Dado's with a Router?

[Canuck]

Hi All,

Need some advice. I have not yet invested in a dado set for my tablesaw and continue to depend on my using my router for cutting dado's. My latest undertaking is a cabinet to house my new compressor and bench grinder and I attempted to use the router for the shelf dado's. I am using 3/4" plywood that of course is not exactly 3/4" - just a wee bit less, hense my joint is sloppy when using a 3/4" straight bit in the router. Do you know of a straight router bit that I could use in this application? (I seem to recall seeing something in a magizine by CMT (i think), but am not sure if that is what I need and where to get one. (I don't have the patence to use a 1/2" bit and nudge my way to the correct width of dado.)

I would appreciate any suggestions that you could send my way.

Thanks,

Wayne

[Monty]

I bought the undersized plywood bit set from Freud.



All these bits are 1/32" undersized, IIRC.


The other option, of course, is to use an adjustable dado jig with a ½" bit, in two passes.

[Canuck]

Thanks. I will check these bits out......

[D L Ames]

I have the same set by Freud, they seem to work pretty good. I wish I could have gotten them with 1/2" shanks though.

D L

[McRabbet]

Canuk,

I have a 9-piece set of bits from Woodline America that give you both undersize and oversize bits along with 1/4", 1/2" and 3/4" straight bits on 1/2" diameter shafts. They are one sale right now for $39 on their website at http://www.woodline.com/scripts/prod...?idproduct=591. I bought mine at the Charlotte WW Show last year and they work well. You can also get a 1/4" shank set for $49. While not the quality of the Freud set, they are carbide and do a good job (I always score my dado lines and tape them on plywood to avoid chipout.) I also use a 50" Tru-Grip Clamp 'n Tool Guide to guide the cut. BTW, when you do buy a dado blade for your tablesaw, I recommend the Freud SD506 (6") or SD508 (8"). They are sweet!

Rob

[Steve D]

You can make a simple set of jigs that will let you get it exactly right without "sneaking up". Below is a quick sketch:

Hopefully this will make sense with the sketch. Above is the board to receive the dado and the two jigs made from scrap. Take a straight piece of wood 3/4" x 2" x more than the length of your dado. Glue and screw that to a piece of plywood or masonite 1/4" x 6" x the length of board #1. Clamp that overhanging a bench. Put a 1/2" straight bit in your router and extend it more than 1/4". Run the router along the fence on top of the 1/4" piece. That will trim the jig to the exact width from the base of your router to the outside edge of the bit. Do the same on the second jig. Clamp jig #1 along the top layout line of your dado and then space jig #2 using a piece of your plywood in between the two jigs. Clamp jig 2 in place, remove the "spacer" and run the router (set to the depth of your dado plus the thickness of the base of the jig (1/4") along both jig fences. You will have an exact fit with a flat bottom and very simple layout. If this doesn't make sense, I'll try and post more sketches to clear up any questions.

[McRabbet]

Steve's method is a really good one and one that's very easy to implement -- but remember that you need to make a different set of these jigs if you're going to use a 3/8" bit for an undersized 1/2" dado, because the router-to-bit distance changes. But of course, all of us have plenty of scrap!!

[Steve D]

If short on scrap just call Dave O

[D L Ames]

Dave, send me some scrap so I can make one of these will you?

D L

[Monty]

Here, take a look at this, too. Same idea, just uses a bearing guided bit. Either way, the idea is to rout the groove exactly the same width as the thickness of the shelf.




Hope this helps.


You do realize, of course... now that you've received all this help, you have to show us the finished project when you're done!

[Joe Scharle]

This is a jig I made from Shopnotes plans. They have a short video on their site. It works great. I use a 3/8 spiral bit no matter what size groove I'm cutting.
Found the url

http://www.shopnotes.com/main/sn76-toc.html

Joe

[DavidF]

I like the bearing guided bit method myself

[D L Ames]

Joe, does that work with a bushing guide in the router base or a bit with a pilot bearing like Insom posted?

D L

[Charles M]

Originally Posted by D L Ames

I have the same set by Freud, they seem to work pretty good. I wish I could have gotten them with 1/2" shanks though.

D L

We are coming out with a 1/2" shank set very soon. Item number will be 89-650. Should be available within about 2 months.

Charles M
Freud America, Inc.

[Charles M]

The sets are nice to have but you can also get an individual bit for 3/4" plywood. Freud item number for the 1/2" shank version is 16-116 and 1/4" shank is 16-103.

Charles M
Freud America, Inc.