Router Bit Speed
posted on January 24, 2007 by Rockler

What's the best router speed for a given router bit? It’s not always the manufacturers recommended maximum.  Maximum speeds can be used as a guideline, but the actual performance of any bit will always depend on a number of factors - speed is just one. Below, in answer to a Woodworker's Journal eZine reader's question, two expert woodworkers expand on the conditions that make for a good router cut:

Q. Are there better guidelines for determining router speeds than those provided by the manufacturer in the owner's manual? (This particular woodworker didn't think the recommended speeds produced good results.)

A. (Rob Johnstone) "With very large router bits, you need to slow down the RPMs for safe cutting. Smaller bits should spin faster (for more information on large bits, check out Woodworker's Journal, April 2000, page 66). But this is a complex question and without more information, I wonder if the poor results were due to the speed settings per se. Manufacturers' recommendations are the correct place to start. Then, if experience tells you all is not working well, make your bit speed adjustments.

There is a relationship between bit speed, sharpness and feed rate (the speed at which you move the bit through the wood or the stock across the bit) and how well your bit cuts, as well as the characteristics of the individual piece of wood you are working with. So to suggest that a specific speed setting would solve this problem is questionable. The correct answer, as with much of woodworking, is to start with the recommendations and make adjustments if all is not working well."

A. (Ian Kirby) "The answer to the question lies in this particular woodworker's thoughts or experiences. The results of all wood machining are related to cutter speeds, depth of cut, feed rate and hardness of the stock. And all of these assume that the setup of fences, guide blocks and holddowns are correctly in place. Good results come from the totality; picking out one link in this chain doesn't make a strong chain. Put the parts together as you think appropriate and then begin the task of methodically improving the processes if improvement is needed. That's the most important guideline."

From the Woodworker's Journal eZine archives

Manufacturers don't always agree on top speeds for router bits of a given diameter, and as mentioned above, there are other factors to consider. For a rough guide, here's a typical maximum router bit speed chart:

Router Bit Diameter Maximum Speed
Up to 1" 22,000 - 24,000 rpm
1" to 2" 18,000 - 22,000 rpm
2" to 2-1/2" 12,000 - 16,000 rpm
2-1/2" to 3-1/2" 8,000 - 12,000 rpm

Remember, that's just a reference; Always follow manufacturers recommendations and the sage advice that if something doesn't feel like it's working right, there's a good chance that it isn't. Better yet, pick up a Router Book and get to know your router inside and out. Or, for a beginning-level overview of router bits, read Rockler's article "Router Bit Basics".

posted on January 24, 2007 by Rockler
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Comments

5 thoughts on “Router Bit Speed”

  • Stanley Wiedmwyer
    Stanley Wiedmwyer May 31, 2009 at 1:21 pm

    what do you if you only have a single speed router ?

  • John Schaben

    I understand the guidelines for speed relating to bit diameter but I have not seen any mention about speed relative to bit cutting length?
    I am pretty new to routing but I have a couple of bits with a 3" cutting length that I ordered for a, hopefully, one time project. I got through the project ok but I intuitively reduced the router speed somewhat. Just seemed like that was an awful lot of steel flying around out there.

  • Rockler Blog Team
    Rockler Blog Team June 1, 2009 at 6:05 am

    Good question Stanley. Single speed routers are usually set to run at the high end for the RPM scale, which makes sense since they tend to be lower horsepower routers that wouldn't be suitable for large diameter bits. They're great for small-diameter edge forming bits and making 1/2' and 3/4" dadoes, etc. but not really intended for "big" routing jobs.

    A variable speed router with enough horsepower to drive large bits is really the only answer if you want to raise door panels, make large pieces of molding, etc.

  • Rockler Blog Team
    Rockler Blog Team June 1, 2009 at 6:06 am

    Thanks for the comment John. As both Rob Johnstone and Ian Kirby mentioned above, there are a number of variables - sharpness of the bit, hardness of the stock, rotation speed, depth of cut, and feed rate - along with other factors, such as whether the bit is well balanced, the condition of the router bearings, router horsepower, etc. So it's hard to offer a by-the-numbers approach that fits every situation.

    The more cutter area the bit has, the more force it takes to make each lineal inch of the cut. So with a tall narrow bit, it makes sense and feels more comfortable to slow the bit down and use a slower feed rate. If the bit speed and feed rate are too slow, however, you may have trouble getting a good cut with no burning. Making a few test cuts is the best way to find a good balance of comfort and quality.

    Assuming everything is set up correctly and functioning well mechanically, the most likely mistake would be trying to take off too much material at a time. If the bit is the kind that removes a lot of material - such as a molding bit that makes deep cuts into the wood - making the cut in several passes can greatly improve both the quality of the end results and the comfort level of the operator, even if it takes a little longer.

  • Dennis Brown

    I'm trying to find recommendations for bit speeds related to wood hardness. I use wood from poplar and pine to purple heart and oak.

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