Reflooring dump bed

[Franz©]

First consideration in dump boxes in my mind is what's the truck carrying and hw is it loaded.
A hopper loading sand or dirt is pretty easy on the floor, a loader or shovel dropping rock is a much nastier insult to the floor. That floor looks like a base drum head as the load hits it.
Back when Sewer Ontario started overtopping to make politicians happy thousands of loads of blast rock from quarries started riding to the lake in trucks with old bodies put back on. Patched floor don't mean much to a rock 5 feet in every dimension. Rocks poked thru the floor, add another patch. One genius found some road plate and wanted it on his floor. My bud Sam was out of work welding pipe, so he welded the plate in just like the owner wanted after the old floor and patches were cut out. Sam did it by the book and to the owner's expectation.

That owner was a proud peacock when them 3 rocks didn't even wow that floor. He got to the Lake and backed in, and when he hit the lever that body full of rock just sat still. Seems a telescopic cylinder in a doghouse has a capacity limit when it comes to lifting. Rocks pulled off fine with a dozer and chain, and when he hit the scale at the quarry he found out the truck was near capacity with all that plate.

Floor of a dump has to be elastic to a degree, packer is rigid because it functions differently. Sanitary dumps and boxes are complete nightmares.

I'm not sure AR-450 is the right alloy for a truck floor that will be in general use. Unless it's fully welded at edges and plug welded to crossmembers sufficiently to keep the assembly monolithic, it's going to crack in my opinion. The abrasion resistant sounds good to the owner, but he'd probably be better served with poly.

Rule #2, the job is paid in full before the truck leaves the welding shop.

[Noel]

Maybe Zig can post a picture and we can see what he's up against?

[Zig]

Hey guys again thanks for the replies. I like talking to likeminded folks about things I enjoy doing. So I haven’t laid eyes on the truck yet I’m going to assume it’s beat down between the crossmembers and not very flat anywhere. In my research so far it looks like several companies build dump bodies out of ar450 steel and since that’s what he ordered I guess that’s what’s going in there. I think my strategy is going to be a light preheat depending on outdoor temp it’s 25 degrees this morning going to be in the 70’s tomorrow with all the seams welded solid and plug welded on the crossmembers.

[ryanjones2150]

Sounds like you have a solid game plan. Got a brand new can of 7018 or coming out of a stabilizer?

If you’re going to over lay it, you can consider the added weight of the new steel. I’m not sure how much more ar450 weighs over mild steel, but the equation for mild steel is weight/sq. Ft.=40.8(plate thickness). So in your case:

7.65 lbs/sq. ft=40.8(.1875)

Not counting the weld alloy of course. So it’s not a terrible addition of weight to the overall capacity of the truck.

25 degrees huh? It was down to the 50s here the other day, then it went back up to almost 80, now it’s back in the 50s again. I need 65 in the shop for my lathe project...that paint doesn’t like being chilly.

[Franz©]

28 and white crap laying all over the green crap I was planning to chop here.

I'd be explaining to that fellow how the entire truck body needs to be at minimally 70° without any wind for proper welding.
I got rid of a lot of do me a favor snow plow work years ago by adding that requirement, and may have postponed my close relationship with Art Ritus.

[Zig]

I’ve got a couple of fresh 10 lb cans of Excalibur’s I’ll pick up a couple of more before his steel comes in I’m sure its going to eat some rods

[ryanjones2150]

I like that rod. Good luck my friend! Snap a couple pictures of the before and after if you remember to. I generally forget or don’t feel like it, but it’s cool when you can.

[MMW]

Have fun with stick. Mig is the way to go, either dual shield or inner shield. Stick will work but it is slower and harder to fill gaps. If it's pretty beat up you are going to have gaps to fill and ar doesn't let you beat it down to match the dents. Any seams you should over lap a little bit, don't try to butt weld. Start at the back and work forward so the over lap is a drop down instead of a step up for the material to slide out easier. Get some 1/4" and 3/8" mild steel round bar to help fill any gaps. Make sure you have it all tacked well before welding full. I would just warm it up enough to remove the moisture, you will see it go away, does not take much. I use Hobart 21b inner shield and have never had an issue. Dual shield is fine also or as you said 7018. I have done many garbage trucks with 1/4" AR plate. If you can find spots on the floor where it sits flat in the center of the sheets cut some 1" or so holes to plug weld it also. This helps a ton. If the floor is flat I will usually burn holes every 24" to plug weld. If it is not flat then where ever you can find a spot to do it, usually where the cross members are. Last item is try to get it pushed down as tight as you can. A piece of tubing clamped on top of each side wall allows you to use a jack or porta power to push it down. Good luck.

Edit--- I would only warm it up in temps below freezing.

[ryanjones2150]

I was hoping you’d chime in. I recall from previous threads that this is in your wheel house. And I figured those garbage truck tubs were some sort of AR plate. I can go on living well enough if I never have to climb inside another garbage truck again to be honest.

There ya go Zig.

[Zig]

Thanks for the reply mmw. I’m going to have to stick weld that’s all I’m set up for. What is the reasoning on not butt welding? I’m guessing because you most likely won’t be able to make a flat seam with the beat up bed

[MMW]

Main issue is time/money but it just makes it easier. Nothing has to fit perfectly, you will have a much easier time fitting because you have wiggle room on the sheets. No gap to big or to tight. A little out of square, no problem. Lap welds are much easier than butt welds. You also get a little extra strength as that over lap area is now twice as thick, even if it is only a 1/2" or so over lap. Welds will be much more consistent, again because no irregular gap. Speed because you can run probably one size bigger rod without worrying about burn through. I usually shoot for a 1/2" to 1" over lap.

Let me know what kind of truck you are doing? I will reply with some tips depending what it is. I'm thinking single axle dump, 10 foot body? 3/16" is a little thin for a tandem or tri axle in my opinion but the customer is always right. Also is floor kind of flat or really hammered? Do you have a machine to lift the sheets or are you muscling them around?

[MMW]

If the floor is hammered you will probably wind up with the edge of a sheet hanging in mid air because the floor is pounded down. Bring various thickness of flat bar with you to fill gaps. You can stack them if needed as long as you weld them good. You don't want to try and bend the new sheet to match so I just fill the gap in spots so I can support it some and attach it to the old floor. The goal is to keep the new floor flat as you can so the material slides out like it should. You do not need to fill the whole gap just in spots. Nobody sees it anyway as it is covered over by the next sheet. If you are starting at the back with full width sheets and no center seam then I will full weld the sides and the exposed (towards back) seam while only stitch welding the seam that will get over lapped. Then when you lay the next sheet, same thing and just work your way forward. If you are going to have a center seam then I usually just over lap whatever it winds up in the middle. For instance if the floor is 84" and you have 48" sheets then I just lay them in and you have about 12" over lap. Saves time by not stripping one sheet and it is usually scrap anyway. None of my customers care how it gets done as long as it works and looks nice.

Just my advice. Your customer may want different.

[snoeproe]

I’ve done quite a few dump box floors. The most wear is always at the back. The old floor is the thinnest in this area.
I’ve used AR 200 and AR 400 for the floor. Usually 3/16” thick.
I always carbon arc aired out the old floor. My local steel supplier keeps large sheets in stock to do a dump box floor in one piece. As long as you have the means to handle a piece this large.
When removing the old floor with carbon arc air, you must be aware of air lines and wiring etc that are under the box.
Generaly, all I’ve used to weld the new floor back in is .035 70s-6 mig. It’s only 3/16” thick. No reason to use duel shield and no reason to preheat anything. Never had any issues with anything.

[ryanjones2150]

I bet wrestling around with a sheet that size is fun.

[snoeproe]

Lifting lugs and an overhead crane or an excavator come in handy. Doing it with one large piece greatly speeds up the job. A lot less welding is required.
Nothing wrong with doing it with multiple 4x8 pieces. Just takes longer.