Engraving glasses revisited (long)

[Bob Cole]

Please do as I am thinking, not as I'm typing. Or better yet, maybe ignore my posts.

I've corrected my post to reflect the accurate statement by Dan.

[Mike Null]

Dan

That's not foolproof either as raster speed varies widely by mfr and model.

[Dan Hintz]

Mik,

Understood, but it's a much better rule of thumb than what Bob was originally suggesting, don't you think? ;-)

[Dave Johnson29]

I would love to know how you can get 1000 dpi from your laser.

Hi Richard,

The DPI is not related to dot size directly. It is how much the beam is stepped over each step.

With your 0.006" diameter (as are most 2" lenses) focused beam, with the dots touching you would get 167dpi on both X and Y for step over of 0.006". By increasing the dpi you get dot overlap so at 1000dpi each step over is only 0.001" and it takes 6 such steps to equal the raw 167dpi.

The dpi applies to both the X and the Y axis step-over. That's why Don said it takes longer to do 1000dpi than it does 600dpi.

[Martin Boekers]

I find that 1200 dpi is more consistant for myself overall.

I do quite a bit of "front surface" engraving on black mirror from JDS always use soap the difference is amazing!

The on problem I have occasionally is that the glass will look engraved , but the "frosted effect" will vary depending upon the angle it's held. Sometimes when you look at it head on it will have slight "drop outs" (fully engraved but reflecting a bit different)

I've tried this with different dpi settings but still every so often it happens.

A second pass usually helps.

I can't do that with the rotary, as even if I leave the glass in place the second pass won't be registered.

Marty

[Bill Cunningham]

Bob, I am with you on the colorfill of glass. I have tried dyes, inks, paint, rub n buff, etc. and just have not had any luck producing something that not only looks really nice, but also lasts. I do remember about a month ago somone posting about using craft paints from Michael's. Americana brand? Not sure if that is right or not. not sure exactly what the thread was about, but I am most certain it was within the last month.

BTW Bob, we are our most critical critic.

On plain text, and line art logos rubbing a little bit of white acrylic craft paint into the etch with your finger, and rubbing it off with a cloth within about 15 - 30 seconds, will whiten up the etch quite a bit.. I wouldn't use this on glassware that has to survive a dishwasher though, and may make a glass award look cheap! I run most text and art (not photos) using 100% power, 20% speed @ 400 dpi If it's just text, I run at 600 dpi
If it looks fine to me, I doubt if my customers will see a problem.. Sometimes we get Waaaaay over critical of our work. In years past, I've done rush jobs I've felt truly embarrassed about, and sheepishly handing over to the customer.. Then, the customer says something like WoW thats great!! Just what I wanted...

go figger..

[Mike Null]

Dan

I think that it would work as an inches per second setting but as a percentage, no.

Machines vary so much, some are as low as 40 ips some are at 140 ips raster speed.

[Dan Hintz]

Again, it's meant as a basic rule of thumb, a starting point, not a set value... just pointing out the backwards settings Bob originally mentioned.

[Nick Napier]

Frank, You mentioned using thin paper and a little soap. What kind of paper are you talking about and what's it's purpose. I'm trying to laser some maple syrup bottles and looking to get the clearest lettering I can get. Any more suggestions?

Nick Napier woodworknick@yahoo.com

[Bob Cole]

The type of glass really makes a difference also. The test piece I was using was a glass bottle for martini mixer (I happened to finish it off before I started this When I got as good as I could get it on that one, I went to the award and the award came out better.

The starting settings I put above seem to work fairly well and may translate pretty well to other laser wattages/systems. I went back and did some more testing and for my 60watt, using 100%black, my settings are 100pwr, 30spd,500ppi (500dpi). This looks very close to using the settings above without changing the black to 60-70%.

I also tested with a 1.5 lens and really didn't notice any improvement over the 2.0 lens that I use for most everything else. I had to clean the 1.5 lens more frequently due to the residue from lasering the mask.

I am using a red mask (not really sure the proper name) that is very sticky. I tried the mask with and without soap with no notice of benefit with soap. I also tried the paper with and without water. Once I added water to the paper, the paper started to bubble a little (not stick to the surface) and in those areas, there was a difference. I need to do some more comparisons between using the red plastic laserable mask and the paper mask to see if there is a difference. It would be easier for me if I can just use the paper as it is easier to work with. The red stuff is very sticky and I have to apply it like vinyl.

I am still having difficulty with color fill with using anything other than the gold leaf rubnbuff. I tried several different styles from the craft stores (Americana) but having difficulty with filling, then weeding without damaging the other colorfill or waiting for it to dry then cleaning up without having the fill get wiped off. I'm sure it is a technique thing that I am not getting but so far scoring zero. I have 20 crystal awards to do in the next couple of weeks and need to use a darker blue to fill it. Can't use the gold leaf.

[Devon Jones]

i had a question how much soap do you put on the glass? i find that too little does nothing and when i put more then that on it turns white and messes it all up? i also wanted to know is it something in the soap that makes it look better in the engraving or just that it is a film over the glass that helps? if so is it at all possible to just use a stick of deodorant not the powder but the gell kind and just evenly wipe it over the part that you are trying to engrave? so it is a little more even and not as messy? thanks

[Tim Bateson]

What type of soap are you using Devan? Using a thin layer of liquid dish soap keeps the glass cool to control the chipping/fracturing. That’s what the laser is doing to the glass & keeping it cooler minimizes over chipping or fracturing the glass – better detail.

[Tom Bull]

The only thing that has worked well for me was wet (soaked) paper and engrave through it.

[Brian Robison]

I use both, cheap dishwashing soap and a blue paper "shop towel" brand of paper towel soaked with water and squeezed out. I also use 600 dpi. I'm very happy with my results.

[Bill Cunningham]

I keep a shot glass of dish soap next to the laser when doing glass, and just wipe it over the area with a finger. I find that it does not even make a difference if it drys out.. I think the soap, when it gets hit with the beam vapourizes, dampens down the chipping factor, and allows a much finer etch.. Particularly on small print.