The most recent attempt at tube construction tested trying to remove 1mm of material from the mandrel. When constructing using the cash register tape and packaging tape technique this is about the difference in size noted between final part and target. This attempt went extremely poorly.

The dowel used has poor concentricity to begin with. In addition to this chucking it in a drill and sanding it does not work very well. This gave me a tapered rod. Those two things coupled together have lead me to finally order an aluminum tube to use as a mandrel instead.

The aluminum mandrel will allow me to use the difference in expansion/contraction with temperature to more easily remove the part. This eliminates the cash register tape from the process. However, as I wait for material to arrive the temperature has been dropping, thus increasing cure times.