Cutting Flight Control Gap Seals from Pool Noodles
In this video we go through the process of converting pool noodles into low-cost lightweight, and easy to install foam gap seals for the EMG-6 electric motor glider.
Let’s go through the detailed procedures on how we came up with the final results that we have been using on the EMG-6 electric motor glider. We have cut nearly 30 different dies and guide blocks to come up with the final results that we found that work very well.
the cutting jig assembly consists of a 2 inch thick laminated piece of plywood that is used to hold the pool noodle rigidly in place as we extruded through the cutting dies. We then use about (4) 1/4 inch washers on each one of the attach bolts in between the wooden block and the cutting dies this keeps the temperature of the cutting dies hot while insulating the guide block. We clamp the guide block into the vise on the workbench. This allows the cutting dies to maintain temperature without dissipating the heat into the vice. we then use a propane torch to heat the 2 cutting dies this usually takes about 15 to 20 minutes to saturate the cutting dies with heat before we can begin the extruding process.
each one of the cutting dies will were manufactured from.375 inch-thick 6061 T6 aluminum the thickness of the cutting blades needs to be about .060 minimum thickness and we have done it up to about .090 without any detriment. We taper the leading edge of each one of the cutting dies down to about .020. And we put the taper on the outside of the final product which draws the excess cut foam away from the centerpiece and the parallel cutting edgethat is against the final product will act to seal the surface as the foam is drawn along the .375 inch blade.
since we are cutting 4 sides of the pool noodle we can only cut 2 sides at one time which requires that we have cutting dies that cut different profiles but stacked together end up with the final product. The machining process on each of the dies is the same which draws the scrap foam away from the internal part holding the pool noodle rigid in space as it drawn over the cutting dies.
when the cutting dies or stacked together you can see how we end up with the final shape. In the picture below we can see the dies are cut with a large relief on the outside edges which allow the excess pool noodle material to be drawn through without making contact with the hot edges of the cutting die. The guide block very specifically positions the pool noodle as it is drawn through the cutting dies.
The amount of heat that’s necessary can be determined prior to pushing the pool noodle through the dies by taking a scrap piece of material and testing it against the backside of the cutting dies.. once you can push the foam in the reverse direction over the dies and it melts cleanly the temperature is ideal for extruding the pool noodle. We used a thermal thermometer to come up with perfect temperatures and document exact temperatures during different tests. we found it to be unnecessary and the simple test of pushing scrap material in reverse direction was as good as any attempt to perfectly controlled the temperature going into the cutting dies.