Should you be using IGUS polymer bushings?

Should you be using IGUS polymer bushings?

Hey everyone, Tom here, and IGUS recently
sent me this insane sample package, and i would like to take this opportunity to talk
about whether or not, when and how you should be using these over regular linear ball bearings.
So e.g. in an LM8UU linear ball bearing, there are recirculating bearing balls, so you never
end up with an actual sliding surface to bear any loads, it’s always a macroscopic steel
ball that does the rolling. In a lubricated bushing, the lubricant itself takes that role
of the steel balls and acts as a microscopic interference layer between the two sliding
surfaces, and it doesn’t matter whether they are rotating or linear slides, it’s
the same principle. Now, brass bushings or these IGUS drylin polymer bushings take a
bit of a special position here, as the bushings themselves are the lubricant as well. Brass
bushings are typically sintered and oil impregnated, so as they slide, they deposit tiny amounts
of oil into the sliding contact and lubricate it that way, or, as a backup, plain brass
also slides on steel reasonably well even without a lubricant, but of course, it wears
down much faster when there’s no interference layer between the mating partners.
Actual self-lubricating polymer bushings like the IGUS types work in much of the same way,
they deposit a lubricant that is an integral part of the polymer blend, and you can actually
feel your fingers getting all slippery and stuff when you play around with a drylin bearing
that’s sitting on your desk. How do know that? Well, what do you think i’ve been
doing while i was scripting this video? What that means is that in order to function,
there needs to be tiny amount of abrasion happening so that the actual lubricant can
work where it needs to be. So a polymer bushing will degrade during its service life and gradually
gain more internal clearance and consequently, increased play as it ages. After a quick go
at it with IGUS’ bearing life calculator and an i3-ish configuration, it does match
up with my experiences, which is basically – they will last forever in that application,
with an expected service life easily past several thousand prints. And when they do
fail, it won’t be like an LM8UU that just randomly starts locking up, the polymer bushings
will keep working just fine, albeit with slightly increasing slop.
Now, if you’ve seen them in actual use before, you’ll most definitely have noticed that
these are already loose like sleeve of wizard even when they are factory new. But… so
are cheap LM8UU bearings. Still, it’s one of the main reasons why people recommend against
using polymer bushing. Ok, so, ideally, you want a tiny amount of pre-tensioning in your
bearing. In a decent LM8UU, or HIWIN MGN rails, that is generated by the linear shaft or mating
surface being ever so slightly oversized for the bearing, and that will have the actual
bearing case ever so slightly deform and act as a very stiff spring, and for an LM8UU that’s
this steel sleeve you see from the outside, which the balls ride against on the inside.
In a polymer bushing, the bushing itself can compress and deform to achieve that. However,
due to how these bushings are manufactured, they are intended to be used in an interference
fit with a slight press fit as you install them, so not just, like, loose, zip-tied to
some holder, but actually pressed into a tightly tolerated bore with a 40kg force, and when
you do so, these assume their final tolerance with regards to the linear shaft. So actually,
if used correctly, the common RJMP type are specified for a maximum of roughly 50 microns
of play, if used on a proper linear shaft, like IGUS’ own anodized aluminum ones, or
the common chromed linear shafts that you would use for a linear ball bearing – which
are actually not that great for polymer bushings, stay tuned. So you’re never going to get
any actual pre-tensioning with these regular polymer bushing inserts, that’s just not
how they are designed, but if you use them properly, you’ll get a very respectably
low amount of play. It’s just that it’s kinda hard to really use them that way on
a 3D printer unless you’re actually using precision machined aluminum or steel parts,
and trying to get that press-fit H7 bore just right with common tools is pretty close to
impossible. IGUS does offer these RJUM bushings, which come with a massive aluminum sleeve,
so you can use them exactly like LMUU bearings, but they are pretty expensive and you could
easily buy a brand-name LMUU bearing for the price.
Now, if you’re designing a printer from scratch and are set on using polymer bearings,
then there are other options available like these simple N-series slides that have an
ever so slightly pretensioned sled available for them, but of course, once you apply the
tiniest amount of force, that pretension stops being effective, or you could use adjustable
slide blocks like this one on the W-type. This concept is really similar to the adjustable
linear ball bearings, so, really, you could achieve the same effect with either one if
you want discrete bearing blocks. These W-type rails fall into the same category as HIWIN
MGN rails, which you can order with zero bearing play, and for that reason, are considered
pretty much the king of linear slides. You do have to be a bit more careful with dust
and contamination, as with any ball bearing, but that’s typically not much of an issue
in FDM-based 3D printers anyways. The IGUS drylin bearings are supposedly immune against
dirt, you know, there are no super small moving parts that would get shredded if any foreign
object made its way in. One thing polymer slide bearings or even brass
bushings excel at is noise, especially compared against cheap LMUU bearings. Because there
are no moving parts, there really is no noticeable noise. And what’s great is that it doesn’t
depend on you mounting them perfectly in line – if you’ve ever had the joy of trying to
line up a pair of caged LM8UU, also known as SC8UU, you’ll know that even if you ever
so slightly misalign them, they are going to sound like they are grinding away your
linear shaft, and they are. I mean, it’s super easy to mar your linear shafts just
by running a misaligned LM8UU up and down once. Now, if you misalign polymer bushing,
they aren’t going to run perfectly, either, they will stick and squeak, but they aren’t
going to break anything. Still, aligning them is one of the tricky bits.
For these polymer bushings, you don’t really need any sort of special linear rods, sure,
it should be a precision rod with a good tolerance on its diameter, but if you can only get plain
ground stainless steel rods, then those will work just as well. IGUS even offer anodized
aluminum rails, which of course are a bit less stiff than steel, but you can compensate
that by going for a slightly larger size, so overall, those can get you some weight
savings, which might help you out if you have moving rods like in an H-bot setup.
One more thing i want to point out, is that polymer bushings definitely feel different
to linear ball bearings when you try them outside of a printer. They are still very
smooth, but you can definitely feel them having a bit of drag as you move them along. Now,
that is not necessarily a bad thing, you see, the main load on a 3D printer’s stepper
motor is going to be dynamic, so from the inertia of the carriage it’s pulling. If
you add a bit of dampening to the axis, which this slide bearing drag essentially is, then
you’re not going to see any performance hit when it comes to achievable speeds, but
you might actually see a reduction in any sort of oscillation artifacts. Granted, i’d
still need to test how much of a difference it makes, if any, but, you know, just to get
that out of the way. And i’ve looked this up specifically for the IGUS bushings, you
can also add lithium grease to the rails to support the bushing’s “natural” lubricant
if you want them to glide along a bit more easily.
So, in conclusion, when should you use polymer slides over ball bearings? What it comes down
to is whether you want and can spend a bit extra time and money on mounting them properly
and possibly using the aluminum caged ones, but once you get them lined up properly once,
they are going to give you basically an infinite service life in a 3D printer application.
You don’t need to be particularly careful with the rails or any sort of oil or grease
that might need to be reapplied periodically, and while, from a precision standpoint, HIWIN
MGN rails are probably the better choice all-round, they aren’t quite as foolproof once out
in the field and, of course, require the printer to be designed specifically for these rails.
If you’re looking to upgrade from LMUU bearings, again, you’ll probably want the aluminum
case version, but those those should be a direct drop-in replacement in most cases for
a quieter and more reliable machine. Alright, i hope that clarified a few things
– if you’ve got your own experiences with igus bushings, share them in the comments
below. Other than that, get subscribed, and if you want to support this channel directly,
use my Amazon affiliate links for your shopping and have a look at my Patreon campaign, links
for those are in the video description. As always, thanks for watching, and i’ll see
you in the next one.

100 thoughts on “Should you be using IGUS polymer bushings?

  1. Unfortunately those aluminum cased ones are 16 mm outer diameter which is larger than the standard LM8UU outer diameter of 15 mm so it's not necessarily a drop in replacement.

    Tom, would you be able to review IGUS's RJ4JP bearings? The gray ones? Their website states that they are used for 3D printers, have "japanese dimensions".

  2. I have been researching water wheel bearings and found out the low speed rotation does not lend itself to good lubricant layer distribution. What is suggested is wood bearings. Bees wax lubricant according exhaustive testing done by others. The porous nature of wood and wicking seem to be a major advantage. If I ever get to the point of building and testing I will share the results. Does this make any sense?

  3. Never use those! they are just ok for drawer slides. I had lots of trouble with them in a machine at my work. You just can't get any precision out of them. Carriage alignment is a pain, play is a pain. You keep fiddling with the set screws in the sliders, and it never is as you like it to be. Dust and dirt load the sliders and they stop running smoothly, and you start fiddling with the set screws. The soft Aluminium rail gets nicked easlily and that becomes a friction point, and you start fiddling with the set screws again. (yes the anodised layer is hard… but still…). just spend the little bit of extra money on a linear guide with ball bearings. The weight saving in a 3d printer is marginal. you can buy small sized linear guides which can withstand the forces in a 3D printer easlily, weigh about the same, don't cost much, and are factors better than the igus drawer slides.

  4. linear bearings need corning silicone grease! they will last indefinately. Lithium grease breaks down the plastic cage…etc..

  5. the video got me thinking, was prepared to use an igus wsx-10-40 over some 1700 mm rail length, end to end. out of that, useful trip would be around 1400 mm, centered to the rail. i gave it a quick thought about friction, i read how polymer rails work, but didn't have the luxury of having one to play with. many thanks to tom for the video, might have to rethink my design.

  6. Hi Tom Outstanding job as usual. I am building an FT5 now and have upgraded to aluminum and fiberglass parts. I am looking to upgrade the z axis liner nuts for driving the bed. I came across these and was skeptical. Would you recommend them as an upgrade to the stock brass screw setup? I believe they were 16 mm vs the stock 8mm but should not be a problem right? Since i am still fabricating parts, i have not drilled those yet and am very interested in what you have to say on the topic. Very curious about thread pitch impacting quality of movement. My thought is higher TPI= smoother movement but not sure that is accurate once a stepper motor is added to the mix. would fine threading be better?

  7. I am planing to replace the bearings on a mk2. I got myself some RJ4JP and some RJZM. Unfortunately the RJZM have quite a bit more slop than expected – despite the aluminium casing. Checking with igus that's expected behaviour though. In your video it sounds differently but the RJ4JP have a tighter tolerance than the RJZM. The rep from igus said that the RJ4JP would probably be a better choice for a 3D printer and a press fit is not required.

    I am still going back on worth whether I should use the igus aluminium rods or keep the steel rods.

  8. I split the IGUS bearings along one of the slots with a hacksaw and then it's much easier to set a slight preload on them even with clip-in housings such as on the Replicator clones, work just the same as any other split bushing/bearing then.

  9. I needed up getting the bushing with the metal housing for a massive printer that I'm building, not because they were our first choice, which they would be after using them, but because we could only get them in the time frame we had, they are amazing, very expensive but worth it if you really need it

  10. what about 3d printed bushings?
    i have 2 which actually work fine on a pretty cheap prusa model (But to be honest, i haven't used it much lately…)

  11. how would you upgrade the lm bearings on a wanhoa, do you get better version of lmu bearings that whats in the machine

  12. Hi great video
    I found a couple 11mm=7/16in diameter linear shaft, can't find bearings that size, can anyone help me?

  13. Good video Tom.
    I have been using IGUS W and T for a long time at work.
    It is good stuff.
    But, I am now using Hepco.
    Just food for though.
    They are like the V rollers on say a CR-10.
    Difference is they are all metal and I think they are better ( certain applications ) than Hiwin.

  14. Basically you're saying "That slop you are trying to get rid of, the thing that is killing the precision of your printer, yea that's normal and will bet worse, you should just accept it because no good reason", then make up a bunch of reasons that don't really exist (alignment).

  15. Nice and very informative. @Tom: Do you recommend to use Igus bearings on Prusa i3 MK2S? Any experience in regard to reduced noise and reliability?

  16. really you should be lubricating the lm8uu bearing /rails.. they will last longer and be quieter

  17. Don't forget to do closeups when you showing the elements you talking about, we can barely see from the distance you made the video, what you talking about.

  18. What about static friction. With any bushing you have to overcome static friction. That's why ball bearings are used. They give better print quality, because they don't have to overcome static friction, each time they stop or reverse, which gives a brief moment of high acceleration as they start to move.

  19. Hi Thomas! Would you mind sharing where you find the 40 kg force press fit specification? Can't seem to find any specs on it!

  20. Why would anyone use stainless steel or aluminum rods? Just use proper precision rods made of hardened steel and you're good to go.

  21. Just helped a friend remove these. They had a weird issue where they would print the first cm fine and then it would start to have a Y axis tilt that was nearly 45 deg. Not sure why but putting the stock bearings back in was a instant fix. Tested over several prints and all had same issue. Same prints were flawless with return to the stock ball bearings.

  22. Hi Tom, I hope you get this… I have a slight problem with my new DryLin bearings. I just rebuilt and installed them on the X-axis of my ROBO R1+ and one side slides easily while the other side has friction. Both 8mm smooth rods were completely degreased and appear to be true. Would I be correct to assume that over time they will “give” a little and also move freely?

  23. I tossed some drylins on my wanhao duplicator. Havent tested them yet because my hotend broke, and i cant in good faith recommend taking apart a wanhao, but just installing the bearings i could already tell that theyre an improvement, especially considering that all the balls fell out of one of my lm8uus when i took apart my machine

  24. linear bearings all the way. only if you print with a nozzle smaller then 0.1mm for experimental high quality prototypes for research you can use the polymer crap ones bla bla bla.

  25. Hi this is an interesting topic. I run my own firm Nolin CAD and we have been designing industrial machines including CNC machines for 8 years and before that I was working as a machine designer for 15 years. What I found out is the tolerance requirements for IGUS bearings are lot higher than linear ball bearings (THK, Hiwin etc). And they seem to work well only when IGUS rods are used. With other shafts they either have more clearance and play than desirable or run too tight thus reducing life of the bearings which are not so robust. On the other hand with normal linear ball bushings (LM8 etc) variations in shaft diameter can be bit more acceptable. This is my observation and might not be necessarily true.

  26. Thanks for the helpful overview, Tom. Your videos are great. One of the Igus savings is weight. The linear bearings in my carriage weighed 9.25 g each v the Igus ones at 2 g each. Replacing the steel rods (271 g) with carbon fiber (24 g) resulted in a tighter fit with the Igus bearing and a substantial reduction in mass (from 308 g to 34 g total). I also switched to a Bowden setup (carriage mass from 271 g to 77 g). I've been quite astonished with the improvement in print quality. The result is a quieter, smoother machine that runs at higher speeds without ringing. Thanks, too, for the tips on the SilentStepper drivers. The steppers are practically silent!

  27. Well, I'm ready to remove the IGUS bushings from my Monoprice Maker Select V2 Y-axis (admittedly I bought it used), because not only are all three bushings wearing unevenly, with one feeling quite tight and the others moving but with a grating texture in the motion, and one of them having noticeable side-to-side slop, but even after lubricating with the recommended "Super Lube" synthetic PTFE grease, the natural warp in the stamped steel cradle for the build plate (after leveling) causes unaccepable stiction and binding, leading to resonant "juddering" as the (quite tight) Y-axis belt stretches and the stress is relieved by the platform starting to move. I'm going to LM8UU and grease for my needs, at least until I become smarter and can figure out the dark art of how to apply these bushings 'properly'. I think their implementation in the Maker Select V2 is marginal; they are "pressed in" to split plastic housings that hold them in place but do not compress them.

  28. I'm glad I came here before I installed my drylin bearings on my chrome rods. I will be ordering the aluminum rods for the bearings.

  29. I replaced the Y carriage on my prusa I3 Mk2 with IGUS bushings (the ones without the aluminum shell) and they work flawlessly as they are pressed a bit by the u-bolts.

  30. Thanks, that is very interesting. I am just getting into 3-d printers, but I have about 30 years experience with high end xyz tables on semiconductor tools. This gives me a better look at things. In the semiconductor world, money is not an issue.

  31. My printer came with bearings that seemed to have worn very quickly (they were probably never lubed), replaced them with drylin and it's like a whole new printer. Smoother, quieter, less vibration. The only pain was cutting them to size.

  32. Without seeing the video I will say: NO. They are ridiculously priced. Better spend more gold on a good linear rod instead and get cheaper linear ball bearings that you can easily replace when needed. The reason why you want a good hardened rod, is because the bearings will not eat into the metal.

  33. Tom. Polymer grease such as PTFE grease made specifically for these, tradename Thomson "linear lube". Been using it on cnc machines for years and doesn't stain polymer parts yellow and brown like lithium.

  34. I had to replace the linear bearings on my 3D printer, and found that they were full of rust in less than 6 months. Keeping in mind that high humidity is 20% where I live. Those caged linear bearings are a real pain.

  35. Great video Tom!

    I opted for the IGUS AVM-08 aluminum (anodized) shafts on all my MK3's axis'. On the Z axis, I installed four RJ4JP-01-08 (15mm) polymer bushings, and six RJZM-01-08 (16mm) on both the X and Y axis (with revised Y bearing holders and X carriage). Yes, some would say that the Z axis doesn't see much action and do not require such an upgrade (less violent travel), but I I'm not one to take shortcuts and the extra $30 on the AVM shafts with polymer bearings gives me peace of mind).

    My previously MK2s had the factory shafts/LM8UU bearings and after 200 (+-) prints, the X and Y axis shafts were scored (Prusa did indeed replace them free under warranty, BTW). Yes; I had taken the time and great effort to ensure that Y axis shafts ran parallel (within 0.001"), but the shafts took a beating, regardless.

  36. I want to see the webshop with prices not "price upon request!" I hate the idea of "price upon request". I don't know if they are trying to charge me extra or is it just regular price. maybe they will not like my name and charge extra 100%. who knows.

  37. Ive really like my roller printer, but one of my printers has the igus and ille never ever evarrr go back to metal after using these. 2 years on my go-to printer.

  38. I like that you cover all the subjects and your knowledge about what you are talking about but I think you explain too much in all of your videos, and it makes people tired. I never could finish watching any of your videos, in my opinion if any one needed very detail information about something they can research themselves later.

  39. As a noob, not sure if I got them installed correctly on our monoprice maker select v2. The bed used to slide freely when tilted, with new bearings we get stuttering.
    I set up the bearings like the Prusa has two on one side one on the other. Lightly tighten them down run into same problem. Lightly loosen the screws and it moves a little more freely but I fear they will loosen up too much and cause problems.
    Anybody can suggest anything

  40. Im a bit late here, but the answer to "should i use igus" is "depends"…. Do not expect great tolerances using it, but you can expect ridiculously high life. i have assemblied 4 printers using igus to try (i have used the full kit, with rails, bushings and housings), while it worked nice for printing toys, it didnt get the me positioning tolerance on parts i needed ( <0.01mm ) when measured by three dimensional machines

  41. To stay serious, you can refine maybe the play of the rails until you you can't measure it, but how about the belts? How about their tension depending on the acceleration? Would everyone replace those to ballscrew rod? I would say the difference between ball and polymer is more a good feeling than a fact in case of printing for home use. Or how we use to say in Germany : "let the church placed in town"

  42. I replaced my bearings from my ANET A8 by Drylin bushings and the noise was greatly reduced and the play was gone!
    I HATE the bearings, never coming back!

  43. Thomas, I'm still staying tuned for the comment about combining IGUS with a chromed rod. Where can I find the info? It's not in the video 🙂

  44. If I pick a handful of YouTubers about 3D printing (you being one) and I can get us all all in a conference call with video if possible so “talking with hands to help with visuals” will help. ….
    And in this live group call we form a “company/Organization” for my truly revolutionary design of a printer to be sold as a product. I’m not asking for money, I am a over the road semi truck driver, I make plenty of money for everything needed, I just don’t have the time to do anything other than talk really. And I live out of my Simi Truck. So I don’t have build space.
    Most of my design is set in stone, but there are multiple ways to do different factors of my design, can we all discuss it and maybe add tweaks to make it better. But what we all discuss as a collective does not leave the project and stays private until it is ready for sale, can we all agree on this and talk about

  45. After 4 years of use on my taz 5 the igus bearings had a significant amount of slop especially in the x and y axis. Replaced them with the high precision (grey colored) version RJ4JP with very good results in reducing print artifacts (compared to old ones with slop)

  46. Getting H7 fit with regular tools being nearly impossible? Totally why hand reamers are not made then in that size spec … oh wait. Yeah, sure.

    Location and axis perpendicularity is a tangential problem to getting hole bore within specified diameter and circularity. And also something that can be compensated for in the design, given you sacrifice easy part replacebility and opt in for manual adjustments on each piece made.

  47. No mention of their pillow block bushings. The fix all the problems described:

    * No pre-tensioning required, already mounted in containment
    * They can accept a certain amount of misalignment because they are spherical inside the housing, so they self align when there's more than one
    * Bolt them to your carriages/ends, no silly zip ties, no deformation
    * Price competitive compared to name-brand LM8UUs

  48. can you add a video on linear slides for a different type of motion explaining how that is setup and how that works? like extruded beams?

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