plasma cutter

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  #1  
Old 12-27-04, 04:39 PM
chavella
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Wink plasma cutter v electric shears

1. Is a plasma cutter the best and neatest way to cut sheets of thin copper?
2. I have an oxy- gas set up...is there ANY way I can use it?
3. What is the cheapest I can expect to spend on a plasma cutter-used or new 4. What do I need to look for?
5. And, do I have to have a generator to supply air?
OR,
What about using electric shears? I've seen two types...one looks like shears and the other a bit like a jig saw. I need to be able to cut 3 inch circles.

Obviously I don't know much about this! I am an amateur craftsman (who also makes a living as such) and have a tendency to purchase equipment I don't end up using...hence cheap and/or used are the key words here! My present need is to cut only thin sheets of different metals.

I appreciate any suggestions. Thanks.
 

Last edited by chavella; 12-27-04 at 09:50 PM. Reason: clarification
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Old 12-27-04, 07:14 PM
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You can use several different tools to cut thin sheets of copper. Snips, shears (stomp, electric unishear, double cut shear), nibbler, slitter... Depends on what you want to accomplish, or what is laying around.

I remember seeing, at a car show, a rather unique torch that was oxy- gas, cut nicely like a plasma cutter. Do not remember the name, though. Looked kind of like a pistol.

Small 110v plasma cutters can be bought with an on-board compressor. No generator needed. Many of these machines are rated to cut 3/16 mild steel, and will sever cut (takes longer, not as nice) 1/4 inch mild steel.

Slightly larger units require either a 20 amp 110v source or 220v. Last time I looked, they required an air source.

The small unit was more than capable of cutting 24 ga galvanized steel, and had a nice duty cycle. I was looking at a Miller, but have not bought one yet...

They can be had at local welding supply places or even ebay.
 
  #3  
Old 12-28-04, 07:03 AM
chavella
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Thanks danski,
I've been looking around and wondering if electric shears might do the trick. I am curious about the cutting device you discribed (from the car show)-if any one knows what that might be.
 
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Old 12-28-04, 02:44 PM
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Check out a nibbler

You might want to visit a sheet metal shop or auto-body repair to see what they use. An air or electric nibbler would be much less bulky as well as less expensive.
 
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Old 12-28-04, 03:08 PM
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I wish I remembered the name of that cutting torch. I have never seen anything else like it. Maybe an inquiry at a more specialized welding forum would lead somewhere. Last time I saw it was at Street Machine Mationals about 10 years ago.

In any case, I suppose really small tips or even a jewelers torch set up would cut the metal for you.

Electric shears are nice, but the minimum radius spec is something to pay attention to. Unlike a nibbler, shears can distort the metal being cut. A nibbler makes a mess and they also have minimum radius specs. Many of the 16ga rated (mild steel) nibblers have a minimum radius equal to the size of the round punching die. Nibblers with a square die do not turn as well. Most nibblers I have looked at can start cutting anywhere and in any direction in the sheet through a round hole. That is much harder to do with any kind of shear without spiraling out from the start point.

Double cut shears supposedly cut distortion free, but I personally do not like them. They are usually cheaper than a unishear or a nibbler, and are best suited for straight line work or very mild curves. More expensive models may better at the curves than Milwaukee or DeWalt.

The plasma setup is limited only by your imagination, but leaves that rough edge. On copper, it also discolors the metal slightly (it may buff out, but I like that look). A traditional gas torch setup would likely do the same thing.

A really nice alternative at around $40 is the Malco Turbo Shear. It fits in an electric or cordless drill. Think powered sheet metal snips. The only drawback I have found is it leaves marks on the metal if the tool is not held up properly. It is also more cumbersome than a dedicated tool.

There are nibblers that fit an electric drill in a similar fashion.

If your main cutting task is 3 inch circles, and a lot of them, I would be looking at nibblers, torch tips or plasma. I would find it difficult to shear cut something that small. A portion of a 1.5 inch radius is different than completely cutting the circle.

Cutting 3 x 3 squares on a jump shear and trimming them out by hand with some good snips may not be that bad, unless the quantity is very high.

I think you will find it challenging to accurately cut 3 inch circles with a plasma cutter or a torch without some kind of guide to rest the tool on.

You should try and find someone with these tools and try it before you buy it....
 
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Old 12-28-04, 03:28 PM
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I guess if I was cutting 3" diameter holes in copper sheet, I would use a 3" hole saw. Nice clean cut, minimal expense.

Rick
 
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Old 12-28-04, 03:40 PM
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Depends on the desired outcome. If you want to make 3 inch circles, holesaw does no good.

If you want to make 3 inch holes in something, then ok. I have tried using holesaws in thin galvanized sheet, and it does not work unless there is a wood backer. The large diameter holesaw tears the material. A carbide tipped blade run backwards might work ok.

An adjustable circle cutter would be better as long as the material is soft and thin.
 
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Old 12-28-04, 04:07 PM
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I guess I don't understand the difference between a 3" circle and a 3" round hole.
 
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Old 12-28-04, 04:23 PM
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If someone asked me for a 3 inch copper circle, I would give them a piece of copper 3 inches in diameter.

Not the same as asking me to put a 3 inch diameter hole in a piece of copper.

I wonder which one chavella needs to do.

 
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Old 12-31-04, 05:06 AM
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If it's a round piece of sheet copper, 3" in diameter you want, by far the simplest way to cut this is with compound left or right hand cutting aviation style snips.
Draw a circle and after a few tries the cuts should be fairly decent.

Click image:
<img src="http://doityourself.com/ori/200x200/6050892.jpg">

For a more true circle I have used a hole saw to cut thin metal but have to use a backer as suggested.
 
  #11  
Old 12-31-04, 05:54 AM
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The picture in Greg's reply is of "straight" snips.

There are also "offset" snips.

I find the offset style to be easier to use, by far.

There are also several different manufacturers of snips such as Midwest (also likely made Sears brand), Wiss and Klenk (there are more).

Be sure to try whatever you can find because they all cut and feel different. I couldn't cut tight curves with a set of "straight" snips if I had to. Neither can I use the Wiss offset product... don't know why.

Midwest also has a unique style with the handles perpendicular to the cutting blades. Useful for close quarters work and a different squeezing motion.
 
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Old 12-31-04, 06:56 AM
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Thumbs up Thanks danski.............good eye!

Posted too quickly.

This compound type are actually my favorite snips.


Click picture:
<img src="http://doityourself.com/ori/200x200/6869457.jpg">
 
  #13  
Old 01-13-05, 05:50 PM
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I am curious about the cutting device you discribed (from the car show)-if any one knows what that might be.

I found it. It is called a Henrob 2000 torch.

http://www.cut-like-plasma.com/index.htm

Here is another one called a Meco:

http://www.ottofrei.com/store/produc...at=1230&page=1

An interesting metalworking site:

http://www.tinmantech.com/index.html
 

Last edited by danski0224; 01-13-05 at 06:46 PM.
  #14  
Old 01-14-05, 09:59 AM
chavella
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Welll! If I can't figure out how to cut a copper circle or hole now, there's no hope for me! Had to lol....I don't want to cut out circles...just need to be able to. I do art work and am making fish. The fins etc are sheet metal. After discovering the high cost of the plasma cutter (which I would love to have) I went to freight harbor and bought some cheap shears. I think with practice I will be able to make them do what I want. If this new project of mine works I think i'll try some nibbler cutters.
I will definitely look into the the alternative cutting that you mentioned danski... and check out the sites.
Thanks every one for your help...all good advice.

....since there are so many helpful thinkers out there I have another problem. I am spot acetylene welding pieces of 1/8 in. welding rod together (to make decorative frames). Sometimes I use brass which is good because with the lower heat I don't burn so much of the copper coating from the welding rod. But when I try to weld (using 1/16 inch rod) I have a hard time confining the heat to a small area and too much surrounding copper gets burned off. With a larger tip (202 rather than the 203 I use for brazing) I seem to be able to get in and out quicker and this seems to help a little but it is inconsistent and still to much is burning off messing up the finish...but not always so I know its possible.

if you were to take one piece of 1/8 welding rod and one piece of piece 3/32 and bend them into cirlces (3" of course...lol) and set them side by side, flat on the table and spot weld at the one place where they touch...well, this is what I am more or less doing. I need to keep the burned area to a minimum... ideally no more than 1/4 inch on each side.

Any suggestions? I am pretty sure I should be able to do this with the oxy-actelyne.
 
  #15  
Old 01-14-05, 12:19 PM
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I used silver-solder for copper.
But it will have a silver color.
stay-silv-15
about 1500 deg melting point, melts faster then brass rods.
The brazing flux your using with the brass rod should work with the silver rod for what your doing.
copper to copper may not require flux with the stay-silv-15 rod.
 
  #16  
Old 01-14-05, 01:13 PM
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The product that GWIZ is referring to is in my circles referred to as sil-phos 15.
A silver/posphorus alloy that is used for copper to copper joints only and has very good filling properties.
It doesn't require any flux and leaves a dark finish.

Silver solders normally have a silver content of 25% or better and require the use of flux.
There are silver solder rods available that have a flux coating on them or the type I prefer is just the bare wire with separately applied flux.
The most common, again in my field, is Stay-Silv 45%.
Silver solder is commonly used for copper/brass, copper/steel, brass/steel or any combination of these three.
It can also be used for some types of stainless as well as a few other alloys.
Silver solder will leave a finish from a silver to a light yellow.

Sil-Phos link.
Silver solder link.
 
  #17  
Old 02-08-05, 03:01 AM
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There is a sheet metal shop tool called a circle cutter. It has a clamping device to hold the piece of metal and an adjustable rotary shear to cut the stock. No holes are put in the metal.

They turn up on eBay once in a while, and places that sell used sheet metal machinery sometimes have one.
 
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