Dovetail bits

[David Kloete]

I have a Porter Cable dovetail jig Model 4216. It came w/ (3) templates. I've been using the 'mini' template , which utilizes the 1/4" width dovetail.

That bit, and the corresponding 'straight' bit are getting dull and I purchased compatible bits - dovetail , that is. I would like to know if the straight bit size matters when cutting the pins, since I already have some straight bits, but didn't come w/ the Porter Cable 4216 kit.

As well, I'm interested in a 3/8" width dovetail. If I decide to go w/ a 3/8" width dovetail, would I have to get a compatible 'straight bit as well?

I understand I would have to get new guide bushings if I decided to go w/ the 3/8" width dovetail.

Dave

[Bill Dufour]

I use a solid carbide straight bit to clean out the dovetail slot. As long as it is no wider then the narrowest part of the dovetail cut it is fine. I set it a fraction shallow. Like an index card thickness shallow.
For 3/8 in theory no need to precut the slot. In fact remove as much as possible with a cheaper to replace straight bit as wide as possible. You existing will help but the more the merrier
Bill D

[Richard Coers]

I have a Porter Cable dovetail jig Model 4216. It came w/ (3) templates. I've been using the 'mini' template , which utilizes the 1/4" width dovetail.

That bit, and the corresponding 'straight' bit are getting dull and I purchased compatible bits - dovetail , that is. I would like to know if the straight bit size matters when cutting the pins, since I already have some straight bits, but didn't come w/ the Porter Cable 4216 kit.

As well, I'm interested in a 3/8" width dovetail. If I decide to go w/ a 3/8" width dovetail, would I have to get a compatible 'straight bit as well?

I understand I would have to get new guide bushings if I decided to go w/ the 3/8" width dovetail.

Dave
Are you asking about the through dovetail option? The instruction manual doesn't tell you?

THROUGH-DOVETAIL BITS



If you choose to purchase alternate through-dovetail bits, keep in mind the following:


The dovetail bit must have a 7° angle. This angle matches the tapered fingers used to guide the straight bit.

The sum of the diameters of the dovetail and straight bits must equal 15/16". For example, a 5/8" dovetail bit
must have a 5/16" straight bit - the sum of both equalling 15/16".

The length of the cutter determines the maximum thickness of wood that can be cut. The length of the cutter
on the dovetail bit is the maximum thickness of the pin board. The length of the cutter on the straight bit is the maximum thickness of the tail board. If your bits have 1" cutters, you can make through-dovetails with 1" thick boards.

Purchase bits that will not cut into the template guides. The template guide used with the dovetail bit has an inside diameter of 21/32". Use bits that will fit into this dimension. Some larger bits might work, but with minimal depth (Fig. 18A).

The inside diameter of the template guide used with the straight bit is 17/32". Use straight bits that are smaller than that dimension.

[David Kloete]

Hello Richard, thanks for the reply!

I'll respond in ascending order to your post.

1. (7 deg. angle bit) - I'm using the 14 degree dovetail cutter which came w/ the kit - and have successfully made the fits. Furthermore, on the PC4216 , the dovetail template 'fingers' aren't tapered, they're straight - the 'pin' side of the same template , are 'tapered'.

2. I understand your arithmetic, yet do not understand 'why' they (the bits) , must add up to 15/16".

3. Yes, I agree on the depth of the cutter regarding the material thickness. Additionally, I just bought , used a 'Freud' dovetail (and btw, it was a 7 deg. cutter) and damaged my guide bushing. The cutting flutes on those bits extend a lot. I guessing they're used for CNC machinery. Thus, I some new 14 deg. dovetail cutters, although cheap, but will not damage my 'new bushings'.

4. I've been cutting 1/4" dovetails lately, mostly...so yes, I experienced damage to my original bushings, thus getting new ones that fit the 1/4" template.

5. Ok, thanks for that information w/ regard to the size of the straight bit - that was my main question as I started this post. I really , continue to 'not get it' since I thought 'any size straight' bit would do the pins, since afterall, I'm following the 'pin template'. I could use a 'needle' to cut the pins (being facetious) if I had to...
Dave