Building a chain driven Plasma table.

I have been thinking of adding a laser cross to the machine.
Did a search on this forum. But did not find anything. If I missed it please point me tho the right thread.

My question is how many watts that you can see it nicely. Are there any safety issues for eyes?
Are those cheap ones you get on aliexpress ok? 

No eBay APP ID and/or Cert ID defined in Kunena configurationI use one similar to this:



 

How do you power it do you have a separate power supply?
Does it need a resistor ion series?

I use a cheap adjustable "buck converter" which is supplied from the 24V supply.
 

Something like this?

www.aliexpress.com/item/1005007245832712...2c-a4a2-79fd969bd58f

or rather one that only uses ceramic capacitors?



 

So it turned out the ohmic sensing was not so reliable. 
while at 25 mm above it started to cut. (False ohmic on when torch is wet) 
My machine is especially sensitive to that. 
I use a hand torch on a steel mounting. 
Distance from mounting to shield is about 3mm. 

so I came up with this experiment. 

I made a break out board. 
with a voltage divider. 

6 30k resistors in parallel so that is 5k ohm.
on the other side 5 5k Ohm resistors in parallel so that is 1k ohm

So I tested with a multimeter when torch is in contact with the negative of the power supply I get 5volt. 
when I put a wet paper in between I get 4.2 volt.  Looks like this helps to get a solid difference between wet contact and real metal to metal contact.

With so many resistors in parallel. I don’t think torch voltage will overload then. 

is it safe to use this kind of  voltage divider. On my Thad.  I was wondering if it would be wise to   add some diodes for safety. Since torch voltage is opposite polarity?