Flying Engine Mount Build Part 1, Parts? DIY Centering Rings

This is a spare parts odd-roc based on Steve Lindeman's Little Me-Me.
Steve's design was a left over engine mount from the Estes Jetliner kit. He upgraded the Jetliner to 18mm engines. The leftover 13mm engine mount was assembled and launched as a spool.

To build it you'll need:
2    5/60 Centering Rings
1    2" Length of BT-5
1    1 3/4" long Engine Hook
1    13mm Engine Block
      Electrical Tape

I couldn't tell the length of the BT-5 engine mount tube. Assuming the cross section drawing from the instructions was to scale, I enlarged the monitor picture until the engine mount tube wass about 1/2" diameter. That gave me the BT-5 at 2" long.

This is a spare parts build. I thought I had all the parts and started looking for the 5/60 centering rings. I have every centering ring except the 5/60 size.
I'll have to cut them from .050" thick mat board.
I did have 50/60 rings.
First trace around the outside of the ring. Trace a few more than you'll need and use the two that best fit the BT-5 tube.
After tracing the outside circle, set and circle a BT-5 in the center.
Use a sharpened pencil so the line is close to the tube sides.
It may take a few BT-5 tries to get the inner circle centered.


Using a new sharp knife, cut the inner circle first.

Cut a little inside the pencil line for a friction fit over the BT-5.
Don't try to cut all the way through in a single pass. Make a few light passes to cut out the center.