Spar caps clean up

[lstinthot]

We are about ready to take the spars apart and begin deburring and cleanup process.

Waiex spars on left, scratch built Sonex on right

Are we supposed to clean up the milled edge where the tie down is installed? This would allow the piece to sit flat, but does it take away from the strength of the spar cap? Does it matter?

[Bryan Cotton]

Looks good. I did sand mine down so the angle would sit flat. I think the reduction in strength is minimal. Bending loads primarily go through the vertical section so that bump will not add much.

[Sonex1243]

I had asked Sonex tech support the same question and they said go ahead for a good flat fit.

[lstinthot]

I was leaning toward cleaning them up so the parts sit flat. Thanks.

[lstinthot]

How about adding a shim under the tie down. Allows the tiedown to sit flat. What say the crowd?

Slight gap that could be worked to remove it.

Here you can see the shim.

[Bryan Cotton]

That would work too, if sanding down that spot bugs you. I saw it as a weight reduction opportunity! I read Paul Dye's column in Kitplanes yesterday and he is right, I should lose 20 lbs. By God I'm trying but injuries have really messed up my running. So, I go after those micro-oz wherever I can.

[kmacht]

I did the opposite and filed down the angle tiedown piece a little bit rather than trim the spar. I figured I wanted the little bit of extra material was better on the spar than on the tiedown.

Keith
#554

[lstinthot]

I was thinking about trying removing material from the tie-down angle to make it sit flat. The shim is less than .025" thick. It would not take that much time to channel out the relief for the spar edge. I'm going to finish cleaning up the spars and try a few different options to see what I like best.