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I'm waiting.......??????
(I have a couple 24's and a 48)I have a question about capacitance qty and correlation to watts/joules vs discharge time. I'm just going to throw out numbers....24 volts 1000uF vs 24 volts 2000uF....both being discharged by touching wires together. Will the 2000uF cap version have greater watts or discharge time? (probably both to make it hard to understand
)My understanding is that watts = volts x amps.......So in my mind a larger cap is going to sustain a higher voltage longer during discharge and result in a longer discharge time.
I'm waiting.......??????
I have a question about capacitance qty and correlation to watts/joules vs discharge time. I'm just going to throw out numbers....24 volts 1000uF vs 24 volts 2000uF....both being discharged by touching wires together. Will the 2000uF cap version have greater watts or discharge time? (probably both to make it hard to understand
My understanding is that watts = volts x amps.......So in my mind a larger cap is going to sustain a higher voltage longer during discharge and result in a longer discharge time.
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
That is what I was afraid of....adjusting volts and adjusting total capacitance both are effecting output watts. I had looked over similar calcs and was trying to understand how time plays into it and kept getting lost.
It seems regardless of which components are used camera/LM2577/power supply/etc and total capacitance, we are stuck at relatively fixed weld time. A little more weld duration is were I think we could gain some stickemm. But for what we are doing, it seems like taking some time to dial in the voltage/etc is working for most.
Out of my depth...but here goes my idea for the day....There has been success with the LM2577 maxed at 35v and 1000uF cap.
Using the above calc = 30.65 watts
30.65 watts / 35 volts = 0.875 amps (yes as the volts drop the amps go up, but I have no clue how to calc that) so lets just say it under 4 amps.
Could multiple caps be charged and released one after the other using something like these 4a 50v SCR/Thyristors, increasing your weld duration by the number of caps?
It seems regardless of which components are used camera/LM2577/power supply/etc and total capacitance, we are stuck at relatively fixed weld time. A little more weld duration is were I think we could gain some stickemm. But for what we are doing, it seems like taking some time to dial in the voltage/etc is working for most.
Out of my depth...but here goes my idea for the day....There has been success with the LM2577 maxed at 35v and 1000uF cap.
Using the above calc = 30.65 watts
30.65 watts / 35 volts = 0.875 amps (yes as the volts drop the amps go up, but I have no clue how to calc that) so lets just say it under 4 amps.
Could multiple caps be charged and released one after the other using something like these 4a 50v SCR/Thyristors, increasing your weld duration by the number of caps?
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I dont know much about electronics but I do know a bit about welding and molten metals. If I understand you correctly you are suggesting keeping the metal in a molten state longer. Molten metals and O2 create slag which is mainly comprised of oxides. Have you tried using an acid flux? I normally would not sugest an acid flux for electronics but since this will be cleaned before coiling and the flux will help provide an O2 deprived enviroment at the same time as the acid is keeping the wire clean, it might be the simple solution. Almost all moten metal joins use a flux of some sort to keep O2 from the welded joint until solid.
I have thought of using acid flux myself and will be trying it once I finish my new build, it seems feasible.
How about a secondary trigger circuit to release a second capacitor to discharge right after the first discharged?
That's kinda what I was thinking with the SCR but to my limited knowledge there are two ways to open an SCR. Either apply voltage to the gate or at the avalanche voltage point.
The only thing my tiny mind could come up with is to use something like a timer to send voltage to the SCR gates like 20ms apart.
Probably starts getting a little complex for what we are doing.
If you got something figured out you could probably get it to where with a number of caps, and have them charge once fired, and get a contious loop that you could set for different time lengths. Similar to CDI ignition in a car.
Doing such things at all is over my head, let alone cheaply and easily
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."
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."
gsa, did you get a chance to test? I just found some 2200uF 50v and 4700uF 35v caps and maybe some nickel wire
Also just broke down and ordered 100' of 32g nickel....really wanted 30 gauge as good in between for 28-30-32 kanthal....but $11 for 32g vs almost $40 for 30g didn't add up
I did a test, but something completely differant
I wanted to test to see how good my weld was with this lm2577 setup so this was my test:
34g nichrome
30g silver
No cleaning of wires, they welded first time with 35v at 1000uf
I made 2 of these at 1.2ohms each
I then made a dual coil on my ody which measured .6ohms
Fresh charged aw imr 18650 at 4.2v off the pila and into my ggts
= 30 watts and 7 amps
I'm currently in vaping my .... off.
will update if the coils fail.
I wanted to test to see how good my weld was with this lm2577 setup so this was my test:
34g nichrome
30g silver
No cleaning of wires, they welded first time with 35v at 1000uf
I made 2 of these at 1.2ohms each
I then made a dual coil on my ody which measured .6ohms
Fresh charged aw imr 18650 at 4.2v off the pila and into my ggts
= 30 watts and 7 amps
I'm currently in vaping my .... off.
will update if the coils fail.
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I have some results to share. 24v and two 4700uF caps produced amazing results 30g kanthal to kanthal. I was using the below hand spot weld method.... + & - to the brass posts, I would hold the wire in my "wussy" flat clip (both wires in clip) on top of the bottom post, then bonk. One time I had the wires nice and parallel snugged up to each other for a decent length and the wires were welded together at least two times the length of the actual post contact area each way!!! I know this is kanthal to kanthal but the results are very promising IMO. The weld is more subdued. My 24v power supply is adjustable from ~20v-27v, and I played around in that volt range with one and two 4700uF caps. Like breaktru indicated a lot!!!! of the weld success is do to good camping. I had clamps on each end of my weld wires, one end clamped to the capacitor and the other end for welding. Noticing some inconsistency I soldered one end of the wires to the cap and it made a huge difference in both the weld intensity and consistency. I think that once I get a good solid setup together I can drop to a single capacitor and/or lower volts.
Thinking some good solid copper wire will work nicely for the spot welder post.
flat clip (both wires in clip) on top of the bottom post, then bonk. One time I had the wires nice and parallel snugged up to each other for a decent length and the wires were welded together at least two times the length of the actual post contact area each way!!! I know this is kanthal to kanthal but the results are very promising IMO. The weld is more subdued. My 24v power supply is adjustable from ~20v-27v, and I played around in that volt range with one and two 4700uF caps. Like breaktru indicated a lot!!!! of the weld success is do to good camping. I had clamps on each end of my weld wires, one end clamped to the capacitor and the other end for welding. Noticing some inconsistency I soldered one end of the wires to the cap and it made a huge difference in both the weld intensity and consistency. I think that once I get a good solid setup together I can drop to a single capacitor and/or lower volts. Thinking some good solid copper wire will work nicely for the spot welder post.
I did a test, but something completely differant
I wanted to test to see how good my weld was with this lm2577 setup so this was my test:
34g nichrome
30g silver
No cleaning of wires, they welded first time with 35v at 1000uf
I made 2 of these at 1.2ohms each
I then made a dual coil on my ody which measured .6ohms
Fresh charged aw imr 18650 at 4.2v off the pila and into my ggts
= 30 watts and 7 amps
I'm currently in vaping my .... off.
will update if the coils fail.
Is there any chance you could make a dummies guide to making your lm2577 setup ? it sounds very promising but I'm not very experienced with circuitry.
My LM2577 board came today. Haven't done anything with it other than verifying that it works. I have made up a MOSFET design that I am considering for a slower discharge. Gated by a variable frequency (1000Hz - 15kHz) and variable duty cycle oscillator. I am thinking that if the weld started out slowly and then increased the discharge, the weld would not spark as much, obtaining a more thorough weld instead a tack.
Breaktru would not approve, but I do like to tinker!
Breaktru would not approve
, but I do like to tinker!If anyone wants to pay for the parts, I will build one and do a step by step photo guide and then send them the finished product.
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