Rebuilding my Super Big Bertha

My Super Big Bertha was damaged during its first launch on 11/17/23.  Because of the size of the body tube (2.6" diameter) I was unsure about how I could cut it evenly, since my tube cutting guides don't go that big.  Luckily, I came across a posting on the Facebook Estes group by Orestes showing he used an adjustable tube clamp as a cutting guide to repair his Super Big Bertha.  

I bought a clamp at my local hardware store (2 ~ 3" diameter) for $4 and it fits!  

I unhooked the swivel holding the elastic shock cord to the Kevlar so I could remove the nose cone and pushed the Kevlar down into the body tube so it was below where I was going to cut.  I put a new blade in my Exacto knife so I'll get a clean cut.  Okay, so it didn't cut exactly straight so I'll need to sand and probably use some filler to smooth the joint but at least I was able to make a pretty clean cut.

The teeth from from the clamp left a few knicks on the body below the cut so I'll have some extra sanding to do to blend everything.  I've got replacement body tubes (BT-80) that are 14.2 inches long as well as a BT-80 tube coupler (3 inches long) so will just need to cut off ~4 inches of damaged body tube then cut a 4 inch replacement and glue it in place using the coupler.  It will add a slight amount of extra weight forward but allow me to keep the same length and overall stability without adding the full 14 inches of new tube.  Luckily, I've got the clamp I can use as a cutting guide for the new tube as well.

I still need to fill the gap, prime and sand the new tube, then paint it to match the rest of the body.  I'll post pictures when done.  Stay tuned!

Feb 2, 2024 Update:

We finally had a 50 degree day and I was able to paint the Super Big Bertha.  It's back on display.  I've also 3D printed a BT-80 tube cutting guide for use on future projects (described here).



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