Rust Removal from Precision Cast Iron Surfaces in 2020: techniques and when to stop

[Devin Brenan]

Razor blade, scotch brite on a cup wheel of an angle grinder. Don’t overthink it.

"Don't overthink it" <--story of my life.


Cup wheel of an angle grinder---assuming there's a hook-and-loop or similar way of attaching the pad? I have a dewalt buffer with a hook and loop wheel but it wouldn't be as fast.

[Devin Brenan]

Barkeepers friend and scotchbrite

That's a 1st for Barkeepers friend...at least that I've heard as a newbie to this. Thanks.

[Devin Brenan]

Cleaned up the column on an old drill press with a Scotchbrite pad and WD-40 with no problem. Same with some light rust on a table top of a Unisaw I restored.
There are other commercial rust removal products out there for the heavy stuff. Naval Jelly is good but leaves a funny looking protective residue which I don't like.
The least invasive the better; hand power only for the light stuff. Wire wheels in a grinder for the heavy stuff.

Nice, thank you. Do you just clean off the WD-40 with mineral spirits or similar when you're done? A few folks said they favor Naval Jelly, but I'll be on the lookout for residue if I go that route.

[Devin Brenan]

My reconditioned 8” jointer has pitting of the table surface, as well as dings in the tapered metal pieces at the opening. They are a lighter shade of gray than the tables, but don’t seem as soft as aluminum. They’re no longer available, but a shop could surely fabricate those, couldn’t they?

How do you find somebody who can do that work, and do it well? When I’ve called machine shops, (a hobbyist, not a pro) my amateur way of describing what I need either confuses the guy, or convinces him that he’d be wasting his time.

How do you choose a shop, then describe resurfacing a jointer surface? What’s a fair price?

I read an article or two about this over on the vintage machinery site. They have a wiki section. Look for sections 2.8 Jointers & Planers (Grinding Jointer Tables) and 2.11 Restoration Tips ( Flattening Cast Iron Surfaces)

[Devin Brenan]

Soda blasting does not harm the base material at all. It removes rust and other crud and leaves a light dust on the surface.

I'll have to look that up...is that just similar to sand blasting...same basic process but with a different media? Thanks for the reply.

[Devin Brenan]

ROS with grit to match the work required. Better to get thru it in a few minutes than to go very slowly and spend a long time. The faster approach will encourage you to finish all the surface the same rather than focus on the bad spot.

No fear

I think I'm going to try this on *something*..maybe not this planer bed this time around if I choose not to resurface it...but if I do choose to resurface it, think I'm gonna experiment first. And a 'throw caution to the wind' approach with a ROS is a popular vote.

[Devin Brenan]

You would have to do some serious rust/base metal removal to make a difference in flatness measurable by any normal tools in your shop. I doubt you would remove even a few thousandths unless you wanted to remove all traces of serious pitting..

You are in agreement with a LOT of others, and there must be a reason for that..probably truth. I'm still looking to verify that the volume/thickness of surface rust is 100 times thicker than the iron layer needed to create it. It would make a lot of sense base on everyone's experiences with maintaining acceptable flatness after abrasives.

[Devin Brenan]

These work for me.
https://www.google.com/search?sxsrf=...sclient=psy-ab

Thanks for the reply. These wire wheels would be a more aggressive approach, but hey if it works for you, it works. And I guess you could use softer-metal wheels if need be as well..doesn't have to be steel.

[Devin Brenan]

I also use wire brushes, like Lowell's Google link, wipe with mineral spirits, and wax. The wires aren't as hard as the tables, so only the rust is removed.

Mike thanks for the reply. Yea I thought about the wire-hardness as I was responding to Lowell's link; if you choose a softer metal that the table that should work. Sounds like you've done it before anyway, so another good way to go about it.

[Devin Brenan]

Devin. I've seen a lot worse. If I were you, I would scotchbrite that table to give it some "grain", wax thoroughly with johnson's paste wax, then run some boards through it. See what it does before you make any decisions. Pulling the table and having it machined should be a last resort.

Erik

Erik thanks for the reply (and the earlier replies too). I was planning on taking it all apart anyway and replacing the head (with byrd or hermance) but thought it'd be 'fun' (and maybe even good-enough at the end) to see what happens after cleaning the table up. Was just unsure how I wanted to go about it, so I thought I'd solicit some opinions here. A lot of great advice, and it seems there are many ways to go about this and get good results. I'll just have to pick one to try first for the bed. Think I'm gonna go the Evaporust route for all the small parts. I will post more pics once I clean up the bed as best I can, and then I'll decide if I'm gonna have the bed resurfaced. Figure I could probably find a machine shop in the LA area that will do it. Would like to plane it, old-school style, if I go that route.

[Devin Brenan]

.006" would bug me, especially if i went through the hassle of repainting the machine, replacing other parts, and general cleanup. However, Erik is right, that level of dip really wont make a difference. That is a little less than 1/128", which is pretty slight if it transmits to the surface and thickness of a board. With that said, if you are already pulling the table, then i would be very hard pressed to not have the top reground. As an example, i havent dug into my Martin T17, but i know the bevel sprocket is missing a tooth. It doesnt affect the chain mechanism and beveling the blade, but its hard for me to leave that broken part in place knowing im going to spend 20-30 hours on this thing and another couple hundred bucks.

Bugs me too, and I only sorta know what I'm doing off advice from others and assuming things. No restoration experience.

Yea that missing tooth on the sprocket would keep me up at night ...well maybe just irk me.

As far as the planer bed, I'm the type of person where if I see that same wallow transferred to my freshly-planed boards, it's gonna be unsat...especially like you said if I've already taken the whole thing apart.

Thanks for the replies.

[Devin Brenan]

You really need to redefine precision. You are just talking the ground surfaces that the wood moves over. i thought you meant the sliding surfaces. I do not think I have ever heard of a wood machine having scraped in surfaces like many metal working machines will have. Any thing around 1/1000 is plenty good for wood working.
Bil lD.

Oh I see what you're saying...you mean the table alignment ways on the front and back that are machined into the casting. Yea I want those flat too...but I figured the table would be more important? No?

And I was just aiming to be able to measure and setup the machine to what the manual stated, if I could. It said 0.001 from knives-to-bed as measured across the bed as a reference, so that's what I was aiming for.

And appreciate the replies, thank you.

[Bill Dufour]

I read years ago that. height difference of 1/1000" is the point at which the human eye can spot a step in a wood tabletop before finishing. Not using a ruler or anything, just looking at an angle in decent lighting.
Bil lD

[Alan Lightstone]

I read years ago that. height difference of 1/1000" is the point at which the human eye can spot a step in a wood tabletop before finishing. Not using a ruler or anything, just looking at an angle in decent lighting.
Bil lD

Bill, I'll be blown away if that is true. Will make me rethink every piece I've ever made.

[Brian Holcombe]

I worked in an automotive machine shop, many times we were required to resurface parts becuase the mechanic took a scotchbrite wheel to a machined surface to clean off a gasket.

So if you think you aren’t affecting your table, you are wrong.

A light touch with scotchbrite (by hand!) with light oil as a lubricant.

I don’t see the logic in wrecking a surface to make it pretty, I’d rather have it ugly and flat.