Which Shim Stock

[4GSR]

OK guys, we got a crash course on Galvanic corrosion or erosion as it is in most cases, here. Let's get back to basics. We are talking about a tailstock the OP wants to shim up to get it back on center. And this is a lathe. In all of the years I've worked on tailstocks where shim stock or equivalent was used, I have never see any significant evidence of corrosion or erosion. Now what I have seen is discoloration in the shims used, and it didn't matter if it was brass or steel. Of course, everything was covered with crud and old oil. As long as all the components are covered with a oil film of sorts, galvanic activity should not happen or exists.

Now, where I have seen it is on a lathe bed where people let the coolant rancid chips pile up on the bed for weeks or months at a time. Water being the electric current and the chips being the electrodes, it will etch the bed. I have evidence of that.

Anyways, enough of my ranting for now.

 

[John Hasler]

i guarantee if you were to try to remove an untreated SS bolt from your trailer, it would soon break

I took one out and looked at it this afternoon. It's fine. Of course, the bolts are not threaded into the aluminum: they are bolted through it. They are in direct contact with the aluminum but are only exposed intermittently to rainwater, not constantly immersed in meat juice and cleaning solutions. There are no steel fasteners exposed on the upper surface of the aluminum deck where they would be exposed to manure and urine. There are welds and some show signs of intergranular corrosion.