Re: Scratched rods from linear bearings
Thanks everbody for your input.
@Teptec
Good thing, I got some 3-in-one white lithium spray grease here. Left it in the car a few weeks and we already got temperatures around 0 degree Celsius. Anybody knows if it damages the grease or aerosol?
Did you recommend the grease in a tin or is it as spray just the same?
Is it nessesary to degrease the bearings before adding the lithium grease?
The problem seems to accumulate. Like you said, there is no way to blame prusa. There are obvious many printers without this problem. So the best solution is to invest in higher quality bearings and rods?
When your lower X rod got scored just from slidig the bearing on, it is obvious not an assembly error.
So Misumi is the way to go?
Just wondering if the Misumi bearings on stock rods would be the same improvement as with hardened g6 tolerance rods, but maybe the tolerance is nothing like g6.
Re: Scratched rods from linear bearings
I prefer the one from the tin because a) it's cheaper b) I can smear it where I want it c) it doesn't get where I don't want it. Never tried the sprayable stuff, but I'm sure I don't want to disassemble any of my printers to just put some grease on a threaded rod without greasing everything in a radius of 30 cm 😀
I usually don't degrease them, but I have no idea which would be the "correct" procedure. Didn't cause me any trouble yet though.
As for the stock rod tolerances: I have no idea how precise they are, maybe someone else knows more. Personally I'd say everything is good as long as the bearings slide on the rods nice and tight without engraving them or wobbling around like a damn Igus plastic bearing that's not been made for precision movements (and still ends up in quite a few "improved" printers, getting wider and sloppier every hour).
If we wanted super precise movement we'd be using linear slides instead of bearings on a rod, cable tied to a piece of plastic anyway 😉
I dont know if Misumi is the "way to go", but their bearings have a good price/perfomance balance for me. Going for 20€ bearings would probably not make any visible difference for us. Misumi is good quality stuff from what I've seen and used. Rod-wise there are enough cheaper options that are still more than good enough and slightly cheaper. I just ordered the rods from them because I was ordering the bearings anyway.
The rods in my other printers are not chrome hardened and from a different random online shop for mechanical precision parts. No scratches and wear after thousands of printing hours. Just make sure they're absolutely straight.
I prefer the one from the tin because a) it's cheaper b) I can smear it where I want it c) it doesn't get where I don't want it. Never tried the sprayable stuff, but I'm sure I don't want to disassemble any of my printers to just put some grease on a threaded rod without greasing everything in a radius of 30 cm 😀
I usually don't degrease them, but I have no idea which would be the "correct" procedure. Didn't cause me any trouble yet though.
As for the stock rod tolerances: I have no idea how precise they are, maybe someone else knows more. Personally I'd say everything is good as long as the bearings slide on the rods nice and tight without engraving them or wobbling around like a damn Igus plastic bearing that's not been made for precision movements (and still ends up in quite a few "improved" printers, getting wider and sloppier every hour).
If we wanted super precise movement we'd be using linear slides instead of bearings on a rod, cable tied to a piece of plastic anyway 😉
I dont know if Misumi is the "way to go", but their bearings have a good price/perfomance balance for me. Going for 20€ bearings would probably not make any visible difference for us. Misumi is good quality stuff from what I've seen and used. Rod-wise there are enough cheaper options that are still more than good enough and slightly cheaper. I just ordered the rods from them because I was ordering the bearings anyway.
The rods in my other printers are not chrome hardened and from a different random online shop for mechanical precision parts. No scratches and wear after thousands of printing hours. Just make sure they're absolutely straight, but that's often an issue more related to shipping and handling.
Re: Scratched rods from linear bearings
5 out of the 6 rods on my MK3 already show scratches/grooves from the linear bearings.
Pix?
Re: Scratched rods from linear bearings
No pix (I am at work and the pics would be super boring:-)) - but you see the groove where the balls are supposed to be "rolling". And you can put your finger nail in the groove - so it is not "optical" but actually worn out. After maybe 20 hours of printing. At my printer, only the left Z rod is OK, all others show damage already.
And they were perfectly looking when I installed them.
Re: Scratched rods from linear bearings
same here.
but it still works fine.
what will it look like in 6 month... i only have 40h printet...
Re: Scratched rods from linear bearings
same here.
but it still works fine.
what will it look like in 6 month... i only have 40h printet...
I am not keen of finding out:-) I also experience quite some ringing and ghosting. I think I know where it comes from as increasing belt tension let to no improvement:-)
I will receive a package from Prusa Support today - it should be 5 new rods and a corresponding number of bearings:-) I will see...
Re: Scratched rods from linear bearings
If 3-5€ for Misumi bearings seems to expensive I'd suggest to just grab a bag of cheap ones (probably around 1€ per piece) on ebay/amazon and just throw out the bad ones.
Care to give some part numbers for the Misumi bearings/rods you are using!
PSSFJ8-370
(the 370 is for the length, X-axis)
https://de.misumi-ec.com/vona2/detail/110302634310/?HissuCode=PSSFJ8-370&PNSearch=PSSFJ8-370&KWSearch=PSSFJ8-370&searchFlow=results2type
I should add that chrome hardened surface is probably overkill. The original Prusa rods are pretty okay as long as they're not ruined by ultra cheap bearings 👿
Might I suggest that you use https://uk.misumi-ec.com/vona2/detail/110302634310/?HissuCode=PSFJ8-370
PSFJ8-370
The PSSFJ8 is for stainless steel which is softer than the PSJF8 and may get damaged with the bearings. The hardness of the SS is only 56HRC where as the [Iron] EN 1.3505 Equiv. is 58HRC and the hardness of the LMU8 bearings are also 58HRC, I spoke to Misumi and the EN 1.3505 material complies with USA standard (52100 Bearing Steel).
Re: Scratched rods from linear bearings
I prefer the one from the tin because a) it's cheaper b) I can smear it where I want it c) it doesn't get where I don't want it. Never tried the sprayable stuff, but I'm sure I don't want to disassemble any of my printers to just put some grease on a threaded rod without greasing everything in a radius of 30 cm 😀
I usually don't degrease them, but I have no idea which would be the "correct" procedure. Didn't cause me any trouble yet though.
As for the stock rod tolerances: I have no idea how precise they are, maybe someone else knows more. Personally I'd say everything is good as long as the bearings slide on the rods nice and tight without engraving them or wobbling around like a damn Igus plastic bearing that's not been made for precision movements (and still ends up in quite a few "improved" printers, getting wider and sloppier every hour).
If we wanted super precise movement we'd be using linear slides instead of bearings on a rod, cable tied to a piece of plastic anyway 😉
I dont know if Misumi is the "way to go", but their bearings have a good price/perfomance balance for me. Going for 20€ bearings would probably not make any visible difference for us. Misumi is good quality stuff from what I've seen and used. Rod-wise there are enough cheaper options that are still more than good enough and slightly cheaper. I just ordered the rods from them because I was ordering the bearings anyway.
The rods in my other printers are not chrome hardened and from a different random online shop for mechanical precision parts. No scratches and wear after thousands of printing hours. Just make sure they're absolutely straight, but that's often an issue more related to shipping and handling.
So you put some grease even after assembling with the Misumi Bearings? Doesn't the seal prevent to get it in them? But good points, I will head to Obi tomorrow.
I will do the same then I think, degreasin before would be nothing but time-consuming.
Maybe the support can tell me about the stock rods. So maybe I will just buy new bearings for the stock rods then, if only the bearings make a big difference. I'm always asking me why people are still talking about the Igus bearings instead of sintered bronze bearing if they want sliding bearings.
Yes, these machines are not made for exact precision. Just want to prevent the problem with the grooves 🙂
I hear so much about Misumi, not only from you that's why I'm asking. Haven't heard before from them, just companies like SKF or THK. The price for the Misumi is really good, I will definitely go for them. Does you also put them on your Z-axis?
Okay, maybe I look for some other rods or even the stock ones then.
Thank you very much for your input Teptec!
Are you using lithium grease on your new bearings now Stahlfabrik? Let us know if everything went fine with them yet
Re: Scratched rods from linear bearings
So you put some grease even after assembling with the Misumi Bearings? Doesn't the seal prevent to get it in them? But good points, I will head to Obi tomorrow.
Sorry for the confusion, I was talking about greasing threaded rods and spindles once in a while and the mess a spray grease would make. Sometimes my smooth rods get a paranoid drop of sewing machine oil, but as far as actual greasing goes, no.
SKF and THK are great (judging by only a few mechanical parts that I used from them), but in this particular case I think we just want proper bearings that do what they're supposed to do, so with my limited will to throw endless amounts money at problems Misumi seems like a good choice.
Also thumbs up for sintered bronze bushings, I use them in all my cartesian printers. I considered throwing some on the Prusa, but the alignment has to be absolutely perfect and they have to be fitted with the correct pressure. I could mill some aluminium housings for the latter, but I dont see how the general style of a prusa printer and the tolerances of printed parts wouldn't make the whole idea a major pain in the butt without replacing half of the machine. I think the construction is good as it is and (actually functioning) linear bearings are probably the best choice for what it' supposed to do. Sinter bushings are great for really fast movement. Something a heavy direct extruder in a somewhat flexible frame isn't great for. I'd like to see someone do it just for the sake of it, but the practical benefits seem questionable.
Edit: Also, no, I won't replace the Z bearings for now, they're on the good 50% side of the chinese bearing pool.
Re: Scratched rods from linear bearings
Might I suggest that you use https://uk.misumi-ec.com/vona2/detail/110302634310/?HissuCode=PSFJ8-370
PSFJ8-370
The PSSFJ8 is for stainless steel which is softer than the PSJF8 and may get damaged with the bearings. The hardness of the SS is only 56HRC where as the [Iron] EN 1.3505 Equiv. is 58HRC and the hardness of the LMU8 bearings are also 58HRC, I spoke to Misumi and the EN 1.3505 material complies with USA standard (52100 Bearing Steel).
You're absolutely right, thanks!
Never had problems with stainless rods on other machines, but just to be sure I'll second that. PSFJ8 are definitely the safest pick
Re: Scratched rods from linear bearings
So to do the X & Y, how many bearing would you need? Is it 8?
Tempted to get order some before i build mine.
Re: Scratched rods from linear bearings
X - 3
Y - 3
Z - 4
Re: Scratched rods from linear bearings
Cheers.. might order 6
Re: Scratched rods from linear bearings
Are you using lithium grease on your new bearings now Stahlfabrik? Let us know if everything went fine with them yet
I received a complete set of new bearings and rods from Prusa today! Awesome!
I am not to keen on rebuilding the entire machine 😯
I think yes: I will oil the rods after they are installed and I ordered a grease (which I guess is lithium but it does not say so):
https://www.amazon.de/gp/product/B001BAU3VY
I guess this fits perfectly to the manual which says: "Super-lube, or any other multi purpose grease, will do."
I will apply this grease on all bearings lightly. But first I will try it out on an old rod and a bearing - not in the printer but just with my bare hands while disassembly
I also ordered the original Super Lube from the USA but I will not use it I think because it contains PTFE, which I heard would be bad for linear bearings.
But was it quality issue with the old bearings, the old rods? Or were the bearings fine but not greased enough? Who knows.
My plan currently is to build an enclosure first, then rebuild the machine.
Re: Scratched rods from linear bearings
I received a complete set of new bearings and rods from Prusa today
That's great. As you now have them in hand could you measure and advise the length of the Z axis rods (the short ones), please? The assembly instructions have the Y at 330mm and the X at 370. I am considering ordering a complete set of Misumi rods and bearings to have for my initial build.
TIA.
Re: Scratched rods from linear bearings
z-320
y-350
x-370
Re: Scratched rods from linear bearings
You absolutely sure about that - support told me they are y=330, x=370, z=320
Re: Scratched rods from linear bearings
You absolutely sure about that - support told me they are y=330, x=370, z=320
Just measured to double check and the Y is 330
Re: Scratched rods from linear bearings
Thanks for checking and confirming Jason.
Re: Scratched rods from linear bearings
Sorry for the confusion, I was talking about greasing threaded rods and spindles once in a while and the mess a spray grease would make. Sometimes my smooth rods get a paranoid drop of sewing machine oil, but as far as actual greasing goes, no.
SKF and THK are great (judging by only a few mechanical parts that I used from them), but in this particular case I think we just want proper bearings that do what they're supposed to do, so with my limited will to throw endless amounts money at problems Misumi seems like a good choice.
Also thumbs up for sintered bronze bushings, I use them in all my cartesian printers. I considered throwing some on the Prusa, but the alignment has to be absolutely perfect and they have to be fitted with the correct pressure. I could mill some aluminium housings for the latter, but I dont see how the general style of a prusa printer and the tolerances of printed parts wouldn't make the whole idea a major pain in the butt without replacing half of the machine. I think the construction is good as it is and (actually functioning) linear bearings are probably the best choice for what it' supposed to do. Sinter bushings are great for really fast movement. Something a heavy direct extruder in a somewhat flexible frame isn't great for. I'd like to see someone do it just for the sake of it, but the practical benefits seem questionable.
Edit: Also, no, I won't replace the Z bearings for now, they're on the good 50% side of the chinese bearing pool.
Now I get what you mean 😉 That's definitely better, I have to cover the frame on my other printer with a piece of paper everytime I use Ballistol spray.
The company I worked for a couple of years used THK Linear Motion Guide and I'm really impressed about the quality. But that's for industrial machines, not for us. Musmi will be fine then 🙂
Actually I have sintered bronze bushings on a Prusa style printer (P3steel toolson edition MK2) and they work really good. altough they are just in printed holders. Like you said, there is no problem with fast speed with them.
Here are some test videos from the author of it, in case you really want to see it:
Okay, I hope mine will be okay also and the "scratch" will not turn into grooves when I'm continuing printing.
I received a complete set of new bearings and rods from Prusa today! Awesome!
I am not to keen on rebuilding the entire machine 😯
I think yes: I will oil the rods after they are installed and I ordered a grease (which I guess is lithium but it does not say so):
https://www.amazon.de/gp/product/B001BAU3VY
Nice! How long did it take after you contacted the support?
Based on the review it is indeed lithium grease, so it will be fine.
That's a good idea to test the bearings first.
I think it will be the bearings and/or rods which failed. Mine were overall greased.