welding cable reels

[Hooked_on_HP]

I am trying to come up with some ideas on building some reels for holding the welding cables on my service truck. I have about 100ft of pos. cable and 50ft of neg.Is there any way to figure out how big they need to be. I have looked at some of the professionaly built ones.but most of them are bigger and fancier than I need.
Bill

 

[alltoys]

Take measurements of fabricated ones then make your own. Also you should have the same length of cable for negative and positive cables for your machine. Unequal lengths of cable will cause stress on your welding machine.

 

[jenkinsph]

Bill,

I would hand coil the leads into the size you want and then size the bundle to determine what you need. Avoid tight bends and twisting the wire too much, that stuff is expensive now.


Steve

 

[jenkinsph]

Also you should have the same length of cable for negative and positive cables for your machine. Unequal lengths of cable will cause stress on your welding machine.

Could you explain this further?



Steve

 

[Willl]

"Unequal lengths"

Ya, never heard of that one, got any more info ?

 

[Spudland_Dave]

Take measurements of fabricated ones then make your own. Also you should have the same length of cable for negative and positive cables for your machine. Unequal lengths of cable will cause stress on your welding machine.

Dunno about that one...my brand new Miller came with "unequal length" cables...my Stinger is longer then the ground...

 

[BrentD]

From an electrical standpoint I can't see how unequal lengths would stress a welder. Yes, all wire has an inherent per-foot resistance and the longer the cables, the more power your welder has to be able to produce to get the same current at the weld. Thing is, once the arc is struck, the current is traveling down one wire and up the other making a complete circuit. I can totally understand how making the total length too long might stress the welder and heat up the cables, but I've only seen equal paths have an effect when operating at really high frequencies on things like a computers primary data bus. That's why sometimes you'll see circuit traces zigzag in apparent wasted space because they have to make the length of the trace from one side of a chip equal to the length from the other side to make sure the resistance is mostly identical across all data lines.

No idea how that would come into play in a welder.

 

[Skyco]

Unequal lengths won't matter at all. IOW 100 ft in source and 50 ft in ground would be the same as 75 ft in each. Quite a few welders are supplied with a longer source lead than ground.
Now I might be a little concerned about coiling that much wire up, as you've created an inductor (choke), and that can affect things. I'd go with as large a coil as practical, smaller with more turns will create more inductance.
I've read of people being unable to start a motor with a coiled long cord in line where the same cord layed out will start the motor fine. Total resistance is the same in either case but the inductance changes a lot. An inductor resists sudden changes in current. An old radiomans trick is to power a base station through a long tightly coiled extension cord, it suppresses lightning induced surges. Sometimes even coax cable was coiled tightly right before the equipment to suppress lightning currents on the shield.

BTW in high speed circuits the total length is important not necessarily for resistance but propagation delay. Some large mainframe computers I worked on in the late 70's had specific length cables for this reason. A signal had to arrive at the right time, not too early (short cable) or too late (long cable).

 

[BrentD]

BTW in high speed circuits the total length is important not necessarily for resistance but propagation delay. Some large mainframe computers I worked on in the late 70's had specific length cables for this reason. A signal had to arrive at the right time, not too early (short cable) or too late (long cable).

I have no idea why I wrote resistance in my previous post. I know at the time I was writing it I was trying to figure out a way to explain propagation delay in a way that would make sense to somebody that was still under the impression that electricity moves near the speed of light through a conductor and is therefore instantaneous. I guess I thought saying it was to make sure that all the data bits arrive at the connection at the same time would sound completely made up. I remember how amazed I was the first time I read about a time-domain reflectometer. (Isn't that a fun phrase to say? Spectrum Chromatograph is antoher fun phrase. )

 

[jenkinsph]

I don't think my Miller is smart enough to know the difference.


My only concern is total combined length of the leads and their wire guage.


Steve

 

[alltoys]

30 years of welding has taught me that unequal lengths of cable does make a difference. I have also learned to unroll the full length of cable off the reels no matter how close you are to the project.

There is a difference in arc characteristics between a short ground cable and equal length. One of my first winter jobs using a portable in the oil patch I used unequal length cables and had 2 break downs with my machine. When my welder mechanic asked me what I was doing to have such problems with my welder. I showed him. Soon as I used his equal length cables there was no more problems. There is a higher load on the machine with unequal length cables.

For those of you who are weekend welders you probably wouldn't notice the difference.

 

[Willl]

For those of you who are weekend welders you probably wouldn't notice the difference.

Ya, that must what it is.

 

[Scotty370]

Easy ...Willl....!!! That's what I'm blaming all my bad welds on from now on! Maybe if I took a couple vacation days, and welded during the week........Hmmm........

 

[jenkinsph]

It seems that most of the companies such as Lincoln and Miller provide accessory kits with unequal length cables from my research this morning.

I am looking for facts about this issue of unequal length cables and prefer to be open minded. Having been a broadcast engineer for many years I feel that I hae a basic understanding of electricity. This unequal length theory is in conflict with my understanding of electrical properties. Would like to know how the unequal length cables load down the machine more than equal length cables do.


Might be a good test for Myth Busters.

FWIW, I have equal length cables.



Steve

 

[tommu56]

I've never seen a problem with unequal length's.
I worked in a fab shop after high school and they used the building frame as ground and a shepherds crook off the steel to ground piece with 100 - 150 foot of lead wire to welder and the ran the best welds with that set up
they were ac motor/ dc gen welders from Lincoln.

on the reel thing remember you are making a electromagnet in dc and a transformer in ac that could produce some unwanted results.

again in the fab shop we had old car rims mounted near welder and the unused wire was put on in a figure 8 or looped off one side back same side to the other side with the excess left on rim while the were welding. This helped with the kinking and twist problems too.

tom

 

[BrentD]

You know... I just thought of one possible, albeit indirect, way using unequal cable lengths could cause problems.... If you happen to leave part of the longer cable coiled up you'll make an inductor / choke and at high currents, you can create reverse voltage spikes into the welder as the magnetic field collapses in the coil.

 

[Hooked_on_HP]

Well, with all these posts I would have thought some one would have had some thoughts on making some reels. BTW they are putting a new water tower up on my way to work so I stopped to ask the welders about the different length cables. They thought it was funny.
Bill

 

[JoelD]

One thing I can definately attest to is that you definately do not want to weld with coiled leads. I fried my rectifier in my bluestar. I purchased my machine, amazing ebay deal by the way, 70 hours on the machine, and about 400 foot of 0 cable. Each length is about 50 foot. I was welding with the cable coiled up as I typically weld near the machine. Well after probably 5 or so hours of intermittent welding my machine would rev up, then stumble to it's knees then rev up and stumble, it was a violent act. Anyway after much volt meter testing I diagnosed with the help of the miller tech on the phone that the rectifier had fried. His first question was, do you unwind the leads and I said no, and he said, there you go.

I replaced rectifier (tech had one at his desk and actually mailed to me, amazing customer service, even if he hadn't mailed he spent many hours on the phone with me over a number of days). New rectifier and problem gone, I've used machine for two years since without a hitch (104 hours as of today).

The wound cable made huge resistance, huge magnet actually and fried the rectifier.

This note reminds me, I should make up shorter leads as I never need that much length.

Joel

 

[sandman2234]

If different lengths of cables matters, what happens when you hook the ground to a steel building halfway around the block from where your actually welding (and hundreds of yards nearer to the machine)? I can't see the machine knowing where the copper ground starts and the steel building starts, so I have my doubts about the validity of this myth/truth.
David from jax

 

[BrentD]

On the original topic of cable reels, I really like the mechanism they use to wind wire off the big rotating rack at the local Lowes. The "spool" is made of a bunch of flat stock with joints so it can bend kind of like one of those Hoberman Sphere toys. The "spool" part expands and the flat fingers form the outer rim of the spool and hold the wire on. When you're ready to take them off, the flat finger all bend toward the center of the spool and the spool's diameter colapses so the entire coil of wire slides right off the side. Don't know how practical that would be for your setup, but it would definitely make for a fast unroll.