Measuring router bit diameter

Talk about all things CNC
Post Reply
Posts: 244
Joined: Tue Apr 15, 2014 6:31 pm
Location: SVE - Mesa, AZ

Measuring router bit diameter

Post by woodworkerbob » Tue Aug 27, 2019 3:36 am

I cut a couple of dados on my SO3 and the width was too small. Chased the problem for a while, then I think I traced it to a router bit being slightly small. The bit is a spiral bit, 2 flute, .25 inches diameter. I measured it at about .242 to .248. Found an Amazon a "one star" review for this bit saying it was undersized and measured .242 inches

I have 2 digital calipers and both read just less than the nominal .25 inches. But I can't get a consistent reading on the bit itself. I also can't get a consistent reading measuring the width of a single pass cut with this bit.

Any good way to get the real diameter of this bit.

Shapeoko 3 - #13, dust deputy, precision collets, limit switches.

Posts: 8588
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15

Re: Measuring router bit diameter

Post by WillAdams » Tue Aug 27, 2019 12:28 pm

Best thing to do is cut a slot in a given material and measure it, and note in a notebook that that router bit in that material cuts a slot as measured.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets
Nomad 883 Pro #596 (bamboo)

Post Reply