Mechanical help?

[Dan Forman]

In the course fo doing some maintenance on my MiniMax 14" jointer/planer, I discovered that there was rust both on the cutterhead bearings, as well as the cast iron block that houses them. What was once a fairly simple task, removing the head, became very difficult, as the bearings were essentially frozen into the block. With some persuasion from a wooden mallet, they eventually seperated.

Of course this had to happen on the weekend when I can't call MM, so I'm asking here.

I think I'll have the bearings replaced, as the outer surface looks kind of groaty. Here is a pic after it was cleaned up.


I took a bit of 1500 grit sandpaper to the cast iron block the bearings seat in, but didn't want to disturb the fit, so just went lightly. There isn't any pitting, but it didn't clean up entirely.

I still have the old Tersa head, with it's own bearings intact, so I think I'll put that back until I can get this sorted out.

My two main questions are: Why did this happen?, and how can I prevent it from happening again?

Should I have greased the cavities before intalling the new head?

Do I have to remove all of the rust on the block to keep it from coming back, and if so, how, without creating a loose fit?

Any advice will be greatly appreciated.

Dan

[Bob Genovesi]

Dan,

Looks like some moisture might have caused the light rust, humidity also can cause this. It looks very light so I don't think there's anything to worry about.

After a thorough cleaning I'd reassemble it and put a light coating of grease or Never Seize. These lubricants will protect the surfaces for a long period of time against any changes in humidity preventing the rust from returning.

I don't think a light oil is suitable as it may evaporate over time as well.

[Mike Marcade]

I would try a coat of this on those surfaces.



Humidity is most likely your enemy here. Honestly though, I don't know that I would be too worried about the surface rust on the outside of the bearing as long as the fit between the bearing block and the outer race is good.

[josh bjork]

the outside of a bearing means very little. if it was too shiny that would be another matter.

[Dan Forman]

Thanks, looks like a good cleaning of the outside surfaces with mineral spirits followed by a touch of grease should do the trick. I don't know how moisture would have gotten in there, I don't have a problem with rust on any of my other tools, except in relation to fingerprints, and the shop generally stays below 50% humidity. I wonder if I contaminated the surfaces when I was changing out the cutter head earlier. That would be my guess.

Dan

[Bruce Page]

I wonder if I contaminated the surfaces when I was changing out the cutter head earlier. That would be my guess.

Dan

That would be my guess.
If the sealed bearings rotate freely then I wouldn’t worry about it. Apply a thin film of white lithium grease to the journals and bearing surfaces and reinstall.