Corrosion?

pds0006 · Post by **pds0006** » Wed Feb 26, 2014 4:00 pm

What is this I'm seeing? Some king of blemishing in the metal and white deposits in some cases. The blemishes are rough textured; in the picture you can see some of it on the miter lock assembly, left of frame and out of focus.

[ATTACH]24186[/ATTACH]

billmayo · Post by **billmayo** » Wed Feb 26, 2014 4:32 pm

Yes, that is what happens to the aluminum parts when exposed to humid conditions such as barns and outside sheds. Any building that is not heated and cooled can cause the Shopsmith parts to corrode and rust if left there for a long time. I have a few dozen Shopsmiths disassembled that the parts have suffered from these conditions that prevents me from using them. I normally can buy the same used parts for less money than bead blasting, priming and painting the part. I have found bead blasting and an aluminum primer normally helps keep the corrosion from reoccurring. Wire brushing normally cannot get all the areas clean and the corrosion will return in a year or two. I am interested if anyone has a cheaper or better solution to clean these parts.

rpd · Post by **rpd** » Wed Feb 26, 2014 5:08 pm

This looked interesting to me. Soda Blaster Primer

I have bought the gun but have not had occasion to use it yet. Looks like it should be gentle on the base metal.

garys · Post by **garys** » Wed Feb 26, 2014 5:13 pm

It is the aluminum version of rust. I guess oxidation is a better description.

pds0006 · Post by **pds0006** » Wed Feb 26, 2014 5:52 pm

Great. Well I'm going to try and salvage these for now. I don't use the miter gauge much if at all so I'm more concerned with the jointer bar for the fence, the rip fence, and the table. Hopefully I won't be incurring replacement costs and can get it out with some elbow grease/sanding.

I actually bought the soda blaster Cap'n Eddie used and had mixed results on the legs. I'll give it a try on some of this aluminum and let you know how it turns out.

pds0006 · Post by **pds0006** » Sat Mar 01, 2014 6:12 am

The soda blaster was a no-go for me on removing this. The feed is too inconsistent, the hopper is too small (frequent reloads), and I suspect that the baking soda is the wrong media for this. I think that for small parts like the Forstner bit he cleaned up it would work. But given the volume of items I'm dealing with between this oxide and the rest of my rebuild it's underpowered. YMMV though.

dusty · Post by **dusty** » Sat Mar 01, 2014 6:47 am

This will not be a "dip it and dry it" process. Aluminum corrosion is stubborn and most cleaners don't work well because the aluminum is sensitive.

Glass bead blasting might be the best (most effective) but is not readily available to most and can be very expensive if available.

I would try a mixture of white vinegar and lemon juice (two common household acids) and a stainless steel wire brush. If the corrosion has been long term, you will almost certainly have some pitting that probably cannot be eliminated.

If this works, do something to protect the exposed aluminum as soon as possible. I mean - don't wait until tomorrow or you can start all over.

algale · Post by **algale** » Sat Mar 01, 2014 8:49 am

In 1956 my dad was awarded a patent for soldering aluminum that relied on hydrazine flux to remove aluminum oxide. http://www.google.com/patents/US2756497

BuckeyeDennis · Post by **BuckeyeDennis** » Sat Mar 01, 2014 9:03 am

The guy who wrote post #8 of this thread sounds like he knows what he is talking about, and he gives some good information on what NOT to do. But I've never tried the products that recommends.

If it were me, I'd try some Bar Keepers Friend before buying even more chemicals. I have it on hand, and the oxalyic acid in the stuff is reputed to remove aluminum oxide. In fact, you are not supposed to use it on anodized aluminum, for exactly that reason.