Jig for routing dovetail keys

[Rocker]

Here is my version of a jig that Ryanarcher posted in in his thread on his blanket chest, see http://www.woodworkforums.ubeaut.com.au/showthread.php?t=16966&page=2
Mine is similar to his, but is made of MDF with a hardwood fence. I think, though, that my jig would probably be easier to clamp to the workpiece.

Rocker

[ryanarcher]

Is that a picture, or a 3d cad drawing? Why is there space between the support faces? I bet you're right, it will clamp easier. it looks like you used a straight bit in it?

good improvements!
-Ryan

[Rocker]

Is that a picture, or a 3d cad drawing? Why is there space between the support faces? I bet you're right, it will clamp easier. it looks like you used a straight bit in it?

good improvements!
-Ryan

Ryan,

It is a picture - a bit easier to produce than a CAD drawing in 3D. There is a gap between the support faces mainly because it didn't occur to me to mitre their top edges, but I don't think it makes much difference. I used a 3/4" straight bit to rout the slot, and will use an 11/16" 8-degree dovetail bit in it (I have the 8-piece Leigh dovetail bit set from Lee Valley, which I think is good value at US$ 74.50).

Rocker

[MajorPanic]

Hey Rocker,

How about you give the CAD programs a rest for a while & learn how to use a graphics package, the pictures are awful!...... sorry. :o

GREAT jig by the way!!!!!! http://www.woodworkforums.ubeaut.com.au/images/icons/icon14.gif http://www.woodworkforums.ubeaut.com.au/images/icons/icon14.gif http://www.woodworkforums.ubeaut.com.au/images/icons/icon14.gif

[Rocker]

Major,

Touché. I forgot to adjust the resolution.

Rocker

[Dan]

Have you tried it out yet Rocker?
I'm a bit curious to know if there's any problems with tearout and what's the best way to make the cut. Do you cut from both sides or just go all the way through in one pass?

[ryanarcher]

Ryan,

There is a gap between the support faces mainly because it didn't occur to me to mitre their top edges, but I don't think it makes much difference.
Rocker


There will be no support at the very corner of the workpiece which might result in some tear out. I used a leigh #80 8 degree bit too. I really like it. let us know of any mods you would make after using it.
-Ryan

[Rocker]

Dan,

I haven't yet tried it on an actual cabinet, but I did try it on an offcut of straight-grained jarrah. Rather to my surprise, there was no tearout when I routed the dovetail cut in a single pass without first removing the bulk of the waste with a straight bit. I suspect, though, that it would be a different story if you attempted to do the same thing with blackwood, which I find to be very susceptible to tearout. However, I think it should be easy enough to prevent tearout in difficult wood by just putting a couple of pieces of 3 mm MDF between the jig's support faces and the workpiece. It would mean that you would have to plunge the bit 4.25 mm deeper to get the same depth of cut, but it should prevent tearout.

Rocker

[Ladislav]

Rocker,


What exactly does the complete joint look like :confused: , and how do you make the bits to fill the routed slots. Are they triangular, so they "span" the inside of the corner, or are they "L" shaped. Exuse my ignorance. I have not seen this type of joint in real yet. Only on pictures. Would like to give them a go. The joint looks quite nice.

Thanks Ladislav

[Rocker]

Ladislav,

Go to the thread that I referenced in my first post to this thread (Ryanarcher's blanket chest), which shows the dovetail keys reinforcing mitre joints.

The triangular stock to fill the routed dovetail groove is made with the same dovetail bit in a router table - preferably one with a micro-adjustable fence. You rout both sides of the edge of a wide board held upright against the router-table fence, and make successive minor adjustments to the fence position until you achieve the correct width of dovetail key. Then you rip it off from the board.

Rocker

[Ladislav]

Thanks Rocker,


that sounds pretty easy. I'll give it a go one day.:)

[scooter]

Haven't done it myself but have heard of some WWs routing the key on the router table oversize, then hand planing the wide edge down for an exact fit.

Could be useful.


Cheers...........Sean

[Rocker]

Have you tried it out yet Rocker?
I'm a bit curious to know if there's any problems with tearout and what's the best way to make the cut. Do you cut from both sides or just go all the way through in one pass?

Dan,
I have at last tried the jig out; and it worked perfecly with a single pass and no tearout in Silver Ash. See my thread on a silver ash chest of drawers. I guess, though, that it would be a different story in a less forgiving timber like blackwood.

Rocker