Glass Engraving Frustration

[Don Young]

I just can't get the hang of the glass engraving. There does not seem to be any consistency to the speed and power necessary for any type of glass. I have tried (and wasted) many a pint glass, wine glass and pilsner glass trying to get a decent etch. Often times the bitmap is distorted vertically or horizontally and I can't afford to commit to a job without first mastering the process. The rotary tool doesn't appear to be slipping and the engraving looks great on wood. This forum has been a godsend for me so any help is greatly appreciated. I have been anywhere from 30%-50% power and 200-300mm speed. http://www.chineselasersupportforum.com/Smileys/default/embarrassed.gif

[Ross Moshinsky]

Honest opinion? Find a company to do silk screened or sand-carved glass. There are ways to get acceptable results from glass, BUT glass is ultra inconsistent and to get consistent acceptable results is usually a waste of time. Lasers engrave glass; they just don't do it that well.

[Dan Hintz]

Don,

Can't help with distortions as that's a user/equipment battle... you just need to figure out how to edit images quickly and prevent rotaries form slipping. But you settings shouldn't vary that wildly. I find my bare minimum power setting, add 10-15%, and call it a day. If you're seeing swings that wild, check the level of the glasses... the cheaper ones are rarely made to the same diameter, so you may have to refocus on each piece.

[Martin Boekers]

Not only the level, but I find wine glasses esp. that the stems aren't straight.
This causes the "goblet" portion to move about, bring in some distortion and
focus issues.

I have distortion issues too, most is not due to slippage but it seems to be a problem
with how the laser scans its passes. it almost seems that the the speed "per piece"
is inconsistant. What I mean by that is that the rotation sometimes appears to be
less than it should, thereby compressing the engraving. Usually it is through the full
piece and is consistant that's why I don't believe it is slipage. So far I haven't seen anyone
address this thoughly.

Rotary seems to be an issue that hasn't been resolved completely. Some are better than others
but I have yet to see someone (an actual user ;)) say just how great it is.

Marty

[Rodne Gold]

Distortion of the image is due to the fact that the diameter of the piece is either entered wrongly or that the software isnt passing it on correctly to the rotary, the rotary effectively becomes the Y axis and if its too "fast" , the image widens and if its too slow the image narrows. if the item was slipping ,you would get lines and overengraving areas or bands etc.

[Joshua Hopper]

Don,

I started out doing glassware for local bars and restaurants using the rotary attachment with my Epilog Legend 32, (Old Timer) and have not experienced any difficulties with the rotary attachment except for the random slipage issues due to high volume and not getting the rotary wheels cleaned thuroughly, but even then I have no problems running 15-30 16oz. Pint glasses before seeing slipage issues. it sounds to me like what you're exeriencing is either a software issue where the program used (Corel; AutoCAD; etc.) is not sending the right data to the machine, or that your machine may be slightly out of whack. I had to have my machine driven to me from Texas (I'm in Colorado) and when it got to me there were some adjustments I had to make to the belts due to the high vibration from the trip up. I found that one of my belts had slipped one tooth over and it was causing my images to come out severely distorted. After correcting it though it has been smooth sailing ever since. I attached a photo of a shotglass I just did yesterday. It would be great and very helpful in diagnosing the issue if you could upload an image of the problem(s).

Thanks,

Josh

188183
http://www.sawmillcreek.org/images/misc/pencil.png

[Joshua Hopper]

Also,

The quality of this photo is not so great due to the fact that I took it with my phone. I was out of the shop and didn't have my digital with me. I have many other photos if you'd like to see others.

[Don Young]

Thank you to all for your advice. I have taken a deep breath and am going to try again. This group always makes me feel like maybe I'm not the only one STILL figuring this laser thing out.
Thanks again

[David Fairfield]

Lots of stuff can go wrong doing glass. But for me, glass quality has never been an issue. I've always gotten a nice frosted appearance on any glass, from beer bottles to wine glasses.

Drawing the graphic is tricky, as you are compensating for curvature, basically you are trying to make a drawing that looks normal when its held up to a fun house mirror. There are algorithms for that I'm sure, but I do it by eye and feel. The envelope distort feature in Adobe is very handy for that, Corel must have similar.

You are ahead of the game if you have a cylindrical glass, or a glass with a simple taper. Rounded objects are harder. Also if you find a particular glass that works well, remember the catalog number, find a steady supply and stick with it. Some glasses do work better than others, as a general rule the straight sides, large size and heavy weight are better than curvy, stemmed, lightweight and highly tapered. Some manufacturers make warped inconsistent glasses, those are just awful to work with.

The Epilog rotary tool is like a surly employee. Some days it works OK, some days its just passive aggressive and screws up. You gotta keep the rubber wheels clean and dry. Every 10 or so glasses, wipe it down with a dry cloth. Every 30 or 40, take em off and wash em. Also it helps to wash the glasses so you get good traction.

People will argue this, but I always get better frosting when lasering through wet newspaper, and two sheets is better than one.

That's about all I know on the subject.
HTH
Dave

[Chris DeGerolamo]

Also,

The quality of this photo is not so great due to the fact that I took it with my phone. I was out of the shop and didn't have my digital with me. I have many other photos if you'd like to see others.

looks great to me!