Thermoforming refers to a process wherein plastic sheets are heated using a heat gun to particular temperatures and then molded to form specific shapes. Thermoforming is an affordable alternative for underground installations or home projects involving PVC pipes.
Step 1: Identifying Bend Center
Using the dry marker and tape measure, identify the location on the PVC pipe where the bend’s center has to be. The general consensus for thermoforming a PVC pipe is to place a separate mark about 6 or 10 inches on either side of this center marking. This represents the heat zone and will be the region where the heat gun will focus on.
Step 2: Setting Radius Forms
The next step is to set radius forms beside the pipe that is to be heated. The nearer the bucket or can is from the pipe, the easier it becomes to thermoform the pipe. The bucket or can needs to be set on the end with the open part facing in an upward direction.
Step 3: Laying the Pipe
Next, you need to lay down the marked portion of the pipe over the scrap wooden pieces of 2x4 measurements. The marks representing the heat zone need to be within the wooden pieces and the pipe has to be supported off the ground.
Step 4: Plugging the Heat Gun
Plug the heat gun and switch it on. Hold the gun in position 2 or 3 inches away from the PVC pipe to prevent burning the outer plastic surface.
Step 5: Moving the Gun
Move the heat gun in a slow manner across the entire length of the heat zone that you marked earlier. As soon as you finish making one pass to a black mark, turn the PVC pipe clockwise about a quarter turn.
Step 6: Heating the Pipe
Continue to heat the PVC pipe in the same manner until you see the plastic covering outside start to sag between the two wooden piece supports.
Step 7: Turning off the Heat Gun
Switch off the heat gun and keep it to one side at a safe distance away from you so you don’t burn yourself.
Step 8: Thermoforming
Take the sagging plastic portion of the PVC pipe on either side of the marked heat zones and then lay it gently on top of the radius forms. Gently thermoform the PVC pipe or mold it over the curved surface while rolling it clockwise to preserve the shape of the pipe. Pull the PVC pipe gently around the radius form to form the specific bend you need.
Step 9: Laying the Pipe
Once you find the PVC pipe has reached the desired form and shaping, lay it down on the ground and wipe off the warm PVC pipe with a wet rag. This rag will help to cool the pipe and set it to facilitate re-hardening of the plastic.
It helps to practice on scrap pieces of PVC pipe with the heat gun first before graduating to the pipe you want to work on. Perform all such thermoform operations within well-ventilated environments because toxic fumes maybe emitted from heated plastic.
Looking to purchase a new heat gun? Check out our Heat Guns Buyer's Guide.