How sharp is a carbide router bit?

[will sanders]

Okay, bought a couple of used Whiteside carbide insert straight router bits the other day ( 5$ a pop sounded good) and need to know, how sharp should the inserts feel?Reason I ask is that I tried to make a dado in some scrap pine and it really struggled.If they are dull it will cost $3 each to get sharpedned so I guess that $8 bits are all right.
Thanks

[Gary Keedwell]

Will....How big was the bit and how deep did you go with it?

Gary K.

[will sanders]

1/2 inch and tried about 1/2 inch.

[Blaine Harrison]

A couple of (perhaps random) thoughts here:

• A new 1/2" Whiteside straight bit is going to cost more than $8 new. By all means, you got a good deal and keep the bit (or send it to me for disposal ).
• You are probably pushing the bit to its limits by taking a 1/2" dado/groove with the bit, even in a soft wood like pine. A rule of thumb that I've learned is to go no deeper than the width of the bit.
• To what are you comparing the performance of this bit? In other words, are your expectations appropriate? (Not questioning you on this one.)

Good luck with this. It sounds like you've done well.

Blaine

[will sanders]

No expectations. This is my first time using a router at all. I am trying to learn and wondering if what I am seeing is right. What I need a "Routers for dummies" book!

[Jim Becker]

Routing a groove or dado like that, even with a brand new cutter should be done in multiple passes. I typically take only about 3/16" or so in a pass and make the last one at precisely (presumably... ) the correct depth to clean things up.

[glenn bradley]

I follow the rule of thumb; remove no more than a 3/8 by 3/8 area at a pass. So, in my book I would make no deeper a pass with a 1/2 bit than 1/4 deep. I generally back this off to 1/4 by 1/4 unless the cut or time limits demand it. Just MHO.

[Robert E Lee]

Will, take the bit out of the router and scrape the bit along your thumb nail and it should cut your nail if it is sharp.
Bob

[Tom Walz]

Edge radius on properly sharpened tools
standard carbide
10 – 18 micron .0004” to .0007” (4/10,000 – 7/10,000)

micrograin carbide
8 -12 micron .0003” to .0005” (3/10,000 – 5/10,000)

cermet
3 – 4 microns .00012” to .00016” (12/100,000 – 16/100,000)

razor blade .000003” (3/1,000,000)

Look for a shiny edge which indicates wear.

Slide it down a smooth finger nail and see at what angle it grabs. (Start at about the middle of the nail and slide it towards the outer end.)

See if you can shave a bit off your fingernail.

Note: Go at these tests gently.

[Scott Whiting]

If it is an insert bit it is not designed to be resharpened. You buy boxes of inserts (10 per box) and just replace them. Inserts are either 2 or 4 sided so you can turn them at least once before replacement. I know this doesn't answer the question about sharpness but that is a hard thing to teach a feel for in print.

[will sanders]

I mispoke about the bit being an "insert" it is just a regular carbide bit. Thanks for all the advice.