Joinery newbie sliding dovetail question. 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
Replies
I'm not picturing a sliding dovetail in this application; is it possible that you are thinking of a butterfly joint/key?
Like this: http://www.loggia.com/vignette/113b.html
Well, it's half that. Can you imagine just two pieces a male and female?Vic
Vic,
I suspect what you want is just a dovetail joining the two sides? I'm thinking a sliding dovetail would be end grain to end grain on the two mitered ends. But to do a simple dovetail between the two mitered ends would probably best be accomplished with hand tools
The problem is I'll be doing a lot of them so they must be machined somehow. thanks for your response.Vic
I don't understand why any sort of dovetail would be used in a miter jointed picture frame. The joint does generally need some sort of reinforcement, but by far the most common is a spline. Much, much easier to make, dramatically easier to assemble, and fully adequate strength for any use.
Hi Vic,
Known as a DT key when going across the corner of say a box and a butterfly or bowtie when going down through the thickness like already mentioned.
Difficult to do by machine--going down through the full thickness of already dimensioned stock without blow-out. If I was going to add them, I would hand saw them before gluing up the frame. Then use the pulled together frame to mark out on the bowtie patch, cut and carefully make it fit so it doesn't push the frame apart.
On picture frames, I typically just use splines as seen here...
View Image
However, if I wanted the bowtie to not go through and wanted to use a router, I would use an inlay bit and collar, using a pattern and add a thin, perhaps no more than 3/16" inlay on the show side. My inlay set is Whiteside and this is a situation where skimping on the quality of the pattern bit set doesn't pay off.
These router inlay sets have a removable collar which allows the 1/8" bit to first cut the "hole" in the surface, remove the collar and then cut the patch using the same pattern. There is still careful paring involved on the inside corners due to the small radius of the bit.
Take care, Mike
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
No worries, Vic--it's my problem as well not understanding. But that's what further communication does, it helps refine and allows understanding.
I *think* I know what you are describing. That should work. The challenge is going to be in holding the work extremely well if you choose to router each individual board. Any slight deflection of the miter gauge/sled will allow the cut to be not true across a face. Further, expect to perhaps need to tweak the fit because any deviation of center of the female joint half will cause the miters to not align or not close.
In a production environment, I would use a sled and route the female portion following glue-up of the competed frame. That would keep the pieces in perfect alignment obviously.
A sled for your router table or shaper which has clamps to hold the frame would be necessary. But it also then would allow integral stops so you could have repeatable placement.
You will need a backer board to keep the DT bit from blowing-out the exit. Also consider using small, fine DT bits such as thoughs sold by WoodRat. These will take less wood, have a finer neck on them. They are HSS bits, so you can use the small paddle-type diamond sticks to refresh the edge occassionaly.
Of course, all that above assumes I know what you are talking about <g>.
Take care, Mike
Mike, thanks, I think you've got it. The only part of you response I didn't understand was in reference to production and routing after the glue up. Don't worry about it, I think I now understand what I'll need to reproduce this joint repetitively. Vic
Hi Vic, the reference was simply that DTs across a join are difficult to do as individual pieces and keep them aligned. Therefore if I were doing this I would investigate cutting the female portion after glue-up and use a sled large enough to hold the entire glued frame.
Good luck--it sounds like an interesting project.
Take care, Mike
I think what Vic is asking about Mike is what's shown in the attached sketch. I could be wrong. If I'm correct it's similar to your splined mitre picture.
Construction of this joint is quite straightforward with a bit of jigging for the router do the key after basic frame assembly. Glue the mitre. Attach you dovetail spline jig to the assembled corner. Bash out the dovetailed housing with the router. Stick the separately machined piece of dovetail key in place. Clean up. Add some polish. Sell to customer. Slainte.Richard Jones Furniture
Hey Richard, howz it?
Well, I'm easily confused and thought that as well at first. Takes a DT bit with a mighty skinny neck on it to do it thatta way. The WoodRat cutters are skinny enough, at least the smallest one.
But I actually think Vic is referring to the female portion going through, or across, one of the faces at a 45 degree angle to the corner. But then again, I'm probably wrong.
But like has been said, it isn't what I would try to do in a production sense. I *might* be crazy (no reflection on you Vic) to try doing it for giggles. But I sorta doubt it.
Take care, Mike
Vic,
Even if you could cut the joints, which would be difficult, a four sided frame will be difficult to assemble since all four joints would have to be slid home at the same time. So far as I know, this joint has never been seen, there is probably a really good reason for this...
John White, Shop Manager, Fine Woodworking Magazine
Hi John,
I agree it is an odd joint. Assembled it is doable. As well, the miters can be brought closed with glue applied and the DT be slid into place.
But assembled would be the way to cut the female joint and install the male portion at that point...
But, splines are faster and more assured.
Take care, Mike
As I'm reading his second more complete description, the two halves of the dovetail are on the normally flat mitered surfaces, there is no separate dovetailed part that is installed after the faces of the miter are brought together.
John W.
Hi John,
First, we are discussing something which would not likely be done in a production environment...
There is still a separate dovetail "key" or piece to be inserted. If I were to do what I think Vic is talking about, that being the female portion across a face at a 45 degree angle to the miter, I would only do it after the miters are glued. Else there would be alignment issues.
Here's why I think that's what is being discussed: "...would create the female portion of a dovetail from one side of the face to the other."
Just like I cut keys (both straight and DT) on something following glue-up, I would also do it across a mitered face frame following glue-up and then insert and glue the male portion following the routing of the female portion. That is, if I were to do it in the first place.
But like I mentioned to Richard, I may not really understand what Vic is talking about. A scanned sketch by Vic would clear things up...
Take care, Mike
Vic
I have a set of tables that I make (coffee and end tables) where the legs are joined to the aprons at a 45° angle, and I use sliding dovetails to make it as strong as possible. Since I make a lot of these, I made a jig, like a tenoning jig, to slide in the miter slot on my router table. It's angled at exactly 45°, and has a backer board that has two functions: it holds the apron at exactly 90° to the router bit for a straight dovetail in reference to the apron, and it acts as a backer board to prevent tearout.
For you tearout with be a large issue, as you will have short endgrain at the end of each pass, wanting to blow right out the back. You could construct a similar jig for sliding your frame parts through a router bit which will be quite repetative.
Jeff
I musst say I am still confused (what's new). My question goes back a step and asks what is the design impetous for this joint? The question I have is more "why" rather than "how". After the why is known it is often easier to develop the how.
Steve
In a thousand years, I'll never know why a sliding dovetail would be needed for a picture frame. However, rather than be argumentative, I figured I'd just tell him how to build the jig for what he wants to do. He'll figure it out on his own that it's major overkill.
For a table apron, it's quite a strong joint, though. <g>
Cheers,
Jeff
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.I 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
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