Rounding Fin Edges

Sorry, no posts yesterday - blame the slow, crappy ship internet connection.

I'd read on The Rocketry Forum where some have had problems rounding fin edges.
Some on TRF were looking for a specific tool that could help.
No tools are needed, just a sanding block and some 400 grit sandpaper.
If you use 400 grit you'll only take off a little at a time. You can correct things before too much has been sanded off.

If you just sand back and forth over a leading or trailing edge, you run the risk of rounding off the square corners of the fin.
Use some 400 grit on a sanding block for more control.
Again, don't just sand back and forth, Set the block on the edge, then sand.
Roll the block around and over the top keeping it flat against the edge.
The block goes over the top as the fin slides down the block.

Make a single pass and check the fin.
Set the block squarely on the fin edge again and make another pass.


When you've got the fin edge rounded go very lightly over the middle of the edge with a piece of scrap 400 grit.
Sometimes when sanding with the block you will sand more off the sides leaving the middle a little square.
Depending on how well you did with the block this step may not be needed.

Here's a good example of rounded leading and trailing edges.
Sight down the fin from the root and outside edges to check the roundness.

The grain is ready to be filled.