Selecting Keys and Router Bits

The Hoffmann Dovetail Joining System is used in custom and production picture framing shops as well as woodworking, furniture manufacturing, window and door production, architectural millwork designs, store fixtures, pre-fab housing and much more, in shops and plants around the globe. To best suit an ever expaning range of joining application, a total of four different Dovetail Keys and corresponding Dovetail Router Bit sizes are offered, designated as W-1, W-2, W-3 and W-4.

These sizes refer to the cross-sections of the Keys (the size of the "bowtie"), and Keys in each size are available in a variety of different lengths.


W-1 Dovetail Keys

In custom picture framing, W-1 Keys are used for thin shadow box moulding, for most floater frames, for small and delicate applied profiles and for thinner display case designs.

W-2 Dovetail Keys

For most mid-sized to larger moulding, including thicker shadow box moulding (5/8” wall thickness or more) our W-2 Keys are a good choice.

W-3 Dovetail Keys

W-3 sized Keys are at times used for joining large and heavy frames and some of the larger stretcher bars, however often times if the material is large enough to warrant one W-3 Key one might also use two W-2 Keys side by side.

W-4 Dovetail Keys

The largest W-4 Keys are for timber framing, large windows and entry doors, sauna and sunroom construction, etc. and rarely find an application in the picture framing field.



Selecting the correct Key length

As a rule of thumb, always use the longest Key possible for a tight joint on the front or face side of the frame. The keyways (dovetail slots) in the moulding should be routed close to  the front, about 1/16" to 1/8" below the finished side of the moulding.

For example, for 3/8” thick moulding use a 1/4” Key, for 5/8” moulding use a 9/16” Key, for 1” moulding use a 7/8” Key, for 1 1/2”moulding use a 1 1/4” Key, etc.

Shorter Keys can be stacked on top of each other and if Keys are a bit too long, they can be trimmed flush after they have been inserted.


Selecting the correct Dovetail Router Bit

Hoffmann Dovetail Router bits are made in two size versions - “standard” and “oversized” - to best match different joining situations.

  • Standard Bits are used for general joining applications including most picture frame moulding. A standard W-2 bit is factory installed in every new machine.
  • Oversized Bits (which are slightly larger in diameter) are used in situations where tall and thin moulding is joined (typically shadow box and display moulding).

W-1 standard bits - used for small moulding with dimensions (profile cross sections) from 1/2” x 1/2” and up.

W-1 oversized bits -  best for small and thin floater frames with wall thickness from 5/16” to 5/8”

W-2 standard bits - our “all around” bit and will work great for most moulding from 3/4” x 3/4” and up

W-2 oversized bits - good choice for taller shadow box designs with heavier wall thickness from 5/8” and up

W-3 standard bits – for large and heavy moulding used in large frames

W-3 oversized bits – rarely used in picture framing as standard W-3 bits work well on heavy moulding

If you have any questions as to which Keys to use, or whether you should use a standard or oversized bit, please call us toll-free (866) 248 - 0100 or send us an email to We look forward to helping you get the most out of your Joining System!

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W9100600 W1 x 1/4" for 5/16"+ stock
Part # Length (inches) Length (mm) Price per box of 1000 W..