A Wood Grip for a Delicate Brass Tube
© Frank Ford 2008; Photos by FF

My wife, Joy, has been a full time potter for these last four decades, and currently her work is "high fire" functional pottery with a soda glaze. She uses a thing called an "Indian Fire Pump," a back-pack water squirter used by foresters to douse small fires.  It looks a lot like this one:


Here she is in action, spraying a solution of sodium bicarbonate in water directly into the kiln at something over two thousand degrees Fahrenheit:

My part in this endeavor was to modify the nozzle with a swivel joint and spray head that could take the heat.  Oh yes, and I get the job of maintaining the gear, too. 

It's a nice little pump but I must say that the baking soda solution really wants to corrode all that brass.  So, every few months I have to take it all apart, clean, polish and lube it up for the next round of firings.

At first it was easy enough to unscrew the parts by hand, but as the pump ages, the threads are getting a bit rough, and it seems they tend to lock up rather solid sometimes.  The body of the pump is a super thin wall brass tube, and I wanted to have a good way to grip it without damage.

Clamping litghtly in the vise with a bit of leather and fine sandpaper proved to be too risky:


So I measured the diameter of the tube:

And found I had a Silver & Deming drill just that size (1-1/32")


I chopped up a two-by-four and made two little blocks, along with a 1/8" separator piece:


Clamping the sandwich in the drill press vise, I drilled right on through:


Then I had a grip that would squeeze very well without distorting my thin wall tube so I could unscrew that stubborn end easily:


And, since I labeled, strapped the pieces together and stashed them in the drawer with the spare pump parts, I'll have them handy next time:



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