Spring Boom Vang

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Fenstermacher Spring Loaded Boom Vang

This write up is for those that like to play with metal. For those that are better with a checkbook than a power tool, contact Dave Ramos at Chesapeake Performance Models. He has them in stock. Buy on line at http://www.rcyachts.com/store.asp?ItemID=141

All Fenstermacher parts are considered public domain. Feel free to take this design and improve on it. A lot of really nice aluminum stock was turned into worthless shavings getting to this point. All that is asked is that you share your refinements on the EC12.org discussion page.

The supplies for this project came from McMaster-Carr (www.mcmaster.com) and Tower Hobbies (www.towerhobbies.com).

McMaster-Carr
	Part Number
	4568T11	¼” Aluminum Tube, Wall Thickness .065”, ID .120”
	8974K14	1/8” Aluminum Rod
	1986K1	1” Compression Spring, OD 5/32”, Wire Sixe .016”
	91772A076	18-8 SS Pan Head Phillips Machine Screw 2-56, 3/16"
	93181A007	6-32 Aluminum Machine Screw Nut
Tower Hobbies
	Dubro 2139	Dubro Swivel Ball Links 2-56 w/4-40 Hardware (2)

Cut two pieces from the ¼” tube 1 ½” long. One we’ll call the Spring End and the other will be the Adjustment End. Using a #16 bit, drill out each tube 1 ¼”. This leaves ¼” at one end undrilled.

Using a 10-24 tap, thread the first ½” of the section you just drilled out.

Spring End

Drill out the undrilled end using a #30 bit.

Adjustment End

Using 1/8” drill bit, enlarge the hole at the undrilled end.

Using a 6-32 tap, thread the end with the 1/8” hole.

Vang Rod

Cut the 1/8” diameter rod 6” long.
On one end, drill and tap to receive the 2-56 machine screw listed above.
The other end will be threaded for 1 ½” using a 6-32 die.

Dubro Ball Links
The shaft of each ball link needs to be threaded using a 10-24 die.

Assembly

Install the screw in the end of the Vang Rod. Push the threaded end of the Vang Rod into the bigger opening of the Spring End and out the small opening.

Insert the Compression Spring in the same direction the Vang Rod went in.

Take one Ball Link and screw it into the end of the Spring End.
Add the 6-32 Nut to the threaded end of the Vang Rod.

Thread the Adjustment End onto the Vang Rod.

Screw the other Ball Link into the end of the Adjustment End.