Dowel case joinery guidelines

Basics on doweling for case construciton. April 25, 2001

I am looking for information on techniques for doweling as a method of joinery. I have been a faithful biscuit user, but now have the ability to machine dowel holes quickly and accurately. What size and type are used for cabinet construction?

Forum Responses
The rule of thumb is the diameter of the dowel should equal one half the thickness of the parts being joined. The length of the dowel penetration should be one and one half to two times the diameter of the dowel. Apply the glue to the dowel and not in the hole. Make sure you get well-adjusted equipment.

I was happy to switch to biscuit joints when that technology became affordable.

There are several dowel rules to remember. Ignoring any of them poses problems you will need to overcome:

1) You need one dowel connection front to back for every 6" of panel plus the first dowel.

2) AWI standard, the only written rational standard I have been able to find calls for the first (nearest the front of the case) dowel to be centered not less than 1" from the front. (It is due to this standard that Ritter drills are factory set for construction holes beginning at 25mm - inside 1" on center.)

3) The dowel used in edge drilled parts should be drilled in such a way that no distance from the edge of the dowel is less than the radius of the dowel away. More than the radius is fine; less than the radius produces problems.

4) In horizontal parts, dowels should have 2/3 of their length inside the shelf or horizontal component and 1/3 of the dowel should be extended to be fitted into vertical members.

5) Use multi-groove straight dowels, not spiral dowels.

These rules have drawings that demonstrate their application further. They can be found in my articles archived at WOODWEB.

Jon Elvrum, forum technical advisor