Batten Splicing procedure

[dalecyr]

Seeking the wisdom of the list:

In the theatrical world, we use schedule 80 1.5" pipes, called battens,
to raise and lower curtains or drops.
These battens are suspended by cables at, usually, 10' intervals.
The battens in this instance are about 70' long.
Occasionally, we have to extend the battens to 85'.

So, the procedure is to add a 7.5' section to each end of the existing batten.

This is done as follows:
insert a sleeve inside one end of the existing 70' batten.
drill a bolt hole about 9" from the end of the batten, vertically,
thru both the batten and the sleeve.
(see diagram)
batten splice.jpg

Drill another bolt hole about 3" from the batten end, horizontally.
So one bolt is rotated 90 degress from the other.

Slip an extension pipe onto the exposed half of the sleeve,
and repeat the process.

So, two bolts, one on each side of the splice are vertical,
and two bolts are horizontal.

This seems like the installer is not sure which is right,
so they put one in each way,
thinking at least they will have one of them right.

So this is a call, to ALL of you, for your opinion:
are we doing it right?
should all four bolts be oriented in the same direction?
if so, which way?

[jboggs]

First, I don't think its going to make a big difference either way because with the multiple support points the battens aren't under a great bending stress.
I've often seen things that puzzle me and I wonder why someone did something a certain way. I then try to do it my way, and I quickly learn why they did it their way.
This arrangement strikes me as one of those things.
So, what would be the functional difference if all bolts were parallel? The first thing that comes to my mind is that the arrangement would resist bending in one direction better than another. The "crossed" arrangement provides equal stiffness in all directions, which then makes the orientation of the batten itself unimportant.

[PinkertonD]

That is the way I would do it, but that got me thinking as to why I must have decided that approach a long time back. I would not just default to doing something a certain way unless I had established at some earlier point, that, that was the best way for it.

The thoughts I have come up with are that tube and pipe is all lineally manufactured so that any grain structure in the metal will always be longitudinal. Having holes in line could lead to cracks between holes, depending on loads, direction of loads, frequency etc and a zillion other unknowns at this point.

Having the holes rotated around the axis would prevent or inhibit such faults developing. In fact, possibly having them at 360 / Count would ensure that no holes ever line up longitudinally. Just thinkin' ya know.

[RWOLFEJR]

could possibly be that the pattern was to help eliminate some wag at the joint should the two diameters have excessive clearance. If your "Z" axis bolts allow wag in the + & - "Y" direction... by adding the pins in "Y" direction you reduce that wag. Keep it a little straighter?