LumberJocks Woodworking Forum banner

Project Information

For the past 20ish years I have challenged myself to make stuff with wood that does not require screws or nails. It's just a mental challenge I enjoy. Dovetails, mortise and tenons, and sliding dovetails are my friends in this challenge. The problem is, sliding dovetails are usually a pain to get right and they are not very forgiving if I make a mistake.

That changed when it hit me that a simple guide rail cut with a dovetail bit at the exact same depth as the thickness of the guide(photo 1 and 2), will create a profile (housing) that exactly lines up with the wide part of the dovetail at ANY depth needed (see red lines in photo 3).
So I made two identical guide rails using the same bit that I make the dovetail with. The finished project here is the pair of guides. Each made from 1/4" thick plywood base and a plywood (thickness not critical) rail with a straight edge for the router to ride along.

With a pair of these guides, the process of making the sliding dovetail is pretty simple and reliable.

1. Use the dovetail bit to cut the long dovetail. It does not matter if the dovetail is tapered or the same width throughout. Can be done with handheld router or a router table.
2. (Photo 4) Position the first guide rail on the wood where you need to cut the dovetail housing and clamp it in place good. It must not move.
3. (photo 5) Position the dovetail board you made in step 1 firmly against the guide rail in the position that you need the board to end up.
4. (photo 5) Push the other guide rail firmly against the other side of the dovetail and clamp it firmly in place. It must not move.
5. (photo 6) Slide the dovetail board out the end being careful not to shift the guides. Then set your router to the depth of dovetail PLUS the thickness of the base of the guide. And run it along the left guide, then run it back along the right guide (this avoids a climbing cut)
The housing matches the dovetail exactly. If you set the depth right, it will be a perfect fit.

Super simple game changer if you use sliding dovetails for shelves or battens.

source: More photos and build description of simple sliding dovetail jig.

Gallery

Comments

· Registered
Joined
·
282 Posts
Great jig and good write-up. Thanks.
 

· Registered
Joined
·
204 Posts
Echoing Torus….great jig and good write-up. Thanks for sharing.

TZH
 

· Registered
Joined
·
3,089 Posts
Nice idea for your jig! I haven't made any sliding dovetails yet, but if I do I'll want to use this!
 

· Registered
Joined
·
4,300 Posts
This is definitely worth a try! I've done a few SDTs, but it's always like you describe, fit, fit, fit until it's correct.
 

· Registered
Joined
·
181 Posts
That's great. Using a jig like this, may make sliding dovetails doable.

Thanks
 

· Registered
Joined
·
1,403 Posts
Thanks all. Hope they prove useful.
 

· Registered
Joined
·
124 Posts
Do you use a straight bit to hog out the waste in the middle before using the dovetail bit?
 

· Registered
Joined
·
1,403 Posts
@HowardAppel I've seen a lot of references online to people using a straight bit to hog out the middle before using the dovetail bit. I have never found that to be necessary. Though in full disclosure I have never cut a sliding dovetail housing in anything harder than Southern Yellow Pine, so maybe it is needed on something a lot harder.

Using this guide along with a straight bit would probably not work as the straight bit would have to be narrower than the narrowest part of the dovetail bit, Otherwise it would destroy the guide and cut the housing too wide at the top which would ruin the joint. If you did have a straight bit narrow enough, it would not be a good hogger and would likely get warn before the dovetail bit would. I just don't see the benefit to the added risk of using an additional straight bit.
 

· Registered
Joined
·
4,300 Posts
The only reason I can think of where you need to use a straight bit is if the DT bit is set to cut below the surface such that the bits shaft would be attempting to cut through the top layer of wood. A straight bit will extend the life of the DT bit, but as Swirt points out there are plenty of other considerations and you are effectively doubling your time to make the joint.
 

· Registered
Joined
·
1,403 Posts
@splintergroup that is a good point about the depth. I haven't needed to cut one that deep, but I can picture what you are describing. What you say about doubling your time make the joint is also true… which I read as doubling the number of operations to make a mistake on too.
 

· Registered
Joined
·
6,114 Posts
Clever jig, good thinking.
Yes the more simple we can make it, the more we will use it, that's what I have learned.
This one will go to my favorits.
Best thoughts and a smile,
Mads
 

· Registered
Joined
·
1,403 Posts
Thanks Mafe.
 

· Registered
Joined
·
6,114 Posts
;-)
 
Top