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jweaver
(@jweaver)
Honorable Member
Re: Scratched rods from linear bearings



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The rods are hardened steel (60 +/-3 HRC). Also it's h6 tolerance instead of g6 which means a little less play. I bought them by 1m length and had to cut them myself. You have to use a grinder, no way to make any mark on this with a metal saw, it's really really hard !

If I have understood corerctly, the problem is that some people have steel rods and others have stainless rods ?

Any idea why ? Seems illogical.

I will receive my printer soon and i don't know if i use included rods or not ... I don't want to change them in 2 weeks ...
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Have a MK3 with badly scratched rods myself, but was holding off ordering new rods until the root cause and propper solution came out.

So do you think that the "hardened" rods they are shipping now, are just a stop gap and not the rods they intended to use?

Posted : 17/01/2018 5:55 pm
ed
 ed
(@ed-3)
Reputable Member
Re: Scratched rods from linear bearings


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So do you think that the "hardened" rods they are shipping now, are just a stop gap and not the rods they intended to use?

The rod design has a track record so my money says the replacement rods should be fine, as long as they're what Prusa says they are.

Posted : 17/01/2018 6:04 pm
dryja123
(@dryja123)
Honorable Member
Re: Scratched rods from linear bearings



So do you think that the "hardened" rods they are shipping now, are just a stop gap and not the rods they intended to use?

Jo admitted that some unhardened rods slipped through and current orders will be shipped with proper rods. Anyone who received unhardened rods are getting free replacements.

I received my order this past Monday and it came with the proper hardened rods.

Posted : 17/01/2018 6:12 pm
stoofer
(@stoofer)
Estimable Member
Re: Scratched rods from linear bearings

Thanks for the heads up, early order here and non-magnetic rods. My X axis was showing some scratches, so I've got the replacements on the way.

I may take the opportunity to upgrade the bearings whilst it will be apart and print holders for the Y bearings as I don't like the U clamps so much.

Posted : 17/01/2018 11:14 pm
ed
 ed
(@ed-3)
Reputable Member
Re: Scratched rods from linear bearings


Thanks for the heads up, early order here and non-magnetic rods. My X axis was showing some scratches, so I've got the replacements on the way.

I may take the opportunity to upgrade the bearings whilst it will be apart and print holders for the Y bearings as I don't like the U clamps so much.

At some point I might print a set of these ones...

https://www.thingiverse.com/thing:1819779

Posted : 18/01/2018 12:05 am
gibsonlpsl
(@gibsonlpsl)
Eminent Member
Re: Scratched rods from linear bearings

So I've already received some replacement rods through customer support, but now reading this magnetic test, I decided to go ahead and test everything (original MK3 rods, replacement MK3 rods, original MK2s rods, and some Misumi rods I bought). The results are mostly as expected with one major surprise.

Original MK3 rods: non-magnetic
Replacement MK3 rods: magnetic
Misumi rods: magnetic
Original MK2s rods: all magnetic EXCEPT one of the x-axis rods

If this is a valid test for the rods, then it seems worthwhile to check older orders as well. My MK2s was shipped on June 8, 2017.

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Posted : 18/01/2018 3:22 am
devdoc
(@devdoc)
Estimable Member
Re: Scratched rods from linear bearings

Should the MK2S rods be magnetic as well? I thought they were supposed to be hardened as well but perhaps that was just conjecture as the current add only indicates "Polished smooth rods". The reason I ask is that I have an order in for an MK2-MK3 upgrade which will reuse these rods and I want to make sure everything is the same and correct.

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Posted : 18/01/2018 4:44 am
Area51
(@area51)
Re: Scratched rods from linear bearings


So I've already received some replacement rods through customer support, but now reading this magnetic test, I decided to go ahead and test everything (original MK3 rods, replacement MK3 rods, original MK2s rods, and some Misumi rods I bought). The results are mostly as expected with one major surprise.

Original MK3 rods: non-magnetic
Replacement MK3 rods: magnetic
Misumi rods: magnetic
Original MK2s rods: all magnetic EXCEPT one of the x-axis rods

If this is a valid test for the rods, then it seems worthwhile to check older orders as well. My MK2s was shipped on June 8, 2017.

Just tested the rods I have:

Original MK3 rods: non-magnetic (December 14.)
Replacement MK3 rods: magnetic (got them yesterday)
Original MK2S rods: z-axis magnetic, x and y-axis non-magnetic (April 18.)

Have a look at my designs on Thingiverse or on PrusaPrinters ;)...
Posted : 18/01/2018 4:50 am
reid.b
(@reid-b)
Reputable Member
Re: Scratched rods from linear bearings

Do any of the rods on your MK2s have visible or obvious damage from the bearings?

Posted : 18/01/2018 4:59 am
Area51
(@area51)
Re: Scratched rods from linear bearings


Do any of the rods on your MK2s have visible or obvious damage from the bearings?

Yes, both y-axis and the top x-axis.
Can't remember if PR promised hardened rods with the MK2->MK2S upgrade kit.

Have a look at my designs on Thingiverse or on PrusaPrinters ;)...
Posted : 18/01/2018 5:16 am
devdoc
(@devdoc)
Estimable Member
Re: Scratched rods from linear bearings

Yes. I just went over them with a light and then noticed 2 grooves in them. Then ran over them with my nail and sure enough they can be felt.

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Posted : 18/01/2018 5:17 am
devdoc
(@devdoc)
Estimable Member
Re: Scratched rods from linear bearings


Do any of the rods on your MK2s have visible or obvious damage from the bearings?

Yes mine do. I just went over them with a light and then noticed 2 grooves in them. Then ran over them with my nail and sure enough they can be felt.

...
Posted : 18/01/2018 5:19 am
Area51
(@area51)
Re: Scratched rods from linear bearings

On the Prusa shop the rods are described as "Polished smooth rods" not hardened for the MK2->MK2S kit...

Have a look at my designs on Thingiverse or on PrusaPrinters ;)...
Posted : 18/01/2018 5:22 am
devdoc
(@devdoc)
Estimable Member
Re: Scratched rods from linear bearings

I just checked my newly not yet assembled MK3 which was received last week and it does appear to have the hardened rods. Unfortunately my first MK3 does not. Its pretty darn obvious side by side and with the strong floor magnet I was using to test with. I will have to contact tech support. My guess is that ones shipped in December (like my first one) did not come with the correct rods. I can sorta back this up by saying that they sent a replacement set due to shipping damage and they are not hardened either. Bummer. I would like to figure this all out before my MK2->MK3 kit ships. I really just wish they could have reached out in email to those potentially affected. I don't show any damage on the MK3 rods, but it has only 10 or so hours on it so far. This came to light through a few build videos and I felt a bit duped admittedly, but PRUSA support has been A1 up to now. This is my 5th kit, and they have dealt with any issues I have had swiftly and reasonably, so fingers crossed. Funny thing is that I am listening to my clicky MK3 power supply maintaining bed temp on preheat cycle in the background (the sent a replacement which I haven't had the chance to install yet, so that ones on me).

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Posted : 18/01/2018 5:36 am
Steve
(@steve-6)
Trusted Member
Re: Scratched rods from linear bearings

Received my MK3 today. Rods are hardened. They won't be installed though as my Misumi rods and bearings should be received tomorrow and I'll build with those.

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Posted : 18/01/2018 12:52 pm
michael.s73
(@michael-s73)
New Member
Re: Scratched rods from linear bearings

I received my mk3 on December 20. Noticed yesterday that my smooth rods were less smooth than should be expected (also a bit of a grinding noise on long X-axis moves). I talked to support 10 minutes ago, who had me try magnets on my smooth rods. None of the rods were magnetic (but my z-axis leadscrews are, I checked just for fun).

They're shipping me all new rods and bearings for no cost to me. If you've got gouges in your rods, talk to chat support and they can walk you through this.

Posted : 18/01/2018 4:51 pm
william.o6
(@william-o6)
Active Member
Re: Scratched rods from linear bearings

@devdoc how do you test to make sure the rods you get are hardened without scratching them?

Posted : 18/01/2018 6:00 pm
jweaver
(@jweaver)
Honorable Member
Re: Scratched rods from linear bearings


@devdoc how do you test to make sure the rods you get are hardened without scratching them?

Magnet.. If they DO NOT attract, they are stainless and soft.. if they attract then they are hard.

Posted : 18/01/2018 6:04 pm
john.n13
(@john-n13)
Estimable Member
Re: Scratched rods from linear bearings

Magnet.. If they DO NOT attract, they are stainless and soft.. if they attract then they are hard.

It may be obvious, but just in case... This statement only applies to the two variants of Prusa-supplied parts - the wrong one (non-magnetic stainless) and the correct ones (steel with high enough iron content to be magnetic). The hardness difference is only known in this case based on Prusa's knowledge of the specs of what it shipped.

Posted : 18/01/2018 6:37 pm
devdoc
(@devdoc)
Estimable Member
Re: Scratched rods from linear bearings


@devdoc how do you test to make sure the rods you get are hardened without scratching them?

If you scratch it with the magnet test, that must be some magnet. You should actually be able to run a file on the end and it should skate and leave no marks.

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Posted : 18/01/2018 7:20 pm
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