Center marking options.

So I am looking for options on marking the center point for drilling holes. My company cuts blade blanks for knife makers. Up till now I just use a drill operation on sheet cam and pulse the torch as quick as it can. I get a very very small mark which is perfect. But the issue I have is that the steel I cut is all high carbon or air hardening stainless steels. This means even a micro spot from the torch is now as hard as a rock that can be drilled through. To get around around this I have to center punch with carbide and the use a modified carbide still and drill the center out at 3000rpm. Then I can move on to using standard drill bits to drill the pin holes. With the quantity of blades we process this becomes time consuming and as well as problematic for accuracy. Some times when carbide spot drilling it will glance off the side of the hard zone.

What I’m wondering is if there is a way to incorporate a physical impact punch next to the plasma torch. My thought is use an air cylinder and either use it to shoot a carbide point down into the steel or lower a spring loaded center punch. You guys have any ideas?

Thanks - JT

Plasmac supports an air engraver put perhaps for you a pneumatic drill will be better.

Can you test this:
Load a gcode that you usually use for centre spotting, but with the edited M3 to point to scribe or pen.
If that works, that would be it, use the scribe or pen output to control a pneumatic ram or whatever you may find useful.
Check the halshow while testing this if it is switching the scribe or pen pin on and off.

tommylight wrote: Can you test this:
Load a gcode that you usually use for centre spotting, but with the edited M3 to point to scribe or pen.
If that works, that would be it, use the scribe or pen output to control a pneumatic ram or whatever you may find useful.
Check the halshow while testing this if it is switching the scribe or pen pin on and off.

You forgot that Linuxcnc is multi- spindle so loading a tool containing the XY offsets in the normal way (from the tool file )then issuing a M3 $1 is all that is required. More details in the PLasmac user guide.

I’m kinda thinking of using a 12v long stroke solenoid. I would mod the end to have a carbide point. I already have an extra wire ran to the z axis I can run 12v to. This way I do a tool change and ohmic touch off and fire the solenoid.

It might also be worth trying the Plasmac center spot tool because you can control how long the pulse is in milliseconds..

rodw wrote:

tommylight wrote: Can you test this:
Load a gcode that you usually use for centre spotting, but with the edited M3 to point to scribe or pen.
If that works, that would be it, use the scribe or pen output to control a pneumatic ram or whatever you may find useful.
Check the halshow while testing this if it is switching the scribe or pen pin on and off.

You forgot that Linuxcnc is multi- spindle so loading a tool containing the XY offsets in the normal way (from the tool file )then issuing a M3 $1 is all that is required. More details in the PLasmac user guide.

I did not forget, that is exactly what i meant, but my wording is just plain bad ! :blush:

The other more expensive option is to upgrade your machine to a 45xp that can mark using the torch and argon gas, www.hypertherm.com/learn/applications/marking/metal-marking/

Not the cheapest option but do able.

Just a quick thought...I know a guy here in my state that uses the drilling operation and then will use a annular cutter to "drill" the hole. The center pin lines up perfectly on the divot, and the annular cutter is outside of the hardened area immediately around the divot. May not be feasible if the holes are too small.

dvn4life1972 wrote: Just a quick thought...I know a guy here in my state that uses the drilling operation and then will use a annular cutter to "drill" the hole. The center pin lines up perfectly on the divot, and the annular cutter is outside of the hardened area immediately around the divot. May not be feasible if the holes are too small.

That is a pretty good idea, and I have used it successfully on larger holes but even some small 10mm holes. I think thats the smallest annular drill I have.