Lawnmower box repair

Was the box not cleaned out well after use? Was it left out in the weather? If this continues, no repair will last very long. Just using ss sheet and not taking care of the remaining steel will just give you a short term repair.

Myself, I would use galvanized steel and use pop rivets, like you plan. But, I would also clean the rust and paint the whole unit, then wash it after each use and store somewhere out of the weather.

Paul

"Christopher Tidy" wrote

This bucket is 0.050" stainless bent to shape by hand:

's strong enough to dig and move sand and rocks.

22 gauge galvanized steel is a lot easier to bend and may be strong enough if supported all around. How thick is the original metal?

jsw

Why metal? Can you get heavy plastic, and put it in with some liquid nails?

Christopher A. Young Learn more about Jesus

.

It's been a while since I visited this group. I have a couple of questions. I have a large steel grassbox from a lawnmower, over 30" wide, that I want to repair. There are some fatigue cracks in the box from vibration, but the larger problem is rust holes in the bottom. I don't have a MIG welder, so I want to repair it using stainless pop rivets (for which I have the right tool).

Clearly the box has been repaired once before, and rusted through a second time, but only in the bottom. Is it a dumb idea to think of trying to repair the bottom with a sheet of 1 mm stainless, for permanence? I have some cobalt drills that will make the holes, but will SS sheet be so stiff that it'll be too hard to bend to shape (right now, I don't have the stainless sheet). Also, is there any advantage to using a thick backing washer with pop rivets, when it comes to the vibration resistance of rivets used in sheet of this thickness, or might it make things worse?

Best wishes,

Chris

Clean it VERY well. Use some galvanized sheet steel to repair the bottom. Rivets will work fine. Now give the box a good coat of paint. Let the paint dry and coat the box with bed liner spray.

As a minor point that may help at some time in the future, stainless is slightly LESS stiff than mild steel -- around 10% less.

What you're asking, though, sounds like a question of how bendable it is, and that's a function of yield strength and work-hardening, not stiffness. Stainless would indeed be harder to bend. When you bend it into a permanent shape, you're dealing with the local yield strength rather than the stiffness.

This bucket is 0.050" stainless bent to shape by hand:

It's strong enough to dig and move sand and rocks.

Nice piece of work, Jim. Why did you put the bucket tipping rams high up? To keep them from getting damaged?

I bought a large piece of shim steel last year. 0.5 mm thick and really hard to cut with tip snips, or to punch with a Greenlee-style screw punch. Ultra tough stuff. Probably it was cold-rolled, but I'd rather avoid that experience in the future!

The original metal, after wire brushing, is measuring pretty much exactly 0.040" thick in the undamaged areas. I can also get galvanised steel in various thicknesses, for a bit less than stainless, although it isn't super cheap. Jim, how did you bend those stainless bucket edges? Clamped the sheet and hammered it over the edge of the bench?

The previous owner of the mower left it outdoors for about 10 years. I don't intend to do the same thing. The box will definitely be painted once repaired.

Thanks for the thoughts.

Chris

-Nice piece of work, Jim. Why did you put the bucket tipping rams high

-up? To keep them from getting damaged?

They are used porta-power type rams from a second-hand store that happened to have just what I needed when I needed it, at $20 for the larger ones and $15 for the smaller. As they are single-acting push cylinders I had to make the linkage to pull on the bucket. I located them as far back as possible to reduce weight on the front wheels and axles. It's a Sears garden tractor, more heavily built than a lawnmower but still barely adequate for this conversion.

-Jim, how did you bend those stainless bucket

-edges? Clamped the sheet and hammered it over the edge of the bench?

Yes. A buddy traded me a scrapped welding table with a steel plate top. IIRC I clamped a piece of 3" channel under the edge as reinforcement and extra inertial mass, the same principle as a dolly or bucking tool. I pounded on a block of wood instead of directly on the sheet to avoid peening it and to extend the force of the blows right up to the bend line so the bent flange stays flat. I think I placed an I beam over the sheet to keep it from bouncing up behind the bend line.

At least I've done all those at some time, if not on this job.

If you sight down the bend you can see and correct the high spots. Increase the bend a little at a time evenly over the whole length. When you reach 90 degrees you can clean up and sharpen the bend over heavy angle iron.

jsw