INPUT NEEDED -- Regarding Counter-Weight system for Equinox shafts...

[sgoss66]

Hi all.

Now that I have the prototype shafts built, and will be ordering parts -- within days -- for the first production batch of shafts, I've been able to work some more on the counterweight design, and I have moved very close to finalizing the design.

I have discovered through this extensive testing/design that the amount of weight needed to achieve proper counterbalance is a bit more than I was originally thinking, after the preliminary, "rough" proof-of-concept testing. I would like to present the findings, and get some opinions -- from anyone who has been potentially interested in the counterbalance system -- as to whether these changes are acceptable, or if this would change your desire to possibly purchase the counterweights.

1. The weight needed to counterbalance the 12" x 15" coil, (based on an "average" lower rod extension length), is roughly 28 oz. This is a fairly substantial amount of weight -- BUT -- I must note that when the weight is applied, the machine swings BEAUTIFULLY. It FEELS lighter, even though the "absolute weight" -- i.e. according to measurement as provided by a scale -- is obviously greater. With my forearm in the arm in the arm cuff, swinging the machine normally, I was literally able to hold the handle of the machine with only my thumb and index finger -- and swing the machine effortlessly! The sensation is that the machine FLOATS across the ground! (For the 11" coil, the amount of counterweight needed is of course slightly less -- roughly 25 oz.)

2. To include this amount of weight in the tube extensions, and yet not have the extensions excessively long, I must use larger-diameter carbon-fiber tube than I planned -- I've decided on 31mm outside diameter tubes. I had intended to use the same diameter of tubing as used on the upper shaft (22.15mm outside diameter), but the extension length required was far too long.

3. Using the 31mm outside diameter tube for the counterweights, I calculate that length of the tube extending beyond the end of the shaft will be 7 1/2" for the 12" x 15" coil, and 6 1/2" for the 11" coil.

4. There would be no changes to the shaft design needed; anyone wanting the counterweight system in the future would still purchase a shaft with the same threaded female fitting installed in the butt end of the shaft, and the same threaded end cap that screws into the butt end. The only changes would be to the counterweights themselves (as comparted to what I had originally planned) -- i.e. larger diameter carbon-fiber tubing, and thus a larger end cap for the ends of the counterweights themselves.

SO, my questions are, with the counterweight lengths needed now a pretty-well "known quantity" -- i.e. 6 1/2" and 7 1/2" long (11" coil and 12" x 15" coil, respectively), and the weights to achieve balance being also a pretty-well "known quantity" -- i.e. 25 oz. and 28 oz., respectively, would those interested in the weights find these specs acceptable? Please offer your comments.

Preliminary/rough pricing info would be as follows. One counterweight, $22.50 plus shipping ($30 total). If an EQX user only wanted to order one weight, I would suggest the 6 1/2" long, 25 oz. weight, designed for the 11" coil; this amount of counterweight still achieves a degree of balance that feels GREAT with the 12" x 15" coil. I am of the opinion that no counterweight is needed, for the 6" coil. Two counterweights, one for the 11" coil and one for the 12" x 15" coil, $42.50 plus shipping ($50 total).

Thoughts?

Steve

 

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[cudamark]

Will they fit the stock shaft, other aftermarket shafts, or just your shaft? Is there a way to make them where you can incrementally add or subtract more or less weight as needed for coil size or degree of lower shaft extension? I'm thinking something along the lines of a barbell design where you can add weights as needed or desired. Any photos of your prototype?

 

[sgoss66]

Will they fit the stock shaft, other aftermarket shafts, or just your shaft? Is there a way to make them where you can incrementally add or subtract more or less weight as needed for coil size or degree of lower shaft extension? I'm thinking something along the lines of a barbell design where you can add weights as needed or desired. Any photos of your prototype?

cudamark -- thanks for your interest and questions!

I'll do what I can to answer, and if I miss something, please let me know.

1.) Counterweights compatible with other shafts? Well, to screw the weights onto the shaft, it will require a "female-threaded" insert into the butt end of the shaft. And so, if that "female-threaded" insert would fit into WHATEVER shaft you are using, then YES, the counterweight would be compatible with any shaft. I would simply have to send you one of those "female-threaded" inserts, to glue into the end of your shaft, along with your counterweight, and you'd be all set. IF the insert I am using (sized for MY shaft diameters) does not fit with your shaft of choice, I "could" have my supplier produce a custom-sized female insert for you, that would still accept the counterweight's threads. It would be more expensive that way (to have them produce a customized, "one-off" insert), but it's do-able.

2.) No, based on this design, there's no way to make them "incrementally" heavier or lighter; they would be "sealed" tubes, filled with lead pellets. BUT -- I want to point out two things, that I've been pondering over the past 24 hours, thanks to some other folks' input. Number one, I think I may be getting too hung up on "PERFECT" balance. Initially, I was thinking of a different weight for the 15" coil, different one for the 11" coil, different one for people who extend their lower shaft long, different one for people who extend their lower shaft much shorter, etc. AND YES, from a theoretical/physics point of view, each of these scenarios, and countless other variants, affect what is the "perfect" weight needed at the butt end of the shaft.

BUT -- I think I may be leaning a bit too much toward a "physics equation," and too far away from actual, practical detecting. For instance, let's say you put enough weight on the butt end of the shaft for it to be "80% of the way to perfect balance." The question is, would you even PERCEIVE that there was a bit more "balance" that could have been achieved? What if 80%, or 60%, or even 40% of the way toward "perfect balance" was enough that comfort when swinging, for YOU SPECIFICALLY, was achieved (and thus not needing the rest of the added weight that would have brought "perfect" balance)?

To put it another way -- does the Equinox feel "good" to someone, when swinging the 6" coil, but is "bothersome," when swinging the 12" x 15" coil? Well, the 12" x 15" coil is roughly twice as heavy as the 6" coil (660g, vs. 300g). SO -- that suggests that adding 13 oz. of counterweight IS EXACTLY THE RIGHT AMOUNT to make the 12" x 15" coil feel EXACTLY like the 6" coil, when swinging. So -- if someone is TOTALLY comfortable swinging the 6" coil, but dislikes the weight of the 12" x 15", then for this person, a 13 oz. counterweight would be PLENTY.

Along those lines, that brings me to my second point. If a customer wants SOME OTHER weight, besides the "physics-equation-perfect" balance, I can EASILY produce that, as a "custom" weight, at no additional charge. FURTHER, if a customer is NOT SURE of how much weight he or she may desire, I could perform 90% of the assembly of the counterweight, and then send it -- along with 25 or 30 ounces of LOOSE lead shot, and the "end cap" not yet attached. That way, the end user -- the customer -- could experiment with what the preferred "added weight versus reasonably balanced" point is FOR THEIR SPECIFIC DESIRES.

In other words, fill the counter-weight tube half way with lead, TAPE the end cap on, and go on a hunt. Good enough? Excellent. TOO HEAVY? Just untape the end cap, remove some lead, go hunt again. Then, at which point the "right" combination of extra weight vs. improved balance is found FOR YOUR PREFERENCES, then -- simply trim the tube to the length needed to contain that amount of lead shot, GLUE the end cap on, and there you have it! A "customized" counterweight that is proper for each individual's preferences! Yes, switching coils, etc., changes things a bit, but again, if you find the desired balance, to your satisfaction, for the 11" coil, it will still feel "pretty good" with the 15" coil, AND with the 6" coil, etc.

OR, let's say a customer just wanted me to produce a counterweight for them, that "makes my 12" x 15" coil feel exactly like my 6" coil when I'm swinging it," then I can do that, easily. I'd build them a 13 oz. counterweight...

Make sense?

Finally no pictures yet, but I WILL get them up, as soon as I build the first "prototype" counterweight...

Here is a picture of a couple of drawings, though, that may help a bit -- the top drawing in the picture is the weight unassembled, with each component piece shown individually; the bottom drawing is what it would look like completely assembled, and screwed onto to the shaft...



Thanks!!

Steve

 

[cudamark]

Looks good. I like using the carbon fiber, but, to make it easier to change the weight, maybe use PVC? You can thread it and use a removable end cap to add or subtract weight as desired. That would make it totally customizable for different coils, lengths, and other situations.

 

[sgoss66]

cudamark --

It's a very interesting suggestion. As I think it through, the PVC idea makes some sense, but I'd think it would HAVE to be black, for aesthetics. I can get black PVC tubing, but I have never seen black PVC fittings/couplers/caps, etc.

Thoughts?

Steve

 

[sgoss66]

cudamark,

I've thought about it some more. I would like to hear your thoughts on this, and anyone else's thoughts, as well.

I was able to find PVC fittings, in black (I already knew black PVC pipe was available).

SO, if I were to make the counterweights out of black PVC, here are some thoughts to consider.

Using PVC, price doesn't change much, the threaded end of the shaft does not change, and the threaded end cap FOR THE SHAFT does not change (the cap used to cap the shaft whenever the counterweight is not being used). The PVC tube would screw into the shaft the same way the carbon-fiber one would.

HOWEVER -- if I use 1 1/4" PVC, there are some advantages.

1. PVC is heavier -- and since we are TRYING to add weight, heavier is better, in this case.
2. With the PVC, I will be able to add a threaded end cap onto the PVC counterweight and not have the cost of the counterweight increase from my initial pricing thoughts; the advantage there is having the end cap that screws on and off would make it VERY easy to add/remove weight as necessary (the "adjustability" or "flexibility" that many folks have asked for, with the weights).
3. With 1 1/4" PVC, the inside diameter is larger than the carbon-fiber tube I was going to use. And therefore, length of the PVC tube can be reduced by 30%, and still hold the exact same amount of weight (and this does not include the fact that the PVC counterweight can be even shorter still, since it weighs more than carbon-fiber).

SO -- what this means is, you could make a counterweight extension only 2 1/2" long, that would give you 12 ounces of counterweight, for instance.

And 12 ounces of counterweight is 1/2 of that needed to PERFECTLY balance the 11" coil, and you'd still have a machine with overall weight only about 3 1/2 pounds total weight (since the carbon-fiber shaft system reduces the overall weight of the unit).

OR, another way to look at it is, 12 ounces is the weight needed to make swinging the 12" x 15" coil feel exactly like swinging the 6" coil (i.e. it counter-balances ALL of the additional weight that the 12" x 15" coil adds to the machine, compared to having the 6" coil attached). So, if you feel the machine is comfortable with the 6", but not so, with the 12" x 15", then a 2 1/2", 12 oz. counterweight accomplishes making the 12" x 15" feel like the 6" coil.

I would still give the customer the option to have the weights sent WITH, or WITHOUT, the lead/weight included.

The only negative I can think of, going this "black PVC" route, would be that it would not be as aesthetically pleasing as a carbon-fiber tube would be.

Thoughts?

Steve
​

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[cudamark]

Some might have a problem with the "look", but, that wouldn't be me. Granted, carbon fiber looks great, but, I'm more into function than trying to make a fashion statement. Do they make threaded carbon fibers items? Maybe just use a rubber end cap instead of a glued-on one? Most of us that beach hunt, have tons of lead to use, so, just the can would be all we would need.

 

[relicmeister]

I can make my own -one for the 11” and one for the 15”. If I’m adding weight for the easier swing of near balance, make it be useful. I’m planning mine to also be a bigger stand which I would find useful.

 

[tomtom]

How about a carbon fiber counterweight with an aluminum screw on cap similar to the fittings you make for the two piece travel rod? You could add as much weight as you like, stuff some cotton balls in the end as wadding and screw the cap on.

 

[sgoss66]

cudamark --

The only way I know of to add "threads" to carbon fiber is to add threaded fittings, which is how I've been looking to produce the counterweights -- but each fitting added increases the cost by a non-trivial amount. But yes, the end cap COULD be held on by friction, instead of threads, reducing cost some. And yes, I DO plan to offer the option to sell just the counterweight tubes WITHOUT the lead, if a customer wishes to add their own weight after receiving them.

tomtom --

What you are suggesting was exactly my original plan -- carbon fiber, screw-on cap, etc. The only issues are that 1 -- the more fittings I attach to that carbon-fiber tube, the more expensive (as mentioned to cudamark above), as the fittings are each machined individually by my producer, and so cost is an issue; PVC fittings, though, are much less cost, and thus easier to include the screw-on cap concept, etc., and 2 -- you can make a shorter extension with PVC than with carbon-fiber, since carbon-fiber is so light that it adds essentially nothing to the weight of the counterweight, but PVC does.

relicmeister -- if you are handy and a DIYer, yes, you can certainly make some counterweights tailored to your own specific needs.

Steve

 

[fuceye]

this would be a great way to add an s-bend effect to a straight shaft. make it a 90 degree angle facing down 4-6" should do it.
instead of using a threaded coupling...use a clamp for easy removal. this way you hit the need for a counter balance and the advantage of a bent shaft for the same price.
to add more value to your customers make the bottom of the product wide enough to have a stand effect to keep the equinox out of the dirt.

​

 

[sgoss66]

fuceye -- not sure what you mean by "the advantage of a bent shaft." And I don't follow the meaning of the glasses picture...

Steve

 

[tomtom]

What do you estimate the "non-trivial" amount would be? If someone is going to spend the money for a full carbon rod, going with a matching counterweight housing probably wouldn't break the bank.

Maybe offer it as an deluxe option?

 

[fuceye]

your concept of a counter weight to off set the weight of a coil is useful only when the equinox is held static. adding the swinging motion creates a counter pendulum action
90 degrees to the shaft. this causes the edges of the coil to dip to the earth on the trailing end of the swing. this adds needed twisting effort to keep the coil perpendicular to the ground. the s-bend shaft creates a damping effect resulting in less fatigue through out the swing cycle.
traditionally this s-bend was put between the coil and the handle of the detector. in your case you could put the bend behind the elbow. in order to compact the size of the product a shaper angle say 90 degrees with your counter weight @ the end will accomplish multiple results.
research counter weights on compound bows to grasp the effect I have in mind.

 

[smokeythecat]

Adding that much weight would kill it for me. I can't do heavy machines anymore.

 

[Echoplex]

your concept of a counter weight to off set the weight of a coil is useful only when the equinox is held static. adding the swinging motion creates a counter pendulum action
90 degrees to the shaft. this causes the edges of the coil to dip to the earth on the trailing end of the swing. this adds needed twisting effort to keep the coil perpendicular to the ground. the s-bend shaft creates a damping effect resulting in less fatigue through out the swing cycle.
traditionally this s-bend was put between the coil and the handle of the detector. in your case you could put the bend behind the elbow. in order to compact the size of the product a shaper angle say 90 degrees with your counter weight @ the end will accomplish multiple results.
research counter weights on compound bows to grasp the effect I have in mind.

I agree that a counterweight system would only benefit if coupled with S-Shaft. Before a counter weight can be properly utilized, the swing torque of the Nox must be corrected first, otherwise you are just adding more torquing to the swing. This requires an S-Shaft. I've tested a primitive counterweight here, and while it initially balances the coil weight, when you start swinging, it torques worse than with no counterweight. After a while, you are fighting to keep the coil parallel with the ground, and fatigue sets in much quicker. Spring chickens won't notice this kind of stuff as much, but the older you get, the more you appreciate a balanced machine, which the Nox is not.

Even better than counterweights, IMO, would simply be an S-Shaft. Once you eliminate the torque from swinging, there is no need for counter balancing on the Nox an add more weight overall. I would pay good money for a White's style S middle shaft that fits the Nox perfectly. I know a lot of people that would.

 

[sgoss66]

tomtom --

Yep, that would be what I was thinking -- the counterweights would be an "option," for anyone who desires them. There are some that do NOT want counterweights, and some that do.

As for "non-trivial," so far, unless one idea I'm working on will work, it would take 3 fittings -- a male in one end of the counterweight tube (to fit in the female connector in the shaft), then a female at the other end of the counterweight, and then a threaded end cap. Then the cost of the tube, the lead, plus a thin profit and shipping cost, and you are easily up to $40 per weight; $30 maybe, if shipped with the shaft and without the lead.

The issue is, I'm too small of an operation to have custom pieces, like the fittings, produced by injection molding. Injection-molded parts are CHEAP, AFTER the molds are created. The issue is, mold costs run well into the thousands; last time I checked to have parts made with injection molding, quotes were $5000 to $7000 for the molds to be produced!

SO, that leaves me with two choices, in a case like this. Find fittings that work with my design that have already been created, such that the molds already exist. Then, the parts cost "cents." Otherwise, have each one individually machined using CNC machining -- and thus, much higher cost. I have searched for fittings that already exist, but there are no fittings, for example, that screw into a 22.15mm tube on one side (the upper shaft), and "slip fit" for epoxying into a 35mm tube (the counterweight). That's a custom piece, that is not going to already have a mold in existence somewhere. So, it must be machined, since I can't afford mold fees. That's why using PVC would be cheaper -- fittings are readily available and cheap. The negative? It's not aesthetically pleasing, and that bothers me. I like a polished/professional look for products I sell...

Thanks!

Steve

What do you estimate the "non-trivial" amount would be? If someone is going to spend the money for a full carbon rod, going with a matching counterweight housing probably wouldn't break the bank.

Maybe offer it as an deluxe option?

 

[sgoss66]

fuceye,

OK, now I get what you were saying about the bend. I'm trying to work my mind through the physics of what you are saying about a counter-pendulum action. There would be "momentum" to overcome, with a heavier machine, especially if swinging at a fast speed. But this idea of twisting of the coil, I am not familiar with. I am not saying it's not there; obviously this discussion/debate has been carried out before in straight vs. S-shafts, but I can't say I've felt it. I hunted with Minelab Explorers for about years, which were "s-shafts," and then switched to the CTX 3030 and now the Equinox, which are of course both straight. I don't notice any of the "coil twist" when going from the Explorers to the E-Trac, but not saying it's not there.

Interesting thoughts...which I'll ponder...

Thanks!

Steve

your concept of a counter weight to off set the weight of a coil is useful only when the equinox is held static. adding the swinging motion creates a counter pendulum action
90 degrees to the shaft. this causes the edges of the coil to dip to the earth on the trailing end of the swing. this adds needed twisting effort to keep the coil perpendicular to the ground. the s-bend shaft creates a damping effect resulting in less fatigue through out the swing cycle.
traditionally this s-bend was put between the coil and the handle of the detector. in your case you could put the bend behind the elbow. in order to compact the size of the product a shaper angle say 90 degrees with your counter weight @ the end will accomplish multiple results.
research counter weights on compound bows to grasp the effect I have in mind.

 

[sgoss66]

Adding that much weight would kill it for me. I can't do heavy machines anymore.

smokeythecat,

Point well taken; it would CERTAINLY only be an "optional accessory," as there are a lot of people that prefer the overall weight being light, versus trying to achieve "balance" through additional weight.

Thanks!

Steve

 

[sgoss66]

Echoplex --

As I was saying to fuceye, this "twisting" is not something I'm familiar with, as I have not felt such "torquing."

I actually have the opposite issue. I am tall, and take long sweeps of the coil, and so I am purposely trying to "torque" the coil as I approach the end of my swing. I WANT the coil to "turn outward" near the end of my swings, to counteract the otherwise natural tendency of the coil to "elevate," and "turn inward" as you get out toward the end of the swing (if what I'm saying makes sense -- i.e. the "grandfather clock-like" pendulum motion/coil path that occurs, if you are not deliberate to keep the coil flat and low to the ground).

To keep it low to the ground AND parallel, through the end of the swing, I actually worked (early on, when I was learning the hobby) to learn to gradually turn my wrist "counter-clockwise" as I move toward the left-hand side of the sweep -- to gradually turn the coil "outward," and then gradually "clockwise" as I move toward the right-hand side of the sweep -- again, to gradually turn the coil "outward," to counteract the natural tendency for the coil to do the opposite (turn "inward") when one employs a (not correct) pendulum-like sweep path. What I describe is the attempt to fight that "pendulum-like" sweep, so as to keep the coil "level" and "low to the ground." And so it's hard for me to relate to any "torqueing" being described, as a result of a straight shaft vs. an S-shaft...

Anyway, I do hear you, on the S-Shaft; like I was saying to fuceye, I have seen this debate before, and so for those who love the S-Shaft, I'd love to build one. It sounds like a pretty daunting challenge, though!

Thanks!

Steve​