Process Improvement – Page 10

February 15, 2012February 15, 2012

Bridge Repair – correcting an oops

“Mister Straw, I need your help,” the county engineer said to my grandfather. “We have a dragline in the creek and we hope you can help us pull it out.”

The engineer went on to explain that they were installing a new bridge on one of the county roads. They had fabricated a new concrete bridge to replace the old wooden structure. They had cast a new concrete deck but had retained the original wooden abutments. During the back filling of the road bed, one of the abutments had been pushed off vertical and collapsed under the weight of the new bridge.

One end of the bridge had fallen into the creek. They had brought out the drag line to try to raise the bridge and now it was in the creek too – on its side.

Daddy Straw surveyed the situation and assured him that he could recover both the machine and save the bridge. Back at the shop he had my Dad and my uncle collect cribbing and jacks. HE then had one of the other employees drive the shop crane to the job site.

The shop crane or winch truck as he called it was made from a Ford lat bed truck with most of the body removed. There was a large boom mounted on the back. The rear axle had been replaced with one from a motor grader. A huge winch form a bulldozer was drive by the truck’s PTO. The operator’s seat faced the rear of the truck. Driving it to the job site meant an uncomfortable neck strain for the driver.

First they recovered the fallen machine using the old winch truck. Next, they set about raising the bridge.

My dad and his brother took on the task of wrestling the heavy hydraulic jacks and cribbing timbers down the creek bank and under the concrete bridge.

They built a base and began raising the structure a few inches at a time and re-cribbing with wood. It took about three weeks but they were able to raise the bridge back to the level of the roadway without damaging the bridge section.

Next my grandfather fabricated steel supports out of heavy H beams and my dad and his brother were assigned the task of snaking them down the creek bank and setting them in pace under the bridge. The dug down and created a concrete base to set he beams on.

Once that end of the bridge was stabilized, they move to the other end and temporarily lifted that end off the wooded supports. They cut out the wood and fabricated another steel support for that end. They then carefully set the bridge in its final resting place.

I am always amazed at the stories of how my Grandfather who had only a third grade education was called upon to bail out engineers and others who were supposedly more educated than him. I guess his education at the School of Hard Knocks as he called it was a pretty good one.

February 9, 2012February 9, 2012

Welding Safety

I grew up around a welding shop. My grandfather was a welder and so was my father. A lot of welding safety has just been second nature for me. However, I have recently picked up welding as a hobby myself and I have noticed that munch of the welding safety advice in the books is overly complicated.

So here are some simple tips for staying safe while enjoying making stuff with steel. This list is by no means exhaustive. I am sure there are many different ways you can get hurt while welding but these basic steps will keep you from the most common hazards.

The most obvious hazard of welding is the light from the arc. Not only is the arc flash hazardous to the operator but to those in the area. A welding hood is the common protection. The shade of the lens needs to be around a 10 so that the welder can see the weld puddle and still be protected from the light. I use a 9 on my MIG welder. Higher amperage arcs may need darker lenses.

The light contains a lot of UV radiation so skin protection is needed as well. The welding hood should cover the face and neck. UV resistant clothes need to be worn over the chest and arms. I have a small tanned V on my chest from forgetting to button the top button on my welding shirt. One last note on UV radiation – it is hard on cotton fabric. Be warned that your favorite pair of jeans can easily be reduced to shreds by UV radiation even if you avoid burning a hole in them.

The second most obvious hazard is the heat. Hot molten metal tends to fly out in all directions from the weld. Long leather gloves are the most common way to protect the hands and wrists. The parts will also be hot just after welding so the leather gloves help in handling the hot parts. Just remember that the heat will deteriorate the gloves over time so don’t handle hot parts more than necessary.

Foot protection is helpful as well. Cloth shoes and laces can catch fire due to molten metal falling on them. High top boots are recommended to keep hot blobs off your ankles.

Hot work also adds the danger of starting a fire. Fire protection needs to be considered for all welding and burning. See http://ezinearticles.com/?Hot-Work-Safety&id=5890147 for more info.

One less obvious hazard is handling compressed gas bottles on a MIG welder. While the gas is inert and non flammable, it still has a lot of stored energy that can be hazardous if the cylinder is dropped and the valve is damaged. If discharged in a confined space the Argon or CO2 can displace the oxygen in the air. So, make sure cylinders are properly secured in use and in transit. Make sure the cap is in place anytime the cylinder is moved.

Be aware of hazards that can be created during the welding process as well. When welding on a vessel like a drum or a tank, make sure the inside space has been purged of any flammable liquids or gases than could have been trapped inside. When welding on a vehicle, check the area near or behind the welding area. Ensure that fuel or brake lines will not be damaged by the heat.

One less common but very painful hazard occurs when welding zinc coated or galvanized metals. Know as metal poisoning, breathing the vaporized zinc will cause a severe headache. The old-time remedy is to drink milk on the theory that the calcium will displace the zinc in the body tissues. The condition can be prevented by having adequate ventilation when welding or by using respiratory protection.

Welding provides a great escape for the worries of the day, as it required total focus for me to make and maintain a quality bead. Following basic safety precautions will ensure that welding is done safely and enjoyably.

February 8, 2012

MIG Welder Settings

Setting the gas flow rate on my MIG welder has always been a bit of a mystery. The manual is a bit confusing and lacks a set it at this setting suggestion. After some research and trial and error on the welder I have finally found some settings that work for most welding.

MIG Gas Flow rates:
Minimum 18 CFH
Normal 22-27 CFH
Maximum 40 CFH

Also, a voltage of 19 to 23 volts works for most things. Lower on thinner metal or to build up and higher on thicker stuff to get more penetration.

February 4, 2012February 4, 2012

Differential Skid plate

Differential Skid Plate with Pinion Protection for Jeep 8.25

I like my 8.25 but there is one thing about the design that really gives me trouble. The big flange at the cover mounting point. I am sure it was added for strength, but I am really good at hanging it on rocks when crawling. And if I get one in there just right I can’t go forward or backwards to get off it.

Also, after Jennifer broke her pinion due to a miss-fortunately placed rock, I decided to try to add some protection there as well.

I used some 3/16 scrap and cut a trapezoid to cover from the flange to the center of the U joint. I used 4″ muffler clamps to secure the plate to the axle. I then welded wings to each side to connect the plate to the clamps.

At the front, I shaped a piece to make a stand-off from the pinion. I then used some all thread to make studs and made a plate across the two bosses on the diff housing to clamp the front part to the housing.

The finished piece looks something like the USS Enterprise.

I added a stiffener to the cantilevered part to add some strength. It may also help push rocks to the side instead of letting them slide straight under.

The whole thing mounts easily with six 9/16 nuts so it is easy to get out of the way. I had planned a flange at the rear but I am going to try it on some actual rocks before I add that part. I may not need it.

January 17, 2012January 17, 2012

Jeep Cherokee Tune Up

Jennifer’s XJ has been running a bit rough lately. We decided to try a tune up to see if the engine performance would improve. The spark plugs and wires on her engine were on the engine when we swapped it in a few years ago so we did not know how old they were.

We obtained a Tune Up kit from Crown Automotive. The kit contained wires, Champion Spark Plugs, a Distributor cap, a rotor, a fuel filter, an oil filter and an air filter. We elected to hold the filter changes for later and just do the ignition parts swap.

We began by marking the new distributor cap with the plug number for each terminal. Next we sat at the kitchen table and set the gap on all the new plugs to 0.035 using my Jacobs gapping tool. I sometimes run a larger gap but for this engine I decided to just go with the factory specs.

Next I removed the plug wires. This task proved very difficult as they seemed seized to the tops of the plugs. Even with my plug wire removal tool, several wires broke before separating from the top of the old plugs. With the wires removed, I used a 5/8 spark plug socket to remove the old plugs. I carefully cleaned the area around each hole and inserted new plugs. I ran them down until the sealing washer hit and then turned then an extra quarter turn.

The old spark plugs were the proper tan color indicating that the mixture was correct. However, they did show a great deal of wear on the tips.

Next I removed the old distributor cap by loosening the two Phillips head screws that hold it to the distributor. I left the old wires in place. I then installed the new cap and tightened the bolts.

The old distributor cap showed signs of severe pitting on the internal terminals. There was also some evidence of cross tracking inside the cap.

Jennifer carefully selected the matching wire for each plug from the kit and installed it on the appropriate terminal on the cap and then routed it to the plug as marked on the cap. She set the wires in the holders and then replaced the coil wire.

When she started up the engine, we immediately noticed that it ran much smoother. Hopefully there will be a corresponding increase in fuel economy as well.

Note that we did not install the rotor from the kit. When I ordered the kit, I forgot that she was running a 96 model distributor in her 1992 model Jeep. The cap is the same but the rotor is not. We will source a rotor separately and install it later.