Galvanic corrosion fastener question


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Old 05-19-20, 04:20 PM
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Galvanic corrosion fastener question

I have made a brass hammer head. I was going to attach the handle by drilling and tapping the brass, screw a bolt into the head with some red thread lock then epoxy the bolt into a hole drilled into the wooden handle. I was about to do this until I realized the two different metals may cause a reaction. Could I get away with a 316 stainless bolt or should I use a brass bolt for it. My fear is the brass bolt might bend too easily in the handle of the hammer.
 
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Old 05-20-20, 12:11 AM
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Galvanic corrosion occurs when two dissimilar metals are immersed in a conductive solution and are electrically connected.

Unless your using your hammer underwater your good.

 
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Old 05-20-20, 05:54 AM
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Just look around... dissimilar metals are used together everywhere. Unless you're using your hammer in the ocean corrosion will not be an issue.

Look at how wood handles are attached to hammers. In almost every case you'll see that the wooden handle extends into a big hole/socket in the head. Epoxying a bolt into a hole drilled into a dowel will be much weaker. For more evidence watch some Forged in Fire episodes and you'll see that relying on epoxy to hold a handle rarely ends well.

If you've already got the head threaded you could switch to a meal handle. Instead of wood use aluminum or steel for the handle with a tapped hole in the end. Or you can reverse it and cut male threads on the end of a steel or aluminum handle.
 
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Old 05-20-20, 06:32 AM
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Thanks Marq1 and Pilot Dane,
The hammer is only a small 6oz size 7/8” by 2.5”. It will be used to adjust my hand planes which is why I wanted brass. Will take only very light blows so I’m thinking that the epoxy and bolt in the handle should be fine. If not, I will have to drill out the head and mount a new handle the traditional way.
Ps I love Forged In Fire!
 
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Old 05-20-20, 10:33 AM
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All aircraft use a "dissimilar metals tape" to electrically insulate metals of differing galvanic potential from each other (iaw FAA-E-2968 & MIL-STD-889). Drop by your local municipal airport some time and look at any aluminum-skinned aircraft on the field and inspect a seam where the panels of the skin meet. Every so often you'll see what appears to be bits of scotch tape (but isn't) sticking out from the seam. The exposed bit of tape serves as witness to the fact that there's a steel fastener hidden beneath the skin that has had this dissimilar metals tape applied in compliance with the regs.

OTOH, auto manufactures mix and match metals all the time and don't usually bother insulating them from each other.

Galvanic corrosion can occur just from the moisture in the air, provided it's humid enough and the metals are different enough in electric potential. If it concerns you, plain old electrical tape should do the job nicely, since insulation is one of the tasks it's designed for.
 
 

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