# A Machinist's Calculator for the Holidays

Jon Titus

December 17, 2012

As a technical guy, I like to repair things and make new things. My home shop includes tools for woodworking and metalwork projects. I love to get in the shop and smell the cutting oil, Thread-Magic fluid, and freshly cut wood. My shop has several wall charts that list hole diameters, drill sizes, corresponding tap-and-die information, and metric and English measurements, and I refer to them often.

But usually I must grab a calculator to figure out cutting feed speeds, perform metric-to-English conversions, make trigonometric calculations, and so on. So an advertisement for the Machinist Calc Pro from Calculated Industries caught my eye. The handheld calculator should be a hit with mechanical and mechatronic engineers, as well as hobbyists who enjoy making metal chips and swarf on lathes and milling machines in their shops.

This calculator computes speeds and feed rates for milling, turning, and drilling: cutting speed, spindle speed (RPM), feed rate (inches/minute), cutting feed, etc. Built-in drill and thread size tables (in inches and metric dimensions) will keep you from running to a wall chart or reference handbook. You can even enter the cutting angle and drill size to calculate the drill point cut depth. Key in numeric, fractional, or metric thread or drill sizes, and the calculator displays data for a tap, a roll tap, close and free-fit drill sizes, plus pitch, major, and minor diameters. (A roll tap deforms metal to form threads, while a regular, fluted tap cuts metal to form threads.)

The calculator also performs basic math calculations and unit conversions. If you want to add dimensions, for example, you can mix units such as 12.5 inches, 58mm, 5.25 inches, and so on. You also can choose the resolution for the results on the LCD. If you need trig and inverse-trig sine, cosine, and tangent operations, the calculator provides them.

Calculated Industries has an interesting history. The two founders started in real estate careers and realized they needed a way to perform standard property and financial calculations. Though a large calculator company had a similar product, the founders decided in 1978 to create and customize their own dedicated real estate calculator and sell it to other real estate and financial professionals. Over time, their company expanded its line to include calculators for construction, pipefitting, estimating, and machining. You can buy a KitchenCalc Pro-Master Chef to convert kitchen measurements and scale recipes up or down. I already have a Quilter's FabriCalc calculator for Mrs. T on my Christmas list.

Click here to download the calculator's 70-page instruction manual and watch eight short videos that show what the calculator can do. The Machinist Calc Pro sells for \$79.95 and would make a nice gift for the mechanical gal or guy on your holiday list (hint, hint).

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