Hi Jackie,

If you didn't mind getting a bit dirty and spending a lot of time on the cut, you could try using a Dremel / flexshaft with a Mizzy wheel, or some other type of heatless grinding wheel. The grinding wheels allow for curves while the cutting disks usually tend to be used for straight lines as you mentioned above. I've used the heatless grinding bits in a number of shapes and sizes and I think they could be good for shaping curves. Perhaps you could use a sawframe to get a rough cut (to save time and grinding bits), and then use the wheels to grind it to the shape you want? The wheels alone would probably work, it would just take a bit longer and get a bit dusty.

I've experienced hand issues, so I can understand how frustrating things can be when you want to do something and the straight-forward ways won't work.

Good luck.

Christine Woollacott

Thanks very much Christine, I will certainly look into this.  I read a post on a forum just now that said DO NOT try to use Dremel cutting disks for anything other than straight lines, and also beware of using any kind of revolving gadget on metal because of the bits that will fly off and are very dangerous.  They said I should use aviation tin snips. and then finish off with wheels to sort out the edge.  This might work if I soften the copper before enamelling, I will have to try all sorts, clearly.  I shall now go and look up flexi shaft and mizzy wheels!  Jackie

Hi Jackie,

I must admit I'm not very familiar with a dremel - I primarily use a flex-shaft for grinding / hand-polishing. The good thing about a flex shaft is that the speed is controlled by a foot pedal so you can go as slowly or quickly as you feel is comfortable and safe. Jewelers frequently use flex-shafts for the rotary sanding and polishing of rings and other jewellery objects. I think the speed control allows for greater precision and safety when using a rotary tool. As always, when using something like that you should take care to protect your eyes. The friction of grinding will cause the metal to heat up as well, but the speed that this happens will depend on how quickly you decide to grind. I'd definitely recommend using a dust mask with the small grinding wheels, because you're going to generate a ton of dust from metal and the the wearing down of the rubber abrasive grinding wheel.

My main advice is not to do anything you feel uncomfortable with, or anything you feel is unsafe. I have been trained as a metalsmith, so I feel comfortable using a flex-shaft, however they can be quite dangerous if you don't take precautions. I've heard many a horror story of people with long hair getting it caught and ending up in the hospital (Eeek! tie long hair back!).

Snips or shears will probably deform the bowl a bit when you cut - but if you anneal the metal it will probably be easier to work with, and easier to bend back into place when you're done.

I hope this helps.

Christine

I rather envy you your training as a metalsmith.  I have done a little bit of fold forming, just a day class, it was enjoyable.  I made a copper flower and leaves, amazing to me.  I did speak to a Dremel expert yesterday;  he felt that none of their accessories would be quite right for curved cuts, one could do loads of straight cuts but it would take ages and he said I would definitely be better off with snips and then using the Dremel to finish off edges.  I shall look at the flexishaft...sounds a good idea for grinding enamel off the edges of bowls and finishing edges too, and will anneal a bare bowl and see if I can cut it.  So frustrated that I could not work happily with the plasma cutter - never buy cheap is the answer.  I have since watched YouTube vids where people make it look so easy!

There are some electric cutters for metal.
1) Electric shears. this are easy to handle and are suitable for straight and curved cuts.
Here 2 videos.
http://www.youtube.com/watch?v=5RhnF1SMobA&hd=1
http://www.youtube.com/watch?v=wWM5kaSuw08&hd=1

2) Electric nibber. For this apply the same criteria as under Nr. 1. But it cuts out a small strip out, so that one gets more waste.
Here a video:
http://www.youtube.com/watch?v=R9udH1CXxpc&hd=1  
Both are unusable to cut for example a window or a hole into a sheet.

3) Electric fretsaw or scroll saw. This are more suitable for small objects. But a good saw cuts copper or silver up to about 2 mm. You must absolutely ask the supplier wether the saw is adequate for metal.

You get also a nibbler for hand-cuts. But you must have some power in your hands.

Edmund

thanks so much Edmund.  Strangely, I had a long conversation with Bosch technical guys, and asked them about their shears and nibblers. they said although you can cut curving shapes with them, they are only suitable for working on flat sheets...not on the curved surface of a small bowl.   They were not helpful and infact, put me off completely..directed me back to Dremel, who also, in their tech department, said I needed to use aviation snips!!!.I thought I had it sorted, when I discovered electric shears.

A Fretsaw or Scroll saw would presumably have the same issue...the metal surface needs to be flat.  

Unfortunately, there is also no way to see one in action here, none of the hardware stores offer that option.  It's a frustration, and these things are not cheap to buy, to experiment with.

Hello Jackie,

sorry, I don't understand your question right! To out cut parts of a finished bowl shears and nibbler are not really suitable. If you want to do such work, plasma cutter are, next the much cheaper jewelers-saw, the first choice.
If the bowls are not too big and the wall-thickness are not too thick, a micro-welding-torch with liquid gas + Oxygen or acetylene + Oxygen could work well. Certainly is the cut not so clean as with a plasma cutter, but this tool is not so expensive.
That is only such an idea! I have never tried it.

Edmund

No worries, it is not easy to explain with words!  I dont want to chop up a FINISHED bowl...just an UNenamelled copper bow.  Then, when it is cut, I will add wires and other embellishments and then I will enamel it.

I had a feeling that shears and nibblers would not work, I am glad you confirmed it.  So...it is back to a jewellery saw, I think.  

The Plasma cutter is the ideal thing, I know that, but I would have to spend too much money to get one which is good for quality, I cannot justify it.  I dont think I want to work with liquid gas and oxygen!   Scary!   It was bad enough trying to work out how to use the compressor with the Plasma cutter, and then so disappointing when it chewed up my bowl into horrible holes and melted metal, instead of cutting nice lines!  

If I cannot work with a jewelers saw, I might have to give up the whole idea.  :(

now there's a thought.  I have toyed with the idea of acquiring some etching equipmnt.  Yet another idea to add to the mix.  Being totally ignorant of what is involved I will have to do some research.  thanks for the idea.

Personally if it were me then I would take a look at electric fret saw option which someone has already mentioned, I have one and have used it many times and have a good feel for it. It does not matter if the surface is curved as long as it can be well supported yet freely rotated.

First thing is to make sure that your size and diameter of bowl give a good clearance with respect to the saw and your intended cut path. You may find that raising the workpiece height by means of a raised table (wood or similar) will get around any clearance issues, you would then be cutting using the top region of the blade.

I would have the bowl supported on its outer surface and I would be looking for some kind of very dense bean bag cushion perhaps one each side of the blade, perhaps small bags of lead shot, it would be very important that these bags cannot move around. Experiment needed there. In a sense what you want is a support that molds itself to the outside of the bowl - try without it might work fine!  This is based on my gut feeling, electric fret saws are not always "nice" to use because of the vibration and if the workpiece is metal then it can rattle on the metal table of the fretsaw - this is why my gut feeling is all about molded support and dampening it all down - more pleasant and positive action I think. Again it will likely be a more pleasant experience if the machine is bolted and properly damped on rubber supports.

Blade choice is critical, often the blade will tend to lift the workpiece on the upstroke, an annoying issue if you are working on wood but awful on copper which is a metal well known for "catching" in all machining operations. I would be looking for a fine tooth sacrificing speed but avoiding the nasty jarring of an aggressive blade - the generic blades supplied with the machine might be found lacking for copper.

thanks for taking the time, Jon.

In fact, I sent back the plasma cutter I was unable to get on with, I found a youtube video which showed that the problem was not with me, it was the machine, a far eastern rubbish one....and so got all my money back in the end.  So I invested in a better one.........and now can cut everything beautifully.  I get some lovely shapes in my bowls now.  But thanks everyone, it was an interesting journey!!

No problem and glad to hear that you have found a better plasma torch. The bowl looks very nice I can see why you like to cut in this fashion.

glad you could see the bowl, tho when I looked at it, it seemed to be out of focus.  It isn't - must be something to do with the size.  sorry about that.

I would like to chop sections out of a copper bowl as per the image attached.  I know a plasma cutter would work well, my friend cut the bowl attached, but I bought one and cannot get on with it.  I have hand problems, they shake a little sometimes. Because of this I do not want to use a hand jewellery saw either. I wondered if there is a suitable power tool to do the job - I have a Dremel and I know they have metal cutting discs, but suspect they only cut straight lines.  Any ideas gratefully received, either here, or to me direct at jackiesdesk at gmail.  thanks