Steam Bending Question

[Don_M]

I am steam bending trim for a curved staircase skirtboard.

Q: How long should I leave the material clamped in the form before removing?

[mike4244]

I am steam bending trim for a curved staircase skirtboard.

Q: How long should I leave the material clamped in the form before removing?

I can't answer that as I have done limited steam bending. I have done hot water and water softener bending with success. Try this, place the trim in a vessel like a tub or even a couple of planks nailed at 90° with a short header on one end to keep the V shape upright. Add hot water and water softener. I use Downy. Depending on the thickness of the trim it could take as little as 10 minutes before you bend it, or as long as 45 minutes for thicker stock.
I have bent stair risers , I saw the riser at the bend til 3/16" is left at the bend. The rest of the riser that is straight is left 3/4" thick. Yellow pine riser this way takes 15 minutes before place in a form. Red oak, Honduras mahogany and some other hardwoods take close to 45 minutes.
The only steam bending I have done was for the gunnels on the canoes I made. These were long gentle curves and fairly easy to bend, ash or walnut was the stock I used.

mike

[handi]

I am steam bending trim for a curved staircase skirtboard.

Q: How long should I leave the material clamped in the form before removing?

Until cool, about 1/2 hour or so. I recently bent a whole pile of 5/8” thick by 1” wide strips. They took about 20 minutes to cool and exhibited very little movement after removal from the clamp.

Keep in mind that air dried lumber bends much more readily and easily than kiln dried.

You will need to set your form up to slightly overbend the parts because they will spring back some from the form when unclamped. 

Episode 5 of my show Woodcademy is the beginning of a set of dining chairs. The back splats are steam bent to martch the rear leg profile. I show you the entire process as I did it including the mistakes I made. I show how I soak the kiln dried lumber to make is steam bend more readily.
Episode 5

[Don_M]

Thanks. I am letting dry overnight - seems to be plenty of time for piece to "set".

I did make the bending template a bit tighter radius - but I still getting quite a bit of spring back. Not a big deal for this application.