Resistance-No Resistance wire welder

[breaktru]

Not sure why everyone is so hell bent on using 35v for a weld????
I used a 1000uF cap on the camera at 36v, 2200uF at 27v and 340uF at 75v. I don't see any difference on the weld or find one easier than another. It all works well. It's your hand technique and tightness on the clip tension.
340uF at 75v is what I'm leaving it at. Maybe I'm missing something here.

 

[bapgood]

Not sure why everyone is so hell bent on using 35v for a weld????
I used a 1000uF cap on the camera at 36v, 2200uF at 27v and 340uF at 75v. I don't see any difference on the weld or find one easier than another. It all works well. It's your hand technique and tightness on the clip tension.
340uF at 75v is what I'm leaving it at. Maybe I'm missing something here.

I don't think you are missing anything, at least for my intentions. I'm just that annoying what if guy. I want to try out some different options and learn a few things along the way. I apologize if I'm cluttering up the thread or swaying from its purpose.

I have tried around 440uF with multiple caps and didn't really notice a difference. Others have stated that with 1000uF they noticed a significant improvement.

Breaktru I know you have tried just about everything and have posted thorough results, my curiosity isn't intended to demean you or your effort in anyway.

Moral of the story is dont give the what if guy 40 of anything

 

[bapgood]

One thing I was going to mention....I know spot welders typically have an adjustable weld time, maybe even adjustable voltage/output strength.

Is upping the capacitor size in theroy increasing the weld time?

 

[gsa]

Not sure why everyone is so hell bent on using 35v for a weld????
I used a 1000uF cap on the camera at 36v, 2200uF at 27v and 340uF at 75v. I don't see any difference on the weld or find one easier than another. It all works well. It's your hand technique and tightness on the clip tension.
340uF at 75v is what I'm leaving it at. Maybe I'm missing something here.

340uf @ 75v = 956.25m Joules
2200uf @ 27v = 801.9m Joules
1000uf @ 35v = 612.5m Joules

The first unmodified camera welders were about 2 Joules and obviously a bit too much without a bit of tweaking. They do work though, and I made a month supply of great wires with it. 35v with the lm2577 is just going to be easier to build for people not wanting to start adding parallel caps and such.

I linked this earlier in the thread but will put it here again because I think it is useful in designing a working setup with salvaged parts: Electronics 2000 | Capacitor Charge / Energy Calculator

 

[breaktru]

340uf @ 75v = 956.25m Joules
2200uf @ 27v = 801.9m Joules
1000uf @ 35v = 612.5m Joules
Electronics 2000 | Capacitor Charge / Energy Calculator

Nice link gsa, thanks.
It's interesting to see the difference in Joules but strange that each one produced the same weld regardless of this variance. hmmmm
It goes to show that theory and calculations are no match for hands on actual testing.

 

[dsy5]

Not sure why everyone is so hell bent on using 35v for a weld????
I used a 1000uF cap on the camera at 36v, 2200uF at 27v and 340uF at 75v. I don't see any difference on the weld or find one easier than another. It all works well. It's your hand technique and tightness on the clip tension.
340uF at 75v is what I'm leaving it at. Maybe I'm missing something here.

I'm using a 330µF and around 50V-60V for the welds. I have no plans on trying to modify the output as it works, as is. I only provided suggestions to those that asked how to modify theirs...

I cannot get a good weld on silver, either.

 

[breaktru]

I'm using a 330µF and around 50V-60V for the welds. I have no plans on trying to modify the output as it works, as is. I only provided suggestions to those that asked how to modify theirs...

I cannot get a good weld on silver, either.

What gauge silver are you using? I use 30ga Silver .999 pure. Also used a single copper strand from a stranded wire. It Mic'ed at 32ga.

 

[dsy5]

What gauge silver are you using? I use 30ga Silver .999 pure. Also used a single copper strand from a stranded wire. It Mic'ed at 32ga.

My silver is .999 pure 24ga... that is where I believe the problem lies. Poor decision on the dia at time of purchase. Glad I only bought 10 ft and not 100!

I have no problem with copper, either. Didn't mic the copper but it is transformer wire and appears to be 30 - 32 ga. Welds fine after removing the varnish coating. I do have a problem with my stranded appliance wire that I originally twisted to resistance wire - it seems to have a nickel or tin coating to it. A strand is perhaps 30 ga and it will only produce a small spot weld which is easily broken off.

 

[TBinAZ]

I have the "dead soft" silver wire. Not sure what everyone else has. I wonder if the wire being so malleable has anything to do with the lack of weld stickiness. I'm still trying to figure out why I was successful for one day. It worked a treat. Still have the connected wires. Gonna save those babies for a rainy day for sure.

 

[bapgood]

Ok, bap, one more "cheap" alternative: 2 capacitors in series or a 'capacitive divider'. It is basically a takeoff on the 10 caps in series, where 9 of the caps values are combined as 1 cap. The formula for determining the voltage across each cap is:

V of C1 = (C2 / (C1 + C2)) * V applied
V of C2 = (C1/(C1 + C2)) * V applied

So to get about 42 volts across a 1000µF cap, a 150µF cap needs to be in series with it (assuming 325V applied).

Drawback to this method is that it is not adjustable. The smaller cap must be rated to handle close to 275V, where as the larger one could be perhaps 50V.

Didn't have any time to play last night to try the resistor voltage divider, but I did throw a 1000uF cap in series on a camera quickly this morning. I went up slow, but it went past 35v easily and I stopped at 54v. I thought I had effed something, then the light bulb went on. I didn't know the voltage being applied. Removed the caps and hooked up the meter, sure as poo it was 600v. Doing the math that comes out to 64.3v. Tonight I will try a 100uF 330v and the 1000uF 50v, this should limit voltage to 54.5v.

 

[bapgood]

Thought....Its been a while since I have used a spot welder, but it my recollection there is a variable output/voltage setting and a weld/cycle time setting. During use there was a button to close the clamps on the work pieces, once the clamps were closed and you had the work pieces situated like you wanted, there was another button to perform the weld to the voltage and cycle time settings that were selected.

I don't think something similar can be achieved with a camera, but would it be possible to do with a LM2577 or similar?

My thinking is that you would have the voltage adjustment via the LM2577/other and would need a way to control the weld cycle time. What I'm not sure about is limiting the output current/amp draw and/or the current/amp's needed to perform the welding (possibly more than the LM2577 is capable of ???).

However if the above could be sorted out I envision some kind of posts or clamp to clamp the wires together, weld unit with adjustable volt and cycle time, and a single weld button. Thus taking DT shakes out of the equation and giving more consistent results and more adjust-ability for wire combinations.

I'm quite possibly over thinking all this....but it seems as though we might be trying to insert a thumb tack with a quick blow of a sledge hammer????

 

[gsa]

Thought....Its been a while since I have used a spot welder, but it my recollection there is a variable output/voltage setting and a weld/cycle time setting. During use there was a button to close the clamps on the work pieces, once the clamps were closed and you had the work pieces situated like you wanted, there was another button to perform the weld to the voltage and cycle time settings that were selected.

I don't think something similar can be achieved with a camera, but would it be possible to do with a LM2577 or similar?

My thinking is that you would have the voltage adjustment via the LM2577/other and would need a way to control the weld cycle time. What I'm not sure about is limiting the output current/amp draw and/or the current/amp's needed to perform the welding (possibly more than the LM2577 is capable of ???).

However if the above could be sorted out I envision some kind of posts or clamp to clamp the wires together, weld unit with adjustable volt and cycle time, and a single weld button. Thus taking DT shakes out of the equation and giving more consistent results and more adjust-ability for wire combinations.

I'm quite possibly over thinking all this....but it seems as though we might be trying to insert a thumb tack with a quick blow of a sledge hammer????

If you look back to the first page or two, I linked to some battery tab welders that use a Thyristor to do what you are describing (they added a foot switch to trigger the gate). I think it is a great idea and was planning on doing this initially but am not sure how to properly size this component and they are fairly expensive. There are a few other gated type triggers that may work for what we are doing but, I haven't had time to properly research it yet.

 

[comptechltd]

I have my parts ordered to make gsa's welding box or at least attempt it. Wouldn't it be possible to place an additional momentary switch maybe going to one of the leads so that you could charge up the cap., position your wires so they are touching in a "helping hands" soldering type clamp and then just push the 'fire' button whenever you are ready? Maybe my logic is flawed here but it seems like it would work. The only question I would have is what size and rating momentary switch would you need?

Steve

 

[bapgood]

I had similar idea.

I have been thinking about rigging up something like the below. The bottom post would be fixed, and thinking the top post could be held down and a switch added to release the charge....or maybe just a swift bonk on the center post????

food for thought anyway....I know for me that with good eyes and sometimes shaky hands getting the perfect wire touch is a pita.

 

[BJ43]

I had similar idea.

I have been thinking about rigging up something like the below. The bottom post would be fixed, and thinking the top post could be held down and a switch added to release the charge....or maybe just a swift bonk on the center post????

food for thought anyway....I know for me that with good eyes and sometimes shaky hands getting the perfect wire touch is a pita.

I was thinking of a piece of ceramic with a slot a little bigger than the wire and just slide the wires against each other. At my age getting anything into a small hole is more than a PITA.

 

[gsa]

I like those ideas. Just to play devils advocate though...

bap, looks like you need 3 hands there, 2 to hold the wire and one to push the plunger. Maybe spring load the ram? Maybe add a second sight hole across the wires so you can see how much overlap you have? That teardrop shape is going to be a b..ch to mill. I really like the traditional spot welder type setup, I wonder if we can try out a spot weld another way before you break out the itty bitty files

bj, I like that idea. Choking up on the kanthal is going to be the trick. Maybe a integrated holder for the r wire that is a clamp and a ferrule all in one? Like a mig nozzle....

 

[bapgood]

I like those ideas. Just to play devils advocate though...

bap, looks like you need 3 hands there, 2 to hold the wire and one to push the plunger. Maybe spring load the ram? Maybe add a second sight hole across the wires so you can see how much overlap you have? That teardrop shape is going to be a b..ch to mill. I really like the traditional spot welder type setup, I wonder if we can try out a spot weld another way before you break out the itty bitty files

bj, I like that idea. Choking up on the kanthal is going to be the trick. Maybe a integrated holder for the r wire that is a clamp and a ferrule all in one? Like a mig nozzle....

Haha....my incomplete model...I agree I was thinking a spring on the ram, two insulated clamps holding each wire, I was going to use delrin for the body of my mock up and drill a hole through the center and use a triangle file for the V....not sure what I would use long term

Yeah some additional sight relief would help.

 

[comptechltd]

gsa,

What would need to be the rating of a momentary switch on one of the leads to the wire??

Steve

 

[gsa]

gsa,

What would need to be the rating of a momentary switch on one of the leads to the wire??

Steve

A momentary switch wont work, it needs to be a gated type diode like the SCR switch or MOSFET gate of some type. If you use a momentary switch, the switch will just weld the contacts closed the first time you use it.

 

[UA72Riddle]

Deleted for being ignorant.....