Another Newbie

**Web Goblin** · 24-04-2012

Chris,
If you go for laser cutting you would need someone with an anti reflection/ polarising kit fitted to their laser. Materials like copper, brass and aluminium can cause problems with lasers, especially older types like the one we have at work. Are all of the broaches different designs? If so getting them laser cut would prove expensive I think given the continual changing of programs.
As for plasma cutting some of the smaller hand held machines are air cooled torches so no water cooling required. The big problem with plasma is the fumes it creates when cutting. You will need an extraction and filtration system for a plasma cutter. Also the kerf size on plasma might be an issue for you. Even at a low current cut you would probably still have a kerf value of around 3mm to 4mm and this might be too wide for the slots in your designs.

Ian

**Chris J** · 24-04-2012

Originally Posted by Web Goblin

Chris,
If you go for laser cutting you would need someone with an anti reflection/ polarising kit fitted to their laser. Materials like copper, brass and aluminium can cause problems with lasers, especially older types like the one we have at work. Are all of the broaches different designs? If so getting them laser cut would prove expensive I think given the continual changing of programs.
As for plasma cutting some of the smaller hand held machines are air cooled torches so no water cooling required. The big problem with plasma is the fumes it creates when cutting. You will need an extraction and filtration system for a plasma cutter. Also the kerf size on plasma might be an issue for you. Even at a low current cut you would probably still have a kerf value of around 3mm to 4mm and this might be too wide for the slots in your designs.

Ian

Yes they vary as the whim takes her.
I was looking at some videos on U tube and was worried about the kerf, not such a problem as long as the edge that is left as the job is sharp and crisp but they sometimes have slots in (as per my bad photo) and that would need a narrow precision cut.

I do have a fairly good extractor in the workshop so I guess that could be adapted for plasma.

I'm begining to think that a high speed router might be the way to go.

Thanks

**m_c** · 24-04-2012

There are precision nozzles available for the better brands of plasma cutters, however it all depends on how much you want to spend.
Hypertherm is one of the top end brands that I can think of right now that I think does them.

**Chris J** · 24-04-2012

Originally Posted by m_c

There are precision nozzles available for the better brands of plasma cutters, however it all depends on how much you want to spend.
Hypertherm is one of the top end brands that I can think of right now that I think does them.

The minute someone says it depends on how much you want to spend my blood chills a bit

I guess I was hoping to spend £1k maybe a bit more, not including a pc, so not a huge budget.

**m_c** · 25-04-2012

Originally Posted by Chris J

The minute someone says it depends on how much you want to spend my blood chills a bit

I think it has that effect on most people!
If only I could match those 6 numbers...

I guess I was hoping to spend £1k maybe a bit more, not including a pc, so not a huge budget.

As Ian's highlighted HiDef plasma is out of the budget.
I know normal plasma has a cut width of 2-3mm, and would be fine for doing the main outline cutting, so it may be worth considering a router/plasma hybrid. The two processes do have opposing requirements for cnc, but given your requirements, and with some careful design, should be doable.
Under typical use, a plasma table requires lots of speed with little torque and not very tight tolerances (when you've got something cutting +-0.5mm/trailing behind the torch position, tolerances/backlash requirements aren't that high), whereas a router table needs more torque with less speed but tighter tolerances.
However, given the size of cutters you need, torque won't have to be much for the router, and with the reasonable price of ballscrews, a good compromise of torque, speed, and tolerances should be doable, and combined with a lower power plasma cutter you shouldn't need crazy high cutting speeds.

**Jonathan** · 25-04-2012

I think you'd be best to design a CNC router than can incorporate a plasma cutter, but don't get the plasma cutter until you've tried cutting with the CNC router. I'm fairly confident that with plenty of coolant you'll be able to cut the copper without problems. When I cut that part from 5mm copper the part got exceptionally hot, but with flood coolant that wont be a problem.

**Chris J** · 25-04-2012

Ah coolant, I hadn't thought of that.

I guess that means I could't have any board involved.
I had thought I might clamp the working sheet to a sacrificial piece of board.

Mmmm, there is always something

**JAZZCNC** · 25-04-2012

Originally Posted by Chris J

Ah coolant, I hadn't thought of that.

I guess that means I could't have any board involved.
I had thought I might clamp the working sheet to a sacrificial piece of board.

Mmmm, there is always something

Not a problem just use plastic sacrifical board, hdpe is what I use very flat and stable? . . .BUT a far bigger problem you will have with small items like this is the actual clamping and holding.? Unless they have holes for screwing or clamping thru then it's a night mare holding small items for profiling.!
The thinner the material the worse the problem, I often spend more time making holding fixtures, jigs or repositioning clamps etc than the actual parts take to machine. IE: Recently machined some small Brass items and the total Job time was 30 minutes per 4 buckles the machining time was 17mins the rest was made up having to swap clamp positions without disturbing position and 1 tool change(2mins max).