Need Help!- mathematical problem

[NoWin1]

how to calculate A ?

[g-codeguy]

By using Pythagorean Theory? I take it 'A' is the distance from the right face to the start of the arc?

[NoWin1]

Originally Posted by g-codeguy By using Pythagorean Theory? I take it 'A' is the distance from the right face to the start of the arc?

Correct

Im not that familiar to pythagorean

[naveen.a019]

hi there,
please send me the complete scanned copy of the drawing to naveen.lobby@gmail.com as drawing image above does not clearly show all the dimensions. i will calculate the "a" and post it...and the other option is you can use Autocad , replicate the drawing and find out all the co-ordinates.

Regard's

NAVEEN G

[RICHARD ZASTROW]

"A" is a reference surface, not a dimension. The feature on the opposite (right) end is referenced to "A" for alignment tolerance.

The size of the bore is given (72) and depth (23). What is it about "A" you want to calculate?

Dick Z

[NoWin1]

Hi

I need to know the distance from the right face to the start of the arc, marked as A at the picture

Thats all given

I tried CAD and got 20,4 mm for the length

Is there way to calculate this?



And why diameter is 26mm if the radius is r20???

[Alfonzo]

I assume the designer wants you to ensure that the diameter of the part at the narrowest point is 26mm. This is independant of the radius. Are you sure there isn't a table on the drawing somewhere that describes dimension 'a'? It is common for draughtsmen to do this if one dimension varies across a family of parts, whilst all other details remain the same.

Hope that helps.

Oh, hang on - that's cr*p, because the overall length is described. Are there any notes in the drawing that discuss dimension 'a'? To be honest, if you've worked it out by CAD, than you have the answer!

[samco]

Originally Posted by NoWin1 And why diameter is 26mm if the radius is r20???

That is the diameter of the shaft at the narrowest point - not the diameter of the arc.

I get 20.46 also. As far as calcualting it by hand... I think you would need to setup 2 equations - one for the line and one for the arc. then solve by substitution. You will get atleast 2 answers.

so the circle is (if we use the center of the circle as 0,0 on a grid (for ease).

x^2+y^2=400

The equation for the line is (still using the center of the circle as 0,0)

y=17 (because it is a strait line)

so if you do a substitution
x^2+17^2=400
x^2+289=400 (Square 17)
x^2=111 (subtract 289 from each side)
x=+/-10.5357 (you are looking for the positive solution for this one)

So if the center of the circle is 0,0 then the point that the circle intercepts the line is 10.5357,17.

Looking at the blueprint agian
51-20(radius of circle)- 10.5357 = 20.46


Unless there is a more obvious way to calculate it that I don't see

Clear as mud?

sam

(blowing off the dust from college.)

[naveen.a019]

hi there,
I have attached a jpeg file which shows the calculation sorry for the rough representation as i had not installed Autocad in my portable. hope this help's.

cheers...!!!

NAVEEN G

[NoWin1]

Thank you very much guys for the help!!!

But where that AB 17mm comes from

[Cmailco]

Originally Posted by samco That is the diameter of the shaft at the narrowest point - not the diameter of the arc. I get 20.46 also. As far as calcualting it by hand... I think you would need to setup 2 equations - one for the line and one for the arc. then solve by substitution. You will get atleast 2 answers. so the circle is (if we use the center of the circle as 0,0 on a grid (for ease). x^2+y^2=400 The equation for the line is (still using the center of the circle as 0,0) y=17 (because it is a strait line) so if you do a substitution x^2+17^2=400 x^2+289=400 (Square 17) x^2=111 (subtract 289 from each side) x=+/-10.5357 (you are looking for the positive solution for this one) So if the center of the circle is 0,0 then the point that the circle intercepts the line is 10.5357,17. Looking at the blueprint agian 51-20(radius of circle)- 10.5357 = 20.46 Unless there is a more obvious way to calculate it that I don't see Clear as mud? sam (blowing off the dust from college.)

That's about as obvious as it gets Sam.

Trigonometry seems to be a lost art form... guess we can blame CAD for that though.

Sine, Cosine, Tangent and their inverses; about an hour of study, a $5 scientific calculator along with a little practice, and you'll never need one of those silly Carr Lane booklets again. Every machinist should be able to do this stuff imo.

[christinandavid]

Originally Posted by NoWin1 But where that AB 17mm comes from

Each rad is digging in by 3mm..(32 minus 26=6 divided by 2=3)

20mm radius minus 3 = 17....

DP

ps I'd be more concerned about that 02 linearity tolerance to datum A...