Multi-Metal Rust Risk? Should I just weld this sucker?

[keith204]

I'm welding together a bolt-on receiver & hook widget for my box blade. This began as a willy-nilly project, and as such I planned on it being bolt-on in case it didn't work out as expected. (of course, I'd paint it first.)

But, today's research binge indicates dissimilar metals create electro-something rust risk. And, you can see from the photos below, I'm hodge-podging many dissimilar metals.

Should I just sand the BB, cut off the bolt-age, & weld the sucker on? Or is the rust-risk a moot point?

I suppose now that I see the pic, welding is prob ideal so I can chop off the water-collecting angle iron.

Any other unsolicited advice is welcome too.

 

[hodge]

Dissimilar metals will react and corrode whether painted or not. However, that's between, for instance, steel and aluminum. I don't see any issues with the materials that you're using.

 

[lynnmor]

Your metals are similar, I wouldn't worry about rust after a good paint job. Plated hardware has been used for a century on steel with no real issue. Dis-similar metals would be aluminum, copper, brass and some more.

 

[06B3030]

It's all steel...for something like this I'd just fire up my MIG and go to town!!!!

 

[keith204]

Clarification: I wouldn’t paint the fasteners.

Am I being senseless for using fasteners in the first place?

 

[06B3030]

Clarification: I wouldn’t paint the fasteners.

Am I being senseless for using fasteners in the first place?

I'd weld up the "assembly", and then bolt it on like you're doing.

I just made a mounting plate for a winch and bolted it to the front of the tractor. I prefer to be able to take things on and off!

 

[North Idaho Wolfman]

You should be fine, no extra special rust factors that I can see.

 

[D2Cat]

You can analyze until you're paralyzed. Just nail it and be done!

 

[keith204]

You can analyze until you're paralyzed. Just nail it and be done!

Good point.

In fact, I’ll start by bolting on the assembly to make sure I like it first.

If I like it, I’ll paint and bolt.
If I love it, I’ll paint and weld. Edit: weld & paint!

 

[NCL4701]

The problem you allude to is called galvanic corrosion. This is a swell article on it.

Galvanic Reaction: Incompatible Metals Responsible for Corrosion

During a maintenance check in the 1980s, workers discovered that the Statue of Liberty had a serious structural issue: the statue’s internal wrought iron support system was rusting over because the insulating layer of shellac between the iron and copper had failed and allowed for galvanic...

www.monarchmetal.com

One reason I say it’s swell is because if you scroll down a bit there’s a chart for dummies like me that lists out types of metal that go together with no issues and metals that have galvanic interaction to increase corrosion rates. Back when I was in college I could explain the chemistry behind it, but now I just look at the pretty colors on the chart and I don’t use steel nails to attach copper flashing on roofs.

As others have stated your project’s life expectancy doesn’t appear to be in peril from galvanic corrosion.

 

[KKBL]

Good point.

In fact, I’ll start by bolting on the assembly to make sure I like it first.

If I like it, I’ll paint and bolt.
If I love it, I’ll paint and weld.

If you love it and want it welded, that really should be done BEFORE painting the components.

 

[keith204]

If you love it and want it welded, that really should be done BEFORE painting the components.

Bah. Good point. I worded that wrong..

 

[KKBL]

Bah. Good point. I worded that wrong..

Your fabrication skills look great. Best way to prevent corrosion on steel parts is 95% cleaning and prepping everything - especially the welded areas. Primer and tractor / implement paint, or a polyester based powder coating will keep it looking good for years.

 

[GrizBota]

As others have suggested, I’d weld it, paint it, bolt it wouldn’t have a second thought about it.

Not that you asked but the two bolts at the end, myself I’d put them in a full diameter hole with a good 1 to 1.5 bolt diameters (with about 1/2 or 3/4 inch minimum) clear of the end. But sure what you’ve got going will work fine too.

You’ve recognized the water collection potential of the inverted angle. You might consider drilling a couple 1/4 inch drainage holes, one each at the third points of the length.

The most important aspect is you are fabbing your own custom stuff. Props for that!

 

[keith204]

As others have suggested, I’d weld it, paint it, bolt it wouldn’t have a second thought about it.

Not that you asked but the two bolts at the end, myself I’d put them in a full diameter hole with a good 1 to 1.5 bolt diameters (with about 1/2 or 3/4 inch minimum) clear of the end. But sure what you’ve got going will work fine too.

You’ve recognized the water collection potential of the inverted angle. You might consider drilling a couple 1/4 inch drainage holes, one each at the third points of the length.

The most important aspect is you are fabbing your own custom stuff. Props for that!

Those 2 holes at the end are driving my OCD self bananas. They are to match the existing holes in the BB, and I had to cut them short to avoid hitting the welds on the BB. Er....I think I could have cut them so a sliver of metal was on the outside of the hole, but that felt silly, so I cut them even silly-er.

Good attention to detail - always call me out on this stuff. Also, good ideas on the drain holes. I'll do that!

 

[keith204]

Your fabrication skills look great.

A. I only showed you the good side. . The under-side's pretty porous.
B. After tigging that good-side, I skipped around the garage like a toddler who just hit a lucky hole-in-one at a putt-putt course. I don't know exactly why it worked, but I'm dang proud.

 

[keith204]

I'd weld up the "assembly", and then bolt it on like you're doing.

I just made a mounting plate for a winch and bolted it to the front of the tractor. I prefer to be able to take things on and off!

View attachment 111375

View attachment 111376

Ah yes, I spotted you & this project on a secondary binge today! Nice work and good point. Did you flux mig that?

 

[GrizBota]

Those 2 holes at the end are driving my OCD self bananas. They are to match the existing holes in the BB, and I had to cut them short to avoid hitting the welds on the BB. Er....I think I could have cut them so a sliver of metal was on the outside of the hole, but that felt silly, so I cut them even silly-er.

Good attention to detail - always call me out on this stuff. Also, good ideas on the drain holes. I'll do that!

Attention to detail, I think we both probably know it can be a blessing and a curse.

Putting a hole a couple inches inboard of the existing hole in the back blade at the ends of your bracket would probably be a fair bit stronger than what you’ve got planned. That said, what you’ve got planned should work for all but the most extreme uneven pull on the weld on hooks. I too try to avoid cutting on my equipment, but in the interest of a stronger design, sometimes it’s the way to go. But it’s all good, nothing you can’t modify later if you think there’s a need later.

 

[keith204]

Attention to detail, I think we both probably know it can be a blessing and a curse.

Putting a hole a couple inches inboard of the existing hole in the back blade at the ends of your bracket would probably be a fair bit stronger than what you’ve got planned. That said, what you’ve got planned should work for all but the most extreme uneven pull on the weld on hooks. I too try to avoid cutting on my equipment, but in the interest of a stronger design, sometimes it’s the way to go. But it’s all good, nothing you can’t modify later if you think there’s a need later.

this may be a good argument for welding instead of bolting. Maybe I can add some stabilizer arms of C channel off to the back.

At least what I think you’re saying is that there may be a problem with forward to backward rotational forces, or whatever the engineers call that.

 

[GrizBota]

this may be a good argument for welding instead of bolting. Maybe I can add some stabilizer arms of C channel off to the back.

At least what I think you’re saying is that there may be a problem with forward to backward rotational forces, or whatever the engineers call that.

Bending moments, shear forces, yada yada.

Looks like you know the conceptual considerations and trade offs. Be sure to share some pictures of what you end up with.