Building some boat rods and finding that when I go to glue on a gimbal the air pressure trapped inside will push it back off the blank if I do not watch it carefully for about an hour. So I cooked up a long clamp thing to keep it in place. But then I worry about the pressure left inside the rod and it if will eventually cause the glue holding the gimbal or the tip top to come loose over time. How do you get rid of the air pressure inside the blank other than using parts that are oversized and do not fit well?

If you were to directly measure the air pressure increase or calculate by volume reduction as the part is slid on, you would find the pressure increase is negligible; don't worry about it.

The freshly applied liquid epoxy acts like a lubricant to allow the slight pressure increase inside the blank to slide the part back off, seeing this happen can fool us into thinking the pressure increase is a lot higher than it actually is.

Drill a little bitty hole in the end of the gimbal before you apply glue and slide it on. Problem solved. You will be impressed at how well this works and no more gimbal back off.

If your using tape to build up a arbor for the gimbal. You can cut a couple channels in the tape to let the air escape. Or drill a small hole in the bottom as Ken stated.

Use thread in larger spacings This way the glue will grab the inside of the gimble AND the blank

Bill - willierods.com