Issues Cutting Dovetail Dados with Table Router

Dave, ever make bread dough? When the dough is too wet it sticks and pulls when you try and cut it. When it is dry enough it cuts cleanly. Wood works much the same way. Pine is full of moisture and resins, both things that encourage tear out. In a perfect world we would all have wood that is nicely aged and naturally dry enough to get excellent results every time. In the real world there are steps you can take to ensure better results. Here are some general ideas that should help: Make sure your bit is clean and sharp; remove any resin build up with a solvent such as mineral spirits; examine the cutting edge for nicks or dull spots. Run a small bit like this at top speed using a steady motion as you pass the wood over the cutter. Try Ed's idea of making a straight cut first to remove the bulk of the wood, then follow up with your dovetail bit.(This is the same as making a rabbit cut in multiple passes so no more than 1/4" is removed at a time.) To reduce tear out use a backer board. This is just a piece of scrap used to push your wood across the cutter. It gives support so the wood is less likely to chunk away. Give your wood a chance to get used to your shop before working with it; a couple weeks is a reasonable rule of thumb. Remember that no matter how careful you are, there is always that piece of wood lurking out there ready to twist itself out of shape when you show it your cutting tools.

Thanks for the info everyone.

Just to clarify. The bit is new, the photos were of the first several cuts made with it.

I increased the speed, and changed the depth. Still seeing a little fraying, but I have it to the point where I can knock it off by just running my fingers over the cut a couple of times.

Other than my pitiful table saw skills, the first book shelf is coming along nicely. I have all the dados cut for the sides, the top and bottom shelf are dovetailed. Just have to cut to size 2 more shelves (dangit) and dovetail them.

I do have another issue.

The router table I have is 18"x27" and still seems too small of a workspace to do much with. The furthest from the fence touching side of a piece of wood I can go for making a cut is 3 inches. That worked okay for the top and bottom dados, but for the 2 middle shelves I had to pull the router out of the table and do them hand held. I was looking around today for an extension table or something. Everyone I mentioned it too gave me a look like I was asking them for banana soaked in motor oil. Basically I'm wondering if anyone makes an aluminum table (like the Bosch router tables) with all the slots for fences and table saw miter gauges (I have the same issue with the table saw, the fence will only go out to 12"), that can be secured the main table. Has anyone heard of such a thing?

Thanks again,
Dave

Hi Dave

The router table is always to small when it comes to case work or a book case.

The jig below works best for me, it will put in a dovetail, dado or rabbits.
I use a 23/32" bit for the dado most of the time (for 3/4" plywood).

It's a quick and easy jig to make and it's true, just clamp the bar down and drop on the router or push with the dovetail bit in chuck.

The clamp you can get from just about any home center like ( Home Depot ) and others the key to this one is the Alum.bar on the side of the router base it must fit in to the slot on the clamp and move free but stay true.

I also made one for my power hand saw (6" bearcat) to cut up the nasty 4' x 8' plywood that's hard for one guy to move over a table saw and keep it true.

Saw jig below
http://www.routerforums.com/27897-post17.html

Hope this helps
Bj

Your Welcome Dave

I just Posted a how to make a mortise jig of the forum.
It's a easy jig to make and it works .
"clamping a second piece of wood " down will work but you will get drifting issues but the jig will fix that.
I clamp all the stock I need to make a book case to the work bench and then cut all of them at one time ,in this way they all line up when you go to put them in place.
Sliding Dovetails can be a pain if they don't line up right on the button as I'm sure you found out by now, they can't be off a 1/16 like the dado.
The jig will keep them true.... and they can't drift off because the jig is in the rail of the clamp.
Just a note:: you can get the alum.stock when you get the clamp and then check it to make sure it fits the slot, the one I found was a 1 1/2" x 1 1/4" in the junk box under the work bench for a equipment bracket ,I also found some in a old alum. lawn chair that worked out just right for the power hand saw.

Have a good one.

Bj

I made a "saw guide" out of 1/4" MDF and aluminum angle stock. I have a 4 footer and 6 foot and I can see where you'd want an 8 foot at some point.

Measure your saw plate from the blade to the edge of the plate. Do this on the saw plate's WIDEST section. Let's say this measurement is 4 inches. Cut a strip of MDF. How wide? Let's say you're using 1" aluminum angle. So now you have 4" of plate, plus 1" of angle. Add an inch. You're now at 6 inches. Cut your MDF that wide. Length depends on how long your angle stock is. Now fasten the angle to the strip of MDF. I use screws UP through the MDF with washers and nuts on top. Kinda like this:

Not sure how that looks but you get the idea.

Now if you set the wide side of your saw plate on this thing, well the MDF is too wide!
That's exactly right.
Now clamp it to the edge of a table so you can saw THROUGH the MDF without cutting your table.

This should cut off a strip about an inch wide (remember "add an inch"?).
You now have a guide that you can set right at your cut line. You clamp this to the "keeper" side and run your saw plate against the angle stock.

This will reduce your maximum depth of cut by 1/4" (the thickness of the MDF), but for panels that's usually not an issue.

This falls into my "It Ain't Fancy, But it Works" category. I got this tip from an older fellow in the neighborhood where I use to live. He made cabinets and furniture of all kinds.

I use things like this because I often find myself in a position where... it's just hard to justify spending ANOTHER $25 to $50 on something I may only use once or twice.

Now... if I found I was going to be cutting panels OFTEN... then one of the store-bought guides would be in my shop in a heartbeat.

Just some show and tell snapshots.

Power Hand Saw with Jig to hold it true and sq. with the hold down clamp in place

Bj