# Router speed, bits and wood



## rjbman (Apr 18, 2017)

My 1 ¼hp router finally gave out after many many years. After doing some reading I decided to upgrade to a variable speed 2 ¼ hp (Porter Cable 892). I found a reference table which basically showed recommended speed for 1” to 2” and over. Later I read an article on rail and stile work, and it was recommended that you make 2 passes at 13000 rpm for oak for both rail and stile bits. My question. Is there some sort of reference for style of bit (i.e. cove bits) and router speed and type of wood? Or is there a general rule of thumb for hardwoods and softwoods and bits. Never owned a variable speed router before, so all this is rather new. 
If this topic has already been covered just point me to the thread. Thanks.

RJ


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## kp91 (Sep 10, 2004)

RJ,

The bigger the bit, slower the router. The harder the wood, the slower the speed/feed.

Take a test cut in scrap to see how it sounds, or if it burns. If it sounds scary, slow it down.


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## Cherryville Chuck (Sep 28, 2010)

Along the lines of what Doug said if you are getting burning it's because your feed speed is too slow or your router speed is too high. The bit is rubbing in the cut instead of removing wood. When the bit is removing wood it runs cooler. This varies from one wood to another. Maple for example is one of the bad ones for burning.


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## hawkeye10 (Jul 28, 2015)

This is what I do.


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## Stick486 (Jan 4, 2013)

this is all I have...

Here is a little math router manufacturers use when determining the all-important speed of the outer edges of bits: 
Circumference = pi X diameter
"Tangential" speed (in inches per minute) = circum X rpm
So:
1" circ. = 3.1415 * 1 = 3.1415 ---> 3.1415in * 18000rpm = 56547in/min or 4712.25 ft/min or 53.55 mph
2" circ. = 3.1415 * 2 = 6.2830 ---> 6.2830in * 18000rpm = 113094in/min or 9424.50 ft/min or 107.10 mph
3" circ. = 3.1415 * 3 = 9.4245 ---> 9.4245in * 18000rpm = 169641in/min or 14136.75 ft/min or 160.64 mph
***As you can see from the above equations, a bit 1" in diameter, moving at 18,000 rpm is traveling at 53.55 mph at its maximum diameter. Likewise, a bit of 3" in diameter, also spinning at 18,000 rpm is traveling at 160.64 mph at its maximum diameter.
***So, lets take the example of someone using a 1" diameter straight bit at 18,000 rpm and changed to a 3" diameter roundover bit but did not decrease the router RPM. This person has, in effect, tripled the speed at which the tool is spinning just by keeping their set-up constant.










..


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## chessnut2 (Sep 15, 2011)

I just now printed it and put it up, too.


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## chessnut2 (Sep 15, 2011)

Thanks, Stick. I sometimes forget about the trove of information you've shared on the forum.


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## rjbman (Apr 18, 2017)

Thanks y'all. Going to print the graphics out and post also. Will be good reminder. Also will need to 
experiment with speed/feed. 

RJ


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