Posts Tagged ‘welding’

Fabricating a Bumper for a Jeep Cherokee XJ

Thursday, May 12th, 2011

Fabricating a Bumper for a Jeep Cherokee XJ

The bumper on my off Road Jeep is very simple. It consists of a couple of pieces of angle that extend the unibody frame rails out. The winch plate is mounted on top of them. There are a couple of pieces of curved pipe extending to each side to protect the bottom of the head light surround.

Since Jenny drives her Jeep everywhere she goes, she wanted something that was both functional and nice looking. Had I been fabricating form scratch, I would have used a piece of 2×6 tubing and tapered the ends to make a nice looking bumper. However, the cost of a stick of steel was out of budget for the moment.

What I had to work with was a damaged bumper on a parts Jeep sitting in the grass by the barn. It was made from heavy steel it was just not exactly the shape I wanted. It also had a brush guard and winch plate integrated into the design. Jenny did not want the brush guard and does not have a winch.

I began by removing the bumper from the parts XJ. There was an extra bolt that simply would not come loose. I had to cut it with a torch to get it out.

I began by cutting off the brush guard and its mounting brackets. Next I cut out the winch plate. This left a big gaping hole in the center of the bumper. I cut a couple pieces of angle and used those to fill in the gap.

I did not like the way the bumper stuck out from the front of the Jeep, so I relocated the mounting holes to pull it in closer to the grill. I would have liked to have tapered the ends but that would have meant extensive reworking of the bumper. By setting it back, the tips don’t really stick out too far.

I painted the bumper flat black to mask some of the weld marks and to match her rear bumper. I trimmed the ends of her rear bumper to be similar to the cut of the front bumper.

I removed her twisted stock bumper and the stock air dam.

Mounting the bumper to her Jeep Cherokee, required trimming the front fenders since part of the bumper extends back under the grill. I used a straight edge and a sharpie to make a mark on the fender. I used a cut off wheel in my grinder to make the cut. I touched up the raw edge with spray paint.

I tied the vacuum bottle to one of the fender supports with wire for now. I will move it inside the engine compartment later as the cut of the bumper leaves it venerable to breakage where it is.

The new bumper gives her Jeep a muck more aggressive look. It also improves her approach angle for off road obstacles compared to the stock bumper.

Welding Safety – Fire from the gas tank

Wednesday, May 4th, 2011

Welding Safety – Fire from the gas tank

My dad told me about a time when he was repairing a shock mount on his Chrysler. He used the company boom truck to lift the rear of the car to a comfortable working height.

After the completed the welding job he flipped the stinger back and accidentally contacted the gas tank on the car. He was quickly surrounded by flames dripping from the tank. The little hole in the tank continued to fuel the fire.

He simply reached his gloved hand up and stopped the flow of fuel with his finger. The flame went out but he was then stuck like the proverbial little Dutch boy with his finger blocking the flow.

Soon my Grandfather walked by and asked “What are you gong to do now boy?” Dad suggested that he would continue to hold his finger in place while someone got him a roofing screw with a rubber washer.

My grandfather soon returned with a screw, washer and a wrench. Dad plugged the hole with a screw and the rubber washer made a liquid tight seal. He says that plug was still in place when he sold the cars years later.

Learning to Weld

Tuesday, April 26th, 2011

Learning to Weld

I grew up around welding. My Grandfather had a welding shop where he built bulldozer blades. My dad worked his way through college as a welder. And as Plant Engineer, I supervised welders. However, I have done very little welding myself.

I know a lot of the theory and I know how to set the welder to the specs for the material being welded. But the actual physical skill of making and holding an arc and forming a puddle, I am just learning.

I have three welders to choose from. I have a small flux core wire feed welder. I have a large Lincoln MIG wire feed machine. And I have an old Hobart gasoline powered DC ARC welder.

The little wire feed is great for tacking stuff and welding exhaust. Because it is small and portable, it is great for working under the car. It makes ugly welds however. And with minimal control, it often does not hold very well.

I have learned to make pretty nice weld with my MIG. The Lincoln has continuously variable controls for voltage and wire speed. As long as I keep good tips in the nozzle, it makes nice smooth welds.

Only recently I go the old Hobart running again. It has sat dormant for at least five years. It took a bit of work to get the engine running again. But after the twigs and acorns flew out of the generator, it is making good power.

I have begun learning to use the stick welder. It turns out that the current setting has a much narrower range than I expected. If it is too hot, it blows holes in the metal instead of welding. If it is not hot enough, then the rod will not strike or it will stick. Also, the arc length seems to be critical. If it is too long, then the weld just splatters. If it is too short, then the rod sticks.

Getting the hand coordination right has been the most challenging part for me. I now understand why people say that the only way top learn to weld is to practice. I have been practicing on some simple projects that allow me to grind away my mistakes and try again.

While you can’t learn how to weld by reading a book, you can get some valuable tips. Luckily I have my dad and a good friend to ask when I have a problem. But there is a great reference that tells you all the things you need to know to learn to weld. Get a copy of Welding Secrets Revealed to learn more. Sign up for their newsletter to get timely tips in your inbox. Welding E Book

Hot Work Safety

Thursday, January 27th, 2011

Working safely while welding cutting burning or grinding.

I read in the news lately where an apartment building had gone up in flames due to a fire started by contractors using a torch in the basement. Many people were put out of a place to live due to an error by a contractor using a torch to cut out part of a floor. Based on the story there was no fire watch and not even a fire extinguisher on hand during the hot work.

Like most safety procedures the ways of being safe with hot work are simple. First you realize that cutting, welding or burning metal is going to produce hot bits of metal going places that you may not intend for them to go. These hot bits of metal can catch stuff on fire.

So begin by removing everything that can burn from the area. Most permit systems recommend a 30 foot clear space.

Next, make sure that you have a working fire extinguisher and some one to operate it. Don’t depend on the one doing the cutting, burning or welding to be able to watch for a fire while concentrating on the work.

The both the hot worker and the fire watch need to be aware that hot bits of metal can fly, roll or bounce a long way from the work site. They need to pay particular attention to any cracks or gaps near the work site. Apparently that is what happened in the story referenced above; sparks got into the wall and ignited the insulation.

Another cause of fires that is easily overlooked is material on the other side of the wall from where the work is being preformed. I read about one case where combustible material stacked outside a tank was set on fire by welding inside the tank. Heat can also be transmitted by infrared radiation as well as conduction. So workers need to be aware of all their surroundings when conducting hot work.

There are some locations where hot work cannot be performed at all. For example, in areas near where flammable liquids are present and vapors may be present, hot work should be avoided. Often the fabricators will have to be creative to perform the work without the usual cutting, welding or burning. Parts may have to be bolted or clamped in place rather than traditional mounting methods.

Flammable and explosive dust is a hazard in some operations. Combustible dust can be very hazardous if ignited in a confined area. I remember the demonstration that is done at the Factory Mutual training center. They atomize a cup of flour in an enclosed cave and set it off with a spark. The impact of the explosion can be felt across the street several yards away. Paper and wood dust can easily collect on structures and be difficult to extinguish if ignited by hot work.

Again, most safe work practices are simple to put in place. But often workers may feel prompted to take short cuts in order to expedite a job. Supervisors need to pay particular attention to jobs that begin close to the end of a work shift or done my contractors working on a bid price. There may be incentive to rush the job. The part that is most easily overlooked at the end of a job is the waiting period after a fire watch.

Sparks may take a long time to incubate into a fire. A spark that has fallen into a crack or crevice may smolder for a long time before becoming large enough to visibly see. The fire watch needs to stay with the job continuously for at least 30 minutes after work has been completed. The job site should be periodically checked for the next four hours to make sure that no fires have been created.

I have found it is difficult to get contractors working on a bid price to comply with the four hour fire watch. It is best to assign this duty to a security guard or other trusted employee who is paid by the hour to be there.

Contractor safety often begins in the bidding process. Begin by choosing contractors with a good safety record and who understand the unique hazards of your facility. Make sure contractors understand the hazards that they will be working in before they bid. You do not want to be in a situation where their ability to make a profit depends on taking unsafe shortcuts.

When doing cost estimates for a job involving hot work, be sure that the budget includes man hours for a fire watch during and after the hot work. These may seem like unproductive costs to a contractor not familiar with safe work practices but are required for good work practice. Having a fire watch effectively doubles the man hours required for a job.

When using a torch, care must also be made with the compressed gas cylinders. Compressed gas cylinders have their own unique hazards. Cylinders must be moved carefully using appropriate procedures. If cylinders are to be lifted, they must be properly rigged to reduce the change of dropping and damaging a cylinder. Cylinders must be properly secured both while in storage and during use in hot work. An appropriate cylinder cart will suffice in most cases to properly support the cylinders and safely transport them to the job site.

Electric welders and grinders have hazards normally associated with electricity. Make sure that the machines are of compatible voltage and the wiring is in good repair and well insulated. Hot work can easily damage the insulation of welding and grinding equipment so it needs to be inspected frequently and properly protected during the hot work process.

When welding, grinding or burning on vehicles, there are special hazards that apply. Most vehicles will be powered by a flammable fuel. Make sure the fuel is completely contained and hot work is preformed away from fuel tanks and fuel lines. Welding fuel tanks is a specialty best left to those brave souls who specialize in such work.

When performing hot work on a vehicle it is not practical or even possible to remove all the combustible material such as wiring harnesses, carpets, undercoating and upholstery. Extreme care needs to be taken to make sure heat does not transfer through the car body to combustibles on the other side of where the work is being done. I have read stories of whole cars being lost to fires under the dash or burning carpets due to a simple welding repair igniting material on the other side of the work.

Note that wiring can be damaged due to hot work even if it does not catch fire. The heat from welding in a roll cage or patch panel can easily cause an electrical short by heating up the insulation of wires hidden inside the body panels.

Cutting welding and burning are a part of any fabrication process. Just follow a few basic safety steps to make sure that the work does not cause more damage than good.

Please share your hot work safety suggestions or stories below.