Joinery newbie sliding dovetail question.

[Vic Damone]

I'm trying to find out as much as I can about what I will need to produce what I think is called a sliding dovetail. Imagine a picture frame made of 1 1/2" X 3/4" Basswood with 45 degree mitered corners. I'd like to add one 3/4" sliding dovetail to the miter in each corner.

I currently have a Bosch Colt and a DeWalt 621 plunge router. I have an Incra fence system on my table saw but none of the router related equipment. Should I start thinking about a router table, fence and sliding miter? Would it be smart to stick with the Incra equipment or is there another system I should consider. Will the 621 and a Woodpecker plunger lift be adequate?

Vic

[Don Bullock]

I'm not sure I can help with the sliding miters. I'm not there yet.

It seems to me that if you already have the Incra fence system on your table saw you already have some of the tools you could use to make them. As others here have done, I'm planning to add a router table to the right side of my table saw (can be added on left as well) and use the Incra router system with the table saw fence I already have. The router table will fit right between the rails of the Incra table saw system. I know that slidingmiters are a feature of the Incra router system because I've seen then demonstrated at shows and on their video. There are several recent threads here on SawMill Creek showing router tables set up this way using the Incra.

If you do go that direction you will still need a router and table top. Others will have to tell you the options you have with your routers. There are many opinions out there on router and lift combinations. Some with plunge routers ues them the plunge feature instead of a lift. One thing to consider, that most users don't include in their praise of the system they use the information that once the router is in the table it's pretty much there for the table use and it can be difficult and time consuming to remove it for hand use. Some systems make the change easier than others, but it can still be a problem to use the same router for both types of tasks. You may end up wanting a new router after your "favorite" is placed under a table.

[Jim Grill]

I have a router dedicated to the router table for just that reason. There are several routers sold now with the above-table-lift built in. PC and Freud come to mind. There is also a new kid on the block called Triton. One of the WW rags had an article about routers made for router tables. I think it was FWW and I think the Triton won the review. However, the Freud can be had for a reasonable price from the borg.

For sliding dovetails I would go to the router table for sure. The router table has proven to be a very versatile tool for me - even with a minimal collection of router bits.

I considered buying one of the router tables that replace the extension table on the TS. I found them to be too narrow, but with the incra setup I might reconsider that option. There is some way-cool router stuff for the incra.

[pat warner]

Some data on sliding dovetails (http://www.dewalt.com/us/articles/article.asp?Site=woodworking&ID=511).
If'n you want the dovetail on the face of the edge grain you will not be able to assemble.
The sliding dovetails in the 1/2 lap at the bottom of the picture (http://patwarner.com/images/798m.jpg), is that what you need?

Routers? (http://www.patwarner.com)

[Mark Singer]

Are the dovetails used as splines across the miter or are they tunning across the face of the mitered surfaces? For the splines you make a jig and can do it on a router table....One pass only one a dovetail....since its wider at the top

[Vic Damone]

I hadn't given any thought to the complexities of installing and removing a router from a lift, thanks for the heads up.

Describing joinery without an illustration and a limited knowledge of the vocabulary makes it very difficult for anybody to understand and I apologize. This joint is similar to the wooden railroad track except using a dovetail bit.

I think simply clamping the 1 1/2" face of the mitered stock at a 45 degree angle to a miter sled and passing the centered stock over a dovetail bit would create the female portion of a dovetail from one side of the face to the other.

Clamping the male stock in a similar fashion but cutting the outside portions would create the dovetail.

The more my little brain thinks about it I think I'm going to need a table with some sort of miter setup to pull this off repetitiously. Again, I apologize for all the verbiage and the lack of graphics.


Thanks
Vic

[Mike Buelow]

For me the sliding dovetails took a lot of work and a lot of prototyping.

On the female side I used the router in hand with a clamped edge. You gotta be really careful, esp when backing the bit out of the groove. Trial and error on practice stock will set the depth.

On the dovetails themselves... that's what prompted me to build my router table. You have to set the blade depth just right or it won't work... Exect to use a lot of practice stock here as well. You'll also need a tall, plumb fence or a fancy tenoning jig.

I think Norm used sliding dovetails on his shop storage cabinets (with the mitre station on top), if you have acess to that episode.

[Tim Sproul]

I don't think you can join all 4 miters with integral sliding dovetails...3, but not 4. Same reason why mortised and tenoned miters have to have mortises wider than the tenon, at least on the final joints to be assembled.

You could plow out sockets in the miters on both opposing faces of the miter and then slide a dovetailed key into the joint to lock it but you'll have a hard time assembling a frame where the male and female components of the sliding dovetails are cut into the frame members.

If you still opt for this, leave the frame members wider than finished width and plow out the sockets. Then rip to final width. It it hard not to get some tear out when routing the sockets. And it really is worth spending the time to plow out a good amount of the waste with a straight bit or with your table saw.

[Vic Damone]

Tim, picture turning the dovetail 90 degrees sort of like a toy wooden railroad track. In this case the sliding length is 3/4" long (the thickness of the stock).

Vic

[Tim Sproul]

Make a test joint. I think about it and think it won't look especially good. You can't make the tail too wide because you'll make the socket very weak at the outer edge of the socketed member or you'll need to make the depth very shallow or you'll need to offset towards the inside of the frame.

At any rate, I'd suggest you make a prototype and see how it looks.

The point of a picture frame is to draw attention to what is framed. Not to the frame itself so much. But this is just my opinion. I'd like to see how the frame turns out.... :)

[Vic Damone]

Well I apologize for all the confusion I've created. It's not a picture frame but it's a frame shaped much like a picture frame. The dovetail does not run in the same direction along the miter as say a spline would so there isn't an assembly issue. My goal is to create a joint that will hold to some degree if and when the glue fails.

In any event I fabricated a test piece with hand tools and it should provide all the strength I'll need. The machine version will be accomplished using a jigged miter or sliding fence over a tabled dovetail bit none of which I own at the moment. The good news is I have a need.

Thanks for all your time and help.

Vic