Mini battery operated spot welder
- Thread starter phils2um
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Greg Elmassian
Guest
Worth the few bucks, looks very convenient. I was watching when he almost spot welded the main strip to the outer shell of one battery.... someone commented that was maybe dangerous, and he commented that he was glad he did not do anything stupid... ha ha, he did do something stupid and got away with it...
I have seen these as well and have been wondering, I thought that they may be just the thing for welding batteries together (using tab strip) to make up packs. This is something I have seen done elsewhere and certainly with NiMh I would have thought it to be no issues. But..........
Yes, I've used a similar one, bought from Ebay for £20.
Used it to spot weld 0.37mm (28 swg) tinned copper wire to 96 lithium batteries for my shed solar power project. Two spot welds per wire, that's 384 times using the 12 volt battery that had been saved for a rainy day when I recently had a new battery in my car. Was rather sceptical when I bought it but it did the job, so was really pleased.
Will use it for any future lithium cell garden railway project as it saves buying tagged batteries.
Just tried it in my Peco 250 code track and it wasn't very successfull.
Michael
Used it to spot weld 0.37mm (28 swg) tinned copper wire to 96 lithium batteries for my shed solar power project. Two spot welds per wire, that's 384 times using the 12 volt battery that had been saved for a rainy day when I recently had a new battery in my car. Was rather sceptical when I bought it but it did the job, so was really pleased.
Will use it for any future lithium cell garden railway project as it saves buying tagged batteries.
Just tried it in my Peco 250 code track and it wasn't very successfull.
Michael
Greg Elmassian
Guest
are you specifically talking about bonding wires between rail sections? yes, doubtful it could do a 14 gauge wire
DafyddElvy
1:22.5 & 15mm Scale Trams, , NG Steam Railways
Phil,
Are you suggesting it would be best practice to bond a piece of nickel silver or brass strip to the rail and then bond the wire to that?
I am thinking of feed wires from a BUS wire rather than rail to rail.
David
PhilP
G Scale, 7/8th's, Electronics
Well it would make the soldering process easier, in your case...
But for supply-to, rather than bonding-between, rails:
I would suggest 'solder-tags' on your droppers, and use rail-clamps, for joining track and to attach the droppers..
You can make-up the ends at the bench (a lot more easily than track-side) getting better results.
You are less likely to melt sleepers (ties) this way, as well.
Welding is best for joining similar materials, of similar section (thickness) by melting the edges where they meet, into each other..
So it would be 'better' to spot-weld a strip of brass between two lengths of rail (with a joggle for expansion) than trying to weld a thick copper wire to the brass track..
PhilP
DafyddElvy
1:22.5 & 15mm Scale Trams, , NG Steam Railways
I am now wondering how effective it would be with stainless steel rail and nickel silver which is the rail type I am using.
You have also got me now wondering how and if it would be possible to weld rails together in to continuous lengths of long welded rail, in theory it should be possible if a suitable alignment frame could be made, but now I am digressing right off topic
David
You have also got me now wondering how and if it would be possible to weld rails together in to continuous lengths of long welded rail, in theory it should be possible if a suitable alignment frame could be made, but now I am digressing right off topic
David
JimmyB
Now retired - trains and fishing
Welding joins (fuses) to items (in this case metal) together, by melting each other, often with a filler rod, however no filler rod with spot welding, just the meting of the items. To enable the material to fuse together the metals must be compatible with each other, and there melting point must be within the scope of the welding machine. Unlike brazing, silver soldering and soft soldering when a dissimulator metal is attached (via heat) to the two item of metal, this does not fuse as the material to be joined does not melt
DafyddElvy
1:22.5 & 15mm Scale Trams, , NG Steam Railways
I am now wondering how effective it would be with stainless steel rail and nickel silver which is the rail type I am using.
You have also got me now wondering how and if it would be possible to weld rails together in to continuous lengths of long welded rail, in theory it should be possible if a suitable alignment frame could be made, but now I am digressing right off topic
David
You have also got me now wondering how and if it would be possible to weld rails together in to continuous lengths of long welded rail, in theory it should be possible if a suitable alignment frame could be made, but now I am digressing right off topic
David
DafyddElvy
1:22.5 & 15mm Scale Trams, , NG Steam Railways
Phil,
Now waiting for the G scale Thermite welding kit..
Whilst it should be possible to weld your rail...
I think you might have trouble pre-tensioning it?
Rail stressing shouldn't be required for say 3 x 1m rails welded together, my original comment was just a wee bitty tongue in cheek, but you have now set the grey cells off wondering if it could be possible. I would need to get some carbon shaped to the rail profile and a means to clamp the rail.
It could only be attempted when domestic management wasn't around, of yes, and its nearly 50 years since I experimented with ideas of this nature, otherwise its not a bad idea (V x A = Current) how much current might be required and could their be enough current before I trip the household fuse, och nae bother I'll get someone to hold the fuse up, hey we are getting to a plan.
Now I suppose I should get back to being sensible and some simple model making
David
Greg Elmassian
Guest
Welding rails end to end is probably going to take a much larger machine, notice why the prototype railroads use thermite in the field, rather than a huge welder. Hopefully it makes sense that the larger the area to be welded at one time the higher current is required.
This is also why spot welding can be done with smaller units, since you are only welding a spot.
Flat brass would be easier than a wire for a "bonding wire" just for the mechanics of the spot welding tip balancing on the wire.
But to the recently raised question, you need to take expansion and contraction into account. brass joiners that can move a bit, a flat strip of brass spot welded to the rail web, wonderful, you have perfect conduction and some give for expansion/contraction.
Greg
This is also why spot welding can be done with smaller units, since you are only welding a spot.
Flat brass would be easier than a wire for a "bonding wire" just for the mechanics of the spot welding tip balancing on the wire.
But to the recently raised question, you need to take expansion and contraction into account. brass joiners that can move a bit, a flat strip of brass spot welded to the rail web, wonderful, you have perfect conduction and some give for expansion/contraction.
Greg
My question starting this thread has now prompted me to further investigate (at least theoretically). It's been a long time since I've applied my BSc.E in Metallurgy!
The the type of brass used to make G-gauge rail which I suspect to be alpha single phase material (because of its good cold forming properties and ubiquity), UNS C27000 series or C28000 series, also show good welding performance by spot welding. c28000 - AZoM Search
Copper is most definitely compatible with alpha brasses which are copper - zinc alloys. The alpha phase of the Cu - Zn phase diagram extends from 100% (pure) Cu to around Cu - 35 wt% Zn. So, it's certainly possible to weld Cu to brass.
OFHC (Oxygen Free High Conductivity) Copper, UNS C10100 series, which is used to fabricate electrical conductors (wire) apparently does not perform well with spot welding although it can be welded by other means. Oxygen Free Copper – UNS C10100. My conjecture is that the excellent thermal conductivity of pure Cu is why it is not particularly suitable for spot welding. The heat just dissipates too quickly for a spot welder to develop a good "nugget" with pure copper.
However, with the correct brass wire suitably flattened on the ends as a jumper, it is quite possible to spot weld wire to brass rail . Just look at the brass straps that conduct between the rails on the bottom of LGB turnouts. They are spot welded! Again, having now given up on copper, I wonder if one of these battery powered spot welders can put out enough current density to weld a brass wire jumper between rail sections?
Maybe one of you battery powered types will volunteer to try it out should you purchase one of these inexpensive little welders. Clearly the welders work pretty good at fabricating battery packs. Certainly better and safer than soldering if you want to make a pack for your locos.
To answer David's query, Nickel-Silver which is actually a Cu based alloy typically containing roughly 20 wt% Ni and 20 wt% Zn cannot be welded to stainless steel, which is an Iron based alloy. But, it may be possible to braze the two materials with right filler material. You would destroy the tie strip trying to do it though!
The the type of brass used to make G-gauge rail which I suspect to be alpha single phase material (because of its good cold forming properties and ubiquity), UNS C27000 series or C28000 series, also show good welding performance by spot welding. c28000 - AZoM Search
Copper is most definitely compatible with alpha brasses which are copper - zinc alloys. The alpha phase of the Cu - Zn phase diagram extends from 100% (pure) Cu to around Cu - 35 wt% Zn. So, it's certainly possible to weld Cu to brass.
OFHC (Oxygen Free High Conductivity) Copper, UNS C10100 series, which is used to fabricate electrical conductors (wire) apparently does not perform well with spot welding although it can be welded by other means. Oxygen Free Copper – UNS C10100. My conjecture is that the excellent thermal conductivity of pure Cu is why it is not particularly suitable for spot welding. The heat just dissipates too quickly for a spot welder to develop a good "nugget" with pure copper.
However, with the correct brass wire suitably flattened on the ends as a jumper, it is quite possible to spot weld wire to brass rail . Just look at the brass straps that conduct between the rails on the bottom of LGB turnouts. They are spot welded! Again, having now given up on copper, I wonder if one of these battery powered spot welders can put out enough current density to weld a brass wire jumper between rail sections?
Maybe one of you battery powered types will volunteer to try it out should you purchase one of these inexpensive little welders. Clearly the welders work pretty good at fabricating battery packs. Certainly better and safer than soldering if you want to make a pack for your locos.
To answer David's query, Nickel-Silver which is actually a Cu based alloy typically containing roughly 20 wt% Ni and 20 wt% Zn cannot be welded to stainless steel, which is an Iron based alloy. But, it may be possible to braze the two materials with right filler material. You would destroy the tie strip trying to do it though!
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Greg Elmassian
Guest
I do have a question, I always understood that traditional welding required compatible, in fact very similar materials. But is this true of spot welding, or at least to the same degree?
Brazing is soldering with brass in my understanding, although there must be some brazing for non brass metals I would think, with suitable flux.
Greg
Brazing is soldering with brass in my understanding, although there must be some brazing for non brass metals I would think, with suitable flux.
Greg
Spot welding can join any two metals that will form an alloy. The high current flowing through the relatively high resistance of the interface between the two pieces being joined causes local melting that forms the "nugget" joining the pieces when it solidifies.
Brazing is a joining process that relies on the diffusion of atoms in a liquid filler alloy into the solid atomic surface layers and vice versa of the two materials being joined. The filler material which is often copper or silver based actually "alloys" with atoms in the surface layers of the two metals being joined. The filler material needs to be able to alloy with both metals. Thus, it can join two types of metals that are otherwise incompatible by being an alloy "bridge" per se between the two dissimilar metals.
Soldering is a surface wetting process that creates a mechanical joint.
Brazing is a joining process that relies on the diffusion of atoms in a liquid filler alloy into the solid atomic surface layers and vice versa of the two materials being joined. The filler material which is often copper or silver based actually "alloys" with atoms in the surface layers of the two metals being joined. The filler material needs to be able to alloy with both metals. Thus, it can join two types of metals that are otherwise incompatible by being an alloy "bridge" per se between the two dissimilar metals.
Soldering is a surface wetting process that creates a mechanical joint.
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Micheal - can we persuade you to try again with a piece of flattened brass wire? But, unlike the technique used to attach wires/bus strips to batteries shown in the video I think one electrode needs to be solidly connected to the rail near the weld location. The other pushes the wire against the rail at the intended point of attachment. This is essentially how we spotweld Pt leads used to monitor crack progression in miniature fracture toughness test specimens. A heavy Cu ground cable is clamped on the specimen. A jig holds the Pt wires in position. The welder's other Cu electrode pushes the Pt wire against the specimen and triggers a current pulse that welds the wire to the steel test specimen.