Reflective Mirrors which way?

[Amos De Pasquale]

Ok another question, with reflective mirrors, there is a gold side and a silver side, which way do they go in? Amos, Simple things that impede my progress!!!! PS both sides look good enough to be the mirror!!!

[walter hofmann]

hi there
always the gold side tooutside
greetings
wltfl

[Amos De Pasquale]

AHHHHHHH!!!!!, that is way I originally put it in, but then decided I was WRONG!!!! that means the darker silver/grey colour faces the beam and the gold is the reflective coating facing the lock nut??!! just double checking before I undo it!!?? Amos

[Scott Shepherd]

The beam should hit the gold side.

[Dave Sheldrake]

What make is your Laser Amos? Gold Si mirrors are unusual on 80 watt machines upwards so I wondered what supplier you purchased from.

cheers

Dave

[Bill Huber]

I really don't know about engravers but in general most mirrors that are used with laser are first surface mirrors and the first surface is what the laser should hit.

To check which is first surface is with a pencil, touch the pencil to the surface, if the tips touch that is the first surface, if they do not then flip it over.

With a mirror you can get a double reflection, one off the glass and one of the mirror coating, that is why first surface mirrors are used.

[Dan Hintz]

To check which is first surface is with a pencil, touch the pencil to the surface, if the tips touch that is the first surface, if they do not then flip it over.

There is too great a chance at scratching the surface, so I suggest against a pencil. I'd use lens paper if you can't tell by looking at it.

[Amos De Pasquale]

I should have posted the pictures first up, this is a photo of a mirror I purchased about one year ago, I have never had to replace a mirror before.
Please advise me with your thoughts, all input is valued, AmosMirror silver side (Large).jpgmirror gold side (Large).jpg

[Dave Sheldrake]

Those look like K2 mirrors Amos, the picture on the right shows the gold face that should face the beam. That said K2 mirrors won't survive 80 watts for very long

Chinese machines of 80 watts and over tend to use Moly mirrors due to the heat / cool / heat sequence they have to tolerate.

cheers

Dave

[Bill Huber]

There is too great a chance at scratching the surface, so I suggest against a pencil. I'd use lens paper if you can't tell by looking at it.

Dan, I worked with first surface mirrors for 18 year and use a soft lead pencil to check them and have never scratched one. I guess if you tried to write on it you could but touching it does nothing.

[Amos De Pasquale]

The label said K9, would that be correct???Amos

[Gary Hair]

There is too great a chance at scratching the surface, so I suggest against a pencil. I'd use lens paper if you can't tell by looking at it.

The area that the beam hits the lens is so small, and should be centered, that you could easily touch (and safely scratch) the outer edge of the mirror with no possible impact on the usability of the mirror.

[Amos De Pasquale]

Bill tried your method on the outer edge and the gold surface is the first touch, the silver portion has a double image if you look at it side on.
Meanwhile it was another thing I learnt from Dave, Moly Mirrors,?! I will look them up, there are quite a few mirrors for sale on the net, I wonder if they should state "not suitable for Lasers 80watts and up" ! Amos

[Dave Sheldrake]

K9's will shatter very quickly if you use them on an 80 watt Amos, they are only rated to 40 watts max

Molybdenum Mirrors are pretty much un-breakable and are rated (Chinese versions) to 400 watts+

that you could easily touch (and safely scratch) the outer edge of the mirror with no possible impact on the usability of the mirror.

Once the surface plane of the coating is scored or breeched Gary they can lose their coating quickly due to uneven expansion / stress over the surface. Especially K9/K2 mirrors as they are stressed even when in normal use. I've seen K series mirrors burn through when they are dirty let alone damaged

From Win-Win Mecha

This Focus Lens And Reflect Mirror Can Be Used As A Replacement Lens For 40W CO2 Laser Engravers From China.

FEATURE:

cheers

Dave

[Amos De Pasquale]

Thank God I posted the embarassing question, I thought to myself, these guys will think I'm really stupid!!! I have not used those mirrors yet, I was about to do so, but that will wait for another day. Thanks for the education, Amos