Brass cutting

[drew.h]

I was scratching my head as to which forum to ask this in and thought I'd get the best advice in here.

I have a sheet of brass 200mm x 200mm x 1.2mm and I need to cut two rings from it. The first with an outer diameter of 200mm and inner of 160mm, second with an outside of 60mm and inside of 20mm. The thing is I need to keep this as flat and smooth as possible, so don't think tin snips would be a good idea. I also need it to be as perfect as possible and don't think my sawing skills would be up to the job.

Can anyone recommend a method? I don't mind spending a few quid on tools, but they would need to be reasonably cheap (CNC machine is out of the question).

[Gareth350]

Have you got an engineering firm nearby that could cut it for you? May be worth paying to have it done for a good finsh.

[Odie]

Best way would be to get someone to run it up on a lathe for you.

Or http://www.ostartools.com/products/holesaws/hsssaw...

The do it yourself alternative would be to drill a centre hole and use a piece of wood from the centre with something sharp to score it to the point where you can snap it apart with a pair of pliers. This of course is going to take a while.

[dilbert]

You need a trepanning bar.

[drew.h]

No, it went bust last year. This is a prototype and I'd like to be able to do the bits myself. The trouble I've found with engineering companies is they don't like small jobs and tend not to look after your material.

We've use an engraver for similar work before, but his work is starting to get sloppy. I've got a tool for cutting disks out of wood, mainly used for speaker holes, I was thinking it might work. I didn't want to wreck my brass so thought I'd ask around for suggestions before trying it.

[dilbert]

If it will cut wood, it will probably cut brass without difficulty.

The softest wood working tools will be carbon steel. Carbon steel will be fine on brass, just don't "attack" it too much.

[drew.h]

dilbert said:

You need a trepanning bar.

I think that's basically what I've got, but its a cheap pound shop one. It works well on wood and fibreglass. I have a lath, but unfortunately its to small even for this prototype and the final version will be about 50% bigger.

[drew.h]

Thanks, I'll give it a go.