View Full Version : BUILD LOG: Plasma 3m x 1.5m

20-10-2019, 05:47 PM
I have been asked to help build a plasma CNC capable of cutting 3 x 1.5m x 25mm thickness steel.

The sketch is based on my previous CNC Router but with the differences that the Y and X axis will be rack and pinion.

I have budgeted 6K to 7K for this build, am I in the right ball park?

I intend to use for the Y axis 2 x Nema34, 8.7Nm one as slave. With a spring loaded pinion gear box with tooth belt and pulley reduction. To achieve a speed of 12,000mm/min.
Is this the right way to go if so Rack: Mod 1, Pinion Size? Reduction Ratio 2:1 ?
(or show me a link for calculating)

X axis 1 x Nema23, 4Nm as above.

The drivers will be Leadshine AM882, 68V Toroidal PSU and CSMIO/IP-M4-axis Ethernet Motion Controller. Basically all copied from my existing set up.

I have used the same aluminium section for the X axis Profile (45 x 90S B-type slot 10) two full lengths (1980mm). I believe this will be strong enough as there are not the same forces on a plasma that there are on a router.

The base of the Z axis clears the table by 40mm is this too tight? Should I lower the water bath/bed

The Z axis is again a copy with a 350mm RM1605 ball screw is this to big? Too much travel?
(Nema23, 4Nm)

I will come back with questions on THC and the actual plasma torch when I find out some more details of what is going to be used.

Probably want to add some more steel to the frame somewhere?

Thanks for any suggestions.



20-10-2019, 06:44 PM
As a plasma table is something I keep thinking about (if I do build one, it will have to be designed to live outside!), here's some of my thoughts.

For ease of access/manoeuvring sheets, consider swapping the gantry 90deg to the long axis. Depending on use/position, it means it'll be less likely to be in your way when loading/unloading the table.
Allow for adding a water table.
You'll want more legs, with some good triangulation for additional support.
I'd personally favour using servos, especially at that size.
I'd design the linear rails so they're more protected from the plasma dust settling on them. My idea would be to have the rails sit within their own open sided channel, which only has a slot for the gantry. The slot can then be further sealed using some brush strip, so any dust can't directly fall on the rails.

Boyan Silyavski
22-10-2019, 08:50 AM
If i was to design and build plasma with what i know today:
-use only servo motors
-make a structure separate from table
-design structure to be modular. one day i may want the length to be 5 meters
-on gantry linear movement and rails at the back and only the torch at the front
-make it low
-able to side load