Resistance-No Resistance wire welder

[dsy5]

Fused 30 nickel to 32 kanthal with 27v. I did find it strange to increase the volt output the screw need turned counter-clockwise.

If they would have mounted that potentiometer 180º, it would dial in correctly...

 

[Aflatoxin]

Hot Shoe Camera Flash:

Turnforward and I were both separately wondering, what is that 3rd white wire on the (- side) xenon flash bulb is for?

Answer is here>>> Type of trigger circuit for xenon flash lamp?.......(for successful triggering)
The second post by "BradtheRad" answers all questions in great detail. Something about how the third wire is critical for the xenon gas to pre-ionize before the actual "flash" can be produced.
"The pulse does not have a complete circuit. The trigger pulse is capacitive. Its purpose is to ionize the gas to conduction. The 200 V supply only ionizes it partway.
The trigger pulse is hi-voltage. I suppose there might be a momentary pica-ampere of current. (Femto-ampere?)"

He's saying that the wire isn't a complete circuit (hence a single white wire) but is still spitting some high voltage! ???
I could be wrong, but isnt that reminiscent of a high voltage flyback transformer??? ...Kinda? - Oh well, its not important.


Is this magic "trigger pulse" wire necessary for wire welding? No, I really don't think so.
BUT, for safety, we may have to remove the wire completely, or otherwise render it safe.

Hoping to zap wire soon!

 

[dsy5]

Hot Shoe Camera Flash:

The trigger pulse is hi-voltage. I suppose there might be a momentary pica-ampere of current. (Femto-ampere?)"[/I]

He's saying that the wire isn't a complete circuit (hence a single white wire) but is still spitting some high voltage! ???
I could be wrong, but isnt that reminiscent of a high voltage flyback transformer??? ...Kinda? - Oh well, its not important.


Is this magic "trigger pulse" wire necessary for wire welding? No, I really don't think so.
BUT, for safety, we may have to remove the wire completely, or otherwise render it safe.

Hoping to zap wire soon!

This is indeed high voltage. It is probably around 4000V as there is a high voltage coil that produces the voltage. And no, this is not only unnecessary for a welder, it should be removed. On the camera board welder I made, I went as far as removing that coil completely, so as not to produce any high voltage at all. All that is needed is the 300 V and that really is much higher than necessary. Only around 70 - 90 volts is needed to make good welds with a camera board.

 

[Aflatoxin]

This is indeed high voltage. It is probably around 4000V as there is a high voltage coil that produces the voltage. And no, this is not only unnecessary for a welder, it should be removed. On the camera board welder I made, I went as far as removing that coil completely, so as not to produce any high voltage at all. All that is needed is the 300 V and that really is much higher than necessary. Only around 70 - 90 volts is needed to make good welds with a camera board.

Thank you for the conformation and great advice.

 

[Aflatoxin]

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Everything is up and running. But I'm have big problems and need a few opinions.

I can't get a good weld! I've gotten plenty of weak welds. I'm only able to do the poor overlap method, because I can't control my flinch well enough to perform an end-to-end weld. I charge to 160v and try and touch the 2 wires together, and BANG! - I jump! UHHGG!!!!
I can shoot 30-30's and 44's all day and never flinch like this! I don't know what to do.

My Kanthal is 28awg .32mm, and my Pure Nickel NR wire is 30-Gauge. They look pretty much the same. When zapping, I have never tried going above 200 volts only because 180 is violent as hell! It's strange how the best welds were always the tamest bangs, (not as explosive).
I'm using an insulated "helping hands" to hold one alligator clip & wire, and then I manually bring the 2nd (nickel) wire up to the first.

Any tips, tricks or advice of ANY kind will be appreciated.

 

[Hostile]

Hot Shoe Camera Flash:

Everything is up and running. But I'm have big problems and need a few opinions.

I can't get a good weld! I've gotten plenty of weak welds. I'm only able to do the poor overlap method, because I can't control my flinch well enough to perform an end-to-end weld. I charge to 160v and try and touch the 2 wires together, and BANG! - I jump! UHHGG!!!!
I can shoot 30-30's and 44's all day and never flinch like this! I don't know what to do.

My Kanthal is 28awg .32mm, and my Pure Nickel NR wire is 30-Gauge. They look pretty much the same. When zapping, I have never tried going above 200 volts only because 180 is violent as hell! It's strange how the best welds were always the tamest bangs, (not as explosive).
I'm using an insulated "helping hands" to hold one alligator clip & wire, and then I manually bring the 2nd (nickel) wire up to the first.

Any tips, tricks or advice of ANY kind will be appreciated.

I don't have any experience doing this, cause I'm a lazy turd and haven't made one... but 160v? I thought everyone was using around 30v?

 

[Innocuous]

They balance uF and V and time. Should be a simple calculation, but I am not sure what it is.

 

[Lentulusbatiatus]

Hot Shoe Camera Flash:

I can't control my flinch well enough to perform an end-to-end weld.

Any tips, tricks or advice of ANY kind will be appreciated.

Yeah stop being a ....... lol

Seriously you're thinking about it too much if you cannot stop jumping.

 

[Aflatoxin]

I don't have any experience doing this, cause I'm a lazy turd and haven't made one... but 160v? I thought everyone was using around 30v?

I know right! I read that too. It's gotta be a joules thing. My cap is a large 330v, but only 300UF. A lot of you guys are using a 30v 2500UF cap.
Trust me, I tried 30, 40, 50, ect. I got a good weld at 96 volts. But it eventually broke. It wouldn't have survived coiling, even by my surgeon steady hands.

Thanks for sayin tho!

 

[Aflatoxin]

Hot Shoe Camera Flash:

Yeah stop being a ....... lol

Seriously you're thinking about it too much if you cannot stop jumping.

Gee thanks

I'm telling ya, this thing BANGS! I think it's discharging faster then some of your 30v 2000/2500UF caps.
I gotta play with an electric Black Cat, 2 feet from my face, just to get a "bad weld".

I've seen the cute little pop that your lovely zapper makes. THIS AINT THAT!

Back to work:
After reading past experiences. I'm going to rework my connections for efficiency, put the nickel wire on the positive side, and if that doesn't let me use less juice, then I'll have to borrow Errol's idea, and make a wire welding jig. (Errol post #988)

 

[Aflatoxin]

Hot Shoe Camera Flash:

Photo's of failure.

This Kanthal wire was zapped 3 times. Looks bad. I eventually got a semi good weld on it, till it broke.
The knick in the middle, is from a failed weld. Those missing atoms are components to my indoor air pollution now.

LINK to all photos: (picture titles above pics, and descriptions below)

One day, Photos of successful welds with grace our monitors!!!!!

 

[dsy5]

There is a web site which allows you to calculate the charge in joules with specified cap, resistor and voltage. I can't recall the site as I am at work, but it was mentioned previously in this thread. If I find it again I will post it.

I think that 160V is much too high for the weld at that value capacitance - try shooting for about 100V or less and give it a go.

 

[Aflatoxin]

There is a web site which allows you to calculate the charge in joules with specified cap, resistor and voltage. I can't recall the site as I am at work, but it was mentioned previously in this thread. If I find it again I will post it.

I think that 160V is much too high for the weld at that value capacitance - try shooting for about 100V or less and give it a go.

I found it thanks!

Discharge time is going to be pretty impossible to vary, but from what I have read we are at about 20 milliseconds discharge time here.

So lets use 24v at 2200uf here: Electronics 2000 | Capacitor Charge / Energy Calculator we get .63 Joules

then to convert Joules to Watts use this here (enter .02 as time): Joules to watts (W) conversion calculator and you get 31.5 watts.

The same thing with a 24v power and 1000uf cap = 14 watts

More good stuff.

Hi. If you want to be absolutely sure that your resistors won't fail, you can use Ohm's Law to calculate the wattage that the resistors will be subjected to. You need to know the maximum voltage that will be applied to them.

Ohm's Law Calculator

For instance, if you can charge up to 250v, and choose 30k ohms for the bleeding resistor, you'll dissipate a maximum of about 2 watts in the resistor. That wattage will drop quickly at the higher voltages, as the voltage is dropped from the capacitor, and drop more slowly as the voltage approaches zero. This is why you should be fine with a lower-rated resistor, as they can endure short periods of higher wattage.

The more resistance that you choose, the lower the overall wattage will be, but the longer it will take to discharge the cap. That may be beneficial for fine-tuning the voltage. For example, 250v, 30k ohms, and 350 uF would discharge in about 10.5 seconds.

Capacitor Discharging

You can put multiple resistors in series and/or parallel to reduce each resistor's power dissipation. Putting two or more in series would add their resistances, thus lowering the overall current and wattage of the circuit. Putting two or more in parallel would increase the overall amperage and wattage, but split it between each resistor, based upon their individual resistance.

Series and Parallel Circuits

For example, with 250v stored in the cap, a single 15k ohm resistor will see about 4 watts for the beginning portion of the discharge. If you went with 3 x 10k ohms in series, you'd increase the overall resistance to 30k ohms and double the discharge time, but each resistor would drop only 1/3 of that voltage, while all would pass the same current, thus each would only drop about 2/3 of a watt at the beginning of the discharge.

Here's another calc that you may find useful:

Energy Stored on a Capacitor

That will show you how many joules that you're storing, based upon the voltage and capacitance. My earlier example of 250v and 350uF would store about 1.1 joule. I've found that .9 to 1.4 joules works for the range of wires that I use.

Thanks ALL!

 

[LucentShadow]

I know right! I read that too. It's gotta be a joules thing. My cap is a large 330v, but only 300UF. A lot of you guys are using a 30v 2500UF cap.
Trust me, I tried 30, 40, 50, ect. I got a good weld at 96 volts. But it eventually broke. It wouldn't have survived coiling, even by my surgeon steady hands.

Thanks for sayin tho!

Seems to me that the higher voltage that you are using, possibly in combination with a (small) cap that probably discharges faster than what many of us are using, is causing a more energetic arc from a greater distance away than what many of us get.

Higher voltage allows for longer arcs through the air, per Paschen's Law. I'd guess that's probably fine for bigger wires, but just might be too much for these thin wires.

I'd probably try adding another cap in parallel, dropping the voltage appropriately, and see if that improves things.

 

[dsy5]

I know right! I read that too. It's gotta be a joules thing. My cap is a large 330v, but only 300UF. A lot of you guys are using a 30v 2500UF cap.
Trust me, I tried 30, 40, 50, ect. I got a good weld at 96 volts. But it eventually broke. It wouldn't have survived coiling, even by my surgeon steady hands.

Thanks for sayin tho!

I don't know if you are using the LM board or a camera board, but the voltage rating of the cap does not determine the properties of the cap. It only is a rating for what voltage is allowable without damaging it. Therefore the guys that are using high rated (330V) caps do so because the camera board can put out up to 300+ volts. The guys using the lower rated caps are using LM board, which only go up to about 37V. I personally use a 50V rated cap on my LM based welder.

And the lower the capacitance, the more voltage is needed to achieve the same charge and vice versa. That is why the LM guys are using higher µF caps - lower voltage out of the LM board.

 

[Aflatoxin]

Hot Shoe Camera Flash:

I don't know if you are using the LM board or a camera board, but the voltage rating of the cap does not determine the properties of the cap. It only is a rating for what voltage is allowable without damaging it. Therefore the guys that are using high rated (330V) caps do so because the camera board can put out up to 300+ volts. The guys using the lower rated caps are using LM board, which only go up to about 37V. I personally use a 50V rated cap on my LM based welder.

And the lower the capacitance, the more voltage is needed to achieve the same charge and vice versa. That is why the LM guys are using higher µF caps - lower voltage out of the LM board.

I think LS is right. My camera flash cap is discharging faster then a lower volts/higher UF cap would.

But I see what you are saying too. I would like to change my little fire cracker for something that puts out the same heat in a few millionths of a second slower. (can be done) But like you say and like Breaktru warned, my camera board could blow a 30v or 50v cap sky high in my face!!! It charges over 100v in 2 seconds! It's just to dangerous and fast charging to use a smaller voltage rated cap.

But this is all for discussion sake. I got mine welding without anymore BANGS!!!

 

[Aflatoxin]

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Successful welds: PHOTOS LINK

I have a useful working welder!​

Previously, I was using thick braided copper wire and medium sized alligator clips.
So going with my gut and against logic, I soldered on wimpy test leads that have tiny crappy alligator clips on them. These leads are the kind that cost $2.50 for a pack of six, and each have little vinyl sheathed gator clips on either end. I simply cut one in half to make two separate leads. The gator clips where filled with silver-bearing solder. Then I soldered them to the capacitor leads.
I also kept the R-NR wire I was welding, very short. The pure nickel wire was used only on the positive side.

I got nice molten welds at 90v and I went up to 140v. Every weld shot was much quieter! No more explosions of ionized air an metal!
Just a nice satisfying pop!

Now I just need to work on my technique. Eventually I hope to make a box with push buttons someday too.

Everyones advice, and work on this thread has been invaluable to my build. Thank you.​

 

[Covert]

Just built my 1st one / three today lol, I had the second try up and running, but fried it due to user error..... lesson learned. Now im on the third one, but this board is giving me hell. Can anyone tell me how to stop it from auto charging. I'll weld a wire together then it will automatically start recharging itself again.
And on another note of my learning the hard way as im sure many of you have that these lil suckers pack a punch lol zapped myself by accident

 

[dsy5]

Hot Shoe Camera Flash:



I think LS is right. My camera flash cap is discharging faster then a lower volts/higher UF cap would.

But I see what you are saying too. I would like to change my little fire cracker for something that puts out the same heat in a few millionths of a second slower. (can be done) But like you say and like Breaktru warned, my camera board could blow a 30v or 50v cap sky high in my face!!! It charges over 100v in 2 seconds! It's just to dangerous and fast charging to use a smaller voltage rated cap.

But this is all for discussion sake. I got mine welding without anymore BANGS!!!

LS is not talking about the voltage rating, he is taking about the µF rating. By all means you can safely add a higher µF cap to your camera board (as long as the voltage rating is equal or higher than the output of the board). Be aware that you may possibly experience even worse welds due to the higher charge - you may effectively vaporize the metal and cause spatter, which results in a poor weld.

 

[Aflatoxin]

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If you want to geek out I thought this was pretty cool. Video showing his homemade 600w dual pulse capacitor discharge welder and a link to the blog. The blog has tons of info from building the welder to homemade pcb using "the Toner Transfer Method and a hacked Laminator to make really good looking boards"

I thought this was informative information from the blog.

" CAPACITOR DISCHARGING EXPLAINED
I was browsing the internet and found many sites where the guys think that they will get the same or better welders by making the voltage higher and the capacitance lower. Yes, it will be cheaper and easier to increase the voltage to get more Joules or Watt-second (1/2x capacitance x voltage x voltage) BUT here is the catch: The capacitance of your cap and the resistance that you weld, determine the length of your weld and not the WATT-SECOND. In other words if you have a 1 farad cap, charged to 35Volt (612Ws) then it will completely discharge in 15ms if you weld metal with a resistance of 0.003Ohm (0.005 nickel).
If you increase the voltage to 50V then you will have 1250Ws and your capacitor will still discharge in 15ms at the same resistance.
With a bigger capacitor, lets say 3farad at 20Volt (600Ws), will discharge over a 45ms period.
You can already see what is happening here: A higher voltage will give you more current discharged into your work piece in a shorter time. It will produce more heat, is very hard to control and will make welding thinner metals very difficult, meaning that 0.1ms can give you a nice weld and 0.2 might burn a hole in your work piece.
With a lower voltage and bigger capacitance your weld will be more spread out and will have less current than above but it will give you a much better controlled weld and fuse your metals better and stronger together.
The higher Ws makes a big difference but the capacitance should also be bigger to give longer and better controlled welds.The Volts and Capacitance needs to be balanced to make a good welder.
For battery packs, I will suggest the higher capacitance and that is what I'm building here."

Don't you just love it when your hypothesis is confirmed? Especially in a subject you previously knew little about!
I had to repost this post for those future high volt camera flash peeps, who may be scratching their heads, wondering about capacitor discharge times.

Interesting reads:


Rapid Solidification of Stainless Steels by
Capacitor Discharge Welding (had to read this cached)

How do I calculate how fast a capacitor will discharge?


Capacitor Discharge Time: How can I calculate it? Has tips on increasing discharge time using the idea that some here introduced. Parallel caps.


Capacitor Discharge Calculation