Starfire Rail Guides

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The photos below will illustrate how the rail guide buttons were installed on Starfire.

Click on any photo below to see a larger image of it.

The first step is to drill the aft end of the booster so that a threaded steel insert can be installed into bulkhead B1.

		The steel insert is part number 90192A114 from McMaster-Carr.
	A threaded steel insert is installed using an Allen wrench. It has exterior threads that bite into the wood. It has internal threads for a #10-24 machine screw.

The insert is driven just below the surface of the body tube.

I purchased some black Delrin rail buttons from a private party but you can find some on-line at RailButtons.com. Starfire uses the larger sized buttons for the 1.5"x1.5" rail. Two black plastic spacer washers are also shown here along with a #10-24 x 1" flat head machine screw.

The rail button was temporarily mounted to check fit and alignment prior to painting. It was then removed. A #10-24 x 1/2" pan head machine screw was then installed to protect the threads on the metal insert during painting.

At this point Starfire is now complete except for installing the rail buttons. A thick white nylon washer and a steel washer with a captive rubber backing were used to space the rail button away from the surface of the body tube. This gives a little more room so that the rail does not rub on the airframe even if the buttons (or the rail) are not perfectly straight. The nylon washer and rubber backing are soft enough to conform to the roundness of the body tube.

The rail button is secured with a #10-24 x 1" flat head stainless steel machine screw. Loctite 242 thread locker adhesive was also used on the screw threads. The Loctite makes sure the screw does not come loose yet still allows it to be removed if necessary to replace a damaged rail button. Loctite 242 is available at McMaster-Carr.

A second rail guide button was mounted just above the fins by installing a threaded insert into bulkhead B3. All the same techniques were used on that rail button as are shown here.

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