Mk3 igus bearings
Hi
Just pre-ordered the Mk3 kit.
From the launch material I see that the Mk3 is going to be using regular bearings (?)
Since I already have some igus bearings laying around, would it cause any issues swapping out the regular bearings?
On my previous builds the igus bearings gave a big improvement in lowering noise and makes away with having to lubricate the rods and bearings.
Re: Mk3 igus bearings
I suggest you build as supplied first
the Mk3 uses all sorts of magic for endstop detection and missed step detection, you might find yourself chasing your own tail...
once its working well, then have a play!
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Mk3 igus bearings
Didn't Josef at one point infer they are looking into igus specifically for the MK3 , but no answer one way or the other at this time?
From what people say, they do sound like an attractive option.
Yet perhaps the us,uk function limited their use because of the stepper drivers utilizing resistance as endstops? Seems like operating correctly, there wouldn't be a substantial difference in required torque to start movement , yet maybe a dirty machine could induce issues that are difficult to overcome?
Re: Mk3 igus bearings
Contrary to popular belief igus bearings are not really suited for use in this application. They have really tight tolerances and actually need to be compression fitted to the rails. There are a couple youtube videos on the subject. As such, they can be hit or miss. Unless Joseph used the special tool to pre size them to the rails, it wouldnt work out for some people. Maybe this is why he avoided them on the mk3.
Re: Mk3 igus bearings
Prusa mentioned in one of the videos the reason they didn't go with Igus bearings was because they were worse at tolerating misalignment.
That's doublespeak for "We still have slop in our frame assembly."
It happens.
Igus bearings would be fine with a proper preload and floating setup. And aligned rails.
Re: Mk3 igus bearings
Contrary to popular belief igus bearings are not really suited for use in this application. They have really tight tolerances and actually need to be compression fitted to the rails. There are a couple youtube videos on the subject. As such, they can be hit or miss. Unless Joseph used the special tool to pre size them to the rails, it wouldnt work out for some people. Maybe this is why he avoided them on the mk3.
Ugh, this again? There are IGUS bearing specifically designed not to need compression fitting. The 2 most used in our printers are the Rj4JP-01-08 which has no casing around the bearing and the RJZM-02-08 which has a casing. Neither need to be compression fitted.
Re: Mk3 igus bearings
Contrary to popular belief igus bearings are not really suited for use in this application. They have really tight tolerances and actually need to be compression fitted to the rails. There are a couple youtube videos on the subject. As such, they can be hit or miss. Unless Joseph used the special tool to pre size them to the rails, it wouldnt work out for some people. Maybe this is why he avoided them on the mk3.
They have been working fine for me on the Mk1/Mk2 for over 18 months now. Just regular, off-the-ebay igus bearings, on both X and Y axes.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Mk3 igus bearings
"Special tool" hehe.
When someone uses the word "special", it's usually a red flag.
You can pretty much substitute "magical" in its place.
Re: Mk3 igus bearings
They work fine for most people. But not all. They have tighter tolerances and I have ran the Rj4JP-01-08, and reached out to igus about them and they do recommend press fitting them. Basically, if your rails arent perfect, or they are not fitted correct you can have issues. This is well known, and I have experienced them myself.
"Special tools"
Customer support will tell you whatever is expedient and necessary to get you off the phone. If they think you are a typical consumer and can get you off the phone by telling you stories of mythical "special tools", they will. It's not indicative of best practice or engineering guidelines or anything of the sort. Igus does have actual design guidelines, and they don't invoke "special tools".
They do not have tighter tolerances; their bearings are all over the place.
It's a rail skew issue. If your rails aren't straight or if you have two of them and they aren't perfectly aligned, the Igus bearings may stick more, although on the other hand you have to wonder why some people put the Igus bearings in there in the first place (hint: the original bearings failed anyways, hence making your whole point moot).
Being a rail skew issue at its core, the real answer is to fix the rails or bearing arrangement, not blame the bearings or invoke "special tools".
Re: Mk3 igus bearings
When did I blame the bearings? Also, look online and you can find countless people that switched from standard bearings to igus and had issues. It IS a rail problem in most cases. That brings us to the same result, and what I said in the first place. They might not be best suited for this application. Rails come bent all the time, and its easier for Prusa to keep ones in that will help hide a slight deviation. Tighter tolerances can become an issue on kit 3d printers that are shipped across the globe. Its pretty simple logic.
Re: Mk3 igus bearings
I think where we are going with this is quite simple. A bad workman always blames his tools. Mainly because they can't answer back.
When set up correctly, there will always be some slop in this design; in the main it doesn't matter because the forces in play are not sufficient to cause that slop to have a major effect.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Mk3 igus bearings
When did I blame the bearings? Also, look online and you can find countless people that switched from standard bearings to igus and had issues. It IS a rail problem in most cases. That brings us to the same result, and what I said in the first place. They might not be best suited for this application. Rails come bent all the time, and its easier for Prusa to keep ones in that will help hide a slight deviation. Tighter tolerances can become an issue on kit 3d printers that are shipped across the globe. Its pretty simple logic.
And how many people had the *regular* bearings fail?
When presented with the skewed rails, the Igus bearings might stick more.
When presented with same thing, the regular bearings might roll through it until they just straight up fail.
Yay, I guess? I guess that's a win?
Re: Mk3 igus bearings
Igus works very well and smooth if the printer is perfect aligned. It's also recommended to use the Igus rods with the Igus bearings !
I never tried the original bearings, I switched to Igus from the scratch. So, my MK2-update will also use the Igus.
Thomas
Re: Mk3 igus bearings
I think we all want the same thing. I would love to have igus bearings, they are quiet, I would not need a lubricant, and it would also mean my rails are perfect. I was just trying to explain a potential reason why Prusa does not ship with them. The standard bearings work in every case. Whereas the igus can bind if you have any rail deviation or not properly fit. Prusa has more to lose than they have to gain be putting them in stock machines. I am not saying I agree with it, just that it may not be feasible for kit 3d printers, for reasons Peter explained perfectly.
Re: Mk3 igus bearings
The problem here is that this kit is purchased by users who have never owned a printer before and also some with very little technical knowledge.
As gz1 has mentioned, regular bearings "work better" with incorrectly assembled printers - they simply force the rods into line - if PR shipped Igus bearings with the kits, they would be continuously asked for replacements.
PR have to ship parts that will last as long as possible under the worst possible conditions. If an owner wants to upgrade they have that option.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Mk3 igus bearings
Yes correct, Igus bearings are not recommended for beginners, non-technical people and people without experience.
Thomas
Re: Mk3 igus bearings
The standard bearings work in every case.
This is the sticking point.
If you can point at evidence of failures with Igus bearings as proof that Igus bearings don't work for everyone, then I can easily, easily point at the much greater incidence of regular bearing failures and make your exact same argument against regular bearings. So the whole thing is a wash. Nobody is any further for the argument you have presented.
As gz1 has mentioned, regular bearings "work better" with incorrectly assembled printers - they simply force the rods into line - if PR shipped Igus bearings with the kits, they would be continuously asked for replacements.
I don't think PR would care about being continuously asked for replacements, because all they would have to do is continually say, "no". I mean, they already do that; they just phrase it a little differently. Maybe they'll say it's the user's fault for not assembling the printer properly. Or maybe they'll say it's the user's fault because he didn't use vegetable oil on the bearings. Or maybe they'll say it's the user's fault because he didn't use some "special tool". You guys see how customer support works now?
The regular bearings "work" until they self destruct. There's still metal running along plastic races, just like metal running against a solid plastic bearing. You get some form of failure either way. With the regular bearings, you have an additional danger of metal rubbing against metal and potential gouging of the smooth rods. Which one is really worse?
Maybe making the conscious decision of which failure mode you prefer to run into is indeed for experienced users. That is about as far as I can go with that.
A consumer will look at this and go, "You can't use those bearings!" or "You have to buy the special tool!"
A designer will look at this and go, "Whoah, hold on, there are some issues with this design/implementation..."
This isn't just isolated to PR, either. There have been some rather... big failures in this department from other printer manufacturers. There was one printer in particular where I looked at their bearing arrangement and I was like, "Good luck with that." People kind of didn't want to listen to me, but in the end I was right.
Re: Mk3 igus bearings
I think it is unbelievably silly to say "I don't think PR would care about being continuously asked for replacements." This means unhappy customers, negative reviews, and an overloaded support team. Who wants to get a printer and have to immediately ask for a replacement rod or bearing? Yes, the mechanical bearings will fail eventually, but out of the box they will have a much better chance of working perfectly for the customer. It sounds like you have all the answers, so Ill just leave it alone now. Many people seem to agree that they may not be the right choice for this application, whether you want to blame the customer or Prusa.
Re: Mk3 igus bearings
I think it is unbelievably silly to say "I don't think PR would care about being continuously asked for replacements." This means unhappy customers, negative reviews, and an overloaded support team. Who wants to get a printer and have to immediately ask for a replacement rod or bearing? Yes, the mechanical bearings will fail eventually, but out of the box they will have a much better chance of working perfectly for the customer. It sounds like you have all the answers, so Ill just leave it alone now. Many people seem to agree that they may not be the right choice for this application, whether you want to blame the customer or Prusa.
I don't have all the answers, but I am quick to eliminate the wrong ones.
I also have a bad habit of answering rhetorical questions.
I don't know who wants to get a printer an have to immediately ask for a replacement. But I did.
So since you clearly exist more on the business side of things, given everything that you said, please explain why I received dud bearings, out of the box, on my pre-assembled printer?
Match up your ... "business reasoning" with my out of the box experience. In fact, dig a little deeper into the forums and look for all the instances of out-of-the-box bearing problems and justify what you just claimed PR wouldn't want to happen HAS ALREADY HAPPENED. I have repeatedly pointed you in that direction, and you have repeatedly ignored it.
The majority of your declarative statements of fact are not actual facts.