A Jacob's Staff Is The Third Leg Of A Tripod
> It is not a stand alone device. The point is to allow it to be accurately set in a marked place, not to hold it there.
Have you ever surveyed much with a staff compass? The whole point of a jacob's staff is to be a stable support for the compass which stands by itself without some surveyor holding it up. The method of setting it up familiar to me is simplicity itself. You push the staff into the ground so that it will stand upright, loosen the ball joint, level the compass, retighten ball joint, loosen clamp screw and orient compass, reading needle as necessary, and write in field book.
A scenario that requires the surveyor to hold the compass up while performing the aforesaid operations would be fun to watch and would probably make a good YouTube, but at the end of the day wouldn't get much done. You may be confusing a Suunto with a standard open-sight compass.
> Just going by the staffs I have seen, only one showed evidence of a screw being used to retain the adaptor to the staff.
I decided to make use of the hole by threading it for a 10-32 machine screw and drilling a hole in the staff. A few photos are below.
The reworked hoe handle:
Although Dave Karoly doesn't think much about the quality of the wood used in garden-variety (pun intended) tool handles, this $14 handle seems to be made of pretty straight-grained hardwood. It's hardly furniture-quality, but good enough for my casual purposes.
A closeup of the staff top:
I roughed out the shape with one of those cheese-grater type planes, then refined it with a 10" jack plane. I eyeballed the taper at first, then got it closer by test-fitting the compass adapter.
A closeup of the staff point:
As noted earlier, I ran a Helicoil insert into the factory-drilled hole, then installed the pole point shown. The sheet steel ferrule (dark blue) is a factory installed item, and I just left it alone.
The adapter showing the hole tapped to accept a 10-32 machine screw:
I had to drill the factory hole out slightly; I think it was about 1/8", and I enlarged it with a #21 bit.
I cut the head off of a brass 10-32 machine screw, threaded it into a thumb nut (with brass insert, so no magnetic interference), and ran a brass jamb nut onto it to keep the thumb nut from coming off:
The adapter fits in the factory case, even with the retaining screw attached:
There was some discussion above about a fat point not penetrating some soil types enough to hold the staff up unassisted by the operator. In those circumstances, one can always resort to this:
> A closeup of the staff point:
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The wood looks like ash, which ought to be fine for a staff. The main thing that some of the commercial staff designs have is a turning that works as a hand grip when planting the staff.
You'll find out soon enough whether the staff can be stuck in the ground to make a stable setup or not. If not, the 5/8 in. bolt sharpened to a point, threaded into the helicoil would be the next mod if the ferrule on the tool handle is up to it.
Nice job... should work well, especially w the bipod. I hadn't thought of that. To me, it's much better than the lightweight tripod most of these come with. Nice blending of old and new.
