An algebreic calculation for all you mathmeticians.

[Boomyal]

I am trying to extrapolate a dimension off of a scaled engineering diagram.

If 89 centimeters (from drawing) equals 77.5 inches (actual object height), how many inches does 95.3 centimeters equal?

 

[achris]

Re: An algebreic calculation for all you mathmeticians.

83.334in... Do I need to show my working teacher?

Edit: What the...???? I just did the calculation again, using exactly the same formula, and got a different answer :facepalm:

Same as Bruce, get a ratio between the 2 known quantities with the same dimension (cm) so 95.3/89 = 1.07078651, then multiply that to the inches, 77.5... THIS time the answer comes out as 82.985955...

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

I get 82.985 or basically, darn close to 83!

(95.3/89) * 77.5

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

83.334in... Do I need to show my working teacher?

No Achris, it does not matter if you are correct. It doesn't matter how you arrived there, it only matters if your heart was in the right place and that you meant well.

That being said, I appreciate your effort. If I had not already consumed a pre-dinner mix of Cabernet and Merlot, I might have been able to figure out the formula. I would have had to dig real deep as it has been many a decade since my 9th grade algebra classes.

I have to tilt. from horizontal to vertical, a 35 x 77.5 cylinder (polypropylene tank) . The last 11 inches of the cylinder tapers to 23 inches in diameter. The jobsite has a ceiling height of 83 inches. Do you think that the ceiling drywall will be irreparably damaged by forcing that last .33 inches across the bottom of it?

 

[achris]

Re: An algebreic calculation for all you mathmeticians.

No Achris, it does not matter if you are correct. It doesn't matter how you arrived there, it only matters if your heart was in the right place and that you meant well.

That being said, I appreciate your effort. If I had not already consumed a pre-dinner mix of Cabernet and Merlot, I might have been able to figure out the formula. I would have had to dig real deep as it has been many a decade since my 9th grade algebra classes.

I have to tilt. from horizontal to vertical, a 35 x 77.5 cylinder (polypropylene tank) . The last 11 inches of the cylinder tapers to 23 inches in diameter. The jobsite has a ceiling height of 83 inches. Do you think that the ceiling drywall will be irreparably damaged by forcing that last .33 inches across the bottom of it?

Hey y'all Boomie... 83 inches, ya good to go mate... :facepalm:

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

I calculated it with geometry and got 82.75"

To me you have 0.25" to spare.

Base of the triangle is 35" - (12/2)

Height is 77.5

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

I calculated it with geometry and got 82.75"

To me you have 0.25" to spare.

Base of the triangle is 35" - (12/2)

Height is 77.5

Sounds even better Bruce. I was girding up to sacrifice a little ceiling drywall. I have no other options as I can't change the height of the room and they do not make tanks of a given volume in incremental dimensions. Did you take into account that although the cylinder is is 35.5" at the bottom, it is effectively 23" at the to top of its 77.5" height. Here is a drawing.

http://norwesco.com/PDF/LSTVERT300.PDF

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

Ahhhh...you changed the base measurement on me!



I just put a triangle in there.

The base of the triangle is 29.25" = (35.5-23)/2 + 23
The height is 77.5

Use Pythagorean theorem to solve for the hypotenuse
(77.5)? + (29.25)? = hypotenuse? = 6006.25 = (82.84)?

 

[Tim Frank]

Re: An algebreic calculation for all you mathmeticians.

Did you take into account that although the cylinder is is 35.5" at the bottom, it is effectively 23" at the to top of its 77.5" height. Here is a drawing.

http://norwesco.com/PDF/LSTVERT300.PDF

If it wasn't for the taper, you'd be scuppered....
You'd need 85" + to rotate it.

If that drawing is already dimensioned in inches, why was the scaling necessary?

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

If that drawing is already dimensioned in inches, why was the scaling necessary?

I think it was because he used a ruler to measure the diagonal straight off the drawing.

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

I think it was because he used a ruler to measure the diagonal straight off the drawing.

True, but actually I used a digital caliper to first convert the vertical diagram height to centimeters ( a given dimension of the actual tank, in inches). I then was able to create the ungiven diagonal dimension in the same increment. With that information at hand, all it needed was a mathematician to find the X which was my diagonal centimeter value expressed in real life inches.

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

True, but actually I used a digital caliper. I did this to find a comparative length of the diagonal dimension needed to determine the tilt height. That dimension was not given on the drawing.

Sometimes that will work. Depends on the accuracy of the drawing of course. Never know what happens when you print these out. They could have been compressed or stretched when it was put into the PDF file.

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

Sometimes that will work. Depends on the accuracy of the drawing of course. Never know what happens when you print these out. They could have been compressed or stretched when it was put into the PDF file.

Good point Bruce. I did not think about that. I did ask if the drawings were to scale and I was assured that they were. I guess I will have to keep my fingers crossed that the drawing was not distorted in its reproduction.

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

Ahhhh...you changed the base measurement on me!.....

I just noticed that I did that. The 35.5 is the correct base dimension.

I think the method of your final calculation of 82.84 inches eliminates any variations caused by diagram distortion.

Thanks all!

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

Its going to be close!

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

Its going to be close!

Indeed! (still keeping fingers crossed)

 

[bruceb58]

Re: An algebreic calculation for all you mathmeticians.

Storing beer for the long wet winter ahead?

 

[Boomyal]

Re: An algebreic calculation for all you mathmeticians.

Storing beer for the long wet winter ahead?

Indirectly! I am constructing a Reverse Osmosis System, with re pressurization, to remove silica from water used for makeup water in a large indoor swimming pool. This is being done for a gentleman, of some import, with Intel. When completed, this project will definitely keep me in beer, the whole winter long. :nod:

 

[dingbat]

Re: An algebreic calculation for all you mathmeticians.

I did ask if the drawings were to scale and I was assured that they were. I guess I will have to keep my fingers crossed that the drawing was not distorted in its reproduction.

As a Mechanical Designer and someone who managed a large drafting and design group for a number of years, I don't trust or scale any drawing. It's far too easy to just change a dimension and not modify the drawing.

I tell customers right up front. You either send me a CAD drawing to work, pay for a site visit to verify the dimensions or any problems at site are on their dime.

 

[Bigprairie1]

Re: An algebreic calculation for all you mathmeticians.

I just noticed that I did that. The 35.5 is the correct base dimension.

I think the method of your final calculation of 82.84 inches eliminates any variations caused by diagram distortion.

Thanks all!

Yeah....this is funny watching some of the responses to the intial posting Boomyal.:facepalm:
Lets go back to basics for a quick second, as follows:
89cm is 35.04"...all day long.
95.3cm is 37.52"
The basis for the above is simple metric to imperial conversion noting that 1 metre is of course...100cm (39.37") and that (when put into the ol' metric vs. imperial context) is always just slightly more than a measured 'yard' (36").
Now, the conversion factor for cm to an inch is 2.54 or the inverse .3937...or simply put: 1 inch = 2.54 cm.
(also then....1 yard (36") would be 36*2.54 = 91.4 cm...for general reference sake)
So Boom, your dimension that you've listed at the top (35.5") is indeed very close and the 95.3 cm dimension is indeed 37.52" in imperial.
My two bits.
BP.