Air Scribe with PlasmaC

Hi Guys,

So I am starting to look at how to set up my air scriber for use with PlasmaC.

I am really flying blind here as I dont know much about Sheetcam post processors or how PlasmaC will handle processes that are not plasma torch related.

Couple of questions,

I have looked all over the internet in regards to post processes for Air Scribes, I will post one example in the next post. Can someone guide me how to inset said air scribe code into my current (Rods) post processor.

Also if Phill could chime in with his thoughts on how PlasmaC can handle the turning of the air scribe on and off, The up and down motion, and the x and y motion of the gantry without a plasma torch z axis.

Baseline Sheetcam Post for MP1000 - THC- Scriber post
--************************************************
--*** Set these values up to suit your machine ***
--************************************************

--this is the distance between each torch reference in MILLIMETRES
refDistance = 250

--this is the reference feed rate in mm/min
refFeed = 500

--Put your switch offset value here in MILLIMETRES
switchOffset = 1.5

--Scriber X,Y,Z offsets in MILLIMETRES. Do not use inches here even if you want inch code
--Use the special code 'nil' on the Z axis to disable it.
--In that case no Z values will be output at all while scribing.
--e.g scriberZ = nil
scriberX = 0 Value you will change later on
scriberY = 0 Value you will change later on
scriberZ = nil This is how it should appear.

--scriber axis. Leave this as nil if the scriber is fixed to the same axis as the torch
--scriberAxis = "A"
scriberAxis = nil

--If this value is set to true then use G28 (home) for the Z reference
--Set it to false for G31 probe
refHome = true

--The cutter will slow down for corners and turn off THC below this radius
slowRadius = 10

--Minimum slow down speed.
--This is a scale factor. For instance 0.5 = 50% of the current feed rate
slowPercent = 0.4

--THC on and off codes. Use nil if you don't want THC control e.g:
-- thcOnCode = nil
-- thcOffCode = nil

--here is another example that use M667 and M666
--thcOnCode = " M667"
--thcOffCode = " M666"

thcOnCode = nil
thcOffCode = nil

--************************************************
--*** End of settings ***
--************************************************

phillc54 wrote:

Is an air scribe permanently mounted in a specific X/Y position and then activated into the correct Z position. Does the Z position need to be probed or is air pressure enough to keep the probe on the surface of the material.
Are there any "standard" codes used for air scribes.

Yes, the scribe would be permanently mounted with a fixed X,Y offset. Usually you would use two air circuits. One with 90-100 psi to drive the engraver and another at lower pressure to drive the scribe down to the surface and control the pressure applied while engraving. Stefan and I have been discussing this on the Plasmac thread.

I don't think there is any specific standards to drive a scribe but I think the multispindle features of Linuxcnc combined with a tool offset or tool changer is a really clean way to support this. I'm not sure if there is anything that plasmac needs to do if we can get the tool table set up.

phillc54 wrote:

Do both air circuits operate from the one signal or is a separate signal required for each air circuit.

I'll leave that one for Stefan.At least he's used one! I just bought the parts!
I think I'd use 2 outputs. There might need to be a delay before spindle at speed is asserted to allow the scribe to reach the surface.

phillc54 wrote:

Ok I'll wait for a response from him.

I downloaded SheetCam today and had a bit of play. I think I'll try to find some tutorials as I don't find it very intuitive although I did manage to get a reasonable postprocessor kinda working.

It kinda grows on you. Arclight Dynamics has some good tutorials
www.youtube.com/channel/UCsC9t3WHh6mkLYld2w-gYJg
For your small table, you may even find the line limitation in the free version is not a factor.

tend to use two air valves, one for down and the other for up.

some air scribes only use one air valve as they have a spring which provides the retract.

you can also use a 5port-2 way spring return pneumatic pilot valve which just needs one input as retract will be done by the pressure

yes you normally have a small wait at the start to allow the scribe to pressurise and get to the surface

I use sheetcam which just offsets the axis and then resets it at the end.

procutcnc.com/wp-content/uploads/2017/09/DS-Engraver-Layout.jpg

personally.... I'd leave sheetcam and the post processor to do it with a simple offset... I use m7/m8/m9 to control mine and it works just fine..... m64/m65 would work fine too

Nice diagram robert. Thanks. I made it display.

robertspark wrote:

tend to use two air valves, one for down and the other for up.

some air scribes only use one air valve as they have a spring which provides the retract.

you can also use a 5port-2 way spring return pneumatic pilot valve which just needs one input as retract will be done by the pressure

yes you normally have a small wait at the start to allow the scribe to pressurise and get to the surface

I use sheetcam which just offsets the axis and then resets it at the end.

personally.... I'd leave sheetcam and the post processor to do it with a simple offset... I use m7/m8/m9 to control mine and it works just fine..... m64/m65 would work fine too

It looks like this only uses one output. The only thing I can see is that there should be an oiler inline with the scribe. As far as I know the air ram itself does not need oiling.