Hardest Project you did

So another good forum question came to mind.

Please list a project that you did, could be writing a PLC program, to designing a controls systems or anything difficult that you can think of that really picked your nuts and bolts to overcome, and if you can, how you over came it.

Automating an 11kV base load generator power station. 6 generators, 4 on diesel, 2 on black fuel, heating, scrubbers, all auxiliaries, fuel tanks - 5 x 125,000 litres, black start, load control, capacity control, replace failing generator, SCADA system, SCADA select engine duty order, start what is required with a new duty order, take off what is not required, time and date start an extra engine for several hours due to a large load scheduled to come on, 11 networked PLCs most with remote I/O, 5,500 tag SCADA system. Did all the design work, software and made it work.
Just had to do it - boss had committed us - really tough job and had another 15-16 jobs going on at the same time.

Hi Bob

Well done I was tired just reading about the amount of work you had to do on that project.

My hardest was taking over ( well two of us did) a mixing project that went wrong and trying to work on it while keeping the plant live. The guy how was in charge left on a Sunday night and the plant should have been up and running 1 week before that. This was in August and and I worked on it till afer the new year.I had only two weekend off as we were on call 24/7 because of the mess. The whole thing was a mess and I ended up doing two 24 hour plus shifts in less than 7 days at one point with normal days at least 12 to 14 hours long 7 days a week. The worst part was that the company I was working for at the time were tolded it was going to cost them a lot of money and here two of us were working all hours 7 days a week trying to finish it and also keeping the rest of our projects on the go.
It was during this time I starting dating my wife and this did show me how understanding she is and that is needed when you work at a job like ours.

Donnchadh

I did not include everything either - live power station for the Island and had to keep it all going as well. The description was really pretty brief
It is fun doing things and keeping everything going - beer at the end of the day is nice though!
When commissioning the automation I slept on a mattress in the power station - in case! Four days of that - it did not shut down fortunately.
Have had plenty of others too over the years but that was the hardest,

The hardest project I ever did when I started out was making a light bulb turn on with a switch. In the beginning everything is a huge and hard project.

I was working for a company as an in-house programmer. I took over a web handling line that ran 1300fpm with a L1 ControlLogix 6 Toshiba drives on AB RIO ( no one supported the RIO side not AB or Toshiba ). It was spaghetti code at it's best. I found close to a hundred rungs that just went into a loop. To move data from 1 place to the next. After about a month of tracing out what goes where throughout the program it took 10 rungs to replace it. They where using a lot of indirect addresses. It had no function blocks just ladder. We had 45 sec between rolls to do any modifications that would stop the process. I learned to write code that could be turned off and on with a toggle of 1 bit. It is a lot quicker than using test edits.

Not sure if it was the hardest job but it had me scratching my head for a long while.

I had just started with a company as a manufacture engineer. It was in the 1990's. My boss walked me over to an ABB robot that was placing air conditioning compressors in a box. As the robot ran it would make a fast movement that would cause the compressor to fly out of the jaws over the safety to fence to land in another area roped off so no one got hit. My boss informed me the robot had been doing this for a few months and no one had figured out yet what the cause was. This was my first job.

After looking and looking at the code and not finding anything wrong I hooked the scope up to the axis checked for any random signals, still nothing. The solution came to me after a night drinking with some guys I used to work with. We were joking about how a disk formatter had seemed possessed because the EPROM had not been completely cleared before being reprogrammed. I went in and rather than erase the existing EPROM programmed a new one. Problem solved. I learned more about the innards of a robot on that one problem than on any other robotic job I have done since.

Clay B. said:

Not sure if it was the hardest job but it had me scratching my head for a long while.

I had just started with a company as a manufacture engineer. It was in the 1990's. My boss walked me over to an ABB robot that was placing air conditioning compressors in a box. As the robot ran it would make a fast movement that would cause the compressor to fly out of the jaws over the safety to fence to land in another area roped off so no one got hit. My boss informed me the robot had been doing this for a few months and no one had figured out yet what the cause was. This was my first job.

After looking and looking at the code and not finding anything wrong I hooked the scope up to the axis checked for any random signals, still nothing. The solution came to me after a night drinking with some guys I used to work with. We were joking about how a disk formatter had seemed possessed because the EPROM had not been completely cleared before being reprogrammed. I went in and rather than erase the existing EPROM programmed a new one. Problem solved. I learned more about the innards of a robot on that one problem than on any other robotic job I have done since.

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That doesn't sound like a manufacturing engineer's job. The Manufacturing Engineer is someone who deals with plant efficiencies and process streamlining, not fixing equipment. Probably just a quirk of that particular company's job titles.

As I recall, one of the hardest things was learning Octal and Hex math on paper. Simple in a computer, but on paper a real PITA.

Yes manufacturing engineering is about efficiencies and process control but almost any company will turn to them when you have equipment that maintenance can not fix.

"Hardest" is kind of a relative term. Some jobs it's not that they're hard to do but they feel hard because of the frustration factor. One thing I've found in my short time in this career is that the less control you have over a job, the more frustrating it's going to be. The more you let the customer spec out parts and make decisions, the more likely it is you'll have to re-write most of your program on-site.

Because if there's one thing about dealing with other contractors and customers, it's pretty much a guarantee that you will be given inaccurate information at every turn. You will be told they're using 120V valves and then you get on site and find out that somebody made the decision to switch to 24V and didn't tell anybody. You will be told they're using PNP proxes and find out they installed NPN. This isn't because they're all out the "get" the programmer. It's just a human limitation that you rarely can know the entire impact of any decision you make. You can know as much as you can know, but there will always be something you didn't think of.

I just had one job where we were trying to do a pass/pail of orifices based on air pressure. The operator would put a calibration orifice on, the system would measure it, and then reject everything that came equal or higher than that pressure. Sounds simple enough, except the customer did all of the valving and pneumatic components. Turns out all the fittings they used had smaller orifices than the test orifice, so of course the pressure read the same on every part because it was reading the fittings and not the part. Of course I had spend several days and multiple trips figuring this out even though that wasn't my part of the job. When other people design part of your system, it's still your problem as the programmer. You are the person who is supposed to make it all work regardless of how much control you had over the design.

Clay B. said:

Yes manufacturing engineering is about efficiencies and process control but almost any company will turn to them when you have equipment that maintenance can not fix.

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Seems awfully weird. I was debating going into that field as a career path (decided to do this instead) and took some classes. If the people who were in my classes are any indication, a lot of companies are going to be sorely disappointed in the future if they're going to expect MFG engineers to fix equipment. That's just not part of the curriculum and most of the students don't have that background. Then again, I am in Automotive country and there is a lot of "that's not MY job!" syndrome.

brstilson said:

Seems awfully weird. I was debating going into that field as a career path (decided to do this instead) and took some classes. If the people who were in my classes are any indication, a lot of companies are going to be sorely disappointed in the future if they're going to expect MFG engineers to fix equipment. That's just not part of the curriculum and most of the students don't have that background. Then again, I am in Automotive country and there is a lot of "that's not MY job!" syndrome.

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The Automotive industry is a world all its own. Like Oil and Gas. Personally I think it has a lot to do with certification. In automotive Oil and Gas and pharmaceutics you have tighter standards you have to hold. In most other manufacturing processes if your making a sale-able product everyone is happy. Because of the certifications required jobs are better defined and everyone is in perpetual CYA mode.

brstilson said:

"Hardest" is kind of a relative term. Some jobs it's not that they're hard to do but they feel hard because of the frustration factor.

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I haven't done any hard jobs. I have got involved with many frustrating jobs due to poor design, unrealistic expectations, stupid customers, ill prepared customers, and products that don't work as advertised. I have also got involved with projects where the working conditions were not good.

If I had to pick one it would be a rotary shear. In this case the customer was prepared and knowledgeable. I had done all the math necessary on a Mathcad work sheet or two so I knew what to expect, but I was wrong. I expected that I needed to match the speed of the metal as it went by and this part worked well. We got the shear working what we thought was good enough but later it was decided that when running different products it wasn't accurate enough. There was a feedback problem. When the shear hit the metal it pushed the metal down and this pulled on the encoder that was the master for everything.
So there was a horizontal component that I had accounted for and a vertical component that depended a lot of the thickness of the metal. The vertical component made the metal travel just a little bit faster. This causes the shear to react to the encoder moving quickly for a fraction of a second and that made the shear move more quickly etc. There was nothing that could be done cost effectively to fix the shear pushing down on the sheet metal. What we had to do is make a virtual master that was geared to the real encoder and the shear was geared to the virtual master. Just before the shear hit the metal we decoupled the encoder and the virtual master. Now the encoder would be affected by the pulling of the shear but the virtual master remained very smooth so the shear motion remained smooth. The virtual master and encoder where then re-synchronized so the length between cuts would be accurate. This was the main problem.

A secondary problems was with the drive. The drive didn't respond well in velocity mode where our output to the drive was proportional to the speed. The shear was a heavy rotary shear there were the knife was always pointing down. In a cycle the shear sometimes was aided by gravity and went to fast and sometimes it had to rotate up against gravity so it went too slow. The drive couldn't respond quickly enough to the changes in the load due to gravity. The drive didn't know when the shear was aided or opposed by gravity. We had to change over to current or torque mode where the motion controller's output was proportional to the torque required. We had to add an extra gravity bias to the PID and feed forwards. The feed forward only compensate for moving the mass of the shear but not for the gravitational pull. Since the motion controller knew where the shear was in a cycle we could use a sine function and multiply it by the amount of control signal that was required to maintain the shear a 90 degrees where the output was the highest. This bias made the tracking almost perfect as the rotary shear rotated through 360 degrees. The shear no longer tended to lag behind while rotating up but more importantly it didn't get ahead when rotating down to make a cut.

There have been some others that one could call hard jobs but if one is prepared then you should have 95% of the problem solved before startup. It is the gotchas like those in the rotary shear that make things interesting.

Another one...I was working on a Press program that a service tech had started. The program was not easily readable. Hardly anything was commented. The tech had called in sick two days before he was going to be on vacation for two weeks, so I ended up stuck with it. What was supposed to take a day took me the full two weeks.

The worst part was that I got inaccurate info pretty much from everybody the entire time. The guy that did all the hydraulics and had hired us to do the controls insisted we use this hydraulic servo controller from Delta (once I figured out how to message to it from a Micrologix 1400, it impressed me. Delta makes some nice stuff). My first big mistake was listening to him regarding how it was supposed to work. In fact my main mistake was listening to him at all on almost everything.

I ended up re-writing the whole program from scratch and the first time the operator tried to run it, almost everything he did was not how I was told it would be operated. Turns out it was a much more manual operation than I was led to believe. After I got that all squared away, the operator on the other shift said it was all wrong. So between two operators neither one could agree how the thing was supposed to work.

When the tech came back he eventually made everybody happy. But I still hope I never have to do something like that again (though I probably will!)

A hard job in the making

This a job that I should be involved with but I am not. The application seems to be turning a BIG nut to apply tension on a cable. If you look at the diagram there are 4 hydraulic actuators but some will be pushing and others will be pulling but the 4 hydraulic actuators must remain synchronized.

Notice that the hydraulic people jump on the idea of a flow dividers with out doing any math and get super offended when I suggest closed loop control. It is admitted that the closed loop control will work still it is ignored.

escapizm, was told by Moog that the system should be simulated. I suggested that some calculations. escapizm decided not to because it would cost too much even though he said he has a lot of respect for Moog. escapizm decided to go the flow divider route without feed back because it is cheap and he understands it. What he hasn't taken into account is that flow dividers leak and since two actuators will be pulling and the others pushing they will tend to leak in opposite directions. Also, there is no accounting for the fact that the oil will compress. 0.5% or more for every 1000 PSI of pressure and the compression will be in different directions. Since the cylinder loads are in different directions this too will make the it difficult to keep the cylinders in synch. Then we are told the motion will take perhaps 30 minutes. That is a long time for leakage to have a significant affect.

Read this. What do you think? Is a disaster waiting to happen? It is appears to be for some big construction job, perhaps stretching cables for a bridge or similar.
http://www.eng-tips.com/viewthread.cfm?qid=344803

On threads like these I like to simply wait. I will ask how it went in a few months. They may still be struggling with this.