Roundover Router Bits

[Jerry Bittner]

I have accumulated a few roundover router bits and the other day I was working on something that required a 3/16" roundover. I know I have one but I also have a 1/4" , etc. Of course I knew what I had when I bought them butnow, unboxed, I don't see any identification markings on them.

Question is how do you measure the bit to know exactly its dimension?

[Mark Singer]

Jerry,
The bit is usually dimensioned by radius...so 1/4 " is from the center of arc to the edge of cutter....which is the same as the edge of cutter to horiz distance on far edge of the cuttter on the opposite side

[pat warner]

A good bet on the radius of round over bit:
(Diameter of cutter - .5)/2 = radius of round over. Applies to 1/2" bearing guided tool only.

Routers (http://www.patwarner.com)

[Al Killian]

I am not sure how to measure them. What I do is use a wood burning tip and mark the space below each bit for quick reference. One of my freinds takes a small saple of his molding bits ona glues it above them for quicker searching. This might help instead having to measure them every time you need one.

[Gary Keedwell]

If it fits snug on a 3/8 ths drill bit shank...it is a 3/16" roundover bit also called a radius bit.

Gary K.;)

[glenn bradley]

Gary has the idea. very little room for error using that method. 1/2" drill has 1/4" radius, 38" drill has 3/16" radius, 1/4" drill has 1/8" radius, etc. this is a lot tuffer with ogees (joke).

[Charles McCracken]

High quality roundover bits have shear angles and are difficult to measure with a drill bit or drill rod. Measuring the overall diameter and bearing diameter is a better methid of determining the cut radius:

Cut Radius = (Overall Diameter - Bearing Diameter) /2