Machine Shop Math, sample problems and formulas

[Karl_Kunkle]

I am looking to find a book or pamphlet or a resource that has the formulas for problems that machinist see often.

I have access to a Machinist Calc Pro that makes quick work of bolt patterns and 3 wire measurements, but I want to know how to do it by hand or at least with a dollar store scientific calculator.

An example, I was trying to layout a 7 hole bolt pattern rotated 15 degrees 10 inches left and 6 inches right from my reference 0. The calculator did it in seconds, but the lead machinist made the point that what happens when you drop your calculator or the batteries die or the screen cracks.

So, I am wondering what formulas are often used and where to find some sample problems.

Thanks,

 

[Alchymist]

Machinery's Handbook.

 

[TurboFabSupply]

Bolt hole circles are given in polar coordinates. I.E. an angle and a radius. You need to convert them to rectangular or Cartesian coordinates.

Day 1 of Trig 101:
http://www.analyzemath.com/polarcoordinates/polar_rectangular.html

 

[67Cuda]

I've check this reference booklet many more times than Machinery Handbook. Small, easy to navigate.

Machinist Ready Reference.

http://www.amazon.com/Machinists-Ready-Reference-C-Weingartner/dp/0970339801



Tom

 

[swamp dweller]

Technical Shop Mathematics by John G. Anderson. I use this text regularly

 

[aerodark]

Must have

Amazon.com: Mathematics at Work: Practical Applications of Arithmetic, Algebra, Geometry, Trigonometry, and Logarithms to the Step-By-Step Solutions of Mechanic (9780831130299): Holbrook L. Horton, Henry H. Ryffel: Books

 

[johnoder]

When I was coming up not quite fifty years ago, there were no hand held battery powered gadgets, so we got all the holes where they were supposed to be with

Oscar had (= Sine)
A Heap (= Cosine)
Of Apples (= Tangent)

And a list of trig functions published by such as Illinois Tool Works

I still have my copy, with my Pratt & Whitney Aircraft clock number on it - 169001

You young whippersnappers need to occasionally reflect on the fact that MOST of the stuff made by the USA in the last 200 years was made without involving electronic help.

Here is a favorite of a little exercise performed in 1928 on flapping belt drive machinery.

http://img.photobucket.com/albums/v337/johnoder/8PiecesofIron.jpg


J.O.

 

[kenh]

Yep, still have my log/trig tables and slide rule!

(not that I am old)

 

[TurboFabSupply]

hahahaha slide rules hahahaha

*looks at Valenite SFM, RPM, MRR, Hardness slide rule*

...never mind

When I learned it, it was soh-cah-toa. Can't tell you how many statics/dynamics tests I thought that word.

 

[Armenius]

The modern scientific electronic calculator does make the machinist's and engineer's life much easier. I got my first one in 1972 after opening my textbook in fluid mechanics and saw all those weird formulas with fractional indicies.:-)).

Before the electronic calculator we had mechanical calculators in our tool design department. These could give erroneous results when the clutches got tired.

For most engineering calculations the slide rule was fine with its 3 digit accuracy. A friend of mine had a circular slide rule with a 30 foot long spiral scale that would provide accuracy to 5 significant digits. This thing was 10" or 12" in diameter.

Unfortunately for toolmakers and machinists the slide rule accuracy was insufficient and we relied on hand calculations using logarithms, including logs for trigonometric functions.

Still tedious but simpler and less error prone than trying to multiply 5 or 6 digit numbers long hand.

For those of you unfamiliar with logarithms, the use of these simplifies the multiplication/division of numbers to one of addition/subtraction.

For large numbers done by hand the "log tables" saved much time and errors.

Arminius

 

[Regal13]

johnoder! Thank you! Sometimes I think I'm the only one who learned Trig with that sentence! You don't really need a trig function book or anything if you can draw a right triangle (particularly where to draw them) and remember that sentence and Sin--Cos--Tan in that order.

 

[Alchymist]

When I was coming up not quite fifty years ago, there were no hand held battery powered gadgets, so we got all the holes where they were supposed to be with

Oscar had (= Sine)
A Heap (= Cosine)
Of Apples (= Tangent)

And a list of trig functions published by such as Illinois Tool Works

I still have my copy, with my Pratt & Whitney Aircraft clock number on it - 169001

You young whippersnappers need to occasionally reflect on the fact that MOST of the stuff made by the USA in the last 200 years was made without involving electronic help.

Here is a favorite of a little exercise performed in 1928 on flapping belt drive machinery.

http://img.photobucket.com/albums/v337/johnoder/8PiecesofIron.jpg


J.O.

You need to tell them young fellers about the O, A, and H though, else they won't get it.

Then there was Roy G. Biv, but that's another tale.

 

[John Welden]

I mostly use CAD because it's 2011.

 

[Tom Lg]

I was also taught soh-cah-toa (sine is opposite over hypotenuse, etc.), and there was also the joke about Chief SohCahToa of the Fukahwee tribe; can't remember the joke but the punch line was "where the Fukahwee?"

 

[dstryr]

I mostly use CAD because it's 2011.

LOL x2 . Why waste time going backwards? It isn't like you are going to get tested on it...

 

[John Welden]

It's good to understand the math, but I almost always use CAD because it's faster and I make less mistakes. I haven't done bolt pattern math for 15 years. I'll be done before you get the top off your Dyekem bottle.

If there is an EMP that knocks out all computers, I'll go back to long hand shop math.

 

[crashtestdummy]

I am looking to find a book or pamphlet or a resource that has the formulas for problems that machinist see often.

The calculator did it in seconds, but the lead machinist made the point that what happens when you drop your calculator or the batteries die or the screen cracks.

So, I am wondering what formulas are often used and where to find some sample problems.

Thanks,

Like others have said, CAD. Or Google, or pull out the iPhone. I see no point it trying to remember information I can easily look up.

But I still know pi to 9 digits. I can remember my college id number from 35 years ago. I need to reinstall my operating system and clean out all the crap on my hard drive.

 

[johnoder]

You need to tell them young fellers about the O, A, and H though, else they won't get it.

USN Aviation Electronics School 2/60 - 11/60 NATTC Millington TN (vacuum tube era)

(like here)
http://img.photobucket.com/albums/v337/johnoder/Career%20Related/Navy%20Days/ASchoolScan.jpg

Is where this comes from.

O in Oscar and of is to remember Opposite Side
H in had and heap is to remember Hypotenuse
A in apple is to remember Adjacent Side

And all together:

Oscar (Opposite) divided by Had (Hypotenuse) = Sine
A (Adjacent) divided by Heap (Hypotenuse) = Cosine
Of (Opposite) divided by Apple (Adjacent) = Tangent

The Navy way fifty years ago.

J.O.

 

[John Garner]

Then there was the girly version: Saddle Our Horses, Canter Away Happily, To Other Adventures.

And the cruder one: Oscar Had A Hairy Old Ass.

 

[Larry S]

Well John when I was at Millington in 1963-64 it was
Oscar Had
A Hairy
Old Ass

Larry S
Fort Wayne, IN