[TowerTalk] Widening tower mast opening.

[Grant Saviers]

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 at 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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