# Purpose of oversized bits?



## Tskm (Jun 28, 2009)

I just joined the forum. Originally, I posted the following post in my "Introduction Posting", and then realized this might be a more appropriate forum. Hope you can answer this form me.
Thanks

"Hi,

I just registered to the Router Forum. I am a novice woodworker, but look forward to learning more from the forum's members. And I have a couple of questions for you already.

1. What is the common dado cut application for a 25/32" straight router bit?

I understand why there are undersized straight router bits for making dado cuts. It is because plywood is typically undersized (by 1/32") from its nominal size. But what I don't understand is why there are over sized router bits. Where it is 1/32" LARGER than the nominal size. Furthermore, it seems these oversized bits are more commonly found than the undersized ones. I have found them at Home Depot and Lowes, but was unable to find the 23/32" (needed for making dado cuts in nominally sized 3/4" plywood) size bit.
I was surprised by this.

2. I am told the Freud makes quality router bits. What other manufacters are in the same league as Freud? Is Whiteside?

Thanks (in advance) for your feedback.

Tom (aka Tskm)"


----------



## Hamlin (Dec 25, 2005)

Hi Tom,

If you're after bits for plywood, I suggest you take a look here: MLCS straight router bits You'll find the size(s) you're needing. 

Whiteside is tops, there are others that hold their own with them, Katana and Freud are among them.

Hope this helps.


----------



## BigJimAK (Mar 13, 2009)

Tom,

I too am a novice but the first use that comes to mind to me would be to dado solid 3/4 wood into other solid wood (as in a bookshelf) to leave room for glue and a squash for expansion due to humidity (cross-grain glued into long grain).

How about it, gurus? How close is my answer?

Jim


----------



## Tskm (Jun 28, 2009)

BigJimAK said:


> Tom,
> 
> I too am a novice but the first use that comes to mind to me would be to dado solid 3/4 wood into other solid wood (as in a bookshelf) to leave room for glue and a squash for expansion due to humidity (cross-grain glued into long grain).
> 
> ...


Jim

From what I have read, the dado should be no wider than the thickiness of the shelf. Hence the 23/32 for 3/4" plywood.
(I built some shelves for my garage, using plywood and the full 3/4" straight bit, and it seemed to work OK for that kind of project. I really loaded up with the glue to help fill the gaps. So, it was a bit more messy than if I had a 23/32" bit (I have since ordered one).

Your comment may well be on the mark. I was just sharing what I have read in a number of publications. Thanks for taking the time to tell me what you thought.

Tom


----------



## Mike (Nov 22, 2004)

If you think about the way so much of todays furniture is built the oversize reason will jump out at you. The extra 1/32" is to allow for high pressure plastic laminate.


----------

