Dovetails

[PJC]

Can someone please explain to me the difference between a half-blind dovetail and a through dovetail. I was investigating jigs, and some do only through, some do only half-blind. Why is that?

When would I need to use a half-blind dovetail?

Thanks,
Pete

[Tom Hintz]

Half-blinds are when they stop about halfway through the material, usually the front piece like on a drawer.
Through dovetails go all the way through on both pieces so you see the dovetail from both sides. thes are most often used to build boxes and such. Through dovetails are easier to make than halfblinds though both are reasonably sensitive to bit settings to get the right fit.
The better dovetail jigs do both types. the Leigh is the best but is pricey. I have a review of the Leigh at the link below.

http://www.newwoodworker.com/reviews/leighjig.html

[Armini]

A half-blind dovetail is one where the tails do not go through on one side, meaning that from one face the joint is not visible.

Classically, this is used for drawers, so the drawer face does not show the dovetails. Often used in case carcass construction as well, where a clear presentation face is desired.

I would imagine that some jigs are not set up to cut the pins with a stop - any bandsaw jig would not be able to do them. In fact, they are very tricky (well beyond me) to do with a router without an excellent jig.

Depending on price, if they are commercial jigs you are looking at, I would go for one that could do both, and if you have to choose, go for the jig that could do half-blind. There are many ways to do good through dovetails.

Edit: beaten to the punch by the Tarheel...

[JimD]

It is easier and quicker to use a half-blind dovetail and the jig to make them is also simplier for a couple of reasons. The jig to make half blind dovetails allows you to cut the pins and tails for the dovetail at the same time with one jig setup. It also has fixed spacing so you have nothing to set up for spacing (you can't do it but you also do not have to do it). The male part of the joint ends up with a rounded face that your turn inward when you put the part together. The recess (the female part) is similarly rounded so everything fits together nicely. To make through dovetails you must eliminate the rounding so you end up having to cut the two sides of the joint independantly requiring two cutting operations if not setups of the jig. This takes more time. The through dovetail jigs I've seen also have variable spacing which is a nice flexibility to have but also means more setup time.

My bottom line is I have two inexpensive jigs for half-blind dovetails which I use mainly for drawers but occasionally for boxes. I do not have a through dovetail jig because the one I want (the Leigh) costs about $300 which is more than I want to spend for it right now. My latest purchase was the Harbor Freight half blind jig for about $30. It does a nice job of making half-blind dovetails (you also need a bit and template guide for the router which will cost ~$20).

Jim

[germdoc]

Once again I am going to get on my soapbox for the Keller jig. It only does through dovetails, but does them accurately and consistently. For $129 all inclusive, with high quality bits, it is about as cheap as any quality jig. I guarantee it is the easiest to set up and use. If you want to spend more of your time doing fine cabinet work instead of setting up jigs, then get this one. You can do straight edges of any length, angled joints and even curved surfaces, different width boards, and also can space out the pins to some extent.

There are cheaper half-through jigs (HF for instance), but once you get started using dovetailed joints you will want to try through dovetails, and then that means more $$$. IMHO through dovetails are stronger and much more attractive than any other joint. If you want a clean surface, for drawer fronts for example, you can use a veneer or a false drawer front. Check out the many reviews of the Keller jig online and in magazines.

BTW, I am not a paid consultant for the company but would like to be.

[LarryG]

Disclaimer: I don't own any flavor of dovetail jig yet, so what follows is purely a passing-along of some of what I've learned in researching the things (because I want/need one).

The Leigh D4 appears to be the one that will pretty much do it all, with the most control, albeit with the steepest learning curve. More than one of the reviews I have read say that if you don't use the D4 regularly, you'll be thumbing through the manual for a refresher course every time you haul the jig out to use it.

The Porter-Cable OmniJig appears to offer virtually all the features of the Leigh, with the added benefit of being much, much easier to set up and use (or so say the reviewers). The OmniJig is currently even more attractive since P-C is running a free template promotion that will save you $70-125 depending on whether you purchase the 16" or 24" version of the OmniJig (I would want the latter).

As far as I can tell, the main disadvantage of the OmniJig is that it will only do the steeper, squatty-looking 14deg dovetails whereas the Leigh allows you do use the thinner, more elegant 7, 8, and 9deg dovetails that look more like they were cut by hand.

Since both of these jigs will chew the backside off a $400 bill, I'll likely do like JimD and get one of the inexpensive non-adjustable, half-blind-only models to use while I save up my money for a Leigh. Or an OmniJig. No, I think I'd get the Leigh. No, definitely the OmniJig ...