Planimeters

Hi...I am a YDS student, about to purchase my first planimeter..which I have never used in my life....
I see that Charrette stock two with the main difference being a fixed tracer arm and pole as opposed to an adjustable. Without really knowing how these work, I am not sure whether to go with the pricer adjustable or the cheaper fixed...any advice before I press the purchase button for the cheaper one?????

 

As a (one-time) design student, go with the fixed. It is likely to stay more accurate for a longer time, simply because it is NOT adjustable. The adjustable types are really tough to get used to, and you have to be able to set them EXACTLY the same each time you re-set the scale.
Simpler to use the fixed and just multiply by the constants provided.
I have to admit that my own personal planimeter is a 1914-vintage Stanley adjustable ;-) Bought for 25 pounds (UK) at a street market in Farnham. It works like a dream, but is subject to the limitations stated above.
Steve Baker.

 

Are you familiar with the blade type planimeter? It is easy to make and won't cost more than a couple of dollars.

 

http://baen.tamu.edu/users/munster/agen_468_99/planimeter/planimeter.htm

This is standard form of planimeter used by architects and engineers. Some forty to fifty years back planimeter and integrator are the instrument to measure area, the later unit can also determine first moment and second moment. Hence center of gravity and inertia can be determined for structural section or the ship's sections.

Nowadays, like other architects, I hold these as historical pieces.
We will use the CAD method to measure area and centers.
We generally use pc to calculate data for stability.

Peter

 

CAD works great when you are working with a digitized design. Doesn't do so good when you are working on a refit design using old paper drawings. If you don't have a planimiter, when the client wants you to calculate the volume & centres of that odd-shaped tank you are gonna wish that you did. Like old people, old tools sometimes have a few tricks that leave the young upstarts standing in the dust, shaking their heads and wondering "Wha' happened?"

Go with the cheaper planimeter - if you find you have reason to like using it, you can go for the fancy one a little later whan you are flush with success. I have a fancy adjustable one that I like using a lot, but haven't adjusted it out of it's present setting for probably ten years.

 

Thanks for the all the info..I went with the cheaper, fixed version, and now just have to learn how to use it!