Linear Bearing & shafts ( Mendel Prisa i2 )
January 31, 2013 07:26AM
Hi
I would like to know if I have to buy Linear Rods to accompany the Linear bearing. I was told by the sales agent that I can not use normal smooth rod to run the linear bearing on ( LM8UU bearing ) Is this true that I have to buy Linear shafting ?

Thanks
Vaughan
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
January 31, 2013 08:42AM
smooth rod works fine for me. and almost every kit i have seen only uses smooth rod.
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
January 31, 2013 10:22AM
So the smooth Rod is the stainless steel smooth rod ? (Grade 304 ) is everyone using the stainless steel rods ?.

Thanks
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
January 31, 2013 12:04PM
I used to use stainless rod but I found it wasn't accurate enough for LM8UU bearings. I now use hardened high carbon steel with h6 tolerance.


[www.hydraraptor.blogspot.com]
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
January 31, 2013 12:55PM
Hi Nophead
Is the carbon steel rod a huge difference in price to the Stainless Steel Rod ?

Edited 1 time(s). Last edit at 01/31/2013 02:11PM by scubi.
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
January 31, 2013 06:10PM
after seeing the quality of your prints nophead, i will have to take that into consideration with my next setup.


[mike-mack.blogspot.com]
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
February 01, 2013 01:19AM
Typically the linear bearings use EXTREMELY hard ball bearings internally...like file hard. When they are coupled with a shaft that is not as hard or not nearly as hard, like stainless steel they can and do wear into the shaft which increases the play that is introduced between the shaft and bearing which will affect print quality negatively. The weight of the object being supported plays a big role in how fast they will wear. For example when we were prototyping the initial RPM which has a gantry weighing about 10lbs, we would see wear enough to feel with a fingernail after 1 day of use (an extreme example relative to a lightweight Reprap). The production version uses ground, chromed and induction hardened linear shafting (with a 9RMS finish) and its still perfect after thousands of cycles.

Chelsea - QU-BD
Re: Linear Bearing & shafts ( Mendel Prisa i2 )
February 01, 2013 11:23AM
I haven't seen any particular wear on my smooth rod. I think the cost saving is worth it compared to precision ground. If you periodically rotate your rods but not the bearings then you can get huge life. Stainless steel is very hard anyway.
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