Boy, Bob and I have been disagreeing on everything today! First raised panel bits and now sharpening! 
But, hey, that's okay... after all we're all here to share experience and (hopefully) learn something new.
I'll tell you my dirty little secret.... I sharpen router bits all the time. I have 100's of both steel and carbide tipped bits, some that are over 30-years old, that have been sharpen numerous times with seemingly no ill affects.
There's an article I read a few years ago that gave estimates for how long you can expect bits to stay sharp, carbide outlasted steel but probably not by the factor you'd expect and carbide itself was only good for a few hundred linear feet... now, there are a lot of dependences on something like that such as wood density, feed rate, etc. but it's quite easy to route a couple of hundred linear feet a day... 4x around a 4'x'8 sheet and you're right at 100 lf.
The current brand of bits I've been buying are Bosch, primarily because they 'feel' sharper out of the package than some other brands I've tried recently and partly because they seem to stay sharper longer, another plus is that I can easily purchase them at my local Lowes.
As you probably already know, when you put a new bit in the router, you know it, it just feels like it cuts with no effort at all. However, once I feel the bit start to lag I don't hesitate for one second to give it a sharpening and return it to the just-out-of-the-box feel.
For the steel bits I do them on a fine grain sharpening stone (just like I do chisels) a few drops of oil, a few stokes on each flat side and sharp as ever.
The same for carbide bits, except that they get sharpened with a small, very-fine diamond file. Again, a few strokes on the flat surfaces and the bit is as sharp as new.
At the grits we're talking about here it's a process that's probably closer to polishing, but it does it job and produces a keen edge. I try to use the same pressure and same amount of strokes on all surfaces to keep the original balance, but again, we're removing so little material it's doubtful it'll make any difference one way or the other.
Does it change the original diameter? Well, sure... but, we're only talking a few thousandths of an inch with each sharpening, if even that, plus you'd have to remove a lot of material, a lot more than these fine grits can remove in a few strokes for it to really make a difference. And for bits like round overs, roman ogees, coves, etc. +/- 1/16" makes absolutely no difference at all.
There are some bits I don't sharpen, like spirals, and the only reason I don't is that I haven't found a file with a small enough cross section to fit the spiral profile.
Now, just because I sharpen router bits doesn't necessarily mean that you should... only you can judge for yourself if that's something you feel comfortable doing. I have been doing it for over 30-years and I have never encounter any problems, even with bits that have a critical diameter/dimension; I sharpen rail/stile, dovetails and straight cutters all the time and never experienced a problem with fit... maybe I'm just lucky or maybe my work is so sloppy I can't tell the difference!
Just my 2-cents, you mileage may vary, not affiliated with any of the mention brands, etc., etc.
But, hey, that's okay... after all we're all here to share experience and (hopefully) learn something new.I'll tell you my dirty little secret.... I sharpen router bits all the time. I have 100's of both steel and carbide tipped bits, some that are over 30-years old, that have been sharpen numerous times with seemingly no ill affects.
There's an article I read a few years ago that gave estimates for how long you can expect bits to stay sharp, carbide outlasted steel but probably not by the factor you'd expect and carbide itself was only good for a few hundred linear feet... now, there are a lot of dependences on something like that such as wood density, feed rate, etc. but it's quite easy to route a couple of hundred linear feet a day... 4x around a 4'x'8 sheet and you're right at 100 lf.
The current brand of bits I've been buying are Bosch, primarily because they 'feel' sharper out of the package than some other brands I've tried recently and partly because they seem to stay sharper longer, another plus is that I can easily purchase them at my local Lowes.
As you probably already know, when you put a new bit in the router, you know it, it just feels like it cuts with no effort at all. However, once I feel the bit start to lag I don't hesitate for one second to give it a sharpening and return it to the just-out-of-the-box feel.
For the steel bits I do them on a fine grain sharpening stone (just like I do chisels) a few drops of oil, a few stokes on each flat side and sharp as ever.
The same for carbide bits, except that they get sharpened with a small, very-fine diamond file. Again, a few strokes on the flat surfaces and the bit is as sharp as new.
At the grits we're talking about here it's a process that's probably closer to polishing, but it does it job and produces a keen edge. I try to use the same pressure and same amount of strokes on all surfaces to keep the original balance, but again, we're removing so little material it's doubtful it'll make any difference one way or the other.
Does it change the original diameter? Well, sure... but, we're only talking a few thousandths of an inch with each sharpening, if even that, plus you'd have to remove a lot of material, a lot more than these fine grits can remove in a few strokes for it to really make a difference. And for bits like round overs, roman ogees, coves, etc. +/- 1/16" makes absolutely no difference at all.
There are some bits I don't sharpen, like spirals, and the only reason I don't is that I haven't found a file with a small enough cross section to fit the spiral profile.
Now, just because I sharpen router bits doesn't necessarily mean that you should... only you can judge for yourself if that's something you feel comfortable doing. I have been doing it for over 30-years and I have never encounter any problems, even with bits that have a critical diameter/dimension; I sharpen rail/stile, dovetails and straight cutters all the time and never experienced a problem with fit... maybe I'm just lucky or maybe my work is so sloppy I can't tell the difference!
Just my 2-cents, you mileage may vary, not affiliated with any of the mention brands, etc., etc.
