# Issues Cutting Dovetail Dados with Table Router



## Gazzalodi (Apr 28, 2006)

Router - PC 892
Speed - 10000 & ~13000 RPM
Bit - Bosch 84703MC 14deg dovetail (1/4 collet)
Table - Bosch RA1180
Stock - The best 3/4" pine Lowe's has to offer... or, the only wood in the store.
Depth of cut - 1/4"

This is my first router project since highschool (25 years ago). I have started making test cuts in preparation for this project.

When making a dado cut for shelving I am seeing 'fraying' of the wood along the edge of the cut. This is only happening when I cut the slots. Cuts for the dovetails on the shelves themselves are clean and smooth. The fraying is consistant along the entire length of the cut. After a couple of cuts at 10k rpm I increased the speed to around 13k but the results were the same.

The wood that is not completely removed is easy enough to clear off with my fingers. But I would prefer to be making nice clean cuts if possible.

I have included some photos of the router table setup, the frayed dado, and a joined test.

My questions are:
A - Am I using the router incorrectly? I don't think I am. I have seen this done numerous times so I believe it is within the capacity of a router to make this cut. The case for the dovetail bit even shows a dado cut. I recall making these cuts back in the olden days, but not with a dovetail bit.

B - Do I need to be cutting deeper for the groove? I just eyeballed it.

C - Am I using the wrong speed for the wood stock? Should I be going even faster with pine?

D - Is this just a characteristic of pine? Would a harder wood provide a smoother cut?

Any advice would be greatly appreciated.

Thanks,
Dave


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## reible (Sep 10, 2004)

Hi,

In general the router should be running at it's highest speed with that size bit. The problem you're having can be due to having the bit just a little to deep... hard to tell from the pictures but you need to have a cutting edge at the surface of the wood...

If I were doing this I might opt for using a straight bit for the first cut then come back with the dovetail bit. It would help with getting rid of the chips.

Even after doing all this you may end up with the "fraying" but a piece of sandpaper on a block of wood should clean it up with one or two passes.

Ed


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## bobj3 (Jan 17, 2006)

Dave 
Just my 2 cents.
I know ED said that it was a bit to deep but I always set it for 5/16" deep but it looks like you are using a dull bit at low speed.

Pine is a pain when the stock is a bit green.(not dry)
You may want to try a New Sharp bit.

Bj


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## reible (Sep 10, 2004)

Hi,

Just went to check on the bit in question. The specs say it has a cutter length of 1/2" and from the images it looks like you are no where near a 1/2" deep so that will not be an issue....

Ed


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## Mike (Nov 22, 2004)

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.


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## del schisler (Feb 2, 2006)

aniceone2hold said:


> 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.


i made a couple wood projects out of pine that had been inside for 16 yrs and it made a mess of every tool bit and cut that i made so much pitch in it that i am done with pine del schisler


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## bobj3 (Jan 17, 2006)

Gazzalod

Here's a tip I use all the time. 

All routers and router bits have a voice ♫ ♪ ,they will tell you when they are doing the job you ask them to do.
i.e. Bits will chip at you when they have chips backing up and they need to get out,
they will also tell you when they are cutting in the stock just right.
The same is true for router motors, they will tell you that you over loading them or just working them to light or just right,it's like a new language that you need to learn.

Have a good weekend

Bj


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## Gazzalodi (Apr 28, 2006)

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


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## bobj3 (Jan 17, 2006)

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


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## Gazzalodi (Apr 28, 2006)

Thanks Bj,

I think that's what I'll be working towards, once I get a drill press. The mortise jig looks a bit intimidating though.

Right now I was just clamping a second piece of wood on top to act as a guide. Still had some drifting issues, more with the handheld saw than with the router though. I do think I need to knock out a few more bookshelves for the family first though. I was starting to get nervous looks from the wife because all the material I was buying for the bookshelf project was to expand the workshop and not actually to make the bookshelves. 

Thanks again for the example.

Dave


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## bobj3 (Jan 17, 2006)

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


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## GoonMan (Mar 22, 2005)

Thanks Bob, I had started making a Mortise Jig similar to the one in your pic but it did not have the height adjustments. Now I know what I was missing when I was trying to figure out for taller pieces. Thanks for the tip.


_Sometimes I over look something so simple._


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## reikimaster (Sep 29, 2005)

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.


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## bobj3 (Jan 17, 2006)

You're Welcome GoonMan

I also had the same error with old one and then I put my hat on and said O I get it.
Parts are not right. (the plan one size only) can't have that,time for a rework.

You can also make taller side parts that just bolt on for 3" to 6" or more.

I hope you enjoy like I do.

Bj


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## bobj3 (Jan 17, 2006)

Reikimaster

Can you Please post a snapshot of it, I have a open mind and I love to see new jigs.
I don't get the CODE Item, a little help on that one please.

Bj


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## Gilbear (Dec 13, 2005)

RM - I use similar guides for my circular saw, jig saw and router as I don't have a table saw - this isn't just an "it ain't fancy but it works" thing - it works pretty flippin well!! That edge on the mdf will be right at the saws or bit's cut line (at least untill you change blades or bits)!) - NOTE: make sure your blade is truley at 90 to the base plate or as you change cut depth it will drift away from the guide edge! If you want to make the "Deluxe" model, put some self-adhesive sand paper on the bottom side so they're less likely to slip. Pretty fancy!!


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## bobj3 (Jan 17, 2006)

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


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## Gilbear (Dec 13, 2005)

Hey, BJ!
I think the beauty of addding a base plate to a circular is, not only have you trued-up the edge with the blade, but if you make it zero clearnce by plunging through it the first time, you have a ready gauge to tell you where either edge of the blade is gonna cut as well as providing chipping protection, particularly on plywood - the thing with the guide like RM and I use is there's no additional measuring - mark your cut line on the material, line the mdf edge of the guide right on it and cut away! Once again, many ways to skin a cat - glad I'm not a cat!


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## bobj3 (Jan 17, 2006)

Hi Gilbear

You're right about
"many ways to skin a cat"
This jig just drops in the channel of the clamp bar.
"there's no additional measuring" as well on this one.
i.e. to cut a 24" board off the 4' x 8' you would just mark the cut at 26 7/8 " put the clamp on the marks lock it down,drop the saw in the slot of the clamp and cut away and you will come away with a true sq.cut 24" board, it can't move off the center of the cut because it's in the slot of the Clamp'N Tool Guide.
You don't need to guide or hold it down just a light push and you done.
The mass of the saw and the base board will do most of the work.
No blade jams,no burn marks,no side cuts,no nicks,just a clean cut.

Bj


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## Gilbear (Dec 13, 2005)

Man, BJ -
If we keep this up there's not gonna be any cats left to skin and then whose gonna keep all those rampant dogs under control?!!
Either ways cool in my book and I see what you're saying - you deduct the base plate offset from your measurement - I just prefer having to do a little less math - I've been challenged that way since kindergarten (in fact I barely got out alive)!!


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## bobj3 (Jan 17, 2006)

Gilbear

" (in fact I barely got out alive)!! "

hahahahahahahahahaha

I like it    hahahahahahahaha

Have a good one
Bj


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## Gilbear (Dec 13, 2005)

Back at ya!!


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