Will lasering resist off of brass damage the len?


#1

I want to use my GF Pro to remove the resist off of some brass I plan to acid etch. I understand I want the wattage (pew-pews) to be as low a necessary, but my concern is that when the laser inevitably hits the brass, it could damage the lens.

Just to be clear, I am not intending to use the GF to etch the brass, just remove the resist. Will the laser contacting the brass damage the lens, or is that a no/low risk?


#2

If your brass is mirror polished you may have a reflection issue that may cause damage, but if it is not you should be fine, provided the resist does not do chemical damage to the lens/hardware when vaporized.


#3

I tend to agree with @ben1, but that’s instinct and not data.

There’s no shortage of laser cutters in the world, I would hope that someone has posted a definitive answer somewhere …


#4

Since this question is on materials that were purchased from another company, we can’t offer support for prints that don’t come out as expected or if it will damage your Glowforge.

While using non-Proofgrade materials does not void your warranty, if there is a problem with your materials that damages your Glowforge, the damage caused by your materials would not be covered under the warranty.

The full details of the warranty are available at https://glowforge.com/warranty

I’m going to move it to Beyond the Manual so other folks here can help. Should you have a question regarding a print on Proofgrade materials, please open a new ticket in Problems and Support and we’ll help you right away!


#5

I don’t have data to back the following statements up, only personal first hand experience.

I think the potential to damage a 35 or 40W laser lense is low when lasering highly reflective and possibly polished materials such as stainless, copper, and brass.

I have in the past my job was to operate a 4.4kw (4400W) CO2 laser and while we usually tried to stay away from lasering (cutting) brass and copper, the few times we tried it we would apply a fogged/misted top coat of a proprietary oil to the sheet before placing it in the cutting chamber.

As it was attempts to cut copper with a laser proved troublesome enough to have the job reprogrammed to be performed on a punch (due to both the reflectivity (material reflecting instead of absorbing the energy) and inconsistent cut quality.

That being said we never managed to damage our laser or lenses from these attempts, which used orders of magnitude more power than the GF does.

My gut is that as long as you’re only attempting to ablate/blast off the etch coating, and perhaps do so with multiple lower powered passes that you’ll mitigate the hazards to the lens from any potential reflection.

I also intend to do this form of etch-resist erasure for metals work. I’ll post more when I finally get around to doing it.


#6

Can’t see the laser lens being damaged easily. But wondering about the other two windows on the bottom of the laser head. There is a camera behind one and some electronics behind the other. A reflected beam damaging those windows or the sensors behind them seems more problematic.


#7

A valid point that you raise. I failed to remember the camera and height sensor down there. What IS possible is to use the GF to cut a mask out of transfer/masking paper/tape then to weed it and then use it as a stencil instead of attempting to directly laser the metal.

On the other hand people have successfully lasered SS and aluminum here on the forums. However it begs the question how many times it can be done before the statistics fall out of your favor and the additional under-lense/laser head optics become damaged.


#8

So I did eventually do it. 2 passes at 45%, 400 speed. I had taken steel wool to the brass surface in order to reduce the reflectivity, before I had spray painted it. The laser got ‘nearly’ all the resist off, but left a film enough to prevent the etchant from penetrating, but was still clear enough for me to think it was all gone. Some light wiping with acetone helped get it off (and some of the spraypaint as well). I may try it again at a higher strength, but it worked pretty well.