How to Dewarp Plastic Beams (Success!)

I received a package of 2x structural beams and the two long 2x20 beams were very warped. I don’t have an initial picture but if I was to peg the two together at one end they would form a Y and the other ends would be a full inch apart. I was able to successfully bake the parts and they came out amazingly straight.

I asked a mechanical engineer friend of mine what temperature. Assuming the plastic beams are made from ABS plastic he suggested 200F which is just below the Vicat softening temperature. My kitchen oven has a warming mode that lets me set a temperature of 200F. I placed a flat ceramic tile on a middle shelf with a metal pan covering the top and a thermocouple in the middle. After letting things warm up for 20 minutes the thermal couple read 86C(187F) which I though would be a great temperature to start at. I placed the two sticks on the tile such that they bowed up in the center and covered them with the pan. After 20 minutes I checked them and they looked flat. I put the pan/lid back on top, turned off the oven, and cracked the door to let the system slowly cool. 40 minutes later I removed the parts and they were very flat and appeared to be in perfect condition. This temperature should not cause the pieces to become brittle and the resulting parts appear not to be. However I did not do a destructive comparison test.

Attached are two pictures of my setup and a plot of the temperature profile.
I think you need to use the metal pan as a lid to keep the temperature uniform around the part and to protect it from the hot cycling of the heating coils. Also keep the lid on as they cool.

Note: If you are not an adult do not attempt this. If you are an adult but do not know for sure that your oven will actually go as low as 200F (I checked mine with an special instrument) do not attempt this.





Hi goeckerd,

We’re sorry that you have encountered this issue. If the parts were new and warped as described, this is not a normal condition for VEX IQ beams. In the future if you have any questions or concerns about potentially defective new parts, please contact VEX Support at [email protected] or by calling +1-903-453-0802 so we can make the situation right.

Regards,

  • Art