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(231) 937-4367

 

About Steam Bending


Q: Do some woods bend better than others?
A: We have the best results with the common native American hard woods. There is little difference between ash, cherry, soft maple (red maple), red oak, and walnut. Hard maple (rock or sugar) bends well except at the smallest radii i.e. less than 2 inch radius for 2 inch thick stock.

 

Q: Can white oak be bent?
A: White oak is not difficult to bend, but it is extremely difficult to dry without surface checking caused by re-wetting during the steaming process and subsequent re-drying. Quartered lumber reduces the amount of surface checking however the edges are now vulnerable.  Large, prominent medullary rays (flake) are prone peal off during bending.  Rift cut lumber is probably the best choice if white oak must be used.

Q: Are there woods that cannot be bent?
A: Yes. Except for very flat bends, tropical woods do not bend well. They tend to kink and form creases that are objectionable when a finish is applied. Soft woods like pine and spruce tend to have the same problem.

Q: Can curly or fiddle back maple and cherry be bent?
A: Yes. It bends, but expect to have more bending failures compared to straight grained wood.

Q: How long do the parts steam for?
A: Long enough so the part is soft enough not to break on the out side, but not so long the wood becomes too soft and folds. Thin parts may steam for as short as 15 minutes, but thick wide parts bent to a sharp curve will need as long as 10 hours.

Q: What is the optimum moisture content for steam bending?
A: Although wood much above 25% will steam much quicker, it tends to have more problems with collapse on the inside and separation on the outside of the bend. The steam time for wood below 10% is very long, and fractures on the outside of the bend are more likely. We bend our lumber in the mid teens.

Q: What lumber moisture content is recommended for gluing and machining?
A: The Wood Component Manufacturers Association specifies 6-8% moisture content as this is where lumber machines best. Glues are also designed for this moisture content. Above 8% wood will continue to dry and move. We dry bends to 6-8% moisture content as specified by the Wood Component Manufacturers Association.

Q: Is a support strap necessary for bending?
A: Shallow, flat bends can be successfully bent without a strap, but with a sharper radius, a strap will improve chances of success.

Q: What material can be used for a support strap?
A: Any iron strap (i.e. banding) with end supports will help, but iron does leave black surface stain on the part. Using stainless steel will eliminate this problem.

Q: What are the best storage conditions for my bends?
A: We recommend storing at: 65° F to 75° F with relative humidity at 35%. Do not store bends directly on a concrete floor (absorbs moisture) or where they would otherwise get wet, or in proximity to hot air registers or radiators (too dry).

Q: Can my bends move over time?
A: When bends lose moisture, they tend to pull in or become more curved. When bends pick up moisture, they tend to flatten out. Large radius bends (very flat) tend to just flatten out.

Q: What can be done with parts that have flattened out?
A: If parts have lost some of their curve, a bar clamp across the corners can be used to gently bring the part past the desired curve and then held there for several days usually works to bring the part into tolerance. If they have gained significant moisture, the part may need to be re-dried.

Q: What can be done with parts that have moved in?
A: One method of flattening out a bend is to place it concave down on a work bench aligned parallel with the over hang of the bench top. Use a bar clamp between the bottom of the bench top and the center of the point farthest away from the pattern to gently squeeze the bend a little past (for spring back), hold, release, and repeat if necessary.