Another plasma component...

I've not used one but Air scribes are often offered on low end tables. You need two air circuits. One low pressure one with its own regulator to control the downward pressure applied via an air ram and another high pressure one where the air passes through an oiler to operate the scribe itself. A good one is worth aout $500 and the Chicago Pneumatic one is considered the gold standard. www.cp.com/en-au/tools/products/percussi...ngraving-pens/cp9361

So on an M3, an air ram shoots the pen down and turns on the engraver airflow and allows marking and engraving operations and enough noise to wake the dead!

Here is what I had in mind if I ever build it.

rodw wrote:

I've not used one but Air scribes are often offered on low end tables. You need two air circuits. One low pressure one with its own regulator to control the downward pressure applied via an air ram and another high pressure one where the air passes through an oiler to operate the scribe itself. A good one is worth aout $500 and the Chicago Pneumatic one is considered the gold standard. www.cp.com/en-au/tools/products/percussi...ngraving-pens/cp9361

Ive got a Chicargo Pneumatic scribe on mine. I have not used it yet since I built the table. Ill post some pics later when the machine is finished cutting.

I plan on using it for marking lines for Jigs and fixtures I am making for our workshop. I am going to built a adjustable angle jig and I will mark the angles on the adjustable plate with the scribe.

I am hoping it works out as well in real life as it does in my head.

rodw wrote:

Here is what I had in mind if I ever build it.

Hopefully you get the bug and finish it after seeing mine working! Just got it get it working first!

thefabricator03 wrote:

Hopefully you get the bug and finish it after seeing mine working! Just got it get it working first!

Well I have got everything here including the scribe. (and have had for a few years)

This is the scribe I bought

It had reasonable reviews and spare parts are available. It will work nice I think. My mate has used one to engrave plastic tags etc on his mill minus the air ram to control the pressure and he got good results.

Looks like a good quality engraver,

Funnily I am the same with my projects at home, I have lots of parts I have brought years ago but still have not gotten around to putting together. I just had a son born a couple of months ago and the way I am going he will be old enough to finish my projects before I get around to them!

Well from the docs, I think plasma would become M3 $0 and air scribe would be M3 $1.
The pin spindle.1.on would fire some air solenoids
Andy is the one who wrote it.

linuxcnc.org/docs/devel/html/gcode/m-code.html#mcode:m3-m4-m5

And you would have to define a plasma tool and an engraver tool in the tool table with the offsets.
In plasmac style, you might have to build a dwell into it to allow the air ram to travel down before setting spindle.1.at speed. I have not played with it, but I thought there might need to be an adjustable stop to limit the height above the material to reduce this dwell.

Just explaining my CAD file for a moment as it might be hard to see. The air ram I have has a threaded end on the cylinder so it screws into a bracket affixed to the backing plate. The HGR15 carriage is also attached to the same backing plate. The pen is held in a bracket attached to the end of the HGR15 which also accepts the air ram so when it fires, the ram shoots down instantaneously. The air ram air pressure determines how much down force is applied. The engraver probably runs at a more normal 90pis and just vibrates like crazy. So there is still no Z axis movement required.

This is the air ram that moved the scribe up and down, Just a Pneumatic z axis,



The Chicago Pneumatic scribe mounted to a aluminum mounting plate.



All of the hardware to make it work, Oiler first then pressure regulators and solenoids.

Phill,

A bit of a issue I have come across,

When I am cutting out holes with the THC turned off, At the end of the hole when the torch is cutting into the overcut position, The Z axis will raise up signficantly at the end of cut,

This is causing some of my centers of the holes to not be cut through as the torch lifts before it cuts the left over material away.

I have only noticed it on thicker sheets 20mm thicker and up.

Any idea why the torch is moving upwards?