router dovetails

[Mike Steinhilper]

This is probably a basic question. Why is it ok to remove so much material in one pass when using a dovetail bit? I haven't used it yet, but i am concerned that it is going to tear like crazy. I use the Bosch 1617. I rarely take more than a quarter inch at a time. Am I being too conservative?

[Glen Blanchard]

Well, I think the most obvoius reason is that it will not work any other way. Due to the taper of a dovetail bit, one cannot sneak up on the cut by raising the bit a little at a time - it is an "all or none" proposition.

[Mike Steinhilper]

I guess that is my concern. Would it be better to work with a higher horsepower? Or is that not a factor?

[Andrew Catron]

Are you using a dovetail jig or cutting them on a router table?

I've heard of 2 tricks for the dovetail jig.

1 - use a backer board tight up against the piece you are working with. (this is the one i use)

2- I saw on NYW once, Norm used a striaght bit to take out most of the material in increments first, then when there was just a little bit of material left he switched to the dovetail bit and finished it off.

Drew

[Larry Fox]

I just use a backer-board on my jig (PC 4212) and it significantly reduces (as opposed to eliminates) the tearout.

Oh, and I use a 1 3/4 HP PC 690 series router to cut them and it is more than powerful enough.

[Jim Becker]

One typically also tries to provide additional support behind the workpiece as well as to take a light climb cut across the front board before cutting the pins through and into the tail board. (half blinds) Similarly, when doing through dovetails, best practices include using backer material to help prevent tear out.

Now...this brings up another related subject: The stress on the bit. One of the reasons that 8mm shanks are more desirable for dovetail work is that they are much stronger than 1/4" shank cutters, yet small enough to allow for the typical 1/2" dovetail profile that most HB jigs utilize. When you make that cut, there is a lot of lateral force exerted on the cutter shank...go slow and let the bit do the work. Don't shove it through, especially on the harder woods and in particular if you are using 1/4" shank cutters.

[Mike Steinhilper]

great advice. i believe i'll have my backer board built in because i'll be cutting half blinds on a jig where pins and tails are cut at the same time. I also like that NYW trick with the straight bit.

[Glen Blanchard]

Mike -

I should have asked about the application prior to responding. I was thinking of dovetails on an Incra or Jointech machine - in which case one has to make the whole cut at once. However, if using other dovetail jigs, there are options such as mentioned above. Sorry if I muddied the water.