Stupid Question

You need my handy-dandy "Speed-Feed/Smoke-Color Chart" $9.95 + S&H Visa/MC accepted

With the chart you'll always know you have the right cutting experience, just match the color of the smoke comming from your workpiece to the color swatches on the chart. But wait...there's more! For a limited time I am also including liter size samples of the right smoke for the most popular machining operations so you can make sure that you get the right aroma too. If you act today, I will also include a copy of: "My Favorite Pet Recipes" and as a special bonus: "How to argue Politics with Cliff and Gunner---AT THE SAME TIME"

Start with the number you'll use for cutting speed. A rule of thumb for HSS tools in steel is 60 sfm (surface feet per minute). Now let's estimate PI to be 3. Figure the circumference is PI*diameter which you can approximate as 3*d which of course will give you units of inches if d is measured in inches. To convert inches to feet, you divide by 12;

CIRC (feet) = 3 * DIAMETER / 12 = DIA / 4

Now you figure you get one circumference per rpm, right? And the number of feet per minute of circumference is just CIRC * RPM. Solving:

RPM = 240 / DIA

Thus, if you're turning a 1" bar in a lathe with a HSS tool, or using a 1" end mill, your RPM should be about 240.

If you bump the 60 up to 75 (probably a more realistic number) then you get

RPM = 300 / DIAMETER ;; diameter is in inches

I'm guessing this is the formula you dimly remember. Welcome back!

Grant Erwin

Tom, Would you be interested in some sort of a sub-contract deal on samples of electrical smoke?? I don't work in a machine shop so I only have limited access to those smokes, but through my electronics tech job I do have access to several different varieties of electrical smoke, ie: capacitor smoke, voltage regulator smoke, FET smoke, resistor smoke, various varieties of IC smoke and regular old generic power supply smoke. I also have almost daily access to large amounts of both supervisor and middle-to-high-level management smoke, both available in male and female varieties. You will of course need to specify smoke that came from their ears, or smoke blown up someone's ass. Equal quanities of both available...............

Tom

Tom Gardner wrote:

Found a webpage with some good Info ( and all free )

if your interested - its here

Boc

Yeahbut to use this effectively you need a henway

Gerry :-)} London, Canada

I don't like sae anymore. Metric is a heck of a lot easier. I threw out all my sae tools 5 years ago. Ever see sae tools at an auto parts store? Nothing but.....20 years after metric dominated the auto industry. The formula is: 2000.00 in snap-on metric and 30.00 in 'companion' sae. Those who know what I'm talking about know. Like urban and sub-urban mechanics.