Dowel Hole Layout for CNC Boring

A CNC gives you flexibility in dowel-hole spacing. So what do you choose? March 9, 2008

We just bought our first CNC and will be using 8mm dowels for our construction assembly. I don't want to reinvent the wheel; I am just looking for a 32 mm construction boring pattern, for example 24" base cabinet with stretchers, bottoms, nailers, drawer dividers. I know it's all relative to the way you build your cabinet. We have the 5 mm holes down for hinges, shelves, and slides.

Forum Responses
(Cabinetmaking Forum)
From contributor M:
You might just go by one of the big boxes and purchase one of their frameless knock-downs and check out their patterns. They have probably had their big buck engineers do the head scratching for you.

From contributor R:
This is how I do it!
x 9.5
y 50 mm
yf h-50
Through-bore 25 depth x 7 mm bit

Horizontal bore 32 depth x 5 mm bit

I use confirmat screws, but it would also work for the most part with dowels. Parametric program will work with any size panel and does not need to be on 32 mm centers. I use 5 confirmats on 24" lowers and 3 on 12" uppers.

From contributor B:
Contributor R, I don't understand your answer. Could you elaborate on your x&y? You use CNC but assemble with mechanical fasteners? Do you find this method faster? Have you tried a dowel system?

From contributor P:
I think there are as many layouts for dowel construction as there are shops using the system. I have always looked at the equipment that is to be used to pick the most efficient layout. As an example, we started by laying out panels with sets of 2 dowels on 64mm centers since our CNC has that spacing on its 2 x axis horizontal drills. On our normal 610 deep panel, we used a total of 8 dowels per joint in sets of 2 starting at 25mm off the front and 39mm off the back. The two set in the field were spaced parametrically based on the cabinet depth. Since we installed the Omal horizontal dowel bore and insertion machine we have changed to using a number of dowel layouts in a given panel depth range. A 610 deep base cabinet now gets 3 dowels at the front starting at 25mm and 3 dowels at the back starting at 39 and a pair of dowels in the center all on 64mm spacing. This layout takes into account the CNC machine's 5 x axis vertical drills and the Omal's speed at inserting on a 64mm drill and dowel spacing. Our nailers and stretchers are usually 100mm minimum width, 2 dowels on 64mm centers 18mm from the front. It's great not being locked into a full 32mm dowel layout as we would be with manual doweling equipment or a multiple borer inserter.