Smears on gantry indicitivie of what?

I keep finding used machines with what looks like wear detritus around the gantry bearing blocks and dark smears on the gantry. Are these typical signs of needed maintenance, or signs of more than just neglect? See the attached image. What do you think?

It’s just grease and wipes off easily. The 4x8 I just bought looked just like that. Lets you know that it was lubricated, so I’d take it as a good sign versus a bad


As mentioned, it’s grease from when the linear bearings are lubricated. When the bearings are full, any excess that gets pumped in has to go somewhere, so it generally comes out the side of the wipers on the bearing.

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Are you referring to the greyish vs shiny areas on the aluminum extrusion or the grease marks on the rails? Its hard to tell from the pic but I wouldn’t be worried about what I see in it. If you’re referring to the former, I think that is due to something having cleaned away the oxidation on the aluminum.