Epoxy expansion or baffles too larger

I am building the Estes Ventris and decided to put in a half moon baffle at the coupler. After epoxying in the coupler and baffles I sanded down the tube to get a smooth connection. I noticed that it was raised where the baffles sit. Is this the epoxy expanding the body tube or did I not sand the baffles down to perfection?


Thanks,
Mark

could be the sanding method. If you squeeze too hard when sanding, the air frame will give where the coupler/baffle will not.
Use a straight edge to see if it actually bulged at the coupler/baffle.

I used a sanding block. More a matter of curiosity. If you can see the two lines that cut across the airframe about three inches from the middle, that's where the baffles should be. I'm curious whether or not epoxy soaks in to the BT the same way that CA does?

Mark

Epoxy will soak into the cardboard if the glassine layer on the outside has been removed, and it will somewhat soak into the non-glassined interior of the tube. The lines you are seeing where the baffle plates are is caused by the baffle plate not allowing the tube to flex. However the tube is able to flex on either side of the baffle plate so that inflexible spot is a "high" spot when sanding pressure is applied since it doesn't move but the adjacent areas can be pressed down ever so slightly. The effect is more noticeable with a hard sanding block, I like to use sanding sponges for airframes. The effect of airframe flexing is more noticeable on the lighter weight cardboard airframes.

Here is a coupler that was coated with epoxy as I wiped the excess epoxy away from the glueing process, the epoxy was thinned by the alchohol on the rag. There is not a lot of epoxy but it did kind of "surface harden" the cardboard, thats why the spirals are still natural cardboard color.

Thanks folks. I'll use something softer to sand with in the future, or at least use a lighter touch.

Mark