dovetail jig

[Harry Goodwin]

I have several years ago bought one of those dovetail jigs with the combs from one of these cheap tool sales. I decided to experiment yesterday and it worked fine after some tinkering. Am I right in remembering from this forum and magazine articles that extending the bit loosens the joint. Yesterday, I used the 9/16" highth but it was probably tighter than I would use with hardwood. Harry

[glenn bradley]

I believe the phrase is "higher-tighter, lower-looser". So yes, extending the bit loosens the joint.

[John Lucas]

Harry,
YEs, lower/loosen but make the change very little. If you have snug now, it wont take much to get "form fitting". ANd before you do, try one other thing...after making first cut, come back the other way (climb cut) and that will have effect of nurnishing your first cut...that make be all you need to do.
Once you have it exactly where you want it, cut another side (vertical) and keep it as a guide for setting the bit next time. Let me know.

[Jim Becker]

Yes...the adjustments need to be tested in increments of those "proverbial hairs". Just a little bit will make a noticable difference in the joint. Further, once you have a setup that works for the given thickness of material you are using...make a sample joint to use as a setup template for future use. You'll be able to get your bit-height nearly perfect every time that way with minimal test cuts.

[Marcus Carr]

Jim,

You just saved hours of frustration over my lifetime. I don't know why I didn't think of that.

Marcus

[Jim Becker]

Cutter height is critical for half-blind dovetails in most, if not all jigs, so anything you can do to make it consistant over time (assuming the EXACT same material thickness...which is the reason you still need to do test cuts) is a good thing.

[Steve Clardy]

A dedicated router is a good thing for these jigs.

[David Kauffman]

A dedicated router is a good thing for these jigs.
I agree... went out and got a relatively cheap Craftsman router and once it is set right, I leave it be and use it only for THAT jig, at that thickness board. btw, speaking of these critters, I scored a new still in the package 24" Leigh D4 dovetail jig today for only $150. Craigslist ROCKS!! Just pieced it together an hour ago. I know, Leigh came out with the D4R, but you can still get the D4 if you poke around, think it goes for close to $300 or so now that the D4R is out.

[Jim Becker]

The router is important, but the quality of the guide bushing is even more critical...the cheap ones are not necessarily "round" enough and rotating the router (something you should try not to do when cutting dovetails) will result in imprecise cuts and subsequent fits. If you can buy only one "good" guide bushing, the one you use for dovetails (usually 7/16", but varies by the jig/cutter size) should be "it".

And...getting the base and guide bushing concentric with the router spindle and bit is also key to the mix... the better it is, the better the end result.

[Harry Goodwin]

Thanks for the great help. Harry