hans109h
Well-known member
What tool can I use to flatten 4 AWG solid copper from a round wire to a flat strip? I'm imagining some sort of roller press. I would need to do about 50 continuous feet.
Thoughts?
Hans
Thoughts?
Hans
What tool do I need?
- Thread starter hans109h
- Start date
rlitman
Well-known member
A rolling mill. But be aware that the results will not be what you expect.
Electrical wire is half hard, and copper rolls better when annealed.
Also, the rollers will expand the wire more along its length than its width. Particularly when it is not annealed. So you will end up with a flat ribbon that's no longer then same cross sectional area as a 4 AWG wire. i.e. if you start with 50 feet of wire, you may end up with 200' of ribbon.
Electrical wire is half hard, and copper rolls better when annealed.
Also, the rollers will expand the wire more along its length than its width. Particularly when it is not annealed. So you will end up with a flat ribbon that's no longer then same cross sectional area as a 4 AWG wire. i.e. if you start with 50 feet of wire, you may end up with 200' of ribbon.
Due to the skin effect you can move electrons faster over larger surface areas, so a flattened wire is better for lightning suppression and grounding than a round wire. I have round wire to use, and therefore can save money on buying copper strip or flashing, so am considering if it's worth my labor.
Seems I would need something like this:
https://durston.com/wp-content/uploads/2018/05/Durstons-DRM-C150RE-Rolling-Mill-pic1-1031-510x612.jpg
https://durston.com/wp-content/uploads/2018/05/Durstons-DRM-C150RE-Rolling-Mill-pic1-1031-510x612.jpg
rlitman
Well-known member
That is a rolling mill, and it will flatten your wire, but again, by reducing the cross sectional area as it lengthens it, you'll end up with wire that's useless for lightning protection.
Just buy the right wire. Aluminum isn't that expensive.
Just buy the right wire. Aluminum isn't that expensive.
So lets take 24.5 mm of 4 awg solid copper wire. The diameter of the wire is ~5.2 mm, for a surface area of ~415 square excluding the ends. Using my 20 ton press I was able to flatten the same amount of wire to 1.4 mm with a width of 11 mm. The same length of copper would be 608 square mm for a 32% gain in surface area. Ideally using the right tool I could get the thickness down closer to .3 mm and have an even wider ribbon. Since surface area is the only real factor at play, this is better than just installing the 4 awg as round wire. The conductivity of copper is by far the most practical choice, and since the other portions of the grounding system are copper it is the only choice for my situation.
Can anyone provide details on what width I might expect at .3 mm thick?
Thanks,
Hans
Can anyone provide details on what width I might expect at .3 mm thick?
Thanks,
Hans
sberry
Banned
This is installed 1000's of times the way it is. How much difference do we think this will make? We gonna outhnk the rest of the world cause we are more "special" than other folks?
I first wanted to figure out what I could do with 4 awg and then work through the formula: https://en.wikipedia.org/wiki/Skin_effect#Formula Then at least I'll know if it is worth it.
Commercial operations use 2 - 10 inch copper strap for this purpose, so yes it is worth it when you are protecting very expensive equipment, while my equipment is expensive to my budget, not quite enough for 10" copper strap.
Commercial operations use 2 - 10 inch copper strap for this purpose, so yes it is worth it when you are protecting very expensive equipment, while my equipment is expensive to my budget, not quite enough for 10" copper strap.
rlitman
Well-known member
LMAO. So what's the frequency of lightning? And how do you plan to apply that formula to a non-round conductor?
You're barking up the wrong tree.
racingtadpole
Well-known member
Whats the application? 50’ of 11mm wide 1.4mm thick flat strap will just turn into more metal to vaporise in most lightning contact events. I have a significant amount of experience building lightning suppression in an RF environment, if you can reveal the application I may be able provide ideas that are more robust.
Ground of a single point ground system for a ham shack. It's not so much a direct strike I'm concerned about.
Regardless, there is good information to be had in understanding working with metal and understanding it's principles, so if you don't like barking, then don't read the posts.
Regardless, there is good information to be had in understanding working with metal and understanding it's principles, so if you don't like barking, then don't read the posts.
readhead
Well-known member
Buy a roller and flatten it. Be prepared for the copper to work harden and become brittle. If you are dead set on skin effect, buy welding cable. With it’s many strands it is designed to handle high current.
Slow your roll there sport. We are just trying to understand what you are doing and the best solution to your question.
Slow your roll there sport. We are just trying to understand what you are doing and the best solution to your question.
I was wondering what was going on in this thread. sberry explained it so I understand it now.
racingtadpole
Well-known member
Is this for lighting suppression or is it one side of a direct to earth radiator?
Yes, for my buss bars and grounding in the shack I'm going to use copper pipe, whole.
The path to ground requires even less inductance. I'll probably end up using 16 mil copper flashing as I can get a 6" x 10' roll for $35. If I slice it into 2 inch strips and weld it together I'll have the length I need and it will be a much lower inductance and therefore the path of least resistance for stray energy.
This post was never intended to be about my actually application, but while planning I wanted to consider milling 4 AWG copper wire into a flat sheet.
My only question was what is the best tool for this, and it appears this was answered right away; a rolling mill.
Rlitman was good to point out that such a mill will lengthen more than widen. This lead me to wonder if there is a way to calculate what width is typically achieved at a given thickness. Such information would still be helpful.
Also I wonder if a tool like a treadle hammer would be more effective at widening than lengthening. It would make a good experiment, but if someone else has already done it, please share.
Thank you everyone for your thoughts.
Hans
The path to ground requires even less inductance. I'll probably end up using 16 mil copper flashing as I can get a 6" x 10' roll for $35. If I slice it into 2 inch strips and weld it together I'll have the length I need and it will be a much lower inductance and therefore the path of least resistance for stray energy.
This post was never intended to be about my actually application, but while planning I wanted to consider milling 4 AWG copper wire into a flat sheet.
My only question was what is the best tool for this, and it appears this was answered right away; a rolling mill.
Rlitman was good to point out that such a mill will lengthen more than widen. This lead me to wonder if there is a way to calculate what width is typically achieved at a given thickness. Such information would still be helpful.
Also I wonder if a tool like a treadle hammer would be more effective at widening than lengthening. It would make a good experiment, but if someone else has already done it, please share.
Thank you everyone for your thoughts.
Hans
They do sell those flat grounding wires that is not exact a litz wire....
I have a roll of it with holes about every 2" or 3" not sure where I got it from... oh well... just search for "BRAIDED GROUND STRAP" maybe ?
bradpac
Well-known member
https://www.gacopper.com/022-CopperStrap.html
You can buy 50ft of what you want cheaper than a rolling mill.
You can buy 50ft of what you want cheaper than a rolling mill.
samss
Well-known member
Would a roll of soft copper tubing work? 3/8 od maybe? It would be easy to flatten.
Of course, but that takes all the fun out of getting a new tool!
The copper flashing offered locally is similarly priced, and no shipping.And the soft utility tubing certainly would be easier to mill, you can almost flatten some of that stuff by pinching between your fingers (or at least a small vise). The same question would be how flat/wide can you get it. With that soft tube, I'd probably try to split a seam in it and flatten it out, then run it through a rolling mill.
copper pipes turns green outside after a while Not sure about the resistances of it would change.. if you are using that I wouldn't flatten it if it just fits though...
that way you get 2x the surface area the outside dia, and the inside dia of the pipe.... if that is your concern.. once it's flatten, you only get that OD surface area. No ?
rlitman
Well-known member
He's worried about impedance, not resistance. It's a subtle difference, but it is different.
Lightning protection vertical leads are frequently insulated (for safety purposes), so any green on the surface isn't going to matter. At least, so long as it isn't interfering with the connections.
As for flattening copper pipe, that's a waste of time/effort. Zero electricity will flow on the interior surface, and the cross sectional circumference of the circle will remain the same after flattening.
not really a waste, it may not help the conductivity, but it's easier to work with flat, and if it's outside less chance of bugs and **** filling it up. of course you could always just flatten the ends where it gets connected and in spots where it is bolted to something...just depends on what he plans to do with it. I made some nice antenna mounts out of flattened pipe, but I also have J-poles made from pipe left round except for the ends.
btw, it takes a looooong time to turn green. years in fact. you can rub hard boiled egg yolk on copper to speed it up but that patina is hard to get when you want it.
steaks&anvils
Well-known member
Hans,
I do silversmithing (jewelry), I have two roller mills (both Durstan). I have that exact one (in your link) and another one that makes the first one look small. I have some experience in using roller mills.
Here is what is going to happen if you try this:
You will spend $1200 (or more) and be frustrated.
You will need at least three people (maybe four). One to turn the handle, one to feed the wire (to keep it feeding straight), one to guide the flattened copper out the other side . And maybe one to feed the copper to the guy feeding the wire into the mill, to keep it from getting tangled.
The wire will get longer not wider.
It will not stay straight, it will get all wavy (side to side wavey).
It will work harden and crack.
You won't be able to coil the flattened wire, it will be too hard for that.
depending on thickness and amount you want to reduce, you will not be able to flatten it in one pass through the mill. BUT for the second pass it will be work hardened and then it will crack.
Save yourself a lot of trouble and frustration. Just buy the right kind of manufactured wire. Can't you call and talk to a company rep for a company that makes lightning rods? or there has to be companies that design and install these things?
Just my thoughts on it (since you asked).
-jeff
I do silversmithing (jewelry), I have two roller mills (both Durstan). I have that exact one (in your link) and another one that makes the first one look small. I have some experience in using roller mills.
Here is what is going to happen if you try this:
You will spend $1200 (or more) and be frustrated.
You will need at least three people (maybe four). One to turn the handle, one to feed the wire (to keep it feeding straight), one to guide the flattened copper out the other side . And maybe one to feed the copper to the guy feeding the wire into the mill, to keep it from getting tangled.
The wire will get longer not wider.
It will not stay straight, it will get all wavy (side to side wavey).
It will work harden and crack.
You won't be able to coil the flattened wire, it will be too hard for that.
depending on thickness and amount you want to reduce, you will not be able to flatten it in one pass through the mill. BUT for the second pass it will be work hardened and then it will crack.
Save yourself a lot of trouble and frustration. Just buy the right kind of manufactured wire. Can't you call and talk to a company rep for a company that makes lightning rods? or there has to be companies that design and install these things?
Just my thoughts on it (since you asked).
-jeff
sberry
Banned
Glad you approve. I am always curious when simple stuff that works for me and thousands or even millions doesn't seem adequate for others. I wonder why they need a pipe 3x bigger or wire 2 times larger or how someone always skins a knuckle when using a cman wrench when I can't ever remember breaking one despite hitting them with a 4 pounder.
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sberry
Banned
Nothing fundamentally wrong with trying this, I am usually just curious and don't always word it well. I saw an array on top of a building recently and as I recall it was done with braided cable.
engineer2
Well-known member
We were taught in engineering skool that lightning is fairly high frequency and thus does not conduct around corners too well due to electrical reactance. In other words, it may not necessarily follow a metal conductor around a bend if it can find an easier path to ground. We were told it's best to have lightning protection conductors as straight a possible into the ground.
I believe NFPA 780 “Standard for the Installation of Lightning Protection Systems” might be worth a read.
I believe NFPA 780 “Standard for the Installation of Lightning Protection Systems” might be worth a read.
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