Sheet support for a plasma machine?

[Davek0974]

What is the recommended method of supporting the metal to be cut?

would small angle be any good if fitted with the v-point upwards or is strip on edge better?

this is is a small table about 600x600

[EddyCurrent]

I'm no expert on these but from what I can see most use strip on edge.

[m_c]

What Eddy said.
Usual setup for plasma, is strip on edge, that sits in slots in a bar going at 90degrees. That way once the strips get too cut up, it's just a case of lifting them out, and putting in new ones.
Some are set up so the slots are wavy, that way they're held under tension so they're less likely to move, plus it means you're far less likely to end up with a long cut following a support/strip.

[Davek0974]

Hmm, was only thinking angle as I have a fair bit.

also, is the support area earthed to the chassis of the machine and do you connect the plasma ground to the support strips or direct to the metal being cut?

[m_c]

You can use angle if you want, but remember it's sacrificial so you want it to be relatively easy to replace.

I'm sure they're generally attached to the frame, as there should be enough contact. I know when I use my plasma, I can get away with working on top of a sheet of metal with the clamp attached, and don't have any issues.

[Davek0974]

I know when I use my plasma, I can get away with working on top of a sheet of metal with the clamp attached, and don't have any issues.

Could you clarify that a bit, are you saying your table is a sheet of metal that is connected to plasma ground or something else?

one of my reasons for angle would be that they are self supporting so I would only need a few for small work and can be moved about easily, will look into strips too.

[Robin Hewitt]

Interesting question the positioning of slats...

If you have a small piece of metal to cut then you need the slats closer together.

If you have a large piece to cut then the slats can be further apart.

However, you might decide that all small pieces are to be placed at one end/corner of the table and that is the only part requiring close slats.

If you go for big spacing and big sheets remember to cut all inlines before cutting outlines. It might move.

If you think you will do lots of small stuff with rare forays into big stuff, you might even consider a small water table at one end of a large table.

The possibilities are endless but rarely explored.

[Davek0974]

Great, I'm aiming for a down draught table as I really don't like water in the shop ;)

and the the ground lead - ground the slats or to the workpiece??

[Robin Hewitt]

Great, I'm aiming for a down draught table as I really don't like water in the shop ;)

and the the ground lead - ground the slats or to the workpiece??

Down draught is not without complications. Try drawing it remembering that you have to support the slats so they can support the sheet, parts will try and disappear if you give them any hiding place, the sparks have compressed air behind them and are about as obedient and obliging as a pyroclastic flow.

Why do you want to decide where to connect the plasma ground now? There is a big difference between a nice new shiny plate and that old lump of iron you found in the back of Granny's shed. :rugby:

[Davek0974]

Why do you want to decide where to connect the plasma ground now? There is a big difference between a nice new shiny plate and that old lump of iron you found in the back of Granny's shed. :rugby:

The point was, do you connect it to the work or to the slat-bed?

Or both?

[m_c]

Could you clarify that a bit, are you saying your table is a sheet of metal that is connected to plasma ground or something else?

I only use my plasma manually, but have at times just clamped the earth to whatever sheet I've just cut the end of, then recut bits on top of that sheet. I've never had any issues with it not starting, but then mine has a high frequency/pilot arc start, so may be more tolerant of a less than ideal ground.

[m_c]

The point was, do you connect it to the work or to the slat-bed?

Or both?
Generally the bed, as you don't any leads/clamps in the way of what you're cutting.
Personally, I'd earth to the bed, and then use a jump lead from bed to metal if there were any grounding issues.