Dovetail sled

[jpor4180]

I thought of what I think is a great idea, but because I think it's a great idea I imagine someone has done it before

You know you get those box joint jigs? They tend to make them in the US for table saws with a dado stack but also made for the router table. These are relatively easy to make as it doesn't matter so much where you start and finish your box joint cuts relative to the piece. With a dovetail, symmetry and layout matters, and you can't start halfway through a dovetail (or convention dictates you don't). To get around this, the only thing that really changes is the placement of the 'guide dovetail' to the left of the router cutter, which dictates the dovetail spacing, and the stop block to the right of the cutter which dictates the position of the first dovetail cut.

The jig would need setting up twice I think for the pins and then the tails, but for a kitchen build or something like that it would definitely save time. I won't have cause to make one for quite a few months. SO if this doesn't already exist I would love to see someone else's mock up of the protograph (I think that must be the word, a sketch of a prototype!) that I've appended below, free to use for anything other than commercialisation of the jig of course!

 

[ScaredyCat]

https://www.youtube.com/watch?v=nfuEik2ak00

 

[jpor4180]

No sorry not like that, I don't really get where the value is in his jig as he's still having to mark out, I'm talking about a production jig where you use a dovetail cutter and only have to measure the distance between pins once and the starting position once.

There are quite a few similar designs for box jigs, one at random here: https://youtu.be/-GszYAh0Yhg

The only fundamental difference being that you want to add in adjustability in dovetail spacing and also introduce a starting position reference with a stop block on the offside to ensure an appealing symmetric layout - not required with box joints

 

[jpor4180]

you could have the sled back angle adjustable with a positive stop, so that cutting the tails is 90 degrees to the direction of travel of the sled and then cutting the pins, you are at the required angle for your dovetail cutter. Probably the most finicky part of the set up of the jig in the first place and would need to be done by interpolation I imagine, but once you've got it dialed in for a particular cutter just have a reference line or positive lockout such that the jig reaches that angle every time

 

[ScaredyCat]

I don't really get where the value is in his jig

A single jig for any size pins/tails. Your dovetails will all be uniform in size . That jig allows them to be any combination of sizes using 1 bit for any size. It's closer to the Leigh jig than your box joint one.

If you're just batching them out I guess your jig would be fine but you'll need a different one for every cutter, stock size etc.

 

[jpor4180]

I don't agree with needing a different one with stock size but you would need a different dovetail guide for each cutter, which would be replaceable on the jig via a tslot or slot and insert nut system. I'm intrigued by who has more than one or two dovetail bits in the first place?

 

[ScaredyCat]

I don't agree with needing a different one with stock size

If the depth of cut changes, because the stock thinkness changes, from when you made the jig then your key wont fit properly. You'd need to match the thickness of the stock, so the height of the key would need to change. You could of course use your t-slot solution to raise the existing one up but that might be fiddly to do accurately.

If your stock is always the same thickness then it's not a concern.

 

[Just4Fun]

I'm intrigued by who has more than one or two dovetail bits in the first place?

Perhaps the sort of person who does enough dovetails to justify making or buying a jig to cut them.

 

[custard]

I'm intrigued by who has more than one or two dovetail bits in the first place?

 

[jpor4180]

I'm intrigued by who has more than one or two dovetail bits in the first place?

Perhaps the sort of person who does enough dovetails to justify making or buying a jig to cut them.

That teaches me for having an idea!