New user of Sawmill and Laser engraving. NEED HELP

[Kevin Berkshire]

I purchased a used Accuris Powersharp 46 it is a 60 watt laser and I am having all kind of problems engraving a 6 oz flute glass. After moving it I have aligned the home position, adjusted the aiming of the laser and cleaned the mirrors. It engraves, but instead of getting a even look the first 2 or 3 letters look nice and frostly the remaining are cut to deep. Could this because by the heat ?
I have read to use soap on the glass and this is the way I have been engraving. My settng are from 200, 333 and 500 DPI and power I have tryed from 40 to 100%. The best so far is 333DPI,60 power and 40 speed engraving twice.
If you have suggestions, please let me know. I would really like to e-mail anyone that owns a Accruis 46 on questions about the laser operation.
Thanks for your help.
Kevin

[Dan Hintz]

500 dpi is too dense for glass. Also, reduce the black level of your text to about 70% grayscale... this will dither the etched pattern and cut down on the number of laser pulses in a specific area. Your description is rough (a pic would help imensely here), but it sounds as if some letters are chipping too deep from too heavy of power application... the grayscale will help alleviate that.

[Mike Null]

If you don't have a rotary device then your problem, in addition to settings, is focus. You must maintain the precise focus throughout the engraving operation.

Welcome to SMC.

[Kevin Berkshire]

Dan,
Thanks for the information, I'll try that, but why not turn the power setting down or the speed up?
The manual for the Accuris is the most confussing thing you ever wanted to read. They have a DPI setting for 200,250,333,500 and 1000, they say to leave it on 1000. Everyone else is saying 200 to 250. Do you use soap or wet paper to engrave glass?
I know that I will master it in time, but the glass factory is going to get rich from me...
Thanks for your help.
I'll get a picture to you on Wed. 3-9-11
Thanks Again
Kevin

[Dan Hintz]

why not turn the power setting down or the speed up?

they say to leave it on 1000. Everyone else is saying 200 to 250.
In a nutshell, when you "engrave" glass, you are creating microfractures near the surface. If you place these fractures too close together, such as what happens when you engrave at 1,000 dpi, you can lose entire areas like a layer of skin. By cutting down on the dpi, you spread those fractures out.


Do you use soap or wet paper to engrave glass?
While some claim to get better engraving using such methods, time and time again I have made extremely high-quality engravings without any of those tricks (and I tried them all when I first started). Plenty of others here have come to the same conclusion. Search on my name and glass engraving on the Creek for earlier posts where I go into more detail as to what's actually happening.

[Mike Null]

Dan

Let's see some of your pictures.

[Dan Hintz]

Oh sure, Mike, ask after everything has long since gone out of the door :-/ ;)

I have a bit of cleanup work to do in the shop this weekend, I'll see if I can find the time to etch an example...

[Mike Null]

No Dan, you're supposed to take pictures first.;)

[Kevin Berkshire]

Dan, I tried to take pictures of the glasses but not really having luck get a picture that shows the problem. I am starting to wonder about the actual power form the laser? When I start to engrave it starts out with a slight image and then I notice at times, like you were saying I see flakes coming off after it has engraved a letter and is still engraving the word.
I am using a 2 1/2 distance lens, but focusing with the tool, so I know it is setup correctly. I spoke to the people I purchased it from and they said they engraved the same glass I am trying to usnig 85, 85. When I try these setting it, may make a few marks on the glass but not many.
I ahve engraved a piece of granite and it looks pretty darn good. Glass is starting to be a pain in the glass. - the gl.
I am not really sure how to look up your past threads but I try to figure it out.
Thanks for your help so far..
Kevin

[Dan Hintz]

When I start to engrave it starts out with a slight image and then I notice at times, like you were saying I see flakes coming off after it has engraved a letter and is still engraving the word.

I am using a 2 1/2 distance lens, but focusing with the tool, so I know it is setup correctly.
The focusing tool has been incorrect on multiple machines... you will want to verify it at some point.

That said, poor focus won't really cause the flaking issue you mentioned. It still sounds like the pulses are too close together... are you using a grayscale instead of pure black in areas larger than just a single line?

[Bill Cunningham]

It takes very little power to etch glass. Flaking can be caused as Dan says, by too short of a pulse. But it can also be caused by too much power overall. If you are already using a gray scale and you still get flaking, drop your power, or increase your speed. Pick a 'sacrificial' glass, and put some large text on it. Vary your speed (increase), or your power (decrease), until the flaking ceases. You will eventually find a happy medium for etching cast and machine molded glass on your laser.. Higher quality blown and hand cast glass never seems to have this problem, at least not in my experience.