Best Metal for Conductive, Springy Strip in Gatling Potato Gun Tazer Ignition?

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#1 21661005 31 Jan 2012 21:56

Andrew LeVino Andrew LeVino

Anonymous

Post #1
21661005 31 Jan 2012 21:56

Hey everyone, I'm a first time poster here with very limited electronics knowledge. Long story short, I'm building a gatling-potato gun (I'll upload a few pics as things get built if you are all interested) and I'm using a tazer to fire off each barrel as the cylinder spins. I need a 1/2'' to 3/4'' by about 2'' strip of conductive metal to connect the tazer to each barrel. As each barrel spins past the metal strips, they need to rake across each barrel to maintain connection. Any ideas on which metal would work best?
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#2 21661006 31 Jan 2012 22:58

Bob Loy Bob Loy

Anonymous

Post #2
21661006 31 Jan 2012 22:58

Interesting project! My first guess would be beryllium copper, aka spring copper. However, Wikipedia mentions its anti-sparking qualities, so it might not work so well in your specific application after all.
#3 21661007 31 Jan 2012 23:01

Andrew LeVino Andrew LeVino

Anonymous

Post #3
21661007 31 Jan 2012 23:01

I don't need it to spark, only transfer the current from the 'rakes' to steel plates on each barrel to carry the spark inside each chamber. Or am I misunderstanding the definition of anti-sparking?
#4 21661008 31 Jan 2012 23:05

Bob Loy Bob Loy

Anonymous

Post #4
21661008 31 Jan 2012 23:05

I should add that I believe its non-sparking quality refers to mechanical sparks (think cigarette lighter flint). I would imagine it would have no problem conducting tazer magnitude current to create electric sparks.
#5 21661009 31 Jan 2012 23:06

Bob Loy Bob Loy

Anonymous

Post #5
21661009 31 Jan 2012 23:06

Well, we apparently posted at exactly the same time! Anyway, you're right.
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#6 21661010 31 Jan 2012 23:16

Andrew LeVino Andrew LeVino

Anonymous

Post #6
21661010 31 Jan 2012 23:16

Thanks Bob! Where would I turn to find some? Radio Shack? Home Depot?
#7 21661011 31 Jan 2012 23:23

Bob Loy Bob Loy

Anonymous

Post #7
21661011 31 Jan 2012 23:23

Ah, I was afraid that might be the next question. Actually, since you mention hitting steel plates, maybe just use spring steel instead. It's not like you need great conductivity considering the juice a tazer will put out. Beryllium copper is tough, but not as hard as steel. Spring steel would probably be easier to find, and I would guess a lot cheaper too. Maybe another poster can tell where you can purchase one or the other...
#8 21661012 01 Feb 2012 00:50

Steve Lawson Steve Lawson

Anonymous

Post #8
21661012 01 Feb 2012 00:50

How about springs themselves? They would flex and then return to their original position. Another concern, though. They might have a tenancy to weld to the metal strip.

But springs are readily available at hardware stores, and perhaps even auto parts stores (though at the auto parts store you might need to know the application in order to find the right spring).

Then, how about this for a whacky idea. Spray a stream of water at the metal strips. The water would need some sort of impurity, such as salt, for it to conduct electricity. But, that might make it too corrosive. But, maybe that seeds other thoughts.
#9 21661013 01 Feb 2012 01:14

Andrew LeVino Andrew LeVino

Anonymous

Post #9
21661013 01 Feb 2012 01:14

Damn you Steve! Why'd you have to suggest something cool like using water?? Now I've got the 'go big or go home' gears turning in my head. This could very quickly change from a small workshop project to an impressive feat of engineering.... Oh well. Back to the drawing board to redesign the electrical system on the gun. I'm thinking this might end up looking like one of those old water cooled anti-aircraft/material guns from WWII ships.
#10 21661014 01 Feb 2012 01:15

Steve Lawson Steve Lawson

Anonymous

Post #10
21661014 01 Feb 2012 01:15

Guess I've been watching too much MythBusters!!
#11 21661015 01 Feb 2012 01:24

Steve Lawson Steve Lawson

Anonymous

Post #11
21661015 01 Feb 2012 01:24

And, my head hasn't quit yet...it kept thinking, what about a column of ionized gas? But I dismissed it because it didn't see like it could carry enough current. Then it occurred to me, a spark is conveyed by ionized air. So, how about just letting it arc across. Just mount a pointed rod close to the metal strips, close enough to make it a tiny arc so it only depletes a small amount of the energy so there's enough spark left for it to do it's job inside the gun.
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#12 21661016 01 Feb 2012 01:32

Steve Lawson Steve Lawson

Anonymous

Post #12
21661016 01 Feb 2012 01:32

Perhaps you could use a titanium drill bit, or a tungsten carbide bit. One of them might be able to stand up to the arcing over time.

Or perhaps a motor that feeds the arc rod to the metal plates until the arc voltage drops to a certain level, with feedback so it keeps the stark gap fairly constant. That way, as the metal at the tip of the rod burns away, and the arc voltage rises, the motor would move the end of the rod closer until the arc voltage drops again (i.e. the arc voltage would indicate how close the rod tip was to the steel plates.

I imagine two rollers that would pinch feed the rod.
#13 21661017 01 Feb 2012 01:32

Andrew LeVino Andrew LeVino

Anonymous

Post #13
21661017 01 Feb 2012 01:32

I was thinking something along the same lines Steve, though I'd like my girlfriend to shoot it and I'm not too sure how keen she'd be if she saw sparks actively jumping.
#14 21661018 01 Feb 2012 01:35

Steve Lawson Steve Lawson

Anonymous

Post #14
21661018 01 Feb 2012 01:35

Ah, well then...that does limit your options
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#15 21661019 01 Feb 2012 01:44

Andrew LeVino Andrew LeVino

Anonymous

Post #15
21661019 01 Feb 2012 01:44

As cool as that sounds, I don't have the skills to do that. I'm a pretty good carpenter and have the brain of an engineer, but electrical engineering like that is way above my level.
#16 21661020 01 Feb 2012 02:23

Frank Bushnell Frank Bushnell

Anonymous

Post #16
21661020 01 Feb 2012 02:23

Wow ! This question has evidently provided some much needed deep excitement to the usually rather staid old engineers that inhabit this site ! (No offence meant !)

Anyway, how about a staid old well-established electrical engineering device already designed to provide a great deal of excitement, like . . . a commutator ?

There you already have a high current capability moving connection. Rip the guts out of an appropriately sized electric motor, detach the windings, fit the gun barrels in their place. Make holes in the outer casing to load rounds and shoot through. Drive the shaft by a pulley or gear from another motor underneath.

Each barrel is connected to two opposing segments fed by a pair of brushes, and fires each time it comes in line. Now perhaps with a couple of built-in diodes, the reversed current at 180 degrees would serve the purpose of ejecting the spent casing and loading the next round.

You know what ? I think I've just described what would have happened Mr Gatling had been an electrical engineer.
#17 21661021 01 Feb 2012 09:52

Sarah Harris Sarah Harris

Anonymous

Post #17
21661021 01 Feb 2012 09:52

you could try a ball catch, a sprung loaded ball bearing in a metal tube, then make your track out of pcb. some ball catches have adjustable spring load .
#18 21661022 01 Feb 2012 13:08

Todd Hayden Todd Hayden

Anonymous

Post #18
21661022 01 Feb 2012 13:08

You could use something like this or maybe tear the spring plates out and mount them to your liking. http://parts.digikey.com/1/parts/1641202-conn-battery-2-pos-right-angle-009155002541006.html

Seastrom has berylium copper option on various spring clips http://www.seastrom-mfg.com/subcategories.aspx?pl=Spring+Clips

Or try an outift like this and ask for a sample. http://www.becumfg.com/Becu-Beryllium-Copper.html
#19 21661023 01 Feb 2012 16:43

DAVID CUTHBERT DAVID CUTHBERT

Anonymous

Post #19
21661023 01 Feb 2012 16:43

This looks to be a limited use home project. So, contact wearout is not a big issue. I would use 6061-T6 aluminum. While aluminum will develop an insulating oxide layer this will punch through at Tazer voltages. Additionally, sliding contacts are self-cleaning.
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Topic summary

✨ The discussion centers on selecting an optimal conductive, springy metal strip for a Gatling-style potato gun ignition system using a taser to fire each barrel as the cylinder rotates. Beryllium copper (spring copper) is initially suggested for its conductivity and spring properties, though concerns arise about its anti-sparking characteristics, which are clarified to refer to mechanical sparks rather than electrical conductivity. Spring steel is proposed as a more readily available and cost-effective alternative with sufficient conductivity for taser-level currents. Additional ideas include using actual springs for flexibility, though potential welding to contact surfaces is a concern. Innovative concepts such as water spray with conductive impurities and ionized gas arcs are discussed but deemed complex or impractical. A mechanical commutator from an electric motor is recommended as a proven high-current sliding contact solution. Other suggestions include using 6061-T6 aluminum for its self-cleaning sliding contact properties despite oxide formation. Sources for beryllium copper spring clips and battery connectors are provided, including Seastrom and Becu Manufacturing, along with a Digikey part link for spring clips. Titanium or tungsten carbide drill bits are mentioned as durable arc contact materials. Overall, the consensus favors spring steel or beryllium copper strips for the conductive, springy contact, with practical considerations for availability, cost, and mechanical wear.

FAQ

TL;DR: For a 2-inch conductive, springy contact on a rotating potato-gun igniter, use 6061‑T6 aluminum or spring steel; “sliding contacts are self-cleaning.” [Elektroda, DAVID CUTHBERT, post #21661023]

Why it matters: This FAQ helps hobbyists choose and mount reliable sliding contacts for taser-based multi-barrel ignition.

Quick Facts

Target strip size: 0.5–0.75 in wide, ~2 in long for each barrel pass. [Elektroda, Andrew LeVino, post #21661005]
6061‑T6 aluminum works; oxide breakdown occurs at taser voltage; sliding contact self-cleans. [Elektroda, DAVID CUTHBERT, post #21661023]
Spring steel is hard, inexpensive, and easy to source; ultra-low resistance isn’t critical for a taser. [Elektroda, Bob Loy, post #21661011]
Beryllium copper is springy; its “non-sparking” claim concerns mechanical sparks, not electric arcs. [Elektroda, Bob Loy, post #21661008]
Off‑the‑shelf clips/plates: Digi‑Key battery contacts and Seastrom spring clips; sample BeCu available. [Elektroda, Todd Hayden, post #21661022]

What metal works best for a conductive, springy strip on a rotating taser ignition?

Use 6061‑T6 aluminum for an easy, robust sliding contact, or spring steel for durability against repeated rakes. Aluminum’s oxide gets punched through at taser voltages, and sliding action self‑cleans. Spring steel is cheap and widely available. [Elektroda, DAVID CUTHBERT, post #21661023]

Is beryllium copper (BeCu) a good choice here?

Yes, for springiness and stable contact pressure. Its “non‑sparking” property refers to preventing mechanical sparks, not stopping electrical conduction. It will still pass taser discharge to your barrel contacts. Consider clip forms if you need defined preload. [Elektroda, Bob Loy, post #21661008]

What size should the contact strip be for each barrel pass?

Build around a 0.5–0.75 inch width and about 2 inches length so the barrel plate reliably sweeps the contact during rotation. This footprint balances contact area and manageable spring force in compact builds. [Elektroda, Andrew LeVino, post #21661005]

Where can I buy suitable spring contacts or clips?

Repurpose battery contacts or spring plates from suppliers like Digi‑Key, or order spring clips from Seastrom. Some BeCu manufacturers will provide samples. These parts give consistent pressure and easy mounting. [Elektroda, Todd Hayden, post #21661022]

Will a simple steel spring work as the brush?

Yes, a metal coil or leaf spring can flex and return to position during each sweep. Watch for a failure edge case: localized arcing can cause micro‑welding of the spring to the track under poor alignment or excessive pressure. [Elektroda, Steve Lawson, post #21661012]

How do I keep visible sparks to a minimum for a safer user impression?

Favor a solid sliding contact over intentional air gaps. Avoid pointed electrodes facing the track, and use smooth, flat interfaces. As one user noted, visible arcing can be unsettling to operators. A continuous brush‑on‑plate contact reduces arc length. [Elektroda, Andrew LeVino, post #21661017]

Could I adapt a motor commutator approach for multi‑barrel firing?

Yes. A commutator provides timed conduction via segmented copper and stationary brushes. One proposal ties opposing segments to a barrel, with an event every 180 degrees. This gives robust, repeatable timing on a rotating assembly. [Elektroda, Frank Bushnell, post #21661020]

Quick how‑to: build a simple commutator contact for a rotating ignition ring?

Salvage a suitable DC motor; keep the commutator and shaft.
Remove windings; connect each barrel to opposing commutator segments.
Mount fixed brushes to feed the taser output as the shaft rotates. [Elektroda, Frank Bushnell, post #21661020]

What is a commutator, in plain terms?

A commutator is a segmented conductor on a rotating shaft. Stationary brushes touch the segments to route current at specific angles. In this project, segments can map to barrels, giving synchronized firing as the cylinder turns. [Elektroda, Frank Bushnell, post #21661020]

Can I use a PCB track and a spring-loaded ball for smoother contact?

Yes. A ball catch with adjustable spring force can ride over a copper PCB track. This offers low-friction, self-centering contact and easy force tuning by swapping springs or adjusting preload. [Elektroda, Sarah Harris, post #21661021]

Does aluminum’s oxide layer block the taser current?

Not in this setup. At taser voltage, the thin oxide breaks down. Sliding contact also wipes and refreshes the interface. As the contributor put it, “sliding contacts are self-cleaning,” which helps maintain reliable ignition. [Elektroda, DAVID CUTHBERT, post #21661023]

Is deliberately arcing across a small air gap a workable strategy?

It can work, since a spark uses ionized air as the path. Keep the gap tiny to limit energy loss before the chamber spark. A pointed rod near the strip starts the arc at a lower voltage. [Elektroda, Steve Lawson, post #21661015]

What tip materials survive repeated tiny arcs if I try the gap method?

Use hard, high‑melting materials like tungsten carbide or titanium drill bits for the pointed electrode. Expect erosion; design for adjustability or replaceable tips to maintain a consistent gap over time. [Elektroda, Steve Lawson, post #21661016]

Any sourcing tips beyond electronics suppliers?

General hardware outlets carry springs and small metal stock. Ask auto parts stores for specific spring dimensions if needed. Older electronics retailers carried hobby materials, but specialty distributors now offer better part selection online. [Elektroda, Steve Lawson, post #21661012]

What is beryllium copper (BeCu)?

BeCu is a copper alloy with beryllium that combines decent conductivity with strong spring properties. It resists fatigue and keeps contact force over many cycles, making it ideal for clips and brush fingers. [Elektroda, Bob Loy, post #21661006]

What’s a practical takeaway for first‑time builders?

Keep it simple: a 0.5–0.75 inch by ~2 inch 6061‑T6 aluminum or spring‑steel brush against steel plates. Scale later if needed. This balances availability, durability, and reliable conduction for hobby builds. [Elektroda, Andrew LeVino, post #21661005]