Rockler 42826 User manual

H
4
E
5b
5a
F
3
C
2
1
A
B
G
D
Vent Hole
Thermometer Hole
Condensate
Drip Hole
Steam Box Plan
Kit Contents
1 Steam Generator
2 Steam Hose
3 Brass Fitting
4 Hinges
5 Latch/Clasp
Steam Box Components
A Top/Bottom
B Sides
C Rear Cap
D Door
E Gasket/Seal
F Support Dowels
G Feet
H Thermometer
CAUTION: Burn Hazard. Steam, dripping water, and
heated workpieces are hot. Keep hands and face away
from steam box when opening. Use protective gloves
when handling the steam box and steamed workpieces.
Read and understand all safety information and
instructions that come with the steam generator.
Introduction
Low pressure steam is an age-old method of
softening wooden components for bending
them into curved shapes. The heat and high
moisture soften the fi bers of the wood,
allowing it to bend in the shape of a press or
form. As the wood cools, it retains the shape
that it was formed into with only minor
spring-back. The key elements for steam
bending are a shaped form, a steam source,
and an enclosed steam box. This Rockler® steam kit contains the
portable steam generator and hardware necessary to construct a
steam box using your wood. (See “Kit Contents” above.)
Steam Box Construction
Your steam box should be as small as possible while still
accommodating all of your workpieces. The smaller the box, the
less steam energy it takes to bring it to temperature and keep it
there. The box should also have a fl ow-through design so that
steam enters at one end and exits at the other end, but is relatively
tight so that most of the steam and heat remain within the box.
Here are some tips for constructing a steam box:
General
• The box can be constructed from either solid wood or
plywood (exterior grade preferred).
• The box should be sloped upward slightly on a set of
legs so that condensed water runs to the back, but
also so the steam fl ows toward the front.
• Assembling the box using simple butt-joints with
screws (without glue) will allow you to disassemble
the box and reuse some parts for making
other sizes.
Steam and Support
• Drill a 9/16" hole in the center of the Rear Cap to install the
brass steam fi tting.
• For maximum cross-fl ow of the steam while maintaining good
steam capacity, build the box as tight as possible, and drill a
small vent hole in the lower face of the front door.
• A meat thermometer can be used to monitor the internal
box temperature
• Dowels are used to elevate the workpiece off the bottom of
the box.
• Heat rises, so the workpiece should be elevated to be near the
top of the box.

42826
Rev. 06/11
© 2011 Rockler Woodworking and Hardware
• Wooden dowel stock is available from Rockler or most home
centers. Don't use metal rods.
• The dowel holes can be through-holes, but stopped holes will
keep the dowels captured between the sides without
fasteners, and also prevent steam from leaking out.
Rear Cap and Door
• Note that the Rear Cap (where the steam line connects) butts
to the outside of the box instead of being captured between
the sides.
• This allows you to remove the Rear Cap (and therefore the
brass fitting) without taking the rest of the box apart.
• Make sure you install the brass fitting into the Rear Cap
before securing the Rear Cap to the rest of the steam box.
• For best results, seal the door with 1/8" weather stripping.
• Using the provided hinges and quick acting latch allows you
to remove one workpiece at a time without losing too much
heat from the box.
Steam Box Sizing
The practical limitation on the size of the steam box is how much
steam you have available to heat it, and the efficiency of the box
for heating up and staying hot. Individual results will vary, but
boxes larger than 6" x 6" x 4' or thicker materials may require
compensation to achieve sufficient steam energy, as described in
the following sections.
Thicker Materials
The general rule of thumb is that each inch of material thickness
requires 1 hour of steaming. For thicker materials this may
exceed the length of time a single steam generator can supply
steam without refilling. To increase the length of time that steam
is available without cooling down while fresh water is being
heated, use two steam generators with staggered start times so
that one generator is producing steam while the other is heating
the water.
Larger Steam Boxes
The larger the steam box, the greater the volume of steam
required to maintain the temperature. A simple solution is to use
two steam generators at the same time for a greater volume.
However, there are a few other things that can be done to extend
the efficiency of the existing steam:
• Heating up the steam box itself can take a significant volume
of your steam energy. You can pre-heat the steam box
and then replenish your steam generator while you load the
workpieces into the box for final steaming.
• To reduce the amount of steam energy lost to heating the
box, reduce the thickness of the box material and insulate the
exterior of the box. However, make sure to use insulation
capable of sustaining at least 212°F (100°C).
Basic Operation
Observe all safety warnings that accompany your steam
generator.
1. Make sure the steam generator is unplugged from
electrical power.
2. Fill the steam generator with water to the "Max" indicator on
the side (approximately 5.3 quarts). Use hot water to
decrease the initial heating time.
3. Connect the flexible steam hose between the steam generator
and the brass fitting on your steam box.
4. Connect the steam generator to electrical power.
5. While the steam generator is heating the water, load your
steam box with the material to be steamed. If you are
steaming more than one piece, make sure there is enough
air space between pieces for steam to reach all sides of
the material.
6. Close the door on the steam box and observe the
temperature of the box. When the internal temperature
reaches 212°F (100°C), count the length of steaming time
based on the approximation of 1-hour per inch of thickness
of wood. The steaming time may vary depending on the
species of wood, the degree of bending required, and the
actual thickness.
7. When the steaming is complete, you need to work quickly to
get the workpiece into your forms while it is still hot. Leave
the remaining workpieces in your steam box until you are
ready to clamp them in the forms.
Further Reading
For additional reading and techniques on Wood Bending, the
following books are available from Rockler:
Catalog # Title
41028 Wood Bending Made Simple
36247 Woodworker's Guide to Bending Wood
65913 Complete Manual of Wood Bending
Attention Rockler Plan User
Before starting, please read the plan completely. Check
Rockler.com for updates that may not be included on this copy.
If you have further questions, please contact our Technical
Support Department, 1-800-260-9663 or [e-mail]