# Finger joint blade vs. Dado blade



## egeorge1 (Dec 18, 2009)

Is there any advantage of getting specific finger joint blades over just using a dado blade set?


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## Gene Howe (Feb 28, 2009)

Don't know. Maybe because some dado blades won't give you a true flat bottom. Mine does. Not sure of others. At any rate, I like routers for box joints.


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## egeorge1 (Dec 18, 2009)

Gene Howe said:


> Don't know. Maybe because some dado blades won't give you a true flat bottom. Mine does. Not sure of others. At any rate, I like routers for box joints.


Why is it you prefer a router?

I am actually comparing Forrest blades. I believe they both create a true flat bottom.


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## knotscott (Nov 8, 2007)

Most dado sets have beveled teeth on the outside cutters that protrude slightly above the flat rakers used on the inside chippers. These are what leaves the tiny grooves along the edge, aka "bat ears". The better sets minimize the depth of the bat ears by alternate flat top teeth with the beveled teeth, but very few cut perfectly flat bottoms, though they're flat between the bat ears and are often mistaken for "perfectly flat". The beveled teeth have less tearout and are much more suitable for crosscut grooves. Dado sets are also nearly infinitely adjustable between 1/4" and 13/16". I believe the Forrest, Freud, DeWalt, Infinity, Systimatic, CMT, Amana, and others have the beveled outside teeth, but there are some that have all flat outside teeth and will leave a truly flat bottom. 

The box joint sets typically have limited fixed sizes with a max of ~ 3/8". They have all flat top teeth, so they do leave truly flat bottoms but are more prone to tearout if you crosscut, and obviously are limited to their stated widths. 

If you do a lot of box joints, it might be worth getting a set, but they don't offer the versatility of a good stacked dado set.

You can see both beveled and flat top teeth of the outside cutters in this pic...especially near the top of the rear outside cutter:


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## egeorge1 (Dec 18, 2009)

Thanks for the input. So if I understand correctly it sounds like as long as the dado set creates perfectly flat bottoms, there is not much reason to get the more limited finger joint set unless you have no need for the versatility and want to save some money over a more expensive dado set. According to Forrest, their Dado King dado set does indeed produce perfectly flat bottoms so for me I think it will be the best option.


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## Gene Howe (Feb 28, 2009)

egeorge1 said:


> Why is it you prefer a router?
> 
> I am actually comparing Forrest blades. I believe they both create a true flat bottom.


For my equipment, it's just easier to set up. Plus, the jigs I made are for the table router. Just never got around to making one for the saw.
As far as the cut is concerned, I can't see much difference in the methods.


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## knotscott (Nov 8, 2007)

egeorge1 said:


> ... According to Forrest, their Dado King dado set does indeed produce perfectly flat bottoms so for me I think it will be the best option.


The phrase I'd question Forrest on is "perfectly flat"....ask them to define it. As long as their outside cutters have beveled teeth, there will be minor grooves along the edge that are deeper than the main trough cut by the flat teeth of the inside chippers. This is normal and common for most good dado sets...it may even look flat from a glance, but it's not "perfectly flat" as long as there are tiny grooves from the outside cutters. Can someone with a Dado King confirm that at least some of the teeth on the outside cutters are beveled from the outside in? The good news is that most are small enough that it barely shows and causes discussions like this one!

Here's a quote from an owner review on Amazon that sums it up as well:

_"The review below notes that the bottoms of the dado are 'not flat'. Even though he still gave it four stars, I think it's important to note that this is normal for the Forrest and was not a defective blade. The ouside blades have a scoring profile on alernate teeth that does give tiny 'batman ears' at the each corner, when the dado is viewed on end. This is why the set cuts so well in lamanated materials. But it's true that when making box joints and the like, where the profile of the dado is exposed, they will be visible. "_


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## egeorge1 (Dec 18, 2009)

knotscott said:


> The phrase I'd question Forrest on is "perfectly flat"....ask them to define it. As long as their outside cutters have beveled teeth, there will be minor grooves along the edge that are deeper than the main trough cut by the flat teeth of the inside chippers. This is normal and common for most good dado sets...it may even look flat from a glance, but it's not "perfectly flat" as long as there are tiny grooves from the outside cutters. Can someone with a Dado King confirm that at least some of the teeth on the outside cutters are beveled from the outside in? The good news is that most are small enough that it barely shows and causes discussions like this one!
> 
> Here's a quote from an owner review on Amazon that sums it up as well:
> 
> _"The review below notes that the bottoms of the dado are 'not flat'. Even though he still gave it four stars, I think it's important to note that this is normal for the Forrest and was not a defective blade. The ouside blades have a scoring profile on alernate teeth that does give tiny 'batman ears' at the each corner, when the dado is viewed on end. This is why the set cuts so well in lamanated materials. But it's true that when making box joints and the like, where the profile of the dado is exposed, they will be visible. "_


It would be interesting to see a photo example of this.


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