Dadoing 18mm Baltic Birch Ply

[Alan Smithee]

I want to dado shelves in a cabinet from baltic birch but finding an 18mm router bit is difficult. Would a19mm bit do or is that too sloppy? A 3/4 seems way too loose. What are the alternatives?

[Richard]

I was just shaping some lamp bases with my table saw and I found it to be pretty accurate. Maybe this would work for you.

[dadiOH]

Yes. It is only 0.05 less than a 3/4 bit.

Cut with a 1/2" bit twice (not the full 1/2" on pass #2).

[David]

When you need an odd size, use a shimmed dado on your TS instead of a router bit. I have about 7 sizes of ply bits and I STILL run across material that doesn't correspond with any of those sizes. Besides, I can run dados faster through the TS than by a router bit.

Dave

Alan Smithee wrote:

[Eric Tonks]

Or cut with a 5/8" bit, and cut a rabbet on the end of the shelf to thin it to 5/8" to fit the groove, for strength keep the rabbet at the top.

[SonomaProducts.com]

If you are freehanding with a router, you can make a u-shaped jig that is the width of your router base +18mm. Then you use any smaller bit that is at least 1/2 the width of the final slot (so 9mm min) and do two passes, one against each side of the jig.

18mm + router ]__[

Tip, just use a piece of the material and the router as a spacer while creating the jig.

Or, in my situation I'd use my RAS and shim a dado blade to the right size.

[Alan Smithee]

[Alan Smithee]

Ahh. Ding. A light just went on in my head. Thx.

[Alan Smithee]

I just hate using the table saw for everything but ripping. I prefer to keep my material stationary and move the tools over it rather than move the material over the tool. Doesn't always work out that way. The sides on this cabinet are also particularily large so in this case it also makes sense for my preferred workflow. I agree the table saw is usually a faster set up compared to the router. Thx.

[Lee Michaels]

Don't the rabbits get skittish around the power tools? ;)

[Alan Smithee]

No. They're heavily sedated first.

[Leon]

Use a jig like I designed. You can see the basic pictures of it at Morris Dovey's web site. It will let you use any size board to cut a dado for.

[Lawrence Wasserman]

How about 2 passes with a smaller bit?

[Lawrence Wasserman]

I like to use a tablesaw when I can, too, but it's tough when you are cutting a dado 10 inches from the end of a 6 foot 1X12 for instance.

[Alan Smithee]

Sweet!

[Robatoy]

Very functional design. *Tips hat to Leon* I'd be using bushings instead of top-bearing bits as I like the spirals down-cutting for minimum tear-out and with lots of clearance between the bushing and bit for chip clearance. Like 1" bushing and 1/2" bit. Of course, the bushing/bit combo needs to be perfectly centred...or do not rotate the router while dadoing. (My spell-checker going nuts with the word 'dadoing', just like my brain goes 'WTF?' when it sees the word barfridge.)

[Leon]

Well Thanks to Morris for posting the pictures on his web site. My first used a bushing and you must use a stepped edge on the router jig guide so that you can depend on the lower part of the step on the guide arms to reflect the true width of the board that will fit the dado. Also if you do no always perfectly center the bushing you will slowly eat away at the lower step with the bit and eventually the jig will not correctly adjust to the board that will fit into the dado. I later felt and by suggestions of others that the guide bearing on top would work out the best. IMHO it did work out best and set up time became shorter with not having to fuss with the guide bushing.

[nospambob]

[Lee Michaels]

Endless dicussions of shop wiring??

[David]

A blackout.

dave