offer is only $8 cheaper than a dual z axis lead upgrade for my printer and it has some issues with my printer which is that the lead screw is not long enough or is too long, Yes I could buy the larger one, cut it down to size or keep it as is. The onlything that makes since is the pillow block, but your pillow block solution also wouldn't work, I would have to come up with my own because it also would interfere physically with the bed. If I would to invest in that $104 solution I may aswell go after another printer because my printer only costed $230. That is a little less than half the cost, but not by far. Creatality seems to know the issues with their printers and make addons as a requirement basically to get them working right. Their other solution for this problem is a pully system, that uses both the lead screw and the pully system to do the samething. They seemed to stop carrying your $104 solution, and the pully system still doesn't stop the wobble 100% it only adds resistance against it like this solution you have come up with here does on leads that are bent, but your solution heavily depends on it not being bent. The dual z axis lead upgrade would still have a possiblity of this happening as instead of 1 bent lead now you could have 2 bent leads. But the main problem with the leads is they bend easily because they can not hold the weight of the entire x axis, and commonly they do, which causes them to bend the lead as the whole arm rises, I have seen this first hand. So a holder at the top actually does midigate some of this by adding support to the lead. The problem is there is no 1 solution that fixes it all, it is a multipart issue, which yes would be better under a 2 lead system with pully supports, 4 pillows 2 top 2 bottom and a guiding rail in the middle , so yes your $104 solution would work, perfecting it would be adding pullies to it, but that would bring the cost upto more than the average printer that has this problem. So the problem is we shouldn't be giving our money to these cheapo printer manufactors that only plan to invest on the problems they have with possibly even more problems so you buy upgrade kits for your upgrade kits, so by the time its all said and done you may aswell have gone after that 4k printer. Or you ghetto rig what you already have to the best of your ablity and use multiple solutions and see what effects what you already have for the better.
You switch from threaded rod to acme lead screw without any explanation of the differences between them... Is there a separate video on that? I've seen rather expensive printers using stainless threaded rod with rubber coupling
I just had another question about threaded rod actually, I didn't know folks were still interested since lead screws got cheap, but I guess they are. I used to use it in the past, and I have a few older printers around that use it (malyan, etc), and it can be made to work if you can find straight rod with good threads (the higher grade stuff that is post process rolled and hardened seemed to work best... i got mine from mcmaster carr, but I have no chance of remembering which). Other than that, the issues I remembered were that they had more of a tendency to bind if not careful, and the thinner rod would deflect under load, so a lot of folks started mounting the motors at the top to prevent deflecting under tension. Z-motion is also slow because the pitch is so fine, if that is a concern.
@@AlexKenis Alex Kenis I suppose T8 2mm lead screws are actually easier to manufacture but effects on print quality, resolution etc would be an interesting topic. On the Ender 3 ;)
which one is best for ender 3 vibration dumpling coupler or flexible ones ?
Are you having issues with z-banding? Because the banding on those machines tends to be from alignment and binding, so I could type up a checklist you would want to run through before putting out cash on a coupler. I don't have an ender, so I can't make a vid, but enough people ask about them that I may grab one.
@@AlexKenis im not having but suspicion some layers maybe, its cool if u grab one thank you nice contents on your channel much appreciated
Damn you for that misspelling, now i'm stuck wanting some genuine Cantonese Pork&Shrimp dumplings but nowhere to get them.
hello Alex now u hgave E3 will you make couplers vid for it :)
PS missing your video
It's called screw whip
What do you think about the Toolson Z-Achsis Alignment? th-cam.com/video/bv4AB3YPNwc/w-d-xo.html
God these lines are hipnotizingly straight! I may become straight, gah stop looking.
Different from!
Are you still using Facebook. I have a question if you are.
get a shotgun microphone to reduce ambient noise
You can't show us the 5160 and not follow up within a couple of days. The suspense is killing me!
HA, i know man, I'm sorry about that. I actually started immediately with testing, but had some issues with Marlin's sensorless homing routine, and spent a few days troubleshooting that. but I had some other issues that have kept me from getting much work done, so I'll get back on it soon.
@@AlexKenis thanks for the follow up. We will be waiting. Best of luck!
dont rotate the screw, rotate the nut instead! an example www.thingiverse.com/thing:1274284