What am I stamping?

[JamesBarlow]

My daughter had a project over the weekend that got me thinking about something. The project for the class was to have each student put together a toolbox of what a person would have for a number of professions. She, just out of luck, got to do one for an Engineer. One of the things I did was take a drawing I had of a spindle shaft and printed it full size and stamped it.

That got to think about what am I stamping. Taken out of context the drawing is meaningless so how can a person be held liable for a design simply based on the stamped drawing. I realize that for Civil work there is an enormous amount of information on the drawings that convey function but for Mechanicals I often simply make a few part drawings.

A very simplistic hypothetical would be if someone hired me to make a measuring device to measure parts that range in size from 1in to 10in. I design a ruler that is 12in long and send a stamped drawing, along with my invoice, to the customer. A few weeks later I call to find out about when I will get paid and am told they are not paying because the design was flawed. They tried to measure a part that was 15in and the ruler didn’t work.

I’m looking to get some feedback, and start a discussion, on how everything gets tied back together so things like a ruler can’t be taken out of the context of the actual job for the customer.

 

[MacGyverS2000]

The request specified a device that measured items ranging in size from 1"-10"... the fact that it could also handle 12" items was simply icing on the cake, and the fact that it couldn't handle 15" objects was irrelevant as they did not meet the original specs. Would you refuse to pay for a commuter car because you found out later it wouldn't pull a 50-ton trailer?

Your stamp is a declaration of the suitability of the piece when used in accordance with the specs provided to you (and the ones you specify when handing that design back). If the unit is used outside of those specifications, you cannot be held responsible. If you spec'd the spindle shaft to handle 500rpm and it failed at 350rpm, you could have a lawsuit on your hands. If it failed at 800 because another safety device on the machine failed and it overspun, you could hardly be considered at fault.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[vc66]

A little off-topic, but, that hardly seems like a device that would require a stamp on its drawing.

The major deciding factor in all this is the contract with deliverables that is received by the person doing the work. This would include everything that the device is supposed to do. Whatever is outside the scope of what you and the customer agreed upon is not your fault/responsibility.

Without that contract, everything is hearsay...

V

 

[IRstuff]

"Taken out of context the drawing is meaningless," exactly.

Without the specifications and requirements that were derived to generate such a drawing, no one else can realistically make any claims about the design, one way or another. Your example ruler, on the other hand, presumably was designed per customer requirements, per contract. Their claim of non-compliance is trivial to disprove, based on their specification, hence, there is no non-compliance.

TTFN

FAQ731-376

 

[RVSWA]

Lets not forget you were helping children to become educated about the field of engineering. My hat is off to you.. We already lack the sons and daughters necessary to address a growing demand in population as our building codes mature with our growing knowledge. Anytime a kid tells me they aren't any good at math, I tell them "The Secret". While we occasionally find learning math can be difficult, once an idea is learned, it rarely changes and it is as easy as 2+2. You can learn and understand all parts of math with just that confidence. My dad was a math teacher and he always said math is learned through the elbow, just a lot of practice. What I need is a few simple examples of something interesting that they can see the math for and finally understand why something in our world happens. On a serious note, perhaps noting next to your stamp that this is for educational purposes, would silence even the most ardent critics.