Shank Repair band Sizing

[ontariopiper]

Hi all,

I've got to band a cracked shank on an old pipe that belongs to one of my pipe club gents. According to my digital calipers, the band measures 12.4mm side to side and 13mm top to bottom.

Which size band should i order? Will a 12.5mm band stretch enough to fit? Will a 13mm band be too large, given the out-of-round shank?

He'd like a sterling band rather than a nickel band, so I'd rather not order more than I need to.

Thanks in advance.

 

[Richard Burley]

No experience, just curious: if you used the larger, wouldn't glue fill the .3 millimeter gap on the sides? If you used the smaller and somehow stretched it, wouldn't you then have an oval that wouldn't quite match the stem?

 

[MichaelM]

I'm not going to claim I know the answer, but I do love a bit of math...
I think you want a band that will come as close as possible to having the same perimeter so that when you deform the band it will fit on the oval stem.  If you approximate the oval as an ellipse, you can calculate an approximate perimeter.  Using your numbers and the first formula here:  https://www.mathsisfun.com/geometry/ellipse-perimeter.html
I get perimeter=39.91
Then using the circle formula I calcuate the circle diameter that will give that circumference:
D=C/pi. D=39.91/pi. D=12.7
So the diameter you want is 12.7 mm (assuming that you are not going to decrease the diameter of the shank to fit the band).  If you only have a choice between 12.5 and 13 mm, I personally would go with 12.5 and sand the shank a bit to get a perfect fit.
I hope that helps, or at least provides some entertainment :lol:
Please let us know what you choose and how it works out.
Mike.

 

[ontariopiper]

I'm not going to claim I know the answer, but I do love a bit of math...
I think you want a band that will come as close as possible to having the same perimeter so that when you deform the band it will fit on the oval stem.  If you approximate the oval as an ellipse, you can calculate an approximate perimeter.  Using your numbers and the first formula here:  https://www.mathsisfun.com/geometry/ellipse-perimeter.html
I get perimeter=39.91
Then using the circle formula I calcuate the circle diameter that will give that circumference:
D=C/pi. D=39.91/pi. D=12.7
So the diameter you want is 12.7 mm (assuming that you are not going to decrease the diameter of the shank to fit the band).  If you only have a choice between 12.5 and 13 mm, I personally would go with 12.5 and sand the shank a bit to get a perfect fit.
I hope that helps, or at least provides some entertainment :lol:
Please let us know what you choose and how it works out.
Mike.

You're too clever for me , Mike! That's some good math-ing!

I'm hoping not to sand down the shank at all - the pipe in question dates to 1919-21. It's been through enough without me poking it more than necessary. That said, 0.2mm is a VERY small amount of anything....

I'll cover my butt and order an assortment of bands in a range of sizes - I'll use them all eventually anyway unless I stop restoring pipes for some daft reason. Just wishing the sterling bands weren't 6 times the price of the nickel ones, but there's not much I can do about that.

 

[taharris]

You will want a band that fits on the end of the shank about half way or a little more. 12.5 mm is probably right.

Then heat up the band with a heat gun to expand the metal.

After the band is good and hot you should be able to push the shank down into the band as far as it will go.

Let the band cool and trim off the excess.

Also, pay close attention to the band. Some are made slightly conical so that one side has a slightly larger diameter than the other side.

You want to push the shank into the larger diameter side.

Good luck.

Todd