Allegro-lite mid-panel shear web height mismatch question

[Mike K]

So I got the laser-cut rib set with the vertical balsa webs included.

Got the joiners built and glued on to the bottom carbon strip.
Everything ready to sand the shear webs to the proper angle and test
fit...

Problem is that the vertical webs seem to be uniformly short.
Example: First inner rib height in the slots for the carbon 0.447.
Shear web height 0.428.
And so on down the entire panel...

0.019 is a noticable bump, and I assume would be horrible to leave.

Should I sand the rib bump down before attaching the top carbon, or
attempt to build add height to the shear webs with a little 1/32" balsa?

Not sure which is better, but sanding the rib bump sounds a lot simpler...

First time I am building this way, and the build logs I have seen so
far haven't mentioned this...

Regards.
Mike K.

[Fly2High]

Can you replace one or two shear webs and move them all toward the tip a bit so they will fit? This way you only need to remake the largest one or two at the root.

[Mike K]

Can you replace one or two shear webs and move them all toward the tip a bit so they will fit? This way you only need to remake the largest one or two at the root.

Duh, hadn't thought of that...

It looks much better this way, one or two might need a couple thousands sanded off, but no more than a sheet of paper.

Now to cut out two more...

Thanks!
Mike K.

[rdwoebke]

Are you sure you are not missing a shear web? They are numbered, right? Do the numbers match up with what James Osborn has on his build?

I'd do what the above poster suggested. See if you move them down a slot and see how those fit, then make up a "big shear web".

Else you can also cut new shear webs with a jig like this:

http://www.charlesriverrc.org/articles/construction/markdrela_webcutting.pdf

I made one for cutting the shear webs on my Aegea wing.

Ryan

[Mike K]

Are you sure you are not missing a shear web? They are numbered, right? Do the numbers match up with what James Osborn has on his build?

Yup! They just don't fit as numbered. Number 10 will be tossed.

I'll skip the jig for now. A straight edge, the calipers and the Zona fine tooth saw work nearly as well if you are careful...

Heck, if I used to be able to build indoor microfilm using only a broken-off razor blade and a straight edge, I ought to be able to do this! :)

Regards.
Mike K.

[kak8]

I don`t know if I understand your problem right, but i think you have to support the spar with 0.014 mylar strip before you glue the ribs in place, so there`s some room left for kevlar wrap - still under the surface.

[BrentD]

What KA8 said - you have to LIFT UP the carbon .014 with mylar to later make up for the wrapping.

I wish I didn't find that out the hard way 2 years ago.....

Brent