Description
This article is from the Woodworking FAQ
Collection 1, by multiple authors.
19 Where can I get information about particle board?
The following was provided by Stavros Macrakis (macrakis@osf.org)
and was added to the FAQ with his permission.
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For technical information on particleboard (PB), the National
Particleboard Association puts out some very nice free pamphlets,
which I summarize below. Although they are basically addressed to
industrial users, they cover particleboard joint techniques quite well
for the rest of us. Some of the facts about joints are very surprising.
I've tried to summarize the essential information below, but you can
also order copies from: NPA, 18928 Premiere Court, Gaithersburg,
MD 20879.
Specifier's Guide to PB and MDF
Abstract
There are 15 ANSI grades of particleboard, with diverse
properties. For instance, face screwing strength varies from 90-450
lb, stiffness from 80,000-500,000 psi. Recommendations are given
for matching grade to use.
Dowel Holding Strength of PB and MDF
Abstract
Dowels joints are one of the cost common adhesive-based
furniture assembly joints. Dowelling is a simple, inexpensive, and
reliable means of making butt and miter joints. Joint strength is
largely determined by the holding power of the dowels. Use good
quality dowels, diameter <= 0.5x the stock thickness. The longer
the dowel, the greater the strength. Holes should be 0.005"
oversized for edges, same as dowel on faces. Use 60%+ solids
content PVA adhesive, applying glue to both dowel and hole wall,
with slight squeeze-out.
Adhesive-based Corner Joints for PB and MDF
Abstract
The thicker the panel, the stronger the joint. Simple butt
joints' strength is limited by delamination; glue blocks or edge
banding help. Dowel joints are standard, and work well; they should be
glued only at the dowels, NOT between edge and face (!). Four dowels
for 18" are standard. Biscuits have equivalent strength, but are
easier to align at assembly. The strength of a well-made simple miter
joint without reinforcement (dowels, etc.) is generally comparable to
that of dowelled butt joints (!); dowels add little strength, but
splines and biscuits do. Rabbets 1/3-1/2 the depth of the panel make
strong joints, but tend to split. Dados are better, but less
attractive. Rabbet and dado butt corner joints (= dado and tenon =
dado box corner) combine a dado on one panel and a rabbet on the other.
Dowelled butt joints are stronger (!). Dovetails are excellent, but
require precise and time-consuming machining. Molded polyurethane
joints (plastic splines) are as strong as or stronger than dowel
joints.
Metal Fasteners for PB and MDF
Abstract
Screws, nails, and staples are widely used. Screws are
strongest. The type of screw affects strength by only +-10% (!), but
PB screws are less likely to break. Screw diameter affects strength
little, but screw length directly affects it. Screw diameter should
not exceed 20% of stock thickness. High internal bond strength PB
holds screws better. Edge screws have half the strength of face
screws. Use full-length pilot holes; shorter holes do not increase
strength. Ideal tightening is 3/4 turn past flush on the face; 3/8
past flush on the edge. Applying glue in the hole can increase
strength as much as 45%.
Staples are used for attaching fabric, etc., and to hold glued
joints.
Nails split panels, so should be >3" from a corner, and >6"
apart. Ring shank nails hold better, plastic coated best. Drive
them at an angle.
Mechanically-based Corner joints for PB and MDF
Abstract
Most bolt and cam joints are 20-50% weaker than dowelled joints.
Screw joints are comparable. Plastic corner block units can be much
stronger in outward bending, but only comparably strong in inward.
Even when they are equally strong, mechanically-based joints are often
less rigid. These systems are most useful for ready-to-assemble
manufactured kit furniture.
Particle Shelf Systems (Builder's Bulletin #1)
(not seen)
All the above are free. They also sell:
Particleboard from Start to Finish $12.50
Abstract (theirs, I haven't seen this)
Ten chapters (120pp) of useful information for users of PB.
Includes information on material handling and storage, sanding,
machining and tooling, laminating, wet finishing, edge treatments,
assembly and fastening, construction products, shelving and
formaldehyde.
MDF from Start to Finish $7.50
Similar abstract, 42 pp.
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