This feels like a rather foolish question but this is pretty much the only place I can ask.
Is it possible my air assist is damaging the engraving on the mirrors/ glass I am working on?
I have noticed lately that the mirrors especially tend to get these spots of slightly different colored …texture, I suppose, on it, as if a drop of some liquid fell on it…or as if a brittle piece of the engraved glass has blown off.
Is there any sort of …guide for how much air pressure should be in the air assist?
Are you able to send a photo of what you’re seeing? I would tend to think that you’d need minimal air assist with glass but I suppose this depends on what exactly you’re doing.
I should be able to in about an hour. dont have a good way of uploading from my crappy phone right now.
The current and most common stuff I do is engraving out the back layer of a mirror, for a “sandblasted” effect.
Based on that I’m wondering if you’re possibly liquefying the backing material with the burn and what you see is the residue of that process. Or it’s just the remains of the vaporization of the backing.
The air assist could be contributing to the issue by forcefully blowing back the vapors onto the glass substrate rather than allowing it to dissipate. In that case dial back the air assist and improve lateral air flow across the work surface.
Are we looking at the front of the mirror in this picture? I assume the left side is the side that’s been engraved. And the darker diagonal streaks are the artifacts you’re talking about? Or are you talking about the darker spots on the engraved side?
How do you have your air assist setup? Is it aimed straight down through the lens or at an angle to the work surface?
that is the back of the mirror in this case. because of other work being done on it right now I cant flip it. th two black sides are the backing material and the big stripe is the “engraved” area. the darker spots in the engraved area are what I am talking about yes.
The air assist is straight down through the lens.
I had my air assist set to about …60-is Psi.
I will try lowering the psi for the next piece, but I am in some genuine confusion over if there is a “right” amount of pressure for this.
Let’s see what people who work with mirrors will have to say but 60 PSI seems excessive. I would have assumed that just enough pressure to keep debris off the lens would have been sufficient, let’s say 5 PSI.
I would have to agree with you 100% on this. Just a waft of air from the nozzle to stop debris getting to the lens given this is only engraving.
Even cutting my experience is that 60psi is far too much. It does of course depend on the material being cut but even in demanding cases I would think 20 - 25psi is more than adequate.
I do this with a 2" lens and mid pressure (10 to 12 lbs). If I don’t do that, I have a buildup on the nozzle. I have tried this with the compound lens and mid pressure. The lens is too close/too low pressure as it coats the lens inside the nozzle. That’s why I use the 2" it being almost 19mm away and the compound about 11.
Keep in mind that you are ‘shattering’ glass. I believe the speed/power combination(s) will give you different textures.
After getting back to it and running a couple of tests with different psi I seem to be getting better results. initially tried a low 5 psi as mdorety44 suggested but I was getting far far to much debris from the mirror backing building up preventing a good engrave, however hitting it at about 25 as dvdlock suggested seems to be bringing a much, much smoother result with minimal damage to the texture.
