On the left, just the leading edge thickness is sanded first. I haven't sanded down to the masking tape yet, just concentrating on the leading edge.
The inset picture shows it sanded down to the tape edge. The full length of the taper is flat.
The tapered wedge shape came out sharp.
The remaining black on the leading edge was removed with 400 grit.
The instructions show the 1mm thick leading edge to be slightly rounded.
When sanding down CWF filler, use a block with 400 grit.
If you sand correctly, the filler will sharpen the taper edge even more.
If you aren't happy with the results, you may have rushed the fin shaping or didn't use a good sanding block.
Get the right tools and take your time!
Nobody gets it right on the first, second or even third try.
TIP: Practice on scrap balsa, not on the laser cut fins supplied with the kit.
I love technique posts like this. When I first tried sanding tapers and airfoils, I found it so difficult to get it right - and consistent from fin to fin. But after a while of doing it, I find it... not exactly "easy," but something I can do with confidence - so long as I take my time.
ReplyDeleteBest bit of advice I've gotten from this blog is to get the Great Planes sander, as Chris suggests. It's just a terrific tool.
Hi Daniel,
DeleteI'm glad the technique posts help. This isn't the only way to do this, it's just what works for me.
Too many give up after trying to sand an airfoil (or fin like this) after the first try. Patience and practice do pay off. Just about the time you might be ready to give up, you get it.
The Great Planes block is the best. I wish I had it years ago!
Chris, Do you expect the rocket will rotate (more than without tapered fins) in flight or are you alternating the sanded side every 180 degrees, so force against the fins will equalize?
ReplyDeleteHi Scott,
DeleteI don't know if I understand your question. The taper is even on both sides. Think of an inverted "V".
When sanding the fins I did sand on one side and then the other. I didn't count passes of the sanding block, I just kept an eye on both sides making them as equal as possible.
I see it now after a closer look of the images. ;-)
ReplyDeleteThanks!