Tag Archives: lower arm

How to build a cheap, light, but sturdy metal detector straight shaft

This post will show you how to build a cheap, light, but sturdy metal detector straight shaft for less than $40!

I originally wrote this post because I built a metal detector and did not have a shaft to use with it, but if you are tired of using the stock metal detector shaft that came with your unit, just follow the instructions below and youll have a straight shaft which can be adapted to any metal detector kit.

Benefits

The benefits of a straight shaft include:

  1. Less fatigue from unbalanced weight distribution
  2. Lighter
  3. Customizable arm and mounting positions for weight distribution
  4. Cool factor

Parts

Items youll need:

  1. 47″ Metal Extension Pole (I purchased mine at Orchard Supply and Hardware for $5.99 part #WP-00244).
  2. Rav-X Era X Bar Ends (Found on ebay for $9.99).
  3. Metal Detector Shaft lock off ebay ($12).
  4. Tesoro Lower Arm with Hardware ($10.20 SKU#POLE-LOW. comes with coil mounting hardware. OPTIONAL if you are just making the straight shaft to upgrade your current metal detector shaft – take the old one off and put it on this one).
  5. Garrett Arm Cuff for AT Series ($3.95 SKU#9850601. OPTIONAL if you are just making the straight shaft to upgrade your current metal detector shaft – take the old one off and put it on this one).
  6. 6-32 1″ round head machine screw (to secure the arm cuff to the shaft), and split lock washer.
  7. 4mm Allen wrench for tightening the bar end.
  8. 25/64 drill bit (for the arm cuff hole).
  9. 5/32 drill bit (for the arm cuff screw).
  10. 5/64 tiny drill bit.

Step 1: Cut the Plastic Clad Metal Extension Pole to 39″

Cut the straight shaft to length

Cut the straight shaft to length

Step 2: Locate where you want the arm cuff to be placed and drill a hole using the 25/64 drill bit. I found it helpful to drill several holes in case you want to adjust the cuff out on the field. DO NOT DRILL ALL THE WAY THROUGH, just drill a hole through one side of the pole. You will need to drill a smaller diameter hole for the screw to secure the arm cuff on the opposing side of this 25/64 hole.

Drill hole for the arm cuff using the 25/64 drill bit

Drill hole for the arm cuff using the 25/64 drill bit

Step 3: Place the Garrett arm cuff in the hole you just drilled and use a drill bit small enough to drill through the threaded hole without damaging the screw threads (5/64 drill bit). Drill vertically and as straight as possible, so the hole being made lines up with the screw threads.

Drill within the screw threads to make a small hole on the opposite side of the metal shaft

Drill within the screw threads to make a small hole on the opposite side of the metal shaft

Step 4: Widen the tiny hole made on the other side of the shaft with a 5/32 drill bit. This hole is for the machine screw to fit through.

Flip the Shaft over and widen the small hole made in the last step

Flip the Shaft over and widen the small hole made in the last step

Step 5: Place the split lock washer and 6-32 1″ machine screw into the arm cuff shaft hole and tighten.

Insert the screw with locking washer into the hole to thread into the arm cuff threads

Insert the screw with locking washer into the hole to thread into the arm cuff threads

Step 6: Slide the Era X Bar end handle onto the shaft and place according to best fit and feel. The bar end should be placed so the slight angle is pointed away from the arm cuff. Tighten with 4mm allen wrench.

Rav-X bar end

Rav-X bar end

Step 8: Place and tighten the Shaft lock onto the end of the main shaft.

Shaft Lock for metal detector

Shaft Lock for metal detector

Step 9: Insert the Tesoro Lower Rod into the shaft lock.

Lower rod assembled

Lower rod assembled

Step 10: Drill holes to fit existing metal detector kit onto shaft using mounting holes as a template.

I didnt need to drill any holes to mount my DIY metal detector kit onto this shaft. Instead I used electrical conduit wall hangers that I found for $.50 at Home Depot.

 

Conduit Wall hangers

Conduit Wall hangers

wall hanger installed

wall hanger installed

Inside mounting of wall hanger and kit

Inside mounting of wall hanger and kit (I used shorter screws to mount the hanger to the box)

Kit and hanger on rod

Kit and hanger mount on rod

Kit mounted on shaft

Kit mounted on shaft (this picture was taken from my other shaft with tesoro arm cuff)

Step 11: Enjoy your handy work!

DIY straight shaft for metal detectors

DIY straight shaft for metal detectors (oops, I forgot to pull off the white label wrapped around the pole!)

Finished Metal Detector with coil and shaft

Finished Metal Detector with coil and shaft

I was pretty impressed that this shaft was sturdy, and surprisingly lightweight compared to the plugger straight shaft I have on my tesoro sand shark.

Need ideas and a source on coil housings?

Check out my post on how to use a thermo-formed plastic clamshell to build a durable (and good looking) DIY metal detector coil housing.