Sagitta 600 build 2018 - RC Groups
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Apr 07, 2018, 10:17 AM
ʇsol
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Build Log

Sagitta 600 build 2018


Another glider project for '18.

From my past builds I've had a ton of inquiries about my CNC machine and cutting details, here's a rehash: I'm using a first-generation Shapeoko 3 (the newer ones a little more robust in the Z-axis and have a few other updates) with a DeWalt 611 router for a spindle. I added a 1/8" collet from Precise Bits, and typically use 1/32" downcut bits for thin balsa and parts that need detailed cuts (anything lighter than 1/4"). 1/4" and thicker - and some heavier materials are cut with 1/16" long-reach bits (all from Precise Bits). My wasteboard is covered with 1/2" blue foam to simplify things.

My machine is the smallest Shapeoko they make. It sits nicely on the end of my computer desk. With some careful planning it can be used to cut parts (fuselage sides, etc).

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Back to the glider: the wing design was mostly done in devWing2, with final editing in CorelDraw and Fusion 360. CAM work for cutting is with Cut2D. A couple of weeks of part-time CAD/devWing2, followed by waiting for a wood order (and final editing based on the wood dimensions) I'm ready to start cutting parts. We'll start with the wing - the fuselage would be too much of a giveaway

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The first group of ribs are set up in Cut2D. These are all the inboard wing panel ribs except two special ribs (we'll get to those later):


Each sheet can be cut individually, but to speed up the process I sometimes will do several sheets at a time. This works ok if the parts are set up too close to the sheet edges. I've set everything up so both the right and left wings will have ribs cut from the same sheets of wood while the other sheets were weighed to keep them close to equal. Heavier/thicker materials are used closer to the wing root, lighter/thinner toward the tips. Or at least that's the theory...

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First step is to put labels on the parts:
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Then let the cutting begin!:
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Nearing completion - the parts on the bottom of the last two sheets were really tight but they'll work ok (I set the sheets too far up):
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Some CNC routing in moving pictures - this could be cut a bit faster, I was only cutting at 18ipm:

cutting parts for the mystery project (1 min 16 sec)
Last edited by vulturetec; May 08, 2018 at 12:42 PM.
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Apr 07, 2018, 11:28 AM
ʇsol
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Cut the leading edge sub-strip (to be explained later), popped a couple of ribs out, and test-fit it all. So far so good.

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Latest blog entry: Sagitta 600 build 2018
Apr 17, 2018, 01:47 PM
ʇsol
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Adding sheer webs to the tip panel



Each rib is glued to the top spar using the webs as jigs for spacing and verticle guides.


With the ribs glued in place the webs are glued and set in place, as is the bottom spar. The whole thing is clamped and left to dry.
Latest blog entry: Sagitta 600 build 2018
May 08, 2018, 12:57 PM
ʇsol
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Cutting fuselage sides


Finished up the CAD work on the fuselage, now time for cutting the parts. Long parts are a challenge with my desktop-corner CNC setup, the fuselage sides had to be cut in three sections/tiles. Index holes are planned along a common line at the "home" position of each section break, then the wood is moved into position as each section is cut using the index holes as a guide.



I planned the fuselage sides and bottom with recessed pockets that mate with tabs on the formers. The parts should all self-align if everything is cut correctly.



Everything seems to fit pretty well when test-fitting.

Latest blog entry: Sagitta 600 build 2018
May 12, 2018, 08:45 AM
ʇsol
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Starting an inboard wing panel


To start the inboard wing panels I first pre-cut the joiner-tube filler blocks, webs, and ply plates (designed in Fusion 360), then glued them up separately on a heavy plate of glass.

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With the lower spar caps built, the parts are set in the wing jig to be assembled

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The short pieces of spar material are just to check the fit and hold things together temporarily
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Checking the fit of the spoiler holes. So far everything is perfect. The ribs are laminated with 1/16" ply around the servos. The ply acts as a doubler and mounting plate for the servos.

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Latest blog entry: Sagitta 600 build 2018
May 14, 2018, 07:09 PM
ʇsol
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Top spar cap glued on. I temporarily installed a root rib on each end of the wing panel to support the ends of the spars to keep everything square while clamping. Also added the polyhedral reinforcement ply plate and two inboard nose ribs.

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Checking the fit of the joiner tube.

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Joiner tube and rear inboard ply plate installed, plus the rear halves of the inboard ribs. The vertical angle of the root rib was set with the pre-cut ply plates. The alignment of the root rib was set with a template cut to match the angle of the fuselage. I also took the fuselage floor and checked the alignment against it. It probably isn't perfect, but it'll be close rough fit for now.

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Latest blog entry: Sagitta 600 build 2018
Jun 07, 2018, 04:40 PM
ʇsol
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Sheeting and fitting the spoiler to one of the inboard panels

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Latest blog entry: Sagitta 600 build 2018
Jun 07, 2018, 04:42 PM
ʇsol
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Fin built and test-fit on a fuselage side.

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Getting the other fuselage parts ready to glue together. The bottom ply and balsa are joined with a joint that tends to self-align:

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Latest blog entry: Sagitta 600 build 2018


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