Originally shared by Jeff Keegan
I think one of the LM8UU bearings on my Prusa i2 went bad (at least that’s my best guess). The X axis has extreme trouble moving to the right (it stutters and skips), but it can usually move left fine. If I spray it that morning with silicon lube, it’ll sort of work for a while (but I think that’s just lubricated metal rubbing against metal on a broken bearing). The smooth rods have long sharp scratches in them now. Grrr. Because of the style of the i2 ends, the rods are trapped so I can’t replace them without basically removing the entire Z axis to get at the X axis. Maybe I’ll go with printed PLA bushings instead… Anyone have this happen?
In some use cases, especially in high particulate environments, a brass or bronze bushing will drastically outperform ball bearings. This sounds like it might be one of those cases.
I am also having problems with my X ( Prusa i3 )axis moving freely. Manually move it , it sticks abit. I think I need to change the bearing, maybe have faulty LM8UU bearing.
Yea, it happens from time to time. Remember that we usually use cheapest bearings available.
Mine are new Rods & bearings. Need to try changing the bearings
No Mark I’m using A2 steel…
@Jeff_Keegan When you buy tool steel like that from MMC it’s ready to be hardened using a material composition that is to A2 spec for hardening. The material is annealed so it will be somewhat softer than normal steel until it’s hardened.
Look at the product details on the part number and that will tell you any processing done on the steel.
The A2 part # 8116K37 http://www.mcmaster.com/#8116k37/=111n8rb is not yet hardened. The A, W or O prefix lets you know what process is to be used to harden the steel. Air, water or oil. They sell you the raw material for you to cut to the shape you need then you are supposed to harden it with a process appropriate for the grade you purchased.
The hardened part number doesn’t come in a 36" length and is known as “hardened steel shaft” part # 6112K15 http://www.mcmaster.com/#6112k15/=111n6wr
You appear to have annealed steel, bearings will eventually gouge and wear the surface.
Whoa! That’s incredible news! Yo @Richard_Boyd ,I owe you an apology… Thank you for this clarification! I suspect many others have made this same mistake.
I’d say it’s a common misconception or mistake for those not involved in steel materials or machining. The fact they call drill rod “hardening” as opposed to hardened helps with the confusion.
New hardened rods and (grumble) more LM8UU bearings on the way…