Musings from the Combat Pits

Propane, not air

August 2019

By Buzz Wilson

PROPANE NOT AIR

Hank Hill to his son Bobby: “No Bobby don’t use air, use PROPANE.”

For years we have used an air horn for starting and ending Combat matches that had an adapter that would connect to a propane bottle. Norm McFadden was credited with building the original. Last year at the Bladder Grabber someone managed to loose the plunger as well as mess up the threads on the connector. With the 2019 Bladder Grabber rapidly approaching, I decided to fabricate a new plunger.

I have been using 1/8-inch aluminum welding rod to make pushrods that attach to the control horn with a wheel collar. In an "ah-ha!" moment, I decided that it would make a great plunger. I cut a piece of rod longer than needed and attached the wheel collar using a setscrew. Now this assembly has to fit inside the brass sleeve. To do this I used the disc on the belt disk sander and shaped the collar to fit.

The next step in the process is to cut the plunger to the correct length. The plunger is inserted into the horn connector assembly and then carefully threaded onto a propane bottle. Because we started out with the plunger being long we can slowly sneak up on the correct dimension, length.  Once the correct dimension is set, the plunger end is flattened using the disc sander.

The fit inside the sleeve is sloppy so the final step is to cut a piece of aluminum tube to form a sleeve and Loctite it to the plunger.

Because the threads on the connector sleeve had been messed up, I decided to overhaul the entire assembly. A trip to the local Ace Hardware and I was able to purchase a propane fitting ...

... and an adapter.

Here is the completed assembly with horn and attached to the propane bottle.

As I sat there with leftover parts, I decided to build a backup system. All I needed was a new horn ...

... and a different-length plunger. Here is the old fitting and the fitting with a new plunger inserted

The new horn comes with a can of air. I removed the air can and checked that the female insert in the horn would work with the threads on the propane adapter.

Here is the old fitting attached to the new horn.

On both the primary and backup, I have used an adequate amount of torque on the assembly and a generous amount of Loctite.

Both units will be field tested at Bladder Grabber 41 on Aug. 9-10-11 in Snohomish, Wash. For details, see Where the Action Is.

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This page was upated Aug. 2, 2019