david.s30
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Re: Replacement bearings recommendation

Sat Mar 25, 2017 5:40 am

Yes, I built my printer and have been testing it for about two weeks. The rods and bearings fro Misumi have worked out really good. The lengths I mentioned in my other post were exact lengths to the Prusas default shafts.

Smallest smooth rod: 8mm x 320mm
Middle smooth rod: 8mm x 330mm
Longest smooth rod: 8mm x 370mm

The Bearings glide very well on the shaft. They came nice and sealed in a plastic bag with plenty of bearing oil. Sadly I dont know what any other rods and bearings sound like as this is my first build and I have not used any other bearings or rods. I would love an audio sample or video if anyone has it. The Misumi rods and shafts are pretty quiet. The loudest component on my printer is the fan, which I think I am going to replace in a week or so.

I printed the dampening STL from Prusa and also placed a silverware drawer lining on the table I am using, under the printer and it helps cut down the noise substantially. What format can I post an image and I will post up a few of the samples I have printed so far. I think my 3D Benchy came out pretty good. The Triceratops skull is amazing, looking.

I had a bitch of a time getting my P.I.N.D.A sensor correct and getting the right Y axis length, but once I got that, all has been pretty smooth, minus the learning curve. I had issues with getting prints to stick to the heat bed, but Rave hairspray was 1.98 and works fantastic. But nothing so far related to the Shafts or Bearings.

ales.f
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Re: Replacement bearings recommendation

Thu Mar 30, 2017 4:53 am

Very good to hear. I have got the same Misumi rods as you. But for bearings, I got the LMU-N8 variant without a dust seal. My Prusa kit arrived last week. I will try to put everything together this weekend.

For the dampening feet, are you sure that your printer will not hit its resonant frequency when you are printing something? If it does, the feet may actually cause a lot of stress be put on the printer. I do not know if this can damage it, but it is certainly not good for it. The best solution I have seen is to place the printer on a 16 inch by 16 inch garden tile (a heavy piece of concrete) to eliminate the resonance caused by a wooden desk or table.

Ales

calan.w
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Re: Replacement bearings recommendation

Thu Mar 30, 2017 5:09 am

This might be a noob question but people keep debating on Misumi vs igus. I have to replace my rods and bearing because one ceased up and scratches my rod (same reason why I had to replace my ex girlfriend). From what I gather from a day of research is the Misumi has a better tolerance and Igus is quiet. My question is, does the looser tolerance have any affect on print quality? I haven't found any mention of it anywhere.

richard.l
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Re: Replacement bearings recommendation

Thu Mar 30, 2017 3:43 pm

calan.w wrote:From what I gather from a day of research is the Misumi has a better tolerance and Igus is quiet. My question is, does the looser tolerance have any affect on print quality? I haven't found any mention of it anywhere.
In theory the looser tolerance can introduce lateral movement which could show in the print quality. I changed one of my MK2's from stock to Igus only to reduce noise, which it did. The quality of prints between the 2 remain the same.

calan.w
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Re: Replacement bearings recommendation

Thu Mar 30, 2017 7:29 pm

richard.l wrote: In theory the looser tolerance can introduce lateral movement which could show in the print quality. I changed one of my MK2's from stock to Igus only to reduce noise, which it did. The quality of prints between the 2 remain the same.
What you are saying falls in line with my experience. I received a sample igus bearing from igus the other day and they seem to have the same amount of play as the stock bearing. Assuming tolerance is the big part affecting print quality, igus should be the same as the stock bearings but with less noise. My question for the Misumi people out there, does the tighter tolerance of the Misumis with matching rods actually have a noticeable improvement in print quality.

bryan.r
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Re: Replacement bearings recommendation

Fri Mar 31, 2017 3:58 pm

Hey david.s30 I have a few questions. What/how did you mount the bearings on the Y Carriage? The zip ties or with one of the bearing holders?
I have had my MK2 since the end of September and have printed close to 1000 hrs on it and I seem to be in need of new bearings. The printer is making a decent amount of rattle noise and there is definitely some slop/wiggle in the Y carriage.
Also, did you have any issues with the bearings fitting properly into the X or Z parts?
I am thinking I may do the exact same order as you. Which brings me to my other question - did you get 12 bearings just so you could have a couple extra on hand?
Thanks!
Bryan

david.s30
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Re: Replacement bearings recommendation

Wed Apr 05, 2017 10:50 pm

Sorry for not responding sooner. I haven't had any issues with the bearings or rods based on the parts I ordered. I posted my exact order below for anyone to use. Sadly I don't have a comparison of the rods and bearings for noise, but I haven't had any issues with my install. Z height, but that was unrelated and solved easily. I think the bearings were a good purchase, the sound is fine in my opinion how smooth the bearings glide is very smooth.

I'm no expert but I would check your ties and ensure that they are secure. Check step 12 of the online manual, make sure the rods are correctly installed per the video
http://manual.prusa3d.com/Guide/2.+Y-ax ... /104#s5455

Also to another issue I have found is to make sure the bearings are lined up and not off center from each other.

___________------------- - incorrect bearing alignment

__________ __________ - correct bearing alignment

OK, so silly drawing above but the actual bearings inside need to align, this correction cu out some noise for me.

Wiggle seems like it could also be from a misalignment of the X carriage. If you don't have a set, get a set of calipers and measure, measure, measure everything till its all square. I essentially rebuilt my machine after I picked up a set of calipers. They are golden.

I currently am using the zip ties. I just purchased some orange ABS and am going to try and print some of the bearing holders that have been provided by Prusa. I also think I am going to upgrade to the MK2S as the little U bolt seems like a better design. I ordered extra bearings so I can replace them without having to order and wait.

001 [Item Status]:Processed
[MISUMI Part No.]:LMU8
[Brand Name]:MISUMI
[Product Name]:Linear Bushings
[Quantity]:12
002 [Item Status]:Processed
[MISUMI Part No.]:SFJ8-320
[Brand Name]:MISUMI
[Product Name]:LINEAR SHAFT
[Quantity]:2
003 [Item Status]:Processed
[MISUMI Part No.]:SFJ8-370
[Brand Name]:MISUMI
[Product Name]:LINEAR SHAFT
[Quantity]:2
004 [Item Status]:Processed
[MISUMI Part No.]:SFJ8-330
[Brand Name]:MISUMI
[Product Name]:LINEAR SHAFT
[Quantity]:2

A Misumi bearing engineer recommended this is the grease to get for the LMU8 bearings.
https://www.motionindustries.com/produc ... u=03760972


Some guides, etc...May be worth a print
http://www.thingiverse.com/thing:1846705
http://www.thingiverse.com/thing:1848700
http://www.thingiverse.com/thing:1819779
Last edited by david.s30 on Thu Apr 06, 2017 6:24 pm, edited 1 time in total.

MTJC
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Re: Replacement bearings recommendation

Thu Apr 06, 2017 12:06 pm

Hi David. You linked to a thingyverse page instead of some grease. :)

bryan.r
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Re: Replacement bearings recommendation

Thu Apr 06, 2017 1:04 pm

Thanks for the reply! I ended up doing the exact same order and it will arrive tomorrow so I should be able to do my bearing/rod upgrade this weekend!
I was very careful during the build, and have checked a couple times since, so I am pretty sure everything is square and set up properly. I think the slop/noise from the Y carriage is a direct result, as some have mentioned, of the zip ties stretching/weakening over time due to the many hours of prints. Also they will stretch over time due to removing items from the bed that have adhered really well - there just isn't a good way for the bed to not get torqued a little when removing well adhered items. This has obviously been proven to be a flaw in the design since Prusa is now using those U-Bolts instead of zip ties in that area.
Now I just need to decide which Y carriage bearing holders to print, I wont do the install until I get those done - definitely not using the zip ties in that spot again.
Thanks!
Bryan

david.s30
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Re: Replacement bearings recommendation

Thu Apr 06, 2017 6:26 pm

MTJC wrote:Hi David. You linked to a thingyverse page instead of some grease. :)

I fixed the link in my original post.

bryan.r that actually makes very logical sense. Heat from the bead could also expand, retract the zipties. I know I am looking forward to the us bolts. I just ordered some orange ABS and plan on doing some mods to the machine if I can. I'm just learning ABS as I was using the PLA that came with the machine. My 3D benchy came out decent, but not nearly as clean as my PLA. Good luck to your build, Id love to hear the difference in the original bearings, rods, slop vs the Misumi.

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