Odd Size Dado?

[drw]

The plans for my current project call for boards (red oak) to be dimensioned to 1" thickness. However, in order to get flat boards I had to mill the rough-cut lumber to a dimension slightly less that 1", specifically 3/32". In the big scheme of things this shouldn't be too much of a problem, however, I am not sure of the best way to cut dadoes for this odd dimension. My preference is to cut them with a router bit, since the size of the boards makes use of dado blades on a TS a little awkward. I have a 1" dado bit, but I do not have a 29/32" bit. Are odd bit sizes even available? If not, what is the best way to cut odd size dadoes?

Thank you!
Donn

 

[zapdafish]

http://www.bridgecitytools.com/Products/What's+New/KM-1+Kerfmaker

I got one of these and love it, since we are so close I can loan it to you if you want to go the tablesaw route

 

[Mike Davis]

Make a jig that allows you to use a smaller bit and cut each side of the dado in two passes.

 

[Bas]

The plans for my current project call for boards (red oak) to be dimensioned to 1" thickness. However, in order to get flat boards I had to mill the rough-cut lumber to a dimension slightly less that 1", specifically 3/32". In the big scheme of things this shouldn't be too much of a problem, however, I am not sure of the best way to cut dadoes for this odd dimension. My preference is to cut them with a router bit, since the size of the boards makes use of dado blades on a TS a little awkward. I have a 1" dado bit, but I do not have a 29/32" bit. Are odd bit sizes even available? If not, what is the best way to cut odd size dadoes?

Thank you!
Donn

What Mike Davis said. Or, if you don't want to make a jig and typically route using a straightedge, simply rip a strip of wood 5/32" wide. Clamp the straightedge and tape the strip of wood to it. Route using a 3/4" bit. Next, remove the strip and make a second pass.

Joe Scharle has a nice jig for this kind of application:

 

[Canuck]

Joe Scharle has a nice jig for this kind of application:

+1

Great application for Joe's router jig!!!:icon_thum:icon_thum:icon_thum:icon_thum

Wayne

 

[drw]

Thanks to all of you for your quick responses and insights. I figured that some sort of jig was the solution to my dilemma, but I was concerned that I may be overlooking something. Once again, thank you!

Cheers,
ccasion1
Donn

 

[bluedawg76]

Alternatively, you could rout 3/4" or 7/8" dados and then cut shallow rabbets on the mating boards.

Sam

 

[Charles Lent]

Or you could set up your dado blade for a slightly smaller dado and then add shims between the chippers to get the width correct. Even a thin cardboard shim works for this.

Charley

 

[FredP]

The beauty of Joe's jig is that there is almost no figuring involved. you simply set the shelf in the jig and close it to the shelf. lock it down, clamp it to the work piece and route. one jig fits all.:icon_thum:icon_thum

 

[Joe Scharle]

Donn, I'll be glad to help if you want. This is a busy w/e for me. Youngest daughter's graduation was today and commissioning ceremony yesterday, comes with a full schedule. Call tomorrow if you'd like some help.

 

[ehpoole]

I would route a 3/4" dado then advance my fence/guide 5/32" and make a second pass for a 29/32" dado. If you are close to an end you could also use a precision edge guide for your router to set these offsets or, for something towards the interior, do as I do below.

I find the plastic Handi-Shims that Woodcraft sells very handy for this sort of offset since they include shims for 1/32", 1/16", 1/8", and 1/4" which makes setting up offsets of 1/32" or more very easy. I also use some heavy watercolor paper and charcoal paper for 1/128" and 1/256" shims. I'll secure a clamp behind each end of my fence/guide and simply insert the proper arrangement of shims in between each clamp and the fence/guide. I then clamp the fence/guide in place (with the shims in place to fix the offset) and make my second pass.