Plasma table 2m x 1m

[Robin Hewitt]

Making a plasma cutter table. Bit skeletal at the moment but slowly coming together.

1 MOD racks and steppers for the X and Y, 3mm screw and DC motor for the Z.

Hope to get it moving soon, see how she goes, run her in for a bit. Problems with the pinch roller on the Y axis which stops the torch tilting, think it needs a fatter spring. Needs attention to the fixed rollers on the Z, something isn't quite parralel there :D

Haven't done the X axis guide rail yet, will post updates...

[Robin Hewitt]

Do I spy R&P? be sure to post where you got it from ;)

HPC Gears for the pinions, Huco for the racks.

Plasma cutters usually come in different sizes for the two standard sheets. This is the smaller one :D

Today I want to connect the pinions at either end of the gantry with a common axle so it runs square. Be interesting to see what kind of accelerations I can get.

[Lee Roberts]

Looking good Robin, how much will a Plasma Cutter like that set us back ? Also is there a reson why you have mounted the driver so close?

[Robin Hewitt]

No idea what it cost, probably best if I don't work it out :D

Chopper drivers don't particularly enjoy long leads, plus they could interfere with the signal lines next to them in the chain link trunking.

[Lee Roberts]

Amen to that !

[Robin Hewitt]

Bit of a delay designing the circuitry. Decided the best place for the CPU was at the cutting head. Close connects for the Y and Z axis controls and switches. Reasonably close connects for the X axis stepper controls and end stop.

Decided to use fibre optic links for the computer connection so I don't have to worrry about interference from the torch.

The Z axis is screw driven by a zippy 24 volt DC motor with brake and 4 bit control on the speed.

The motor has a chopper disc to show where it is.. Rather than waste cpu time oversampling to read the chopper I decided to put it on an interrupt. Here's my cicuit. If either chopper optic changes the the cpu interrupt goes low until I read the data on the input pins.

I'll let you know if it works

[Robin Hewitt]

Circuits done, pcb's made, thought I'd start with the fibre optic link because I've never done one of those before :D

Set up a full duplex terminal so anything I typed on the keyboard had to go out around 5 metres of cable as light before it showed on the screen. Worked a treat.

That's a letter 'i' on the 'scope, on it's way back from the optic at 9600 baud. Can't ask for cleaner than that.

Now I know I can upload programs for testin', next comes some steppin' :D

[Lee Roberts]

Whats happend Robin ?

[Robin Hewitt]

Whats happend Robin ?

I think you posted a pic of rack with a Vee shaped bottom which looked like a vast improvement on what I had so I paused. Then I changed units up on the industrial estate, the whole shebang came apart and I became busy doing other stuff. Haven't screwed it together again yet.

[Lee Roberts]

Ahh right ok mate, was just wondering as im following the build log.