Spar Cap finishing

[dbdevkc]

Per the Sonex instructions:

"As a last general step, remove any stress risers that may remain including
scrapes, scratches, or the slight edge from the leg of the angle that was
removed. This can be done with a dual action or palm sander or with the Scotch
Brite pad or wheel."

Does "...the slight edge from the leg of the angle that was removed." mean
remove the entire 'slight edge', or just smooth it out? Seems like quite a bit
of material and would take quite a bit of work on the scotch brite wheel.

Kevin

[MichaelFarley56]

Hi Kevin,

It's been a while since I finished my spars but I'm fairly certain they just want you to smooth them out so there are no spots for cracks to start. Mine were already pretty good but I made sure all was smooth with a scotch brite pad before riveting everything together.

[142YX]

Do the entirety of the spar caps. I did it using a fine (i believe thats the blue colored disk?) 2" scotch bright wheel chucked into a die grinder. Entire process took less than 30 min each.. left a really nice scratch free finish.

[dbdevkc]

FYI, this is what I heard back from Kerry (confirming what I had thought):

"No need to remove that whole lip, which is, in fact supposed to be there. The only place that needs to be be removed completely is where the tie-down brackets attach. The purpose of that note is to make sure each builder removes all scratches from their spar caps. A scratch is a stress riser where a crack could begin in the future."

[Sonex1517]

Thanks Kevin! You had me looking closely at my spars again....always a good thing.

Robbie
Sonex 1517

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