Cutting dados in 3/4" plywood

[a1gutterman]

rdewinter,

The only special thing about bits for plywood as I understand it, is for cutting the proper width. I have two bits for each of the sizes 3/4" and 1/2". One bit cuts a groove exactly 3/4" wide (or 1/2") and the other cuts the groove slightly less wide-the exact thickness of the plywood (the sizes escape me at the moment).

As far as quality, I have to agree with Ed inTampa, but put into my own words: You cannot tell how well a bit will cut until you use it. Being pricey might lead you to believe it is better, but that is not necessarily true.

I have had good luck with Viper bits, which were made by Oldham, but I have never tried Infinity, and it sounds like I should. Ed, do you have a web address for them?

You can count on having more than one project that requires these grooves. For that reason I have made sets of two spacer blocks, each set being the same length as the edge of my router base to the bit I will be using. I then clamp these blocks on each end of my work piece with one edge lined up on the edge of the cut that I want to make and then clamp a straight edge across the opposite edge of the blocks. Now I remove the spacer blocks and make my cut.

[charlese]

...Ed, do you have a web address for them?....

I'm not Ed - but here's your web site http://www.infinitytools.com/department ... YgodqXUH6w

I seem to be one of those dummies that have never heard of Infinity router bits. On the web site they look interesting - !

[charlese]

...The router solution raised a question. I've been told that plywood is death on router bits and special bits are necessary for routing plywood. Is that true? Can someone suggest what kind of bit is good for plywood. I don't want to replace the bit after minimal use in plywood.
Thanks

Naa! Never heard of plywood being death on router bits, but suppose some poorly manufactured bits would dull, or chip, or brake on almost any use.
MDF and particle board are tough on bits.

I have done as Ed, in that I started with a set of bits and replace some as they break down. (My first set was only 16 bits.) I buy any special bits individually, as needed. Although I don't use a router for most operations, I have never run across a poor bit (exception one - explained below). I prefer to buy bits with the filled in area behind the cutters - they have be marketed as anti kick back bits. Rockler bits work O.K. for me, but not for my brother-in-law. He preferrs CMT brand. It goes almost without saying that 1/2" shaft bits are much stouter than 1/4" shaft bits. (Duhh!) But the feeling with the 1/2" bits is noticeably smoother.

The one poor bit referred to was a Sears 1/2" straight cutting bit (HSS - no carbide) that came in a set of 8 bits that was given to me. It was useless after routing out a hand grip in particle board. (part of my tenoning jig). The edges of the bit were actually ground down by the particle board so it couldn't be sharpened, I have purchased other Sears bits (carbide) for rabbets and they work fine.

[a1gutterman]

I agree about using anti-kickback bits exclusively. My first experience with router bits was many years ago with a Sears set of HSS bits that I did not like one bit . I had purchased them used (but they were unused) from my grandfather along with his Craftsman router. After using these, and not liking their performance, it was a long time before I did any more routing. After I discovered the carbide anti-kickback bits, I bought a new router and 1/2" shaft bits and never looked back!:D