just be sure to not let it sit to long, it works well because of the Oxalic acid just don’t leave it on to long or it will discolor the cast iron (which you can remove by reapplying). I use a little bit of water with it and red scotchbrite then clean up all the residue with water and rags and have found orange cleaner/degreaser cleans it up well too.
Yep, just found out how quickly it oxidizes cast iron to a weird green/yellow. I’d say less than 5 mins. I wasn’t sure if I was a dummy for using water as my lubricant. I don’t love the smell of solvents in an enclosed garage. Anyway, it did a bang up job with the scotchbrite pad, ROS, and the powder. I just wiped it clean with mineral spirits and a rag, but I think it will need polished again.
These work for me.
https://www.google.com/search?sxsrf=...sclient=psy-ab
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.
Thanks all for the great replies! Great info. Hope to have more time shortly to answer some replies individually, but here are a few pics of the table condition. Also notice the top of the ways are rusted a bit...bottoms are the same. For the table though, in a nutshell, looks like ?minor? pitting and a ~ 5 to 6 thou wallow in the center. Could easily get a 5 thou feeler gauge under the straightedge, 6 thou had some resistance, 7 nope. Powermatic's manuals for other/similar planers...say the 225 for instance...indicates that one should should set the knives to within 1 thou from end to end on the planer table. "Maximum deviation allowed for good planing is .001 (.025mm)." See 225 manual screenshot below. That'd be tough to do with a table off by 6 thou...yes it's a wallow and the ends of the table are probably at a similar height but this type of stuff irritates me...even if it might not visually impact a good portion of wood/projects that I'd build. The manual says it, and I want it. I'll clean it up as best I can with the advice you all have given, and then decide whether I want to have it reground or planed once I get it all apart.
Cheers,
Devin
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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
Ex-SCM and Felder rep
.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.
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.
Eric, thanks for the reply. Only recently heard about naval jelly. Glad to hear that works for you. And...
"All of my cast iron tables are at least as good and likely better than any of my straight edges that are long enough to span it." <--that's also a good point.
I do have a 48" Starrett straight edge (model 380-48) that claims an accuracy of +/-0.0002 per foot, or +/- 0.0008 over the whole thing with 1.6 thou worst case...but I have no way to measure that with a granite plate or anything. And the square I used to measure the table in a later response is .001 per inch advertised. Anyway, the more responses I get similar to yours, the less and less I'm caring about single-digit thousandths...I just thought why not aim for it if I can since they recommend setting your knives within 1 thou across the table anyway.
Thanks for the reply...and yea point taken about the rust..it'll have to come off no matter what I suppose and then I can assess where the table is at. As of right now when I measure it with the tools I have, it's showing a ~ 6 thou wallow in the center of the table that'll probably be there-to-stay unless I have it resurfaced. I may decide to live with the wallow though, tbd.
Another good point, I guess I'm just trying to control what I can. If I go to the trouble of taking it all apart, might as well try and make the bed all it can be. At any rate, as someone else already mentioned, I suppose the rust has to go no matter what so maybe I'll get aggressive with it