Ripping a large hard wood timber

judaspre1982 · Post by **judaspre1982** » Sat Nov 05, 2011 10:12 pm

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paulmcohen · Post by **paulmcohen** » Sun Nov 06, 2011 12:53 am

The math works out to 2390 RPM with a 12" blade gives the same FPM as using a 10" blade at 3450. I am traveling so I don't have access to my PowerPro but I wonder if the computer had other blade sizes programmed into. I was specifically thinking of things like 6" and 8" dado blades.

BigSky · Post by **BigSky** » Mon Nov 07, 2011 9:58 am

paulmcohen wrote:The math works out to 2390 RPM with a 12" blade gives the same FPM as using a 10" blade at 3450. I am traveling so I don't have access to my PowerPro but I wonder if the computer had other blade sizes programmed into. I was specifically thinking of things like 6" and 8" dado blades.

I wonder if I could impose upon you to "show your work". I am unable to come up with those calculations.

paulmcohen · Post by **paulmcohen** » Tue Nov 08, 2011 4:55 pm

I Googled "RPM to FPM" and found several calculators. Plugged in the numbers and reported the results. I am in Mexico and don't have access to the sites I used until next Wednesday.

JPG · Post by **JPG** » Wed Nov 09, 2011 1:21 am

BigSky wrote:I wonder if I could impose upon you to "show your work". I am unable to come up with those calculations.

Distance traveled by a 10" blade vs a 12" blade = 10/12.

So 3450 x 10/12 = 2875

pi D = 3.14159 x 10 = 31.4159 in / rev

x 3450 rpm = 108,385 in/min

/ 12 = 9032 ft/min

/ 60 = 150 ft/sec

pennview · Post by **pennview** » Wed Nov 09, 2011 6:19 am

The typical arbor hole size in a 12" blade is 1", so you might have some difficulty mounting the blade on a Shopsmith without a special arbor. But you could always have one bored out to fit the 1 1/4" arbor.