My Compact Eqx Shaft Project

[PimentoUK]

In the thread about possible design improvements for the Equinox series, I said the breakdown of the three-piece shaft could be improved. It currently has two reasonably short upper parts, and one excessively long lower rod. To improve packing, the upper rods need to be a bit longer, and the lower rod shortened.

Having done this exercise on my Fisher F75 shaft, I turned my design ideas to the Eqx.
The upper rod obviously has the 'height', due to the control pod and lower stand, and this limits the compactness to 28cm / 11" in that direction. This is slightly larger than the coil, which measures 10.5" on its shortest diameter. The middle rod will pack diagonally, meaning it can be about 7cm / 2.5" longer than the upper rod. I also decided that the insertion overlaps of the lower rod, and the middle rod, could be reduced by a total of about 2.5cm / 1".
So my design ended up with the upper shaft 2.5cm / 1" longer; the middle rod 2.5cm / 1" longer with 12mm / 0.5" less insertion; and the lower rod shortened by 80mm / 3.1" , with 12mm less insertion.
Practically speaking, the upper rod was extended at the rear end with a bit of lathe work, with two new holes for the elbow-cup. The handgrip was moved back 2.5cm / 1", needing one new hole drilling. The middle rod was a bit more complex. I machined an extender piece that adds 33mm to the top end of the rod, trimmed 8mm off the insertion section, and moved the pip location hole 5mm towards the rod end. This makes the rod effectively 38mm longer, but only physically 25mm longer. Trimming 80mm off the carbon rod and making the new pip-hole 12mm closer to the end completes that job.

The end result is the detector will pack in a 47cm x 28cm ( 18.5" x 11" ) space, see pic below.

Individual rod lengths are: Upper = 47cm ; Lower & middle = 53.5cm ( 18.5" & 21" )

I ultimately intend making a new upper rod, with a bend below the handgrip, offsetting the coil and lower rod sections, which will deal with the twisting issue that's been previously discussed here and elsewhere.

 

[GB_Amateur]

I always like garage mods and this one is elegant in part due to your access to a lathe.  But it appears you've sacrificed weight -- that aluminum coupler -- for compactness.  How much weight did this add?  Do you have plans to lighten it in the future?  I.e. is this a prototype for a future version?  Or is the added weight compensated for by improved balance?  (Yes, I know you're going to work on the upper shaft.)

[Joe D.]

 Nice moding P,

  Making the pod easily removable, or foldable will save alot of room too! I've seen printed plastic, and brass mods that accomplish this! But they are not cheap! It would be nice to see your version of this too!

   Something else that may work is a setup similar to the Vanquish! Although the tubing on the Vanquish is not round! Trying to mod a Vanquish would be more difficult! I just bought one,  and i now realize i can't turn the coil to place in a detector bag! A small inconvenience, but one nonetheless!👍👍

[PimentoUK]

The short extension at the elbow-cup is light, it's three-piece construction - the tube is 50 thou ( 1.25mm ) wall-thickness, the joiner is short and large-bore, the end-cap is thin and hollowed-out. There's no plastic plug, obviously.

The middle-rod extender is somewhat over-engineered. The walls are 2mm thick at the insertion sections, meaning they're 3mm thick over the central 33mm length. So I could've bored it to 1.5mm, and had shorter insertion overlaps. The 33mm length could've been 8mm shorter if I'd simply moved the spring-pip 12mm, but aesthetically the under-inserted rod would look ugly. Being at the top end of the rod means the weight's not felt as much as weight lower down, closer to the coil.

The shortened lower rod is of course lighter, but only by 13 grams.

So overall, it is a bit heavier. But I never use the coil cover, which weighs 65 grams ( for the 11" coil ). In practice the weight gain is easily ignored.

The new upper rod is tricky to make due to the thin-wall ( 1mm / 40 thou ) tubing ML use. I can only get 48 / 50 / 56 thou, so I'm going to be boring out some 50 thou over a 65mm length, before I bend it, drill it etc, to make it match the middle rod.

 

Edit: I have no plans for a folding/removeable control box, as the 10.5" coil is the limiting factor in that direction. It would've been nice if the handgrip/control-box assembly was 10-15mm ( 0.5" ) shorter, but it is what it is.