# Cutting a dado with a router bit



## jnbrown (Apr 14, 2013)

Am I correct in thinking if I buy a "dado router bit" with a bearing I can just use the bearing against a straight edge and not have worry about using the edge of the router base and how far the edge of the router base is to my cut?
Is there any reason to do otherwise? I will be using to cut half lap joints in western red cedar.


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## jw2170 (Jan 24, 2008)

Hi Joel, that idea will work but there are several points to watch.

1. Ensure the straight edge is wide enough for the router base to ride on without tipping (say a 6" wide strip of MDF).
2. The cutter length must be short enough so that the bearing is riding on the straight edge and still does not cut too deep into the workpiece (you may need to make the straight edge taller).
3. This method of cutting half laps is demonstrated by Pat Warner in his video, "The versatile Router".


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## harrysin (Jan 15, 2007)

jnbrown said:


> Am I correct in thinking if I buy a "dado router bit" with a bearing I can just use the bearing against a straight edge and not have worry about using the edge of the router base and how far the edge of the router base is to my cut?
> Is there any reason to do otherwise? I will be using to cut half lap joints in western red cedar.


If you intend to rout many dado's over time then it would pay you to make a jig, possibly like this one of mine which uses a straight non bearing bit, preferably a plunge bit which has an extra blade at it's bottom, also a template guide. Because you haven't completed your public profile I'm having to assume that you have some experience using routers and that you have a good basic knowledge of general wood-working. Armed with this information, members will be in a position to give you all the help that you may require.


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## geoff_s (Apr 14, 2012)

I've used top bearing bits for dados but find them a little difficult as you need to do a full depth cut as opposed to being able to plunge into the cut.

I'm currently making the exact width dado jig from the Wood Whisperer.


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## neville9999 (Jul 22, 2010)

harrysin said:


> If you intend to rout many dado's over time then it would pay you to make a jig, possibly like this one of mine which uses a straight non bearing bit, preferably a plunge bit which has an extra blade at it's bottom, also a template guide. Because you haven't completed your public profile I'm having to assume that you have some experience using routers and that you have a good basic knowledge of general wood-working. Armed with this information, members will be in a position to give you all the help that you may require.


Harry were you not talking about being old a few weeks ago? Well old you may be but you are also wise as this is the way to do trenches if you have a few to do, even if you don't have that many to do then still make a jig as it will be there hanging on the wall the next time you want to do a trench, you all should know how much I like jig making and I like this one as well. Neville


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## harrysin (Jan 15, 2007)

"Harry were you not talking about being old a few weeks ago"
Which post are you referring to Neville" ?

My avatar as I've said previously was taken soon after colour photography was invented, I use it to cheer myself each time that I post on this forum.


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## jnbrown (Apr 14, 2013)

geoff_s said:


> I've used top bearing bits for dados but find them a little difficult as you need to do a full depth cut as opposed to being able to plunge into the cut.
> 
> I'm currently making the exact width dado jig from the


So if I understand the rabbet cut in the rails compensates for the guide bushing on the router? So you just set the rails to the exact position and width you want? Also won't the the router be cutting through the jig at the end of the work piece?
I need to remove a lot of wood, 5.5" x 5.5" x .875" twice for each joint. What router bit (brand and model #) would be best for this.
Also if I am just doing through dados then I don't need a plunge router or do I?

Thanks


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## jw2170 (Jan 24, 2008)

Hi Joel, I just saw the dimensions of your half lap.

To support the router over that width, I would use a set of skis. Or a dado jig similar to Harry's, moving the jig after each pass?


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