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MK3A Rebel (K0001) Build Part 3 - Booster Assembly and Finish Prep

Booster Build Elmers Wood Filler Finishing MK3A Part 3 Rebel

Part 3 of this blog series finishes the MK3A Rebel's booster section .  If you missed Part 2 of this series, it is available at this link.

As stated in the assembly instructions provided with the kit, epoxy is required for kit assembly.  I use quick drying 5 minute epoxy, but any two part epoxy is fine.

For Part 3, we will need:

  • Fin can assembly from Part 2 of the blog series
  • 9 inch body tube (Part #6)
  • Chambered Baffle (Part #5)
  • 0.25 inch screw eye (Part #2)

During this series of steps, preliminary work is done to prepare for painting the rocket.  If you prefer to finish after the build is complete, omit those steps.


Preliminary Finish Preparation

  • Fill the spiral groves in the 9 inch body tube (Part #6).  There are many ways to do this.  I find using thinned Elmers Wood Filler the easiest way to get a good finish with little extra weight.  Squadron putty is also very easy to use.  I like the Wood Filler better, as it doesn't have an odor and cleans up easily with water.

  • Once the filler is dry, sand flush to the body with 220 grit sandpaper.  Be careful to not sand the top protective layer off of the tubes as it make the final finishing harder.  The paper underneath will "fuzz up" when you spray with primer, which typically means more sanding.

  • Once the spiral groove is filled and the filler sanded to your liking, spray the tube with a light coat of primer.  I use Krylon gray primer.

  • Set the tube aside to dry.  I usually let this dry overnight.  I've found that lets the primer dry completely which makes it sand better.  Otherwise, the sandpaper tend to clog quickly with soft primer.  When completely dry, sand off the primer leaving the surface of the tube smooth.

  • Wrap the fin can shoulder with masking tape.  This will prevent any wood filler from getting on the shoulder.

  • Fill any imperfections on the surface of the fin can with the thinned wood filler.  Apply a very this layer of filler on the whole surface of the fin can to smooth the striations left from the printing process.  You don't need a lot of filler to smooth the surface.  Remember that the more you put on the more you have to sand off.  Set the fin can assembly aside to let the filler dry.

  • Sand the fin can smooth with 220 grit sandpaper.  Remove the masking tape.

Assembly Steps

  • Using a section of metal angle or a door jamb,  draw an alignment line the length of the 9 inch body tube (Part #6).

This is used to line up the launch lugs on the fin can and the chambered baffle in the next steps.

  • Apply a generous amount of epoxy around the inside circumference of the 9 inch body tube, about 1/2 inch from the edge of the tube opening.

  • With the word "TOP" facing out, insert the chambered baffle (Part #5) into the body tube, twisting the part as you insert it to evenly spread the glue.  Rotate the part so that the center of the launch lug is lined up with the alignment line on the body tube.

  • In the opposite opening of the tube, apply another generous ring of glue inside the tube.
  • Partly insert the fin can assembly in to the tube, leaving some space to apply another glue ring.

  • Spread more glue in a ring inside the body tube.

  • Insert the fin can the rest of the way in the body tube spinning the part as you do.
  • Rotate the fin can so that the center of the launch lug is aligned with the line on the body tube.  If necessary, wipe away any excess epoxy that may have squeezed out of the glue joint.  You can use a small amount of denatured alcohol or acetone on a paper towel to clean off epoxy on any of these surfaces.  Make sure up dispose of the paper towel appropriately.

  • Set the booster section aside to allow the glue to harden.
  • Once the glue is dry, screw in one of the 0.25 inch screw eyes (part #2) into one of the starter hole in the chambered baffle (Part #5).

That's a wrap for this post.  Part 4 will show the assembly of the "payload" section of the MK3A Rebel and start the preliminary finish work.

As always, I encourage you to take a look at the XROX Aerospace MK3A Rebel product page.  This is a unique kit that is simple to put together and fun to fly.

Happy building and safe flying.


XROX Aerospace

The sky is not the limit!

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