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Re: [TowerTalk] Widening tower mast opening.

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Widening tower mast opening.
From: Grant Saviers <grants2@pacbell.net>
Date: Thu, 23 Apr 2020 08:16:07 -0700
List-post: <mailto:towertalk@contesting.com>
Are you sure it isn't some droplets of Zn causing the interference? A quick file touch up has worked for my re-galvanized mast. IIRC the UST mast tube id was about 1/16" ID oversize vs the usual 0.005 to 0.010" spec for HDG Zn thickness. What are your id/od measurements?

I don't think a hone will work, Zn is too soft and gummy, assuming the tube was (should have been) HDG at the factory inside and out. Try a coarse flap wheel on an extension in a drill. Wear a mask as Zn dust, while not particularly hazardous, can give you "welders flu", which I have verified as not fun after welding galvanized pipe.

Plan B: cut off the tube with a recip saw. Grind away what is left with a carbide burr in a die grinder. Then you need a mast restraint to prevent tilt when pulling a rotator.

btw the Harbor Freight metal digital calipers, often on sale for $10, are ok accurate (+/- 0.002") for ham work. I have a bunch of them handy all around the shop for quick checks. Much easier to throw away when damaged than a $180 Tesa/B&S or Mitutoyo.

Grant KZ1W

On 4/22/2020 20:24, w6rgs@cox.net wrote:

Howdy folks,

Having galvanized a 2" mast for my tower, it's now too tight of a fit in the 2" wide x 3" long mast opening at the top plate of the tower.  I already knew that galvanizing would slightly increase the diameter, but did not expect as much as it did.

So, I'm thinking of honing out a few thousandths of steel inside that 2x3 tube for the mast to fit.  There is already a thrust bearing on top, so I'm not worried about a lack of support after honing.

Any thoughts on using a 3-stone cylinder hone to open up the tube a little?

Bill W6RGS

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