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I would love some guidance on how to remove the mandrel from my Columbia Type N. I'm guessing it's clotted with lots of century-old oil because it doesn't spin very freely. There is a set screw, which I've loosened, but the mandrel still insists on holding on tight. I don't want to force things until I understand the nature of the connection. Is it just old oil and grease gluing things together, or is there another mechanism for releasing the mandrel? (See picture)

Thank you!

I believe you'll need to remove the end cover. There will likely be a nut to remove from the mandrel shaft. It may also be possible that the nut will be a left hand thread. (I say "believe", "likely" and "possible" because I have not personally disassembled an N. )

JerryVan wrote: Mon Mar 24, 2025 5:53 pm I believe you'll need to remove the end cover. There will likely be a nut to remove from the mandrel shaft. It may also be possible that the nut will be a left hand thread. (I say "believe", "likely" and "possible" because I have not personally disassembled an N. )

Ahh.... I was worried that i'd have to remove the end cover. I tried that once already by removing the small screws--and that, too, didn't want to budge. I stopped because I didn't want to crack or break it. It looks like there are also two pins that help hold the end plate in place. They're visible on the other side of the casting as well.

I'm considering removing the screws again and gently tapping a thin, clean taping knife into the seam at intervals around the perimeter to see if I can gently and evenly separate the plate from the rest of the casting.

Or, if people recommend against that course of action, I won't! I really, really don't want to damage this machine, which has come to me in such fine cosmetic condition.

Maybe someone who has actually worked on an N can chime in before you trust my intuition . That end cover casting looks fragile.

JerryVan wrote: Mon Mar 24, 2025 7:43 pm Maybe someone who has actually worked on an N can chime in before you trust my intuition . That end cover casting looks fragile.

Thanks! I'll stay tuned. It does look fragile, so I'm very cautious about moving forward.

In the meanwhile, have you tried putting some oil in the two oil holes I see in the end cover?

JerryVan wrote: Mon Mar 24, 2025 7:54 pm In the meanwhile, have yuou tried putting some oil in the two oil holes I see in the end cover?

Not yet! I might give each a tiny shot of WD40 and let it sit for a few days before trying again... very cautiously.

wd40 contains fish oil that corrodes eats into parts over time, I have found that a better alternative is ballistol bore cleaner.

Morell1 wrote: Mon Mar 24, 2025 9:56 pm

JerryVan wrote: Mon Mar 24, 2025 7:54 pm In the meanwhile, have yuou tried putting some oil in the two oil holes I see in the end cover?

Not yet! I might give each a tiny shot of WD40 and let it sit for a few days before trying again... very cautiously.

WD-40 is a poorly-refined fish oil in a naphtha carrier. It is NOT a lubricant, I repeat it is NOT a lubricant. It is a rust-preventer. After the naphtha rapidly evaporates, the fish oil oxidizes and becomes gummy. Not what you want.

WD-40 does not contain fish oil. It is used to "displace water", hence WD. It was the 40th try of chemicals.

Useful to help remove items, but not useful as a long-term lubricant. Lots of information on-line from the WD-40 website.

Marc