I am repurposing an old washing line pole which is 140 mm (14 cm) dia and want to fix a 50 mm pole to it. I’m struggling to find a suitable clamp, anyone know of something suitable?
I think you’ll find various solutions for clamping two vertical poles of different diameters together. Here are a couple of approaches …
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If only it were that simple
3 sheets, 8 threaded rods, washers, nuts, ….
30 Minute
73 Armin
I have successfully used two of those clamps eg fixing a collinear to an aluminium support pole. If it’s not “that simple” perhaps you should elaborate why it isn’t so the rest of us aren’t left guessing.
The line pole is 14cm in diameter, which is probably outside the range of most commercial clamps intended for antenna supports.
There are clamps for metal flue pipes which might form the basis of a bracket but they tend to be made of quite thin metal, and so not very strong for this use…..
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Exactly this, 14 cm is over 5 Inches
14 cm, before we go back round the loop 
It was a typo, I’m on my phone 
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I assume you’re connecting them side by side, not one on top of the other?
Is it a permanent installation or just temporary?
Cable ties 
https://www.accu.co.uk/stainless-steel-cable-ties/767833-HCT-1000-7-9-A4
or jubilee clips:
https://www.accu.co.uk/worm-drive-hose-clamps/849223-HHC-220-15-7-A2
With the wind changing direction and possibly causing vibration, they could come loose or slip over time so you’d have to check them from time to time. Same could be said for the off the shelf mast clamps though.
Does it need to be clamped or could you drill through and bolt them together? If you position the bolts correctly, you could remove all but one and it could tilt over.
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Post of the Amazon ads that I found removed - sorry I read 5.5” for the mast diameter in the Amazon adverts but the 5.5” only referred to the length of the bolts! - FAR TOO SMALL.
If you are talking a permanent solution and if you are happy to have the 50mm pole inside the 140mm one, get some tubular spacers manufactured (either 3D printed or a series of plastic or aluminium tubes of different sizes inside each other), then drill 4 holes (2 N-S and 2 E-W looking at the top, spaced about 50 cm vertically apart, staggered 10 cm, so they don’t clash) drill through all layers and put 4 bolts through and tighten up to make a solid joint.
73 Ed.
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Similar to Armin’s suggestion, but with 140mm inside diameter U-bolts:
2 x 140mm U-bolts
2 x 50mm U-bolts
2 steel plates drilled accordingly
140mm pipe u-bolted to steel plate, steel plate u-bolted to 50mm pipe.
Twice.
Something like that?
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Personally I prefer Ed’s suggestion of having the smaller diameter tube inside the larger one, probably overlapped a minimum of 150mm. Having the smaller tube on the outside of the larger one would create offset loading on one side of the larger tube potentially causing it to bend in the long term. Having the tubes concentric would look better as well.
For the spacers, what about using treated timber battens between the poles? The material is easy to work and the spacers could be chamfered on the faces that sit against the inside of the outer pole and the outside of the inner pole. Assuming a couple of millimetres wall thickness for the larger tube, its inside diameter would be in the order of 136mm. The smaller tube is 50mm, so the distance between the faces would be 43mm making a piece of 50 x 50mm treated timber suitable. Say 4 lengths, each 150mm positioned N, S, E and W, bolted as Ed suggests.
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Unfortunately this washing pole has a welded cap on top of it, so no, nothing can go inside it.
…can’t you cut the cap off?
Geoff vk3sq
No, the inside won’t be treated, so it will just go rusty when rain gets in
139.7mm (5.5”) is a common diameter for commercial tower legs. You get U bolts in that size off the shelf like this m12-galv-u-bolt-to-suit-1397mm-tower-leg-cw-nuts-washers
Drill out two lengths of angle iron to make a pair of standoffs, with a 2” U bolt on the other end.
Or buy off the shelf! mafi-3612-vertical-tower-leg-offset-kit-small-parent-short-brackets
GCA are a good company to deal with and will do card sales.
73 Gavin, GM3GAV
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