by Jeff Eggert
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Boiling Water Warping
This How-To shows how hot water is used to warp gondola bodies - bowed center sill, bowed ends. Experiment to get a feel for results. Videos included.
Use Caution around hot water!

Boiling water warping has two methods to achieve a controlled warping. These methods are intended to be general in nature to show the technique.
Hot water heated in a pot on a stove - bring water to a boil, then turn off heat. Water is ready in 30-60 seconds after cooling slightly.

Method A - Blacksmith Forging

The technique is to heat the part first, then stress it while warm. This method potentially requires less setup, but may lack in precision of an exact warping goal.

.125" x .125" styrene bar to bend a gondola body over to bow the center sill - note the upper one has a wider plate added to spread out the stress applied to the part.
When the water is ready, soak the model in the hot water using a pliers or tongs to not burn your hands. After about 30 seconds of heating, pull the model out and immediately setup like shown in the photo, then press down on the ends, bowing the body. The body may recoil, so it is ok to over bow. Hold bowed till the model cools. If the right temperature range at the start, the body will retain a curved form.
Experimentation! This is what happens when the water is too hot and the car body is left in the water a little too long.

Method B - Post-Weld Heat Treat (PWHT)

The technique is to stress the part first, then relieve the stress by soaking in hot water. This allow for great control of the warping, but potentially requires more setup.

Create a jig to match the shape of the part, in this example a gondola end. Clamps will hold the end to the shape.
Stressed end ready for hot water stress relief. Soak for 30-60 seconds. Part should retain stressed shape after slight cooling and clamp removal.
After and before, left to right, ends.

Demonstration Video of Boiling Water Warping

There is no narration and minimal background sound.

They say pictures are worth a 1000 words.  Well, then a video which is really whole bunch of photos, must be worth a 1000 pictures. Mathematically speaking that means a video is worth 1,000,000 words!

Method A

Method B