rear bumper

[MTNGUN]

* * * warning, many pictures spread over several posts * * *

The stamped sheet metal bumper (seen sitting on top of the bed) that came with my old truck did not survive the winter. Between pulling trucks out of snow drifts, and others trucks pulling me out of snow drifts, the bumper was mangled.
http://i487.photobucket.com/albums/rr235/mountainmolds/new_old.jpg

The old rustbucket is used primarily for snowplowing and woodcutting. It rarely sees pavement. It is a workhorse. The new bumper didn't need to be ultra stylish, but it needed to be hell for stout.

The goal was to build a bumper that would be compatible with pulling/being pulled when someone is stuck. Compatible with a hi-lift farm jack. Part of of sturdy receiver hitch. And, not cost too much or weigh too much.

Instead of using channel, tubing, or pipe, I decided to make it out of 1/4" plate, because I needed to buy a sheet of plate for a couple of other projects, and there would be enough plate left over to make the bumper. Using plate would take longer and require more cutting and welding, but that was OK, because I needed the practice.

The frames on these old trucks are not particularly stout, so I beefed up the frame with some of the 1/4" plate, running it as far back as practical. The plate was welded to the frame with a root pass of 3/32" 6010 followed by 1/8" 7018, using a Hobard AC/DC Stickmate.
http://i487.photobucket.com/albums/rr235/mountainmolds/plate.jpg

A piece of 3" x 3" x 1/4" angle from the salvage collection tied the frame rails together. Originally, I was planning to have the new bumper bolt on. I wanted some way to assemble and tack weld the bumper with it sitting on the truck, but then be able to take it off to finish welding and painting.
http://i487.photobucket.com/albums/rr235/mountainmolds/angle.jpg

Three pieces of scrap were tacked on to serve as a temporary platform for the new bumper.
http://i487.photobucket.com/albums/rr235/mountainmolds/temp_supports.jpg

[MTNGUN]

The bumper was gradually assembled and tacked in place, designing it as I went along. My floor is not particularly level, the truck bed is not too straight, and even the frame was a little tweaked, so it was a bit a guessing game to keep the bumper straight and level.
http://i487.photobucket.com/albums/rr235/mountainmolds/tacking.jpg

I basically formed the 1/4" plate into a C-channel. It would have been faster to make it out of C-channel, but then I wouldn't have got as much practice cutting and welding.
http://i487.photobucket.com/albums/rr235/mountainmolds/tacking_top.jpg

Since this is the HSM forum, we musn't overlook the machining aspects of this project. Here a hole is being drilled in what will be a receiver hitch thingy that will stick out the passenger side. The side receiver is for a side rack that will enable the truck to carry 20 foot sticks of metal. The side rack is a future project so I have no pictures of it to show you now.
http://i487.photobucket.com/albums/rr235/mountainmolds/bumper_drilling.jpg

A couple of 1 1/8" holes were required, one for a license plate light and another for a trailer wiring receptacle. I have a 1 1/8" hole saw -- but I couldn't remember where I put it. The mill and a boring head saved the day.
http://i487.photobucket.com/albums/rr235/mountainmolds/boring.jpg

[MTNGUN]

Tapping the holes for attaching the trailer receptacle.
http://i487.photobucket.com/albums/rr235/mountainmolds/tapping.jpg

After tacking the bumper together, it was removed from the truck and placed on sawhorses for final welding. On the highly stressed joints, a root pass was made with 6010 or 6011 before capping with 7018. But most of the joints would not be highly stressed, plus they were getting welding on both sides, so I omitted the root pass on those less stressed joints.

Most of the welding was done with 5/32" 7018, using 155 - 160 amps DC. This exceeded the duty cycle of the Hobart Stickmate, but it didn't seem to mind, in fact, it welded nicely on DC. I experimented with welding on AC, but even after cranking the amps to the maximum 225, it was still struggling to keep the 5/32" lit. Maybe it was just me, but the Stickmate felt like it maxed out at 150 amps AC output no matter what the indicator said. I gave up and switched back to DC.

Here is an inside corner. Not perfect, but OK.
http://i487.photobucket.com/albums/rr235/mountainmolds/inside_corner_weld.jpg

Here is an outside corner, welded laying flat, done late at night, past my bedtime. I was running the bead as faster than normal, aiming for maximum speed rather than maximum strength, because this was not a highly stressed joint. That's my excuse, anyway.
http://i487.photobucket.com/albums/rr235/mountainmolds/flat_weld.jpg

After several evening's work, the bumper has been painted and is ready to attach. Somewhere along the way, I exercised my right to change my mind, and decided to attach the bumper by welding instead of bolting. In hindsight, I would have designed it a little differently to make it easier to weld on, but, that's OK, I made it work.
http://i487.photobucket.com/albums/rr235/mountainmolds/painted.jpg

[MTNGUN]

Looking up at the bottom of the bumper. This bead was welded directly overhead while laying underneath the truck. Did I mention that I have no PPE for welding ? No jacket, no sleeves, no neck protection ? It's challenging to hold the rod steady when you are on fire. But that's OK, it builds character.

Seriously, this is not the best overhead weld I've ever seen, but it's not too terrible. 1/8" 7018 at 115 amps, using a small circular pattern, on top of a 6011 root.
http://i487.photobucket.com/albums/rr235/mountainmolds/overhead.jpg

After all the welding was done, the paint was touched up, and I'm kinda proud of my bumper. One of the locals strolled by to take a look.
http://i487.photobucket.com/albums/rr235/mountainmolds/deer_bumper.jpg

[doctor demo]

I realy like the provisions for the side rack future thingy. What is the little window above the rcvr. for?

Steve

[hardtail]

007 revolving plates???????.........LOL

News will travel through the deer world.......he forges with fire, watchout for the firestick..........

Seriously nice job, not exactly sure how bulletproof 1/4" will be but it's gotta be waaaaaay better than the original, given thats lasted 30 years.....I like your rings........tough to post your welds on a www forum, expsoses your vulnerability........you weren't taking pics of your best welds just here it is........or grinding to perfection. I'm no welding expert but save for some tig work who would ever want to weld AC anyway?????? I do have respect for those that can and did........

Nice job and post........great dialogue and pix.........

[wmgeorge]

007 revolving plates???????.........LOL

News will travel through the deer world.......he forges with fire, watchout for the firestick..........

Seriously nice job, not exactly sure how bulletproof 1/4" will be but it's gotta be waaaaaay better than the original, given thats lasted 30 years.....I like your rings........tough to post your welds on a www forum, expsoses your vulnerability........you weren't taking pics of your best welds just here it is........or grinding to perfection. I'm no welding expert but save for some tig work who would ever want to weld AC anyway?????? I do have respect for those that can and did........

Nice job and post........great dialogue and pix.........

Great job. Anyone can do a nice job of welding on the bench, sitting down of course and maybe using both hands on the stinger. But you and I both know those stick welds are going to hold, even if they look a little.... not perfect. I built a small backhoe, and both my boys who are good welders poo pooed some of my welds.

Not a one weld has broke so far, and the one son used it for three weeks before I got a chance to use the darn thing!

Thanks for posting!!

[MTNGUN]

I realy like the provisions for the side rack future thingy. What is the little window above the rcvr. for?
Steve
The "little window" is now covered by the license plate. Since it is covered up and since it is not highly stressed (that section of the bumper is welded to the 3" angle, so it is well supported), there didn't seem to be any point in filling that space with 1/4". In fact, the upper portion of that window uses some 1/8" scrap, since all it does is hold the license plate.

Sure, I had the metal available, but there was no point making the bumper any heavier than necessary. Getting back to my original goals -- strong enough for pulling, strong enough for jacking, and strong enough for a hitch. I made it beefy where it mattered and not so much elsewhere.

The old sheet metal bumper and mounts weighed about 100 pounds. I'm guessing the new bumper weighs 150 pounds, plus 20 - 30 pounds was used to beef up the frame. That's a reasonable trade-off. I didn't want to end up with a 300 pound bumper.


But you and I both know those stick welds are going to hold, even if they look a little.... not perfect I try my best, but I've been trying for 25 years, and it's become obvious that I don't have the eyesight or the coordination to be a pro welder. I still enjoy welding, though. I'm still learning and improving in small ways.

[hardtail]

Many people will have never known all those autos in which a bumper jack did the trick, can't think of the last year I'd try it on now.........nice goal to design for.

I'm glad I learned to run a bead before my eyes changed (or at least I thought so......LOL).....just maybe old habits will pull me through.......george you have very valid points on position.......I still have difficulty on vertical and O/H.........

[JS]

nice job............

[Frank Downey]

very nice job.I've been in this type of fab work for about 18yrs. one thing I have seen that you didn't do( and it is a wonderful thing) is make a veritcal weld on the truck frame itself.It will cause failure to the frame and alot of damage to anything standing behind it when you are pulling something.I have installed thousands of goosneck hitchs in trucks and I weld all of mine in and never have had one break.Once again nice job.P.S. nice lathe

[Dawai]

OK, it builds character. reference to welding burns without protection.

BOT:
http://photos-g.ak.fbcdn.net/photos-ak-snc1/v2885/204/30/1298124187/n1298124187_30110598_3263145.jpg
People who have never had a BIG truck with a solid bumper don't appreciate it. I got triangulated bracing going back off the bottom of this to the frame. Rammer-Dammer bumper. Tug, pull, bump, push, ram. This was a wrecker, now a short 8' bed dump truck.
Same frame as under your utility vehicle. well with a lil more reinforcements. It weighs 7,000lbs with the scissor dump. I bet yours weighs in about #4200 or so.
when you wear that body out? just overplate the fenders with diamond tread plate.. make a heckuva home made UTE.

[MTNGUN]

If this had been a newer truck, I would have arranged to bolt the bumper to the frame, as I originally planned to do, but since the truck was an old beater I wasn't concerned about hurting it because almost anything you do to it is an improvement ! ! !

Frank, I've heard several knowledgeable fabricators mention something similar to your comment about how certain types of frame welds can lead to cracking. For example, there's trailer refurb thread on the heavy equipment forum where the trailer's main frame is made out of an i-beam, and the trailer manufacturer warns that welding on the flange of the ibeam was a no-no that would cause a crack. Instead, he said you were supposed to weld to the inner web of the ibeam, plus they seem to avoid "vertical" welds even there, using curves or angles instead..

Here's the link, a long thread but interesting, especially the way they their weldments are formed as curves or angles to spread out the stress.

http://www.heavyequipmentforums.com/Forum/showthread.php?t=12945

In the case of the i-beam, I can halfway understand, because the flange is the most highly stressed part of the beam, while the center web is the least stressed. And even the best 7018 weld is relatively brittle and could be prone to fatigue cracks when it is subject to cyclical stresses. It's also possible that their i-beam is heat treated and welding messes up the temper.

I'm having a harder time following the logic on a mild steel truck frame. The best theory I can come up with is that even the best welds are relatively brittle, and subject to fatigue cracking, and if the weld on the frame cracks, the crack may spread to the frame itself.

I would be more concerned about welding on the flanges of the truck frame's "C" section because that's where the stress is highest, similar to the i-beam in the trailer link. I can see how a poor weld on the flange could lead to cracking.

I can see how it would be better to avoid a "vertical" weld on the "C" web and instead use a curve, taper, or fishplate, because that spreads the stress out over a wider area.

On the other hand, let me play devil's advocate and present a worst case scenario. Let's say you sawed the "C" in two with a vertical cut. Then you welded it back together with a butt weld, without using a fishplate or any other reinforcement. The butt weld would have to carry 100% of the frame stress. OK, but shouldn't a decent weld be just as strong as mild steel, and shouldn't it last just as long as the original mild steel "C" section ?

The only issue that I can see is that, as I mentioned before, even the best weld is relatively brittle and may have less fatigue strength than the ductile mild steel frame member.

Thank you for your comments. I only piddle with welding a few times a years, so I appreciate the comments from the pro welders, even though I sometimes have a hard time following their logic.

BTW, a follow up report on the bumper's performance. It's already hit a big tree, and didn't even get a scratch. It knocked a big chunk out of the tree.

On the other hand, my homemade D rings were a failure. This was my first attempt at fabbing D rings, and I was unhappy with them from the get go, especially with the rings being made out of rebar. Rebar was all I had on hand besides drill rod, and I knew better than to weld drill rod.

Both D rings have already been used hard, skidding big logs up a steep slope. One is still holding, but the rebar snapped in two on the other when a log jammed on a stump and put a big shock load on the truck. All my welds held up fine, just the rebar sheared in two. No surprise there.

So....... I ordered a couple of alloy shackles like I should have done to begin with. I'll grind off the homemade D rings, and weld on shackle mounts. The shackles are rated at 7000 pounds. I figure if yank hard enough to break a 7000 pound shackle, I've got other things to worry about, like me going flying through the windshield.

[Dawai]

My experience with rebar is it is brittle crap-metal with inclusions.

A thick eye welded in with a clevis to screw through it works for me. Of course I have a dozen or more laying about. A 2x2 is a great place to mount tools "bending tools, tube bender, other things" requiring a steady base. Anyways, I don't like the rattle D-rings make. My old junk trucks make enough noises on their own.

[wmgeorge]

The "little window" is now covered by the license plate. Since it is covered up and since it is not highly stressed (that section of the bumper is welded to the 3" angle, so it is well supported), there didn't seem to be any point in filling that space with 1/4". In fact, the upper portion of that window uses some 1/8" scrap, since all it does is hold the license plate.

Sure, I had the metal available, but there was no point making the bumper any heavier than necessary. Getting back to my original goals -- strong enough for pulling, strong enough for jacking, and strong enough for a hitch. I made it beefy where it mattered and not so much elsewhere.

The old sheet metal bumper and mounts weighed about 100 pounds. I'm guessing the new bumper weighs 150 pounds, plus 20 - 30 pounds was used to beef up the frame. That's a reasonable trade-off. I didn't want to end up with a 300 pound bumper.

I try my best, but I've been trying for 25 years, and it's become obvious that I don't have the eyesight or the coordination to be a pro welder. I still enjoy welding, though. I'm still learning and improving in small ways.
You sound like me. Just when I thought I was getting somewhat good at welding the darn eyesight starts giving me problems. Cheater lens help some.
I like to weld, and build stuff just takes longer now that I'm older. BTW I'd think that bumper would outlast the truck!